From c005e5d6e2a7fac44be9eccfc549aad1bf6ebd50 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 1 Nov 2022 10:12:53 +0000
Subject: [PATCH 01/27] feat: implement FileHistory for hg

---
 lua/diffview/config.lua                       |   6 +-
 .../scene/views/file_history/listeners.lua    |   2 +-
 lua/diffview/vcs/adapters/hg/commit.lua       |  41 +
 lua/diffview/vcs/adapters/hg/init.lua         | 714 +++++++++++++++++-
 lua/diffview/vcs/adapters/hg/rev.lua          |  37 +
 5 files changed, 793 insertions(+), 7 deletions(-)
 create mode 100644 lua/diffview/vcs/adapters/hg/commit.lua
 create mode 100644 lua/diffview/vcs/adapters/hg/rev.lua

diff --git a/lua/diffview/config.lua b/lua/diffview/config.lua
index 844351bb..77528acf 100644
--- a/lua/diffview/config.lua
+++ b/lua/diffview/config.lua
@@ -38,6 +38,7 @@ M.defaults = {
   diff_binaries = false,
   enhanced_diff_hl = false,
   git_cmd = { "git" },
+  hg_cmd = { "hg" },
   use_icons = true,
   show_help_hints = true,
   watch_index = true,
@@ -273,7 +274,10 @@ M.log_option_defaults = {
     path_args = {},
   },
   ---@type HgLogOptions
-  hg = {},
+  hg = {
+    limit = 256,
+    user = nil,
+  },
 }
 
 ---@return DiffviewConfig
diff --git a/lua/diffview/scene/views/file_history/listeners.lua b/lua/diffview/scene/views/file_history/listeners.lua
index 32f90c01..6bb38394 100644
--- a/lua/diffview/scene/views/file_history/listeners.lua
+++ b/lua/diffview/scene/views/file_history/listeners.lua
@@ -33,7 +33,7 @@ return function(view)
       local log_options = view.panel:get_log_options()
       local cur = view.panel:cur_file()
 
-      if log_options.L[1] and bufnr == cur.layout:get_main_win().file.bufnr then
+      if log_options.L and log_options.L[1] and bufnr == cur.layout:get_main_win().file.bufnr then
         for _, value in ipairs(log_options.L) do
           local l1, lpath = value:match("^(%d+),.*:(.*)")
 
diff --git a/lua/diffview/vcs/adapters/hg/commit.lua b/lua/diffview/vcs/adapters/hg/commit.lua
new file mode 100644
index 00000000..bf2235b3
--- /dev/null
+++ b/lua/diffview/vcs/adapters/hg/commit.lua
@@ -0,0 +1,41 @@
+local lazy = require("diffview.lazy")
+local oop = require('diffview.oop')
+local utils = require("diffview.utils")
+local Commit = require('diffview.vcs.commit').Commit
+
+local M = {}
+
+local HgCommit = oop.create_class('HgCommit', Commit)
+
+function HgCommit:init(opt)
+  HgCommit:super().init(self, opt)
+
+  if opt.time_offset then
+    self.time_offset = HgCommit.parse_time_offset(opt.time_offset)
+    self.time = self.time - self.time_offset
+  else
+    self.time_offset = 0
+  end
+
+  self.iso_date = Commit.time_to_iso(self.time, self.time_offset)
+end
+
+---@param iso_date string?
+function HgCommit.parse_time_offset(iso_date)
+  if not iso_date or iso_date == "" then
+    return 0
+  end
+
+  local sign, offset = vim.trim(iso_date):match("([+-])(%d+)")
+
+  offset = tonumber(offset)
+
+  if sign == "-" then
+    offset = -offset
+  end
+
+  return offset
+end
+
+M.HgCommit = HgCommit
+return M
diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 8866427e..42dbe411 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -1,18 +1,722 @@
 local oop = require('diffview.oop')
 local VCSAdapter = require('diffview.vcs.adapter').VCSAdapter
+local arg_parser = require('diffview.arg_parser')
+local utils = require('diffview.utils')
+local lazy = require('diffview.lazy')
+local config = require('diffview.config')
+local async = require("plenary.async")
+local logger = require('diffview.logger')
+local JobStatus = require('diffview.vcs.utils').JobStatus
+local Commit = require("diffview.vcs.adapters.hg.commit").HgCommit
+local RevType = require("diffview.vcs.rev").RevType
+local HgRev = require('diffview.vcs.adapters.hg.rev').HgRev
+local Job = require("plenary.job")
+local CountDownLatch = require("diffview.control").CountDownLatch
+local FileEntry = require("diffview.scene.file_entry").FileEntry
+local Diff2Hor = require("diffview.scene.layouts.diff_2_hor").Diff2Hor
+local LogEntry = require("diffview.vcs.log_entry").LogEntry
+
+---@type PathLib
+local pl = lazy.access(utils, "path")
 
 local M = {}
 
+---@class HgAdapter : VCSAdapter
 local HgAdapter = oop.create_class('HgAdapter', VCSAdapter)
 
-function M.get_repo_paths(args)
-  -- TODO: implement
-  return nil
+HgAdapter.Rev = HgRev
+HgAdapter.config_key = "hg"
+
+function M.get_repo_paths(path_args, cpath)
+  local paths = {}
+  local top_indicators = {}
+
+  for _, path_arg in ipairs(path_args) do
+    for _, path in ipairs(pl:vim_expand(path_arg, false, true)) do
+      path = pl:readlink(path) or path
+      table.insert(paths, path)
+    end
+  end
+
+  local cfile = pl:vim_expand("%")
+  cfile = pl:readlink(cfile) or cfile
+
+  for _, path in ipairs(paths) do
+    table.insert(top_indicators, pl:absolute(path, cpath))
+    break
+  end
+
+  table.insert(top_indicators, cpath and pl:realpath(cpath) or (
+    vim.bo.buftype == ""
+    and pl:absolute(cfile)
+    or nil
+  ))
+
+  if not cpath then
+    table.insert(top_indicators, pl:realpath("."))
+  end
+
+  return paths, top_indicators
+end
+
+---Get the git toplevel directory from a path to file or directory
+---@param path string
+---@return string?
+local function get_toplevel(path)
+  local out, code = utils.system_list(vim.tbl_flatten({config.get_config().hg_cmd, {"root"}}), path)
+  if code ~= 0 then
+    return nil
+  end
+  return out[1] and vim.trim(out[1])
 end
 
 function M.find_toplevel(top_indicators)
-  -- TODO: implement
-  return "", nil
+  local toplevel
+
+  for _, p in ipairs(top_indicators) do
+    if not pl:is_dir(p) then
+      p = pl:parent(p)
+    end
+
+    if p and pl:readable(p) then
+      toplevel = get_toplevel(p)
+      if toplevel then
+        return nil, toplevel
+      end
+    end
+  end
+
+  return (
+    ("Path not a mercurial repo (or any parent): %s")
+    :format(table.concat(vim.tbl_map(function(v)
+      local rel_path = pl:relative(v, ".")
+      return utils.str_quote(rel_path == "" and "." or rel_path)
+    end, top_indicators) --[[@as vector ]], ", "))
+  ), nil
+end
+
+function M.create(toplevel, path_args, cpath)
+  return HgAdapter({
+    toplevel = toplevel,
+    path_args = path_args,
+    cpath = cpath,
+  })
+end
+
+function HgAdapter:init(opt)
+  opt = opt or {}
+  HgAdapter:super().init(self, opt)
+
+  self.ctx = {
+    toplevel = opt.toplevel,
+    dir = opt.toplevel,
+    path_args = opt.path_args or {},
+  }
+
+  self:init_completion()
+end
+
+function HgAdapter:get_command()
+  return config.get_config().hg_cmd
+end
+
+function HgAdapter:get_show_args(path, rev)
+  return utils.vec_join(self:args(), "cat", "--rev", rev:object_name(), "--", path)
+end
+
+function HgAdapter:file_history_options(range, paths, args)
+  local default_args = config.get_config().default_args.DiffviewFileHistory
+  local argo = arg_parser.parse(vim.tbl_flatten({ default_args, args }))
+  local rel_paths
+
+  local cpath = argo:get_flag("C", { no_empty = true, expand = true })
+  local cfile = pl:vim_expand("%")
+  cfile = pl:readlink(cfile) or cfile
+
+  rel_paths = vim.tbl_map(function(v)
+    return v == "." and "." or pl:relative(v, ".")
+  end, paths)
+
+  local cwd = cpath or vim.loop.cwd()
+
+  local range_arg = argo:get_flag('rev', { no_empty = true })
+  if range_arg then
+    -- TODO: check if range is valid
+  end
+
+  if range then
+    utils.err(
+      "Line ranges are not supported for hg!"
+    )
+    return
+  end
+
+  local log_flag_names = {
+    { "rev", "r" },
+    { "follow", "f" },
+    { "no-merges", "M" },
+    { "limit", "l" },
+    { "user", "u" },
+    { "keyword", "k" },
+    { "include", "I" },
+    { "exclude", "X" },
+  }
+
+  ---@type LogOptions
+  local log_options = { rev_range = range_arg }
+  for _, names in ipairs(log_flag_names) do
+    local key, _ = names[1]:gsub("%-", "_")
+    local v = argo:get_flag(names, {
+      expect_string = type(config.log_option_defaults[self.config_key][key]) ~= "boolean",
+      expect_list = names[1] == "L",
+    })
+    log_options[key] = v
+  end
+
+  log_options.path_args = paths
+
+  local ok, opt_description = self:file_history_dry_run(log_options)
+
+  if not ok then
+    utils.info({
+      ("No hg history for the target(s) given the current options! Targets: %s")
+        :format(#rel_paths == 0 and "':(top)'" or table.concat(vim.tbl_map(function(v)
+          return "'" .. v .. "'"
+        end, rel_paths) --[[@as vector ]], ", ")),
+      ("Current options: [ %s ]"):format(opt_description)
+    })
+    return
+  end
+
+  return log_options
+end
+
+local function prepare_fh_options(adapter, log_options, single_file)
+  local o = log_options
+  local rev_range, base
+
+  if log_options.rev then
+    rev_range = log_options.rev
+  end
+
+  if log_options.base then
+    -- TODO
+  end
+
+  return {
+    rev_range = rev_range,
+    base = base,
+    path_args = log_options.path_args,
+    flags = utils.vec_join(
+      (o.follow and single_file) and { "--follow" } or nil,
+      o.user and { "--user=" .. o.user } or nil,
+      o.limit and { "--limit=" .. o.limit } or nil
+    ),
+  }
+end
+
+---@param log_opt LogOptions
+---@return boolean ok, string description
+function HgAdapter:file_history_dry_run(log_opt)
+  local single_file = self:is_single_file(log_opt.path_args)
+  local log_options = config.get_log_options(single_file, log_opt, self.config_key)
+
+  local options = vim.tbl_map(function(v)
+    return vim.fn.shellescape(v)
+  end, prepare_fh_options(self, log_options, single_file).flags) -- [[@as vector]]
+
+  local description = utils.vec_join(
+    ("Top-level path: '%s'"):format(utils.path:vim_fnamemodify(self.ctx.toplevel, ":~")),
+    log_options.rev_range and ("Revision range: '%s'"):format(log_options.rev_range) or nil,
+    ("Flags: %s"):format(table.concat(options, " "))
+  )
+
+  log_options = utils.tbl_clone(log_options) --[[@as LogOptions ]]
+  log_options.limit = 1
+  -- TODO
+  options = prepare_fh_options(self, log_options, single_file).flags
+
+  local context = "HgAdapter.file_history_dry_run()"
+  local cmd = utils.vec_join(
+    "log",
+    log_options.rev_range and "--rev=" .. log_options.rev_range or nil,
+    options,
+    log_options.path_args
+  )
+
+  local out, code = self:exec_sync(cmd, {
+    cwd = self.ctx.toplevel,
+    debug_opt = {
+      context = context,
+      no_stdout = true,
+    },
+  })
+
+  local ok = code == 0 and #out > 0
+
+  if not ok then
+    logger.lvl(1).s_debug(("[%s] Dry run failed."):format(context))
+  end
+
+  return ok, table.concat(description, ", ")
+end
+
+local function structure_fh_data(namestat_data, numstat_data)
+  local right_hash, left_hash, merge_hash = unpack(utils.str_split(namestat_data[1]))
+  local time, time_offset = namestat_data[3]:match('(%d+.%d*)([-+]?%d*)')
+ 
+  return {
+    left_hash = left_hash ~= "" and left_hash or nil,
+    right_hash = right_hash,
+    merge_hash = merge_hash,
+    author = namestat_data[2],
+    time = tonumber(time),
+    time_offset = time_offset,
+    rel_date = namestat_data[4],
+    ref_names = namestat_data[5]:sub(3),
+    subject = namestat_data[6]:sub(3),
+    namestat = utils.vec_slice(namestat_data, 7),
+    numstat = numstat_data,
+  }
+end
+
+
+---@param state HgAdapter.FHState
+---@param callback fun(status: JobStatus, data?: table, msg?: string[])
+local incremental_fh_data = async.void(function(state, callback)
+  local raw = {}
+  local namestat_job, numstat_job, shutdown
+
+  local namestat_state = {
+    data = {},
+    key = "namestat",
+    idx = 0,
+  }
+  local numstat_state = {
+    data = {},
+    key = "numstat",
+    idx = 0,
+  }
+
+  local function on_stdout(_, line, j)
+    local handler_state = j == namestat_job and namestat_state or numstat_state
+
+    if line == "\0" then
+      if handler_state.idx > 0 then
+        if not raw[handler_state.idx] then
+          raw[handler_state.idx] = {}
+        end
+
+        raw[handler_state.idx][handler_state.key] = handler_state.data
+
+        if not shutdown and raw[handler_state.idx].namestat and raw[handler_state.idx].numstat then
+          shutdown = callback(
+            JobStatus.PROGRESS,
+            structure_fh_data(raw[handler_state.idx].namestat, raw[handler_state.idx].numstat)
+          )
+
+          if shutdown then
+            logger.lvl(1).debug("Killing file history jobs...")
+            -- NOTE: The default `Job:shutdown` methods use `vim.wait` which
+            -- causes a segfault when called here.
+            namestat_job:_shutdown(64)
+            numstat_job:_shutdown(64)
+          end
+        end
+      end
+      handler_state.idx = handler_state.idx + 1
+      handler_state.data = {}
+    elseif line ~= "" then
+      table.insert(handler_state.data, line)
+    end
+  end
+
+  ---@type CountDownLatch
+  local latch = CountDownLatch(2)
+
+  local function on_exit(j, code)
+    if code == 0 then
+      on_stdout(nil, "\0", j)
+    end
+    latch:count_down()
+  end
+
+  local rev_range = state.prepared_log_opts.rev_range and '--rev=' .. state.prepared_log_opts.rev_range or nil
+
+  namestat_job = Job:new({
+    command = state.adapter:bin(),
+    args = utils.vec_join(
+      state.adapter:args(),
+      "log",
+      rev_range,
+      '--template=\\x00\n{node} {p1.node} {ifeq(p2.rev, -1 ,\"\", \"{p2.node}\")}\n{author|person}\n{date}\n{date|age}\n  {separate(", ", tags, topics)}\n  {desc|firstline}\n',
+      state.prepared_log_opts.flags,
+      "--",
+      state.path_args
+    ),
+    cwd = state.adapter.ctx.toplevel,
+    on_stdout = on_stdout,
+    on_exit = on_exit,
+  })
+
+  numstat_job = Job:new({
+    command = state.adapter:bin(),
+    args = utils.vec_join(
+      state.adapter:args(),
+      "log",
+      rev_range,
+      "--template=\\x00\n",
+      '--stat',
+      state.prepared_log_opts.flags,
+      "--",
+      state.path_args
+    ),
+    cwd = state.adapter.ctx.toplevel,
+    on_stdout = on_stdout,
+    on_exit = on_exit,
+  })
+
+  namestat_job:start()
+  numstat_job:start()
+
+  latch:await()
+
+  local debug_opt = {
+    context = "HgAdapter>incremental_fh_data()",
+    func = "s_info",
+    no_stdout = true,
+  }
+  utils.handle_job(namestat_job, { debug_opt = debug_opt })
+  utils.handle_job(numstat_job, { debug_opt = debug_opt })
+
+  if shutdown then
+    callback(JobStatus.KILLED)
+  elseif namestat_job.code ~= 0 or numstat_job.code ~= 0 then
+    callback(JobStatus.ERROR, nil, utils.vec_join(
+      namestat_job:stderr_result(),
+      numstat_job:stderr_result())
+    )
+  else
+    callback(JobStatus.SUCCESS)
+  end
+end)
+
+local function parse_fh_data(state)
+  local cur = state.cur
+
+  if cur.merge_hash and cur.numstat[1] and #cur.numstat ~= #cur.namestat then
+    local job
+    local job_spec = {
+      command = state.adapter:bin(),
+      args = utils.vec_join(
+        state.adapter:args(),
+        "status",
+        "--change",
+        cur.right_hash,
+        "--",
+        state.old_path or state.path_args
+      ),
+      cwd = state.adapter.ctx.toplevel,
+      on_exit = function(j)
+        if j.code == 0 then
+          cur.namestat = j:result()
+        end
+        state.adapter:handle_co(state.thread, coroutine.resume(state.thread))
+      end,
+    }
+
+    local max_retries = 2
+    local context = "HgAdapter.file_history_worker()"
+    state.resume_lock = true
+
+    for i = 0, max_retries do
+      -- Git sometimes fails this job silently (exit code 0). Not sure why,
+      -- possibly because we are running multiple git opeartions on the same
+      -- repo concurrently. Retrying the job usually solves this.
+      job = Job:new(job_spec)
+      job:start()
+      coroutine.yield()
+      utils.handle_job(job, { fail_on_empty = true, context = context, log_func = logger.warn })
+
+      if #cur.namestat == 0 then
+        if i < max_retries then
+          logger.warn(("[%s] Retrying %d more time(s)."):format(context, max_retries - i))
+        end
+      else
+        if i > 0 then
+          logger.info(("[%s] Retry successful!"):format(context))
+        end
+        break
+      end
+    end
+
+    state.resume_lock = false
+
+    if job.code ~= 0 then
+      state.callback({}, JobStatus.ERROR, job:stderr_result())
+      return false, JobStatus.FATAL
+    end
+
+    if #cur.namestat == 0 then
+      -- Give up: something has been renamed. We can no longer track the
+      -- history.
+      logger.warn(("[%s] Giving up."):format(context))
+      utils.warn("Displayed history may be incomplete. Check ':DiffviewLog' for details.", true)
+      return false
+    end
+  end
+
+  local files = {}
+  for i = 1, #cur.numstat - 1 do
+    local status = cur.namestat[i]:sub(1, 1):gsub("%s", " ")
+    local name = cur.namestat[i]:match("[%a%s]%s*(.*)")
+    local oldname
+
+    local stats = {}
+    local changes, diffstats = cur.numstat[i]:match(".*|%s+(%d+)%s+([+-]+)")
+    if changes and diffstats then
+      local _, adds = diffstats:gsub("+", "")
+
+      stats = {
+        additions = tonumber(adds),
+        deletions = tonumber(changes) - tonumber(adds),
+      }
+    end
+
+    if not stats.additions or not stats.deletions then
+      stats = nil
+    end
+
+    table.insert(files, FileEntry.with_layout(state.opt.default_layout or Diff2Hor, {
+      adapter = state.adapter,
+      path = name,
+      oldpath = oldname,
+      status = status,
+      stats = stats,
+      kind = "working",
+      commit = state.commit,
+      revs = {
+        a = cur.left_hash and HgRev(RevType.COMMIT, cur.left_hash) or HgRev.new_null_tree(),
+        b = state.prepared_log_opts.base or HgRev(RevType.COMMIT, cur.right_hash),
+      }
+    }))
+  end
+
+  if files[1] then
+    table.insert(
+      state.entries,
+      LogEntry({
+        path_args = state.path_args,
+        commit = state.commit,
+        files = files,
+        single_file = state.single_file,
+      })
+    )
+
+    state.callback(state.entries, JobStatus.PROGRESS)
+  end
+
+  return true
+end
+
+function HgAdapter:is_single_file(path_args, lflags)
+  if path_args and self.ctx.toplevel then
+    return #path_args == 1
+      and not utils.path:is_dir(path_args[1])
+      and #self:exec_sync({ "files", "--", path_args }, self.ctx.toplevel) < 2
+  end
+  return true
+end
+
+function HgAdapter:file_history_worker(thread, log_opt, opt, co_state, callback)
+  ---@type LogEntry[]
+  local entries = {}
+  local data = {}
+  local data_idx = 1
+  local last_status
+  local err_msg
+
+  local single_file = self:is_single_file(log_opt.single_file.path_args, {})
+
+  ---@type LogOptions
+  local log_options = config.get_log_options(
+    single_file,
+    single_file and log_opt.single_file or log_opt.multi_file,
+    "hg"
+  )
+
+  local state = {
+    thread = thread,
+    adapter = self,
+    path_args = log_opt.single_file.path_args,
+    log_options = log_options,
+    prepared_log_opts = prepare_fh_options(self, log_options, single_file),
+    opt = opt,
+    callback = callback,
+    entries = entries,
+    single_file = single_file,
+    resume_lock = false,
+  }
+
+  local function data_callback(status, d, msg)
+    if status == JobStatus.PROGRESS then
+      data[#data+1] = d
+    end
+
+    last_status = status
+    if msg then
+      err_msg = msg
+    end
+    if not state.resume_lock and coroutine.status(thread) == "suspended" then
+      self:handle_co(thread, coroutine.resume(thread))
+    end
+
+    if co_state.shutdown then
+      return true
+    end
+  end
+
+  incremental_fh_data(state, data_callback)
+
+  while true do
+    if not vim.tbl_contains({ JobStatus.SUCCESS, JobStatus.ERROR, JobStatus.KILLED }, last_status)
+        and not data[data_idx] then
+      coroutine.yield()
+    end
+
+    if last_status == JobStatus.KILLED then
+      logger.warn("File history processing was killed.")
+      return
+    elseif last_status == JobStatus.ERROR then
+      callback(entries, JobStatus.ERROR, err_msg)
+      return
+    elseif last_status == JobStatus.SUCCESS and data_idx > #data then
+      break
+    end
+
+    state.cur = data[data_idx]
+
+    state.commit = Commit({
+      hash = state.cur.right_hash,
+      author = state.cur.author,
+      time = tonumber(state.cur.time),
+      time_offset = state.cur.time_offset,
+      rel_date = state.cur.rel_date,
+      ref_names = state.cur.ref_names,
+      subject = state.cur.subject,
+    })
+
+    local ok, status = parse_fh_data(state)
+
+    if not ok then
+      if status == JobStatus.FATAL then
+        return
+      end
+      break
+    end
+
+    data_idx = data_idx + 1
+  end
+
+  callback(entries, JobStatus.SUCCESS)
+end
+
+HgAdapter.flags = {
+  ---@type FlagOption[]
+  switches = {
+    {'--follow', '-f', 'Follow renames'},
+    {'--no-merges', '-M', 'List no merge changesets'},
+  },
+  ---@type FlagOption[]
+  options = {
+    { '=r', '--rev=', 'Revspec', prompt_label = "(Revspec)" },
+    { '=l', '--limit=', 'Limit the number of changesets' },
+    { '=u', '--user=', 'Filter on user' },
+    { '=k', '--keyword=', 'Filter by keyword' },
+    { '=b', '--branch=', 'Filter by branch' },
+    { '=B', '--bookmark=', 'Filter by bookmark' },
+    { '=I', '--include=', 'Include files' },
+    { '=E', '--exclude=', 'Exclude files' },
+  },
+}
+
+for _, list in pairs(HgAdapter.flags) do
+  for i, option in ipairs(list) do
+    option = vim.tbl_extend("keep", option, {
+      prompt_fmt = "${label}${flag_name}",
+
+      key = option.key or utils.str_match(option[2], {
+        "^%-%-?([^=]+)=?",
+        "^%+%+?([^=]+)=?",
+      }):gsub("%-", "_"),
+
+      ---@param self FlagOption
+      ---@param value string|string[]
+      render_value = function(self, value)
+        local quoted
+
+        if type(value) == "table" then
+          quoted = table.concat(vim.tbl_map(function(v)
+            return self[2] .. utils.str_quote(v, { only_if_whitespace = true })
+          end, value), " ")
+        else
+          quoted = self[2] .. utils.str_quote(value, { only_if_whitespace = true })
+        end
+
+        return value == "", quoted
+      end,
+
+      ---@param value string|string[]
+      render_default = function(_, value)
+        if value == nil then
+          return ""
+        elseif type(value) == "table" then
+          return table.concat(vim.tbl_map(function(v)
+            v = select(1, v:gsub("\\", "\\\\"))
+            return utils.str_quote(v, { only_if_whitespace = true })
+          end, value), " ")
+        end
+        return utils.str_quote(value, { only_if_whitespace = true })
+      end,
+    })
+
+    list[i] = option
+    list[option.key] = option
+  end
+end
+
+function HgAdapter:is_binary(path, rev)
+  -- TODO
+  return false 
+end
+
+-- TODO: implement completion
+function HgAdapter:rev_completion(arg_lead, opt)
+  return { }
+end
+
+function HgAdapter:init_completion()
+  self.comp.file_history:put({"--rev", "-r"}, function(_, arg_lead)
+    return self:rev_completion(arg_lead, { accept_range = true })
+  end)
+
+  self.comp.file_history:put({ "--follow", "-f" })
+  self.comp.file_history:put({ "--no-merges", "-M" })
+  self.comp.file_history:put({ "--limit", "-l" }, {})
+
+  self.comp.file_history:put({ "--user", "-u" }, {})
+  self.comp.file_history:put({ "--keyword", "-k" }, {})
+
+  self.comp.file_history:put({ "--branch", "-b" }, {}) -- TODO: completion
+  self.comp.file_history:put({ "--bookmark", "-B" }, {}) -- TODO: completion
+
+  self.comp.file_history:put({"--include", "-I"}, function (_, arg_lead)
+    return vim.fn.getcompletion(arg_lead, "dir")
+  end)
+  self.comp.file_history:put({"--exclude", "-X"}, function (_, arg_lead)
+    return vim.fn.getcompletion(arg_lead, "dir")
+  end)
+
 end
 
 M.HgAdapter = HgAdapter
diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
new file mode 100644
index 00000000..53c09d58
--- /dev/null
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -0,0 +1,37 @@
+local oop = require("diffview.oop")
+local Rev = require('diffview.vcs.rev').Rev
+local RevType = require('diffview.vcs.rev').RevType
+
+local M = {}
+
+---@class HgRev : Rev
+local HgRev = oop.create_class("HgRev", Rev)
+
+HgRev.NULL_TREE_SHA = "000000000000000000000000000000000000000"
+
+function HgRev:init(rev_type, revision, track_head)
+  local t = type(revision)
+
+  assert(
+    revision == nil or t == "string" or t == "number",
+    "'revision' must be one of: nil, string, number!"
+  )
+  if t == "string" then
+    assert(revision ~= "", "'revision' cannot be an empty string!")
+  end
+
+  t = type(track_head)
+  assert(t == "boolean" or t == "nil", "'track_head' must be of type boolean!")
+
+  self.type = rev_type
+  self.track_head = track_head or false
+
+  self.commit = revision
+end
+
+function HgRev:object_name()
+  return self.commit
+end
+
+M.HgRev = HgRev
+return M

From 89c9556a62f93d0e394f42d5ad2b127d85b49285 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Sat, 19 Nov 2022 14:14:54 +0000
Subject: [PATCH 02/27] feat: implement diffview for hg

---
 lua/diffview/vcs/adapters/hg/init.lua | 279 +++++++++++++++++++++++++-
 1 file changed, 278 insertions(+), 1 deletion(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 42dbe411..bbe5cbb5 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -15,6 +15,7 @@ local CountDownLatch = require("diffview.control").CountDownLatch
 local FileEntry = require("diffview.scene.file_entry").FileEntry
 local Diff2Hor = require("diffview.scene.layouts.diff_2_hor").Diff2Hor
 local LogEntry = require("diffview.vcs.log_entry").LogEntry
+local vcs_utils = require("diffview.vcs.utils")
 
 ---@type PathLib
 local pl = lazy.access(utils, "path")
@@ -469,7 +470,7 @@ local function parse_fh_data(state)
   local files = {}
   for i = 1, #cur.numstat - 1 do
     local status = cur.namestat[i]:sub(1, 1):gsub("%s", " ")
-    local name = cur.namestat[i]:match("[%a%s]%s*(.*)")
+    local name = vim.trim(cur.namestat[i]:match("[%a%s]%s*(.*)"))
     local oldname
 
     local stats = {}
@@ -621,6 +622,282 @@ function HgAdapter:file_history_worker(thread, log_opt, opt, co_state, callback)
   callback(entries, JobStatus.SUCCESS)
 end
 
+function HgAdapter:diffview_options(args)
+  local default_args = config.get_config().default_args.DiffviewOpen
+  local argo = arg_parser.parse(vim.tbl_flatten({ default_args, args }))
+  local rev_args = argo:get_flag({'rev'})
+
+  local head = self:head_rev()
+  local left = head or HgRev.new_null_tree()
+  local right = HgRev(RevType.LOCAL)
+
+  local options = {
+    show_untracked = true, -- TODO: extract from hg config
+    selected_file = argo:get_flag("selected-file", { no_empty = true, expand = true })
+      or (vim.bo.buftype == "" and pl:vim_expand("%:p"))
+      or nil,
+  }
+
+  return {left = left, right = right, options = options}
+end
+
+function VCSAdapter:rev_to_pretty_string(left, right)
+  if left.track_head and right.type == RevType.LOCAL then
+    return nil
+  elseif left.commit and right.type == RevType.LOCAL then
+    return left:abbrev()
+  elseif left.commit and right.commit then
+    return left:abbrev() .. "::" .. right:abbrev()
+  end
+  return nil
+end
+
+function HgAdapter:head_rev()
+  local out, code = self:exec_sync({ "log", "--template={node}", "--limit=1", "--"}, {cwd = self.ctx.toplevel, retry_on_empty = 2})
+  if code ~= 0 then
+    return
+  end
+
+  local s = vim.trim(out[1]):gsub("^%^", "")
+
+  return HgRev(RevType.COMMIT, s, true)
+end
+
+function HgAdapter:rev_to_args(left, right)
+  assert(
+    not (left.type == RevType.LOCAL and right.type == RevType.LOCAL),
+    "Can't diff LOCAL against LOCAL!"
+  )
+  if left.type == RevType.COMMIT and right.type == RevType.COMMIT then
+    return { '--rev="' .. left.commit .. '::' .. right.commit .. '"' }
+  elseif left.type == RevType.STAGE and right.type == RevType.LOCAL then
+    return {}
+  else
+    return { '--rev=' .. left.commit }
+  end
+end
+
+
+function HgAdapter:get_files_args(args)
+  return utils.vec_join(self:args(), "status", "--print0", "--unknown", "--no-status", "--template={path}\\n", args)
+end
+
+HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, opt, callback)
+  ---@type FileEntry[]
+  local files = {}
+  ---@type FileEntry[]
+  local conflicts = {}
+  ---@type CountDownLatch
+  local latch = CountDownLatch(3)
+  local debug_opt = {
+    context = "HgAdapter>tracked_files()",
+    func = "s_debug",
+    debug_level = 1,
+    no_stdout = true,
+  }
+
+  ---@param job Job
+  local function on_exit(job)
+    utils.handle_job(job, { debug_opt = debug_opt })
+    latch:count_down()
+  end
+
+  local namestat_job = Job:new({
+    command = self:bin(),
+    args = utils.vec_join(
+      self:args(),
+      "status",
+      "--modified",
+      "--added",
+      "--removed",
+      "--deleted",
+      "--template={status} {path}\n",
+      args
+    ),
+    cwd = self.ctx.toplevel,
+    on_exit = on_exit,
+  })
+  local mergestate_job = Job:new({
+    command = self:bin(),
+    args = utils.vec_join(self:args(), "debugmergestate", "-Tjson"),
+    cwd = self.ctx.toplevel,
+    on_exit = on_exit,
+  })
+  local numstat_job = Job:new({
+    command = self:bin(),
+    args = utils.vec_join(self:args(), "diff", "--stat", args),
+    cwd = self.ctx.toplevel,
+    on_exit = on_exit,
+  })
+
+  namestat_job:start()
+  mergestate_job:start()
+  numstat_job:start()
+  latch:await()
+  local out_status
+  if not (#namestat_job:result() == #numstat_job:result() - 1) then
+    out_status = vcs_utils.ensure_output(2, { namestat_job, numstat_job }, "HgAdapter>tracked_files()")
+  end
+
+  if out_status == JobStatus.ERROR or not (namestat_job.code == 0 and numstat_job.code == 0 and mergestate_job.code == 0) then
+    callback(utils.vec_join(namestat_job:stderr_result(), numstat_job:stderr_result(), mergestate_job:stderr_result()), nil)
+    return
+  end
+
+  local numstat_out = numstat_job:result()
+  local namestat_out = namestat_job:result()
+  local mergestate_out = mergestate_job:result()
+
+  local data = {}
+  local conflict_map = {}
+  local file_info = {}
+
+  -- Last line in numstat is a summary and should not be used
+  table.remove(numstat_out, -1)
+
+  for i, s in ipairs(namestat_out) do
+    local status = s:sub(1, 1):gsub("%s", " ")
+    local name = vim.trim(s:match("[%a%s]%s*(.*)"))
+
+    local stats = {}
+    local changes, diffstats = numstat_out[i]:match(".*|%s+(%d+)%s+([+-]+)")
+    if changes and diffstats then
+      local _, adds = diffstats:gsub("+", "")
+
+      stats = {
+        additions = tonumber(adds),
+        deletions = tonumber(changes) - tonumber(adds),
+      }
+    end
+
+    if not (kind == "staged") then
+      file_info[name] = {
+        status = status,
+        name = name,
+        oldname = name, -- TODO
+        stats = stats,
+      }
+    end
+  end
+
+  local find_key = function (t, key, value)
+    for _, v in ipairs(t) do
+      if v[key] == value then
+        return v
+      end
+    end
+  end
+
+  local mergestate = vim.json.decode(table.concat(mergestate_out, ''))
+  for _, file in ipairs(mergestate[1].files) do
+    local base = find_key(file.extras, 'key', 'ancestorlinknode')
+    if file.state == 'u' then
+      file_info[file.path].status = 'U'
+      file_info[file.path].oldname = file.other_path
+      file_info[file.path].base = base and base.value or nil
+      conflict_map[file.path] = file_info[file.path]
+    end
+  end
+  local ours_node = find_key(mergestate[1].commits, 'name', 'local').node
+  local theirs_node = find_key(mergestate[1].commits, 'name', 'other').node
+
+  for _, f in pairs(file_info) do
+    if f.status ~= "U" then
+      table.insert(data, f)
+    end
+  end
+
+  if kind == "working" and next(conflict_map) then
+    -- TODO: read and parse content of .hg/merge/state2
+    --       O(<HASH> : others
+    --       L(<HASH> : local
+    --       ancestorlinknode<HASH> : base
+    --       HASH is 40 hex characters
+    -- hg debugmergestate -Tjson
+    for _, v in pairs(conflict_map) do
+      table.insert(conflicts, FileEntry.with_layout(opt.merge_layout, {
+        adapter = self,
+        path = v.name,
+        oldpath = v.oldname,
+        status = "U",
+        kind = "conflicting",
+        revs = {
+          a = self.Rev(RevType.COMMIT, ours_node),
+          b = self.Rev(RevType.LOCAL),
+          c = self.Rev(RevType.COMMIT, theirs_node),
+          d = self.Rev(RevType.COMMIT, v.base),
+        }
+      }))
+    end
+  end
+
+  for _, v in ipairs(data) do
+    table.insert(files, FileEntry.with_layout(opt.default_layout, {
+      adapter = self,
+      path = v.name,
+      oldpath = v.oldname,
+      status = v.status,
+      stats = v.stats,
+      kind = kind,
+      revs = {
+        a = left,
+        b = right,
+      }
+    }))
+  end
+
+  callback(nil, files, conflicts)
+end, 7)
+
+HgAdapter.untracked_files = async.wrap(function(self, left, right, opt, callback)
+  Job:new({
+    command = self:bin(),
+    args = utils.vec_join(
+      self:args(),
+      "status",
+      "--print0",
+      "--unknown",
+      "--no-status",
+      "--template={path}\\n"
+    ),
+    cwd = self.ctx.toplevel,
+    ---@type Job
+    on_exit = function(j)
+      utils.handle_job(j, {
+        debug_opt = {
+          context = "HgAdapter>untracked_files()",
+          func = "s_debug",
+          debug_level = 1,
+          no_stdout = true,
+        },
+      })
+
+      if j.code ~= 0 then
+        callback(j:stderr_result() or {}, nil)
+        return
+      end
+
+      local files = {}
+      for _, s in ipairs(j:result()) do
+        table.insert(
+          files,
+          FileEntry.with_layout(opt.default_layout, {
+            adapter = self,
+            path = s,
+            status = "?",
+            kind = "working",
+            revs = {
+              a = left,
+              b = right,
+            }
+          })
+        )
+      end
+      callback(nil, files)
+    end,
+  }):start()
+end, 5)
+
 HgAdapter.flags = {
   ---@type FlagOption[]
   switches = {

From 3410b7039a918f10d7550651c5fef9bf5ca01f66 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 21 Dec 2022 07:47:27 +0100
Subject: [PATCH 03/27] fix: handle no tracked files changed

---
 lua/diffview/vcs/adapters/hg/init.lua | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index bbe5cbb5..84706679 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -698,7 +698,7 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
 
   ---@param job Job
   local function on_exit(job)
-    utils.handle_job(job, { debug_opt = debug_opt })
+    utils.handle_job(job, { debug_opt = debug_opt, fail_on_empty = false })
     latch:count_down()
   end
 
@@ -735,8 +735,12 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   numstat_job:start()
   latch:await()
   local out_status
-  if not (#namestat_job:result() == #numstat_job:result() - 1) then
-    out_status = vcs_utils.ensure_output(2, { namestat_job, numstat_job }, "HgAdapter>tracked_files()")
+  if
+    not (#namestat_job:result() == 0 and #numstat_job:result() == 0)
+    and not (#namestat_job:result() == #numstat_job:result() - 1)
+  then
+    out_status =
+      vcs_utils.ensure_output(2, { namestat_job, numstat_job }, "HgAdapter>tracked_files()")
   end
 
   if out_status == JobStatus.ERROR or not (namestat_job.code == 0 and numstat_job.code == 0 and mergestate_job.code == 0) then
@@ -798,8 +802,12 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
       conflict_map[file.path] = file_info[file.path]
     end
   end
-  local ours_node = find_key(mergestate[1].commits, 'name', 'local').node
-  local theirs_node = find_key(mergestate[1].commits, 'name', 'other').node
+  local ours_node
+  local theirs_node
+  if #mergestate[1].commits > 0 then
+    ours_node = find_key(mergestate[1].commits, 'name', 'local').node
+    theirs_node = find_key(mergestate[1].commits, 'name', 'other').node
+  end
 
   for _, f in pairs(file_info) do
     if f.status ~= "U" then

From 71f0518d0d4115fe2f24c96e21fb65238eb06427 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 21 Dec 2022 08:45:20 +0100
Subject: [PATCH 04/27] fix: handle null base rev

---
 lua/diffview/vcs/adapter.lua          |  2 +-
 lua/diffview/vcs/adapters/hg/init.lua | 56 ++++++++++++++++++++++++---
 lua/diffview/vcs/adapters/hg/rev.lua  |  2 +-
 3 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/lua/diffview/vcs/adapter.lua b/lua/diffview/vcs/adapter.lua
index 96fcd718..c08fba92 100644
--- a/lua/diffview/vcs/adapter.lua
+++ b/lua/diffview/vcs/adapter.lua
@@ -329,7 +329,7 @@ VCSAdapter.show = async.wrap(function(self, path, rev, callback)
     cwd = self.ctx.toplevel,
     ---@type Job
     on_exit = async.void(function(j)
-      local context = "vcs.utils.show()"
+      local context = "VCSAdapter.show()"
       utils.handle_job(j, {
         fail_on_empty = true,
         context = context,
diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 84706679..8c4cad53 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -816,12 +816,6 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   end
 
   if kind == "working" and next(conflict_map) then
-    -- TODO: read and parse content of .hg/merge/state2
-    --       O(<HASH> : others
-    --       L(<HASH> : local
-    --       ancestorlinknode<HASH> : base
-    --       HASH is 40 hex characters
-    -- hg debugmergestate -Tjson
     for _, v in pairs(conflict_map) do
       table.insert(conflicts, FileEntry.with_layout(opt.merge_layout, {
         adapter = self,
@@ -906,6 +900,56 @@ HgAdapter.untracked_files = async.wrap(function(self, left, right, opt, callback
   }):start()
 end, 5)
 
+---@param self HgAdapter
+---@param path string
+---@param rev? Rev
+---@param callback fun(stderr: string[]?, stdout: string[]?)
+HgAdapter.show = async.wrap(function(self, path, rev, callback)
+  -- File did not exist, need to return an empty buffer
+  if not(rev) or (rev:object_name() == self.Rev.NULL_TREE_SHA) then
+    callback(nil, {})
+    return
+  end
+
+  local job = Job:new({
+    command = self:bin(),
+    args = self:get_show_args(path, rev),
+    cwd = self.ctx.toplevel,
+    ---@type Job
+    on_exit = async.void(function(j)
+      local context = "HgAdapter.show()"
+      utils.handle_job(j, {
+        fail_on_empty = true,
+        context = context,
+        debug_opt = { no_stdout = true, context = context },
+      })
+
+      if j.code ~= 0 then
+        callback(j:stderr_result() or {}, nil)
+        return
+      end
+
+      local out_status
+
+      if #j:result() == 0 then
+        async.util.scheduler()
+        out_status = vcs_utils.ensure_output(2, { j }, context)
+      end
+
+      if out_status == JobStatus.ERROR then
+        callback(j:stderr_result() or {}, nil)
+        return
+      end
+
+      callback(nil, j:result())
+    end),
+  })
+  -- Problem: Running multiple 'show' jobs simultaneously may cause them to fail
+  -- silently.
+  -- Solution: queue them and run them one after another.
+  vcs_utils.queue_sync_job(job)
+end, 4)
+
 HgAdapter.flags = {
   ---@type FlagOption[]
   switches = {
diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index 53c09d58..d066b2b1 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -7,7 +7,7 @@ local M = {}
 ---@class HgRev : Rev
 local HgRev = oop.create_class("HgRev", Rev)
 
-HgRev.NULL_TREE_SHA = "000000000000000000000000000000000000000"
+HgRev.NULL_TREE_SHA = "0000000000000000000000000000000000000000"
 
 function HgRev:init(rev_type, revision, track_head)
   local t = type(revision)

From 58501368401095e3425c796279095439a11faffc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sindre=20T=2E=20Str=C3=B8m?= <sindrets@gmail.com>
Date: Wed, 21 Dec 2022 17:09:42 +0100
Subject: [PATCH 05/27] WIP: Amend docs

---
 doc/diffview.txt | 117 +++++++++++++++++++++++++++++------------------
 1 file changed, 73 insertions(+), 44 deletions(-)

diff --git a/doc/diffview.txt b/doc/diffview.txt
index 9357877a..29126fb6 100644
--- a/doc/diffview.txt
+++ b/doc/diffview.txt
@@ -179,75 +179,97 @@ COMMANDS                                        *diffview-commands*
             :'<,'>DiffviewFileHistory
 <
 
-    Options: ~
+    What options are available will be determined by what type of repository
+    you're targeting. You will find the available options for the supported
+    VCS tools below. The command completion will do it's best to suggest the
+    appropriate options.
+
+    Git Options: ~
         --base={git-rev}
-                        Specify a base git rev from which the right side of
-                        the diff will be created. Use the special value
-                        `LOCAL` to use the local version of the file.
+                Specify a base git rev from which the right side of the diff
+                will be created. Use the special value `LOCAL` to use the
+                local version of the file.
 
         --range={git-rev}
-                        Show only commits in the specified revision range.
+                Show only commits in the specified revision range.
 
-        -C{path}        Run as if git was started in {path} instead of the
-                        current working directory.
+        -C{path}
+                Run as if git was started in {path} instead of the current
+                working directory.
 
         NOTE: All following options are described in far more detail in the
         man page for git-log. See `:Man git-log(1)` for more information.
 
-        --follow        Follow renames (only for single file).
+        --follow
+                Follow renames (only for single file).
 
-        --first-parent  Follow only the first parent upon seeing a merge
-                        commit.
+        --first-parent
+                Follow only the first parent upon seeing a merge commit.
 
-        --show-pulls    Show merge commits that are not TREESAME to its first
-                        parent, but are to a later parent.
+        --show-pulls
+                Show merge commits that are not TREESAME to its first parent,
+                but are to a later parent.
 
-        --reflog        Include all reachable objects mentioned by reflogs.
+        --reflog
+                Include all reachable objects mentioned by reflogs.
 
-        --all           Include all refs.
+        --all   Include all refs.
 
-        --merges        List only merge commits.
+        --merges
+                List only merge commits.
 
-        --no-merges     List no merge commits.
+        --no-merges
+                List no merge commits.
 
-        --reverse       List commits in reverse order.
+        --reverse
+                List commits in reverse order.
 
         -n{n}, --max-count={n}
-                        Limit the number of commits.
+                Limit the number of commits.
 
         -L{start},{end}:{file}, -L:{funcname}:{file}
-                        Trace the evolution of the line range given by
-                        {start},{end}, or by the function name regex
-                        {funcname}, within the {file}. You can specify this
-                        option more than once.
+                Trace the evolution of the line range given by {start},{end},
+                or by the function name regex {funcname}, within the {file}.
+                You can specify this option more than once.
 
         --diff-merges={value}
-                        Determines how merge commits are treated. {value} can
-                        be one of:
-                            • `off`
-                            • `on`
-                            • `first-parent`
-                            • `separate`
-                            • `combined`
-                            • `dense-combined`
-                            • `remerge`
+                Determines how merge commits are treated. {value} can
+                be one of:
+                    • `off`
+                    • `on`
+                    • `first-parent`
+                    • `separate`
+                    • `combined`
+                    • `dense-combined`
+                    • `remerge`
 
         --author={pattern}
-                        Limit the commits output to ones with author/committer
-                        header lines that match the specified {pattern}
-                        (regular expression).
+                Limit the commits output to ones with author/committer header
+                lines that match the specified {pattern} (regular expression).
 
         --grep={pattern}
-                        Limit the commits output to ones with log message that
-                        matches the specified {pattern} (regular expression).
+                Limit the commits output to ones with log message that matches
+                the specified {pattern} (regular expression).
+
+        -G{pattern}
+                Look for differences whose patch text contains added/removed
+                lines that match {pattern} (extended regular expression).
+
+        -S{pattern}
+                Look for differences that change the number of occurences of
+                the specified {pattern} (extended regular expression) in a
+                file.
+
+    Mercurial Options: ~
 
-        -G{pattern}     Look for differences whose patch text contains
-                        added/removed lines that match {pattern} (extended
-                        regular expression).
+        --rev={rev}
+                Show only commits in the specified revision range.
 
-        -S{pattern}     Look for differences that change the number of
-                        occurences of the specified {pattern} (extended
-                        regular expression) in a file.
+        -f, --follow
+                Follow renames (only for single file).
+
+        -l{n}, --limit={n}
+                Limit the number of commits.
 
                                                 *:DiffviewClose*
 :DiffviewClose          Close the active Diffview.
@@ -285,10 +307,17 @@ enhanced_diff_hl                                *diffview-config-enhanced_diff_h
 git_cmd                                         *diffview-config-git_cmd*
         Type: `string[]`, Default: `{ "git" }`
 
-        This table forms the first part of all git commands used internally in
-        the plugin. The first element should be the git binary. The subsequent
+        This table forms the first part of all Git commands used internally in
+        the plugin. The first element should be the Git binary. The subsequent
         elements are passed as arguments.
 
+hg_cmd                                         *diffview-config-hg_cmd*
+        Type: `string[]`, Default: `{ "hg" }`
+
+        This table forms the first part of all Mercurial commands used
+        internally in the plugin. The first element should be the Mercurial
+        binary. The subsequent elements are passed as arguments.
+
 view.x.layout                                   *diffview-config-view.x.layout*
         Type: >
             "diff1_plain"

From b5c8a0d8811891bfba580e7dbdc764323fb8dc4e Mon Sep 17 00:00:00 2001
From: Zeger Van de Vannet <747627+zegervdv@users.noreply.github.com>
Date: Wed, 21 Dec 2022 17:49:06 +0100
Subject: [PATCH 06/27] fix: correct order of flag options
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Sindre T. Strøm <sindrets@gmail.com>
---
 lua/diffview/vcs/adapters/hg/init.lua | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 8c4cad53..02536dc0 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -953,8 +953,8 @@ end, 4)
 HgAdapter.flags = {
   ---@type FlagOption[]
   switches = {
-    {'--follow', '-f', 'Follow renames'},
-    {'--no-merges', '-M', 'List no merge changesets'},
+    { '-f', '--follow', 'Follow renames' },
+    { '-M', '--no-merges', 'List no merge changesets' },
   },
   ---@type FlagOption[]
   options = {

From 463f60a38fb9636127c1ed9d426275c6597bc837 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 21 Dec 2022 17:44:37 +0100
Subject: [PATCH 07/27] fix: only set oldname when a file is renamed

---
 lua/diffview/vcs/adapters/hg/init.lua | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 02536dc0..649dce97 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -778,7 +778,6 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
       file_info[name] = {
         status = status,
         name = name,
-        oldname = name, -- TODO
         stats = stats,
       }
     end
@@ -797,7 +796,9 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
     local base = find_key(file.extras, 'key', 'ancestorlinknode')
     if file.state == 'u' then
       file_info[file.path].status = 'U'
-      file_info[file.path].oldname = file.other_path
+      if file.other_path ~= file.path then
+        file_info[file.path].oldname = file.other_path
+      end
       file_info[file.path].base = base and base.value or nil
       conflict_map[file.path] = file_info[file.path]
     end

From 264929ea3ac1b796234929ad33a87170632986f7 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 21 Dec 2022 18:18:21 +0100
Subject: [PATCH 08/27] fix: only walk the mergestate data once

---
 lua/diffview/vcs/adapters/hg/init.lua | 30 ++++++++++++---------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 649dce97..55dd5f7a 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -783,31 +783,27 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
     end
   end
 
-  local find_key = function (t, key, value)
-    for _, v in ipairs(t) do
-      if v[key] == value then
-        return v
-      end
-    end
-  end
-
   local mergestate = vim.json.decode(table.concat(mergestate_out, ''))
   for _, file in ipairs(mergestate[1].files) do
-    local base = find_key(file.extras, 'key', 'ancestorlinknode')
+    local base = nil
+    for _, extra in ipairs(file.extras) do
+      if extra.key == 'ancestorlinknode' then
+        base = extra.value
+      end
+    end
     if file.state == 'u' then
       file_info[file.path].status = 'U'
+      file_info[file.path].base = base
       if file.other_path ~= file.path then
         file_info[file.path].oldname = file.other_path
       end
-      file_info[file.path].base = base and base.value or nil
       conflict_map[file.path] = file_info[file.path]
     end
   end
-  local ours_node
-  local theirs_node
-  if #mergestate[1].commits > 0 then
-    ours_node = find_key(mergestate[1].commits, 'name', 'local').node
-    theirs_node = find_key(mergestate[1].commits, 'name', 'other').node
+
+  local nodes = {}
+  for _, commit in ipairs(mergestate[1].commits) do
+    nodes[commit.name] = commit.node
   end
 
   for _, f in pairs(file_info) do
@@ -825,9 +821,9 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
         status = "U",
         kind = "conflicting",
         revs = {
-          a = self.Rev(RevType.COMMIT, ours_node),
+          a = self.Rev(RevType.COMMIT, nodes['local']),
           b = self.Rev(RevType.LOCAL),
-          c = self.Rev(RevType.COMMIT, theirs_node),
+          c = self.Rev(RevType.COMMIT, nodes.other),
           d = self.Rev(RevType.COMMIT, v.base),
         }
       }))

From 0ed37cb7d3111bb229e1cccbd35039a0e6d5ced4 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 21 Dec 2022 18:47:21 +0100
Subject: [PATCH 09/27] feat: add log args for hg

---
 lua/diffview/vcs/adapters/hg/init.lua | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 55dd5f7a..88736f65 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -125,6 +125,11 @@ function HgAdapter:get_show_args(path, rev)
   return utils.vec_join(self:args(), "cat", "--rev", rev:object_name(), "--", path)
 end
 
+function HgAdapter:get_log_args(args)
+print(" args:", vim.inspect(args)) -- __AUTO_GENERATED_PRINT_VAR__
+  return utils.vec_join(self:args(), "log", "--stat", args)
+end
+
 function HgAdapter:file_history_options(range, paths, args)
   local default_args = config.get_config().default_args.DiffviewFileHistory
   local argo = arg_parser.parse(vim.tbl_flatten({ default_args, args }))

From 6ee4efa4c0e4ce7ba5a0492300858bb26df04144 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 4 Jan 2023 12:03:15 +0100
Subject: [PATCH 10/27] feat: add to_range for hg revs

---
 lua/diffview/vcs/adapters/hg/rev.lua | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index d066b2b1..0bffd8b4 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -33,5 +33,12 @@ function HgRev:object_name()
   return self.commit
 end
 
+function HgRev.to_range(rev_from, rev_to)
+  if rev_to then
+    return rev_from .. "::" .. rev_to
+  end
+  return rev_from
+end
+
 M.HgRev = HgRev
 return M

From eec216e0e00835597ce8587b343aad9dd6cc6f27 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 17 Jan 2023 17:32:07 +0100
Subject: [PATCH 11/27] fixup! feat: add log args for hg

---
 lua/diffview/vcs/adapters/hg/init.lua | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 88736f65..90c00bd5 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -126,8 +126,7 @@ function HgAdapter:get_show_args(path, rev)
 end
 
 function HgAdapter:get_log_args(args)
-print(" args:", vim.inspect(args)) -- __AUTO_GENERATED_PRINT_VAR__
-  return utils.vec_join(self:args(), "log", "--stat", args)
+  return utils.vec_join("log", "--stat", '--rev', args)
 end
 
 function HgAdapter:file_history_options(range, paths, args)

From bbca98d8642e2f55ad6a8c9662c857923ae6bd22 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 17 Jan 2023 18:07:44 +0100
Subject: [PATCH 12/27] feat: add get_merge_context for hg

---
 lua/diffview/vcs/adapters/hg/init.lua | 32 +++++++++++++++++++++++++++
 lua/diffview/vcs/adapters/hg/rev.lua  | 12 ++++++++--
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 90c00bd5..3ffa3141 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -129,6 +129,38 @@ function HgAdapter:get_log_args(args)
   return utils.vec_join("log", "--stat", '--rev', args)
 end
 
+function HgAdapter:get_merge_context()
+  local ret = {}
+
+  local out, code = self:exec_sync({ "debugmergestate", "-Tjson" }, self.ctx.toplevel)
+
+  if code ~= 0 then
+    return {}
+  end
+
+  local data = vim.json.decode(table.concat(out, ""))
+  for _, commit in ipairs(data[1].commits) do
+    if commit.name == "other" then
+      ret.theirs = { hash = commit.node }
+      out, code = self:exec_sync({ "log", "--template={branch}", "--rev", commit.node })
+      if code == 0 then
+        ret.theirs.ref_name = out[1]
+      end
+    elseif commit.name == "local" then
+      ret.ours = { hash = commit.node }
+      out, code = self:exec_sync({ "log", "--template={branch}", "--rev", commit.node })
+      if code == 0 then
+        ret.ours.ref_name = out[1]
+      end
+    end
+  end
+
+  -- Base is ancestorlinknode (per file)
+  ret.base = { hash = "" }
+
+  return ret
+end
+
 function HgAdapter:file_history_options(range, paths, args)
   local default_args = config.get_config().default_args.DiffviewFileHistory
   local argo = arg_parser.parse(vim.tbl_flatten({ default_args, args }))
diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index 0bffd8b4..ed47d544 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -29,8 +29,16 @@ function HgRev:init(rev_type, revision, track_head)
   self.commit = revision
 end
 
-function HgRev:object_name()
-  return self.commit
+function HgRev:object_name(abbrev_len)
+  if self.commit then
+    if abbrev_len then
+      return self.commit:sub(1, abbrev_len)
+    end
+
+    return self.commit
+  end
+
+  return "UNKNOWN"
 end
 
 function HgRev.to_range(rev_from, rev_to)

From 7298a7f509e38de36877d415438c8d8c7ecb6d79 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 17 Jan 2023 18:26:38 +0100
Subject: [PATCH 13/27] doc: list hg options and refer to documentation where
 possible

---
 doc/diffview.txt | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/doc/diffview.txt b/doc/diffview.txt
index 29126fb6..788f59dc 100644
--- a/doc/diffview.txt
+++ b/doc/diffview.txt
@@ -263,7 +263,9 @@ COMMANDS                                        *diffview-commands*
     Mercurial Options: ~
 
         --rev={rev}
-                Show only commits in the specified revision range.
+                Show only commits for the specified revset {rev}.
+                See `hg help revsets` for the full list of keywords and
+                constructs.
 
         -f, --follow
                 Follow renames (only for single file).
@@ -271,6 +273,27 @@ COMMANDS                                        *diffview-commands*
         -l{n}, --limit={n}
                 Limit the number of commits.
 
+        -M, --no-merges
+                Do not list merge commits.
+
+        --user={text}
+                Limit the commits to ones with user as specified.
+
+        --keyword={text}
+                Limit commits to ones matching the {text} in the log message.
+
+        --branch={text}
+                Limit commits to a specified branch.
+
+        --bookmark={text}
+                Limit commits to a specified bookmark
+
+        --include={pattern}
+                Include commits touching files as specified in the {pattern}.
+
+        --exclude={pattern}
+                Exclude commits touching files as specified in the {pattern}.
+
                                                 *:DiffviewClose*
 :DiffviewClose          Close the active Diffview.
 
@@ -318,6 +341,9 @@ hg_cmd                                         *diffview-config-hg_cmd*
         internally in the plugin. The first element should be the Mercurial
         binary. The subsequent elements are passed as arguments.
 
+        If your Mercurial install bundles the `chg` binary, this can be
+        configured here to have a significant performance boost.
+
 view.x.layout                                   *diffview-config-view.x.layout*
         Type: >
             "diff1_plain"

From 5175646d97e3ad9b14d605ee8fc21d859c64a6ab Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 17 Jan 2023 18:38:28 +0100
Subject: [PATCH 14/27] feat: add file_restore for hg

---
 lua/diffview/vcs/adapters/hg/init.lua | 57 +++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 3ffa3141..16789b42 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -713,6 +713,63 @@ function HgAdapter:rev_to_args(left, right)
   end
 end
 
+function HgAdapter:file_restore(path, kind, commit)
+  local out, code
+  local abs_path = utils.path:join(self.ctx.toplevel, path)
+  local rel_path = utils.path:vim_fnamemodify(abs_path, ":~")
+
+  _, code = self:exec_sync({"cat", "--", path}, self.ctx.toplevel)
+
+  local exists_hg = code == 0
+  local exists_local = utils.path:readable(abs_path)
+
+  local undo
+
+  if not exists_hg then
+    local bn = utils.find_file_buffer(abs_path)
+    if bn then
+      async.util.scheduler()
+      local ok, err = utils.remove_buffer(false, bn)
+      if not ok then
+        utils.err({
+          ("Failed to delete buffer '%d'! Aborting file restoration. Error message:")
+            :format(bn),
+          err
+        }, true)
+        return false
+      end
+    end
+
+    if kind == "working" or kind == "conflicting" then
+      -- File is untracked and has no history: delete it from fs.
+      local ok, err = utils.path:unlink(abs_path)
+      if not ok then
+        utils.err({
+          ("Failed to delete file '%s'! Aborting file restoration. Error message:")
+            :format(abs_path),
+          err
+        }, true)
+        return false
+      end
+    else
+      -- File only exists in index
+      out, code = self:exec_sync(
+        { "rm", "-f", "--", path },
+        self.ctx.toplevel
+      )
+    end
+  else
+    -- File exists in history: revert
+    out, code = self:exec_sync(
+      utils.vec_join("revert", commit or (kind == "staged" and "HEAD" or nil), "--", path),
+      self.ctx.toplevel
+    )
+  end
+
+  return true, undo
+
+end
+
 
 function HgAdapter:get_files_args(args)
   return utils.vec_join(self:args(), "status", "--print0", "--unknown", "--no-status", "--template={path}\\n", args)

From 4a5b609be1938c46262c3873cd36f1e996d397db Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 25 Jan 2023 07:53:16 +0100
Subject: [PATCH 15/27] fix review comments

---
 lua/diffview/config.lua                 | 12 ++++++
 lua/diffview/vcs/adapters/hg/commit.lua |  1 +
 lua/diffview/vcs/adapters/hg/init.lua   | 50 +++++++++++++++++++------
 3 files changed, 52 insertions(+), 11 deletions(-)

diff --git a/lua/diffview/config.lua b/lua/diffview/config.lua
index 77528acf..0a1cbd4f 100644
--- a/lua/diffview/config.lua
+++ b/lua/diffview/config.lua
@@ -248,6 +248,13 @@ M._config = M.defaults
 ---@field path_args string[]
 
 ---@class HgLogOptions
+---@field limit integer
+---@field user string
+---@field no_merges boolean
+---@field rev string
+---@field keyword string
+---@field include string
+---@field exclude string
 
 ---@alias LogOptions GitLogOptions|HgLogOptions
 
@@ -277,6 +284,11 @@ M.log_option_defaults = {
   hg = {
     limit = 256,
     user = nil,
+    no_merges = false,
+    rev = nil,
+    keyword = nil,
+    include = nil,
+    exclude = nil,
   },
 }
 
diff --git a/lua/diffview/vcs/adapters/hg/commit.lua b/lua/diffview/vcs/adapters/hg/commit.lua
index bf2235b3..3168aaf8 100644
--- a/lua/diffview/vcs/adapters/hg/commit.lua
+++ b/lua/diffview/vcs/adapters/hg/commit.lua
@@ -5,6 +5,7 @@ local Commit = require('diffview.vcs.commit').Commit
 
 local M = {}
 
+---@class HgCommit : Commit
 local HgCommit = oop.create_class('HgCommit', Commit)
 
 function HgCommit:init(opt)
diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 16789b42..86d27cf3 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -135,7 +135,7 @@ function HgAdapter:get_merge_context()
   local out, code = self:exec_sync({ "debugmergestate", "-Tjson" }, self.ctx.toplevel)
 
   if code ~= 0 then
-    return {}
+    return {ours = {}, theirs = {}, base = {}}
   end
 
   local data = vim.json.decode(table.concat(out, ""))
@@ -144,13 +144,13 @@ function HgAdapter:get_merge_context()
       ret.theirs = { hash = commit.node }
       out, code = self:exec_sync({ "log", "--template={branch}", "--rev", commit.node })
       if code == 0 then
-        ret.theirs.ref_name = out[1]
+        ret.theirs.ref_names = out[1]
       end
     elseif commit.name == "local" then
       ret.ours = { hash = commit.node }
       out, code = self:exec_sync({ "log", "--template={branch}", "--rev", commit.node })
       if code == 0 then
-        ret.ours.ref_name = out[1]
+        ret.ours.ref_names = out[1]
       end
     end
   end
@@ -174,8 +174,6 @@ function HgAdapter:file_history_options(range, paths, args)
     return v == "." and "." or pl:relative(v, ".")
   end, paths)
 
-  local cwd = cpath or vim.loop.cwd()
-
   local range_arg = argo:get_flag('rev', { no_empty = true })
   if range_arg then
     -- TODO: check if range is valid
@@ -205,7 +203,6 @@ function HgAdapter:file_history_options(range, paths, args)
     local key, _ = names[1]:gsub("%-", "_")
     local v = argo:get_flag(names, {
       expect_string = type(config.log_option_defaults[self.config_key][key]) ~= "boolean",
-      expect_list = names[1] == "L",
     })
     log_options[key] = v
   end
@@ -228,6 +225,26 @@ function HgAdapter:file_history_options(range, paths, args)
   return log_options
 end
 
+---@class HgAdapter.PreparedLogOpts
+---@field rev_range string
+---@field base Rev
+---@field path_args string[]
+---@field flags string[]
+--
+---@class HgAdapter.FHState
+---@field thread thread
+---@field adapter HgAdapter
+---@field path_args string[]
+---@field log_options HgLogOptions
+---@field prepared_log_opts HgAdapter.PreparedLogOpts
+---@field opt vcs.adapter.FileHistoryWorkerSpec
+---@field single_file boolean
+---@field resume_lock boolean
+---@field cur table
+---@field commit Commit
+---@field entries LogEntry[]
+---@field callback function
+
 local function prepare_fh_options(adapter, log_options, single_file)
   local o = log_options
   local rev_range, base
@@ -246,8 +263,15 @@ local function prepare_fh_options(adapter, log_options, single_file)
     path_args = log_options.path_args,
     flags = utils.vec_join(
       (o.follow and single_file) and { "--follow" } or nil,
+      o.no_merges and { "--no-merges" } or nil,
+      o.rev and { "--rev=" .. o.rev } or nil,
+      o.limit and { "--limit=" .. o.limit } or nil,
       o.user and { "--user=" .. o.user } or nil,
-      o.limit and { "--limit=" .. o.limit } or nil
+      o.keyword and { "--keyword=" .. o.keyword } or nil,
+      o.branch and { "--branch=" .. o.branch } or nil,
+      o.bookmark and { "--bookmark=" .. o.bookmark } or nil,
+      o.include and { "--include=" .. o.include } or nil,
+      o.exclude and { "--exclude=" .. o.exclude } or nil
     ),
   }
 end
@@ -677,7 +701,7 @@ function HgAdapter:diffview_options(args)
   return {left = left, right = right, options = options}
 end
 
-function VCSAdapter:rev_to_pretty_string(left, right)
+function HgAdapter:rev_to_pretty_string(left, right)
   if left.track_head and right.type == RevType.LOCAL then
     return nil
   elseif left.commit and right.type == RevType.LOCAL then
@@ -689,7 +713,11 @@ function VCSAdapter:rev_to_pretty_string(left, right)
 end
 
 function HgAdapter:head_rev()
-  local out, code = self:exec_sync({ "log", "--template={node}", "--limit=1", "--"}, {cwd = self.ctx.toplevel, retry_on_empty = 2})
+  local out, code = self:exec_sync( { "log", "--template={node}", "--limit=1", "--" }, {
+    cwd = self.ctx.toplevel,
+    retry_on_empty = 2,
+  })
+
   if code ~= 0 then
     return
   end
@@ -1110,13 +1138,13 @@ function HgAdapter:is_binary(path, rev)
 end
 
 -- TODO: implement completion
-function HgAdapter:rev_completion(arg_lead, opt)
+function HgAdapter:rev_candidates(arg_lead, opt)
   return { }
 end
 
 function HgAdapter:init_completion()
   self.comp.file_history:put({"--rev", "-r"}, function(_, arg_lead)
-    return self:rev_completion(arg_lead, { accept_range = true })
+    return self:rev_candidates(arg_lead, { accept_range = true })
   end)
 
   self.comp.file_history:put({ "--follow", "-f" })

From b267549d38918dc7636c4c8b02b03aff36d41475 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 25 Jan 2023 07:58:49 +0100
Subject: [PATCH 16/27] fix: update flags

---
 lua/diffview/vcs/adapters/hg/init.lua | 60 ++++++---------------------
 1 file changed, 12 insertions(+), 48 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 86d27cf3..3ea6ddd8 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -15,6 +15,7 @@ local CountDownLatch = require("diffview.control").CountDownLatch
 local FileEntry = require("diffview.scene.file_entry").FileEntry
 local Diff2Hor = require("diffview.scene.layouts.diff_2_hor").Diff2Hor
 local LogEntry = require("diffview.vcs.log_entry").LogEntry
+local FlagOption = require("diffview.vcs.flag_option").FlagOption
 local vcs_utils = require("diffview.vcs.utils")
 
 ---@type PathLib
@@ -1071,62 +1072,25 @@ end, 4)
 HgAdapter.flags = {
   ---@type FlagOption[]
   switches = {
-    { '-f', '--follow', 'Follow renames' },
-    { '-M', '--no-merges', 'List no merge changesets' },
+    FlagOption('-f', '--follow', 'Follow renames'),
+    FlagOption('-M', '--no-merges', 'List no merge changesets'),
   },
   ---@type FlagOption[]
   options = {
-    { '=r', '--rev=', 'Revspec', prompt_label = "(Revspec)" },
-    { '=l', '--limit=', 'Limit the number of changesets' },
-    { '=u', '--user=', 'Filter on user' },
-    { '=k', '--keyword=', 'Filter by keyword' },
-    { '=b', '--branch=', 'Filter by branch' },
-    { '=B', '--bookmark=', 'Filter by bookmark' },
-    { '=I', '--include=', 'Include files' },
-    { '=E', '--exclude=', 'Exclude files' },
+    FlagOption('=r', '--rev=', 'Revspec', {prompt_label = "(Revspec)"}),
+    FlagOption('=l', '--limit=', 'Limit the number of changesets'),
+    FlagOption('=u', '--user=', 'Filter on user'),
+    FlagOption('=k', '--keyword=', 'Filter by keyword'),
+    FlagOption('=b', '--branch=', 'Filter by branch'),
+    FlagOption('=B', '--bookmark=', 'Filter by bookmark'),
+    FlagOption('=I', '--include=', 'Include files'),
+    FlagOption('=E', '--exclude=', 'Exclude files'),
   },
 }
 
+-- Add reverse lookups
 for _, list in pairs(HgAdapter.flags) do
   for i, option in ipairs(list) do
-    option = vim.tbl_extend("keep", option, {
-      prompt_fmt = "${label}${flag_name}",
-
-      key = option.key or utils.str_match(option[2], {
-        "^%-%-?([^=]+)=?",
-        "^%+%+?([^=]+)=?",
-      }):gsub("%-", "_"),
-
-      ---@param self FlagOption
-      ---@param value string|string[]
-      render_value = function(self, value)
-        local quoted
-
-        if type(value) == "table" then
-          quoted = table.concat(vim.tbl_map(function(v)
-            return self[2] .. utils.str_quote(v, { only_if_whitespace = true })
-          end, value), " ")
-        else
-          quoted = self[2] .. utils.str_quote(value, { only_if_whitespace = true })
-        end
-
-        return value == "", quoted
-      end,
-
-      ---@param value string|string[]
-      render_default = function(_, value)
-        if value == nil then
-          return ""
-        elseif type(value) == "table" then
-          return table.concat(vim.tbl_map(function(v)
-            v = select(1, v:gsub("\\", "\\\\"))
-            return utils.str_quote(v, { only_if_whitespace = true })
-          end, value), " ")
-        end
-        return utils.str_quote(value, { only_if_whitespace = true })
-      end,
-    })
-
     list[i] = option
     list[option.key] = option
   end

From 9c6c81de1f471e2229c262364dca4a698f168211 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Fri, 27 Jan 2023 07:56:00 +0100
Subject: [PATCH 17/27] fix: return first ancestorlinknode as merge-base

---
 lua/diffview/vcs/adapters/hg/init.lua | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 3ea6ddd8..c0c70ec3 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -140,6 +140,9 @@ function HgAdapter:get_merge_context()
   end
 
   local data = vim.json.decode(table.concat(out, ""))
+
+  ret.base = { hash = "" }
+
   for _, commit in ipairs(data[1].commits) do
     if commit.name == "other" then
       ret.theirs = { hash = commit.node }
@@ -156,8 +159,14 @@ function HgAdapter:get_merge_context()
     end
   end
 
-  -- Base is ancestorlinknode (per file)
-  ret.base = { hash = "" }
+  for _, file in ipairs(data[1].files) do
+    for _, extra in ipairs(file.extras) do
+      if (extra.key == 'ancestorlinknode' and extra.value ~= HgAdapter.Rev.NULL_TREE_SHA) then
+        ret.base.hash = extra.value
+        break
+      end
+    end
+  end
 
   return ret
 end

From dafbf1aba3ad7b7df5df2b4ff13b90c5c2d14274 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Fri, 27 Jan 2023 08:47:01 +0100
Subject: [PATCH 18/27] fix: use direct arguments to indicate range (WIP)

---
 lua/diffview/vcs/adapters/hg/init.lua | 57 ++++++++++++++++++++++++---
 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index c0c70ec3..26df2451 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -695,11 +695,9 @@ end
 function HgAdapter:diffview_options(args)
   local default_args = config.get_config().default_args.DiffviewOpen
   local argo = arg_parser.parse(vim.tbl_flatten({ default_args, args }))
-  local rev_args = argo:get_flag({'rev'})
+  local rev_args = argo.args[1]
 
-  local head = self:head_rev()
-  local left = head or HgRev.new_null_tree()
-  local right = HgRev(RevType.LOCAL)
+  local left, right = self:parse_revs(rev_args, {})
 
   local options = {
     show_untracked = true, -- TODO: extract from hg config
@@ -743,7 +741,7 @@ function HgAdapter:rev_to_args(left, right)
     "Can't diff LOCAL against LOCAL!"
   )
   if left.type == RevType.COMMIT and right.type == RevType.COMMIT then
-    return { '--rev="' .. left.commit .. '::' .. right.commit .. '"' }
+    return { '--rev=' .. left.commit .. '::' .. right.commit}
   elseif left.type == RevType.STAGE and right.type == RevType.LOCAL then
     return {}
   else
@@ -751,6 +749,55 @@ function HgAdapter:rev_to_args(left, right)
   end
 end
 
+
+---Determine whether a rev arg is a range.
+---@param rev_arg string
+---@return boolean
+function HgAdapter:is_rev_arg_range(rev_arg)
+  return utils.str_match(rev_arg, {
+    "%:",
+    "%:%:",
+  }) ~= nil
+end
+
+---Parse a given rev arg.
+---@param rev_arg string
+---@param opt table
+---@return Rev? left
+---@return Rev? right
+function HgAdapter:parse_revs(rev_arg, opt)
+  ---@type Rev?
+  local left
+  ---@type Rev?
+  local right
+
+  local head = self:head_rev()
+  ---@cast head Rev
+
+  if not rev_arg then
+    left = head or HgRev.new_null_tree()
+    right = HgRev(RevType.LOCAL)
+  else
+    local from, to = rev_arg:match("([^:]*)%:%:?(.*)$")
+
+    if from and from ~= ""  and to and to ~= "" then
+      left = HgRev(RevType.COMMIT, from)
+      right = HgRev(RevType.COMMIT, to)
+    elseif from and from ~= "" then
+      left = HgRev(RevType.COMMIT, from)
+      right = head
+    elseif to and to ~= "" then
+      left = HgRev.new_null_tree()
+      right = HgRev(RevType.COMMIT, to)
+    else
+      utils.err(("Failed to parse rev %s"):format(utils.str_quote(rev_arg)))
+      return
+    end
+  end
+
+  return left, right 
+end
+
 function HgAdapter:file_restore(path, kind, commit)
   local out, code
   local abs_path = utils.path:join(self.ctx.toplevel, path)

From c0e80ed3fab06d2d637b72879b6ba1f93e1ab0d9 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Thu, 2 Feb 2023 08:40:02 +0100
Subject: [PATCH 19/27] fixup! fix: use direct arguments to indicate range
 (WIP)

---
 lua/diffview/vcs/adapters/hg/rev.lua | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index ed47d544..58178361 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -29,6 +29,10 @@ function HgRev:init(rev_type, revision, track_head)
   self.commit = revision
 end
 
+function HgRev:new_null_tree()
+  return HgRev(RevType.COMMIT, HgRev.NULL_TREE_SHA)
+end
+
 function HgRev:object_name(abbrev_len)
   if self.commit then
     if abbrev_len then

From 20f9698db46bdf6ecb035f244f61b9bde29bd967 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Thu, 2 Feb 2023 08:46:55 +0100
Subject: [PATCH 20/27] fixup! fix: use direct arguments to indicate range
 (WIP)

---
 lua/diffview/vcs/adapters/hg/init.lua | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 26df2451..b81b24f3 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -698,6 +698,9 @@ function HgAdapter:diffview_options(args)
   local rev_args = argo.args[1]
 
   local left, right = self:parse_revs(rev_args, {})
+  if not (left and right) then
+    return
+  end
 
   local options = {
     show_untracked = true, -- TODO: extract from hg config
@@ -778,7 +781,7 @@ function HgAdapter:parse_revs(rev_arg, opt)
     left = head or HgRev.new_null_tree()
     right = HgRev(RevType.LOCAL)
   else
-    local from, to = rev_arg:match("([^:]*)%:%:?(.*)$")
+    local from, to = rev_arg:match("([^:]*)%:?%:?(.*)$")
 
     if from and from ~= ""  and to and to ~= "" then
       left = HgRev(RevType.COMMIT, from)

From e3db8f4cff0ec0bbc477e7c089e1a150c9559f25 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Thu, 2 Feb 2023 08:52:34 +0100
Subject: [PATCH 21/27] fixup! fix: use direct arguments to indicate range
 (WIP)

---
 lua/diffview/vcs/adapters/hg/init.lua | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index b81b24f3..09126f4e 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -793,8 +793,13 @@ function HgAdapter:parse_revs(rev_arg, opt)
       left = HgRev.new_null_tree()
       right = HgRev(RevType.COMMIT, to)
     else
-      utils.err(("Failed to parse rev %s"):format(utils.str_quote(rev_arg)))
-      return
+      local _, code, stderr = self:exec_sync({"log", "--rev=" .. rev_arg}, selc.ctx.toplevel)
+      if code ~= 0 then
+        utils.err(("Failed to parse rev %s"):format(utils.str_quote(rev_arg)))
+        return
+      end
+      -- Revset parsed correctly
+      return rev_arg, nil
     end
   end
 

From 868090ecb513a181611760b68c16e98336cacc0f Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 8 Feb 2023 08:30:50 +0100
Subject: [PATCH 22/27] fix: handle empty files

---
 lua/diffview/vcs/adapters/hg/init.lua | 54 ++++++++++++++++-----------
 1 file changed, 32 insertions(+), 22 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 09126f4e..706464e4 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -713,11 +713,9 @@ function HgAdapter:diffview_options(args)
 end
 
 function HgAdapter:rev_to_pretty_string(left, right)
-  if left.track_head and right.type == RevType.LOCAL then
-    return nil
-  elseif left.commit and right.type == RevType.LOCAL then
-    return left:abbrev()
-  elseif left.commit and right.commit then
+  if left.type == RevType.CUSTOM then
+    return left.commit
+  elseif right and right.commit then
     return left:abbrev() .. "::" .. right:abbrev()
   end
   return nil
@@ -781,7 +779,7 @@ function HgAdapter:parse_revs(rev_arg, opt)
     left = head or HgRev.new_null_tree()
     right = HgRev(RevType.LOCAL)
   else
-    local from, to = rev_arg:match("([^:]*)%:?%:?(.*)$")
+    local from, to = rev_arg:match("([^:]*)%:%:?(.*)$")
 
     if from and from ~= ""  and to and to ~= "" then
       left = HgRev(RevType.COMMIT, from)
@@ -793,13 +791,20 @@ function HgAdapter:parse_revs(rev_arg, opt)
       left = HgRev.new_null_tree()
       right = HgRev(RevType.COMMIT, to)
     else
-      local _, code, stderr = self:exec_sync({"log", "--rev=" .. rev_arg}, selc.ctx.toplevel)
-      if code ~= 0 then
-        utils.err(("Failed to parse rev %s"):format(utils.str_quote(rev_arg)))
+      local node, code, stderr = self:exec_sync({"log", "--limit=1", "--template={node}",  "--rev=" .. rev_arg}, self.ctx.toplevel)
+      if code ~= 0 and node then
+        utils.err(("Failed to parse rev %s: %s"):format(utils.str_quote(rev_arg), stderr))
         return
       end
-      -- Revset parsed correctly
-      return rev_arg, nil
+      left = HgRev(RevType.COMMIT, node[1])
+
+      node, code, stderr = self:exec_sync({"log", "--limit=1", "--template={node}",  "--rev=reverse(" .. rev_arg .. ")"}, self.ctx.toplevel)
+      if code ~= 0  and node then
+        utils.err(("Failed to parse rev %s: %s"):format(utils.str_quote(rev_arg), stderr))
+        return
+      end
+
+      right = HgRev(RevType.COMMIT, node[1])
     end
   end
 
@@ -938,6 +943,7 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   local namestat_out = namestat_job:result()
   local mergestate_out = mergestate_job:result()
 
+
   local data = {}
   local conflict_map = {}
   local file_info = {}
@@ -945,20 +951,24 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   -- Last line in numstat is a summary and should not be used
   table.remove(numstat_out, -1)
 
-  for i, s in ipairs(namestat_out) do
+  local numstat_info = {}
+  for _, s in ipairs(numstat_out) do
+      local name, changes, diffstats = s:match("(%s*)|%s+(%d+)%s+([+-]+)")
+      if changes and diffstats then
+        local _, adds = diffstats:gsub("+", "")
+
+        numstat_info[name] = {
+          additions = tonumber(adds),
+          deletions = tonumber(changes) - tonumber(adds),
+        }
+      end
+  end
+
+  for _, s in ipairs(namestat_out) do
     local status = s:sub(1, 1):gsub("%s", " ")
     local name = vim.trim(s:match("[%a%s]%s*(.*)"))
 
-    local stats = {}
-    local changes, diffstats = numstat_out[i]:match(".*|%s+(%d+)%s+([+-]+)")
-    if changes and diffstats then
-      local _, adds = diffstats:gsub("+", "")
-
-      stats = {
-        additions = tonumber(adds),
-        deletions = tonumber(changes) - tonumber(adds),
-      }
-    end
+    local stats = numstat_info[name] or {}
 
     if not (kind == "staged") then
       file_info[name] = {

From e84d44f88bdd01d7e8f4acb3827006de64e28287 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 14 Feb 2023 07:36:37 +0100
Subject: [PATCH 23/27] fixup! fix: use direct arguments to indicate range
 (WIP)

---
 lua/diffview/vcs/adapters/hg/init.lua | 4 ++++
 lua/diffview/vcs/adapters/hg/rev.lua  | 8 +++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 706464e4..6cfe12ce 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -805,6 +805,10 @@ function HgAdapter:parse_revs(rev_arg, opt)
       end
 
       right = HgRev(RevType.COMMIT, node[1])
+      -- If we refer to a single revision, show diff with working directory
+      if node[1] == left.commit then
+        right = HgRev(RevType.LOCAL )
+      end
     end
   end
 
diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index 58178361..ccb6e3e6 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -46,10 +46,12 @@ function HgRev:object_name(abbrev_len)
 end
 
 function HgRev.to_range(rev_from, rev_to)
-  if rev_to then
-    return rev_from .. "::" .. rev_to
+  if rev_from and rev_to then
+    return rev_from.commit .. "::" .. rev_to.commit
+  elseif rev_to then
+    return "::" .. rev_to.commit
   end
-  return rev_from
+  return rev_from.commit .. "::"
 end
 
 M.HgRev = HgRev

From f03052e41e0e2849043f2816017e6a181af8bf38 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Tue, 14 Feb 2023 07:48:55 +0100
Subject: [PATCH 24/27] feat: add rev completion

---
 lua/diffview/vcs/adapters/hg/init.lua | 33 ++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 6cfe12ce..245177bf 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -1181,7 +1181,38 @@ end
 
 -- TODO: implement completion
 function HgAdapter:rev_candidates(arg_lead, opt)
-  return { }
+  opt = vim.tbl_extend("keep", opt or {}, { accept_range = false }) --[[@as RevCompletionSpec ]]
+  logger.lvl(1).debug("[completion] Revision candidates requested")
+
+  local branches = self:exec_sync(
+    { "branches", "--template={branch}\n" },
+    { cwd = self.ctx.toplevel, silent = true }
+  )
+
+  local heads = self:exec_sync(
+    { "heads", "--template={node|short}\n" },
+    { cwd = self.ctx.toplevel, silent = true }
+  )
+
+  local ret = utils.vec_join(heads, branches)
+
+  if opt.accept_range then
+    local _, range_end = utils.str_match(arg_lead, {
+      "^(%:%:?)()$",
+      "^(%:%:?)()[^:]",
+      "[^:](%:%:?)()$",
+      "[^:](%:%:?)()[^:]",
+    })
+
+    if range_end then
+      local range_lead = arg_lead:sub(1, range_end - 1)
+      ret = vim.tbl_map(function(v)
+        return range_lead .. v
+      end, ret)
+    end
+  end
+
+  return ret
 end
 
 function HgAdapter:init_completion()

From 0cd8fb814b635c8178a10ac5bce81d7a44884b1d Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Wed, 15 Feb 2023 19:08:18 +0100
Subject: [PATCH 25/27] fix: match file names from numstat output correctly

---
 lua/diffview/vcs/adapters/hg/init.lua | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 245177bf..a30e6ae8 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -953,11 +953,11 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   local file_info = {}
 
   -- Last line in numstat is a summary and should not be used
-  table.remove(numstat_out, -1)
+  table.remove(numstat_out, #numstat_out)
 
   local numstat_info = {}
   for _, s in ipairs(numstat_out) do
-      local name, changes, diffstats = s:match("(%s*)|%s+(%d+)%s+([+-]+)")
+      local name, changes, diffstats = s:match("%s*([^|]*)%s+|%s+(%d+)%s+([+-]+)")
       if changes and diffstats then
         local _, adds = diffstats:gsub("+", "")
 
@@ -969,17 +969,19 @@ HgAdapter.tracked_files = async.wrap(function (self, left, right, args, kind, op
   end
 
   for _, s in ipairs(namestat_out) do
-    local status = s:sub(1, 1):gsub("%s", " ")
-    local name = vim.trim(s:match("[%a%s]%s*(.*)"))
+    if s ~= " " then
+      local status = s:sub(1, 1):gsub("%s", " ")
+      local name = vim.trim(s:match("[%a%s]%s*(.*)"))
 
-    local stats = numstat_info[name] or {}
+      local stats = numstat_info[name] or {}
 
-    if not (kind == "staged") then
-      file_info[name] = {
-        status = status,
-        name = name,
-        stats = stats,
-      }
+      if not (kind == "staged") then
+        file_info[name] = {
+          status = status,
+          name = name,
+          stats = stats,
+        }
+      end
     end
   end
 

From 673b58fe1a0b13f4a4fdcca5166ac41a2156c5c9 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Thu, 16 Feb 2023 22:04:33 +0100
Subject: [PATCH 26/27] fix: return error message from HgAdapter.create

---
 lua/diffview/vcs/adapters/hg/init.lua | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index a30e6ae8..74744afa 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -94,15 +94,29 @@ function M.find_toplevel(top_indicators)
       local rel_path = pl:relative(v, ".")
       return utils.str_quote(rel_path == "" and "." or rel_path)
     end, top_indicators) --[[@as vector ]], ", "))
-  ), nil
+  ), ""
 end
 
+---@param toplevel string
+---@param path_args string[]
+---@param cpath string?
+---@return string? err
+---@return HgAdapter
 function M.create(toplevel, path_args, cpath)
-  return HgAdapter({
+  local err
+  local adapter = HgAdapter({
     toplevel = toplevel,
     path_args = path_args,
     cpath = cpath,
   })
+
+  if not adapter.ctx.toplevel then
+    err = "Could not file top-level of the repository!"
+  elseif not pl:is_dir(adapter.ctx.toplevel) then
+    err = "The top-level is not a readable directory: " .. adapter.ctx.toplevel
+  end
+
+  return err, adapter
 end
 
 function HgAdapter:init(opt)

From 660ec6988dfae88a123c7cd0c93d6eb80dda3b53 Mon Sep 17 00:00:00 2001
From: zegervdv <zegervdv@me.com>
Date: Sun, 19 Feb 2023 17:52:37 +0100
Subject: [PATCH 27/27] fix: address review comments

---
 lua/diffview/scene/views/diff/diff_view.lua | 3 ++-
 lua/diffview/vcs/adapters/hg/init.lua       | 6 ++++--
 lua/diffview/vcs/adapters/hg/rev.lua        | 2 +-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/lua/diffview/scene/views/diff/diff_view.lua b/lua/diffview/scene/views/diff/diff_view.lua
index fe04da15..dd7935a3 100644
--- a/lua/diffview/scene/views/diff/diff_view.lua
+++ b/lua/diffview/scene/views/diff/diff_view.lua
@@ -17,6 +17,7 @@ local debounce = lazy.require("diffview.debounce") ---@module "diffview.debounce
 local logger = lazy.require("diffview.logger") ---@module "diffview.logger"
 local utils = lazy.require("diffview.utils") ---@module "diffview.utils"
 local vcs_utils = lazy.require("diffview.vcs.utils") ---@module "diffview.vcs.utils"
+local GitAdapter = lazy.access("diffview.vcs.adapters.git", "GitAdapter") ---@type GitAdapter|LazyModule
 
 local api = vim.api
 local M = {}
@@ -125,7 +126,7 @@ function DiffView:post_open()
     name = ("diffview://%s/log/%d/%s"):format(self.adapter.ctx.dir, self.tabpage, "commit_log"),
   })
 
-  if config.get_config().watch_index then
+  if config.get_config().watch_index and self.adapter:instanceof(GitAdapter.__get()) then
     self.watcher = vim.loop.new_fs_poll()
     ---@diagnostic disable-next-line: unused-local
     self.watcher:start(self.adapter.ctx.dir .. "/index", 1000, function(err, prev, cur)
diff --git a/lua/diffview/vcs/adapters/hg/init.lua b/lua/diffview/vcs/adapters/hg/init.lua
index 74744afa..8e259a80 100644
--- a/lua/diffview/vcs/adapters/hg/init.lua
+++ b/lua/diffview/vcs/adapters/hg/init.lua
@@ -727,8 +727,10 @@ function HgAdapter:diffview_options(args)
 end
 
 function HgAdapter:rev_to_pretty_string(left, right)
-  if left.type == RevType.CUSTOM then
-    return left.commit
+  if left.track_head and right.type == RevType.LOCAL then
+    return nil
+  elseif left.commit and right.type == RevType.LOCAL then
+    return left:abbrev()
   elseif right and right.commit then
     return left:abbrev() .. "::" .. right:abbrev()
   end
diff --git a/lua/diffview/vcs/adapters/hg/rev.lua b/lua/diffview/vcs/adapters/hg/rev.lua
index ccb6e3e6..f539831c 100644
--- a/lua/diffview/vcs/adapters/hg/rev.lua
+++ b/lua/diffview/vcs/adapters/hg/rev.lua
@@ -29,7 +29,7 @@ function HgRev:init(rev_type, revision, track_head)
   self.commit = revision
 end
 
-function HgRev:new_null_tree()
+function HgRev.new_null_tree()
   return HgRev(RevType.COMMIT, HgRev.NULL_TREE_SHA)
 end