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#include "cache.h"
#include "builtin.h"
#include "parse-options.h"
#include "refs.h"
#include "commit.h"
#include "tree.h"
#include "tree-walk.h"
#include "cache-tree.h"
#include "unpack-trees.h"
#include "dir.h"
#include "run-command.h"
#include "merge-recursive.h"
#include "branch.h"
#include "diff.h"
#include "revision.h"
#include "remote.h"
#include "blob.h"
#include "xdiff-interface.h"
#include "ll-merge.h"

static const char * const checkout_usage[] = {
"git checkout [options] <branch>",
"git checkout [options] [<branch>] -- <file>...",
NULL,
};

struct checkout_opts {
int quiet;
int merge;
int force;
int writeout_stage;
int writeout_error;

const char *new_branch;
int new_branch_log;
enum branch_track track;
};

static int post_checkout_hook(struct commit *old, struct commit *new,
int changed)
{
return run_hook(NULL, "post-checkout",
sha1_to_hex(old ? old->object.sha1 : null_sha1),
sha1_to_hex(new ? new->object.sha1 : null_sha1),
changed ? "1" : "0", NULL);
/* "new" can be NULL when checking out from the index before
a commit exists. */

}

static int update_some(const unsigned char *sha1, const char *base, int baselen,
const char *pathname, unsigned mode, int stage, void *context)
{
int len;
struct cache_entry *ce;

if (S_ISDIR(mode))
return READ_TREE_RECURSIVE;

len = baselen + strlen(pathname);
ce = xcalloc(1, cache_entry_size(len));
hashcpy(ce->sha1, sha1);
memcpy(ce->name, base, baselen);
memcpy(ce->name + baselen, pathname, len - baselen);
ce->ce_flags = create_ce_flags(len, 0);
ce->ce_mode = create_ce_mode(mode);
add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
return 0;
}

static int read_tree_some(struct tree *tree, const char **pathspec)
{
read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);

/* update the index with the given tree's info
* for all args, expanding wildcards, and exit
* with any non-zero return code.
*/
return 0;
}

static int skip_same_name(struct cache_entry *ce, int pos)
{
while (++pos < active_nr &&
!strcmp(active_cache[pos]->name, ce->name))
; /* skip */
return pos;
}

static int check_stage(int stage, struct cache_entry *ce, int pos)
{
while (pos < active_nr &&
!strcmp(active_cache[pos]->name, ce->name)) {
if (ce_stage(active_cache[pos]) == stage)
return 0;
pos++;
}
return error("path '%s' does not have %s version",
ce->name,
(stage == 2) ? "our" : "their");
}

static int check_all_stages(struct cache_entry *ce, int pos)
{
if (ce_stage(ce) != 1 ||
active_nr <= pos + 2 ||
strcmp(active_cache[pos+1]->name, ce->name) ||
ce_stage(active_cache[pos+1]) != 2 ||
strcmp(active_cache[pos+2]->name, ce->name) ||
ce_stage(active_cache[pos+2]) != 3)
return error("path '%s' does not have all three versions",
ce->name);
return 0;
}

static int checkout_stage(int stage, struct cache_entry *ce, int pos,
struct checkout *state)
{
while (pos < active_nr &&
!strcmp(active_cache[pos]->name, ce->name)) {
if (ce_stage(active_cache[pos]) == stage)
return checkout_entry(active_cache[pos], state, NULL);
pos++;
}
return error("path '%s' does not have %s version",
ce->name,
(stage == 2) ? "our" : "their");
}

/* NEEDSWORK: share with merge-recursive */
static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
{
unsigned long size;
enum object_type type;

if (!hashcmp(sha1, null_sha1)) {
mm->ptr = xstrdup("");
mm->size = 0;
return;
}

mm->ptr = read_sha1_file(sha1, &type, &size);
if (!mm->ptr || type != OBJ_BLOB)
die("unable to read blob object %s", sha1_to_hex(sha1));
mm->size = size;
}

static int checkout_merged(int pos, struct checkout *state)
{
struct cache_entry *ce = active_cache[pos];
const char *path = ce->name;
mmfile_t ancestor, ours, theirs;
int status;
unsigned char sha1[20];
mmbuffer_t result_buf;

if (ce_stage(ce) != 1 ||
active_nr <= pos + 2 ||
strcmp(active_cache[pos+1]->name, path) ||
ce_stage(active_cache[pos+1]) != 2 ||
strcmp(active_cache[pos+2]->name, path) ||
ce_stage(active_cache[pos+2]) != 3)
return error("path '%s' does not have all 3 versions", path);

fill_mm(active_cache[pos]->sha1, &ancestor);
fill_mm(active_cache[pos+1]->sha1, &ours);
fill_mm(active_cache[pos+2]->sha1, &theirs);

status = ll_merge(&result_buf, path, &ancestor,
&ours, "ours", &theirs, "theirs", 1);
free(ancestor.ptr);
free(ours.ptr);
free(theirs.ptr);
if (status < 0 || !result_buf.ptr) {
free(result_buf.ptr);
return error("path '%s': cannot merge", path);
}

/*
* NEEDSWORK:
* There is absolutely no reason to write this as a blob object
* and create a phony cache entry just to leak. This hack is
* primarily to get to the write_entry() machinery that massages
* the contents to work-tree format and writes out which only
* allows it for a cache entry. The code in write_entry() needs
* to be refactored to allow us to feed a <buffer, size, mode>
* instead of a cache entry. Such a refactoring would help
* merge_recursive as well (it also writes the merge result to the
* object database even when it may contain conflicts).
*/
if (write_sha1_file(result_buf.ptr, result_buf.size,
blob_type, sha1))
die("Unable to add merge result for '%s'", path);
ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
sha1,
path, 2, 0);
if (!ce)
die("make_cache_entry failed for path '%s'", path);
status = checkout_entry(ce, state, NULL);
return status;
}

static int checkout_paths(struct tree *source_tree, const char **pathspec,
struct checkout_opts *opts)
{
int pos;
struct checkout state;
static char *ps_matched;
unsigned char rev[20];
int flag;
struct commit *head;
int errs = 0;
int stage = opts->writeout_stage;
int merge = opts->merge;
int newfd;
struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));

newfd = hold_locked_index(lock_file, 1);
if (read_cache_preload(pathspec) < 0)
return error("corrupt index file");

if (source_tree)
read_tree_some(source_tree, pathspec);

for (pos = 0; pathspec[pos]; pos++)
;
ps_matched = xcalloc(1, pos);

for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
}

if (report_path_error(ps_matched, pathspec, 0))
return 1;

/* Any unmerged paths? */
for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
if (!ce_stage(ce))
continue;
if (opts->force) {
warning("path '%s' is unmerged", ce->name);
} else if (stage) {
errs |= check_stage(stage, ce, pos);
} else if (opts->merge) {
errs |= check_all_stages(ce, pos);
} else {
errs = 1;
error("path '%s' is unmerged", ce->name);
}
pos = skip_same_name(ce, pos) - 1;
}
}
if (errs)
return 1;

/* Now we are committed to check them out */
memset(&state, 0, sizeof(state));
state.force = 1;
state.refresh_cache = 1;
for (pos = 0; pos < active_nr; pos++) {
struct cache_entry *ce = active_cache[pos];
if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
if (!ce_stage(ce)) {
errs |= checkout_entry(ce, &state, NULL);
continue;
}
if (stage)
errs |= checkout_stage(stage, ce, pos, &state);
else if (merge)
errs |= checkout_merged(pos, &state);
pos = skip_same_name(ce, pos) - 1;
}
}

if (write_cache(newfd, active_cache, active_nr) ||
commit_locked_index(lock_file))
die("unable to write new index file");

resolve_ref("HEAD", rev, 0, &flag);
head = lookup_commit_reference_gently(rev, 1);

errs |= post_checkout_hook(head, head, 0);
return errs;
}

static void show_local_changes(struct object *head)
{
struct rev_info rev;
/* I think we want full paths, even if we're in a subdirectory. */
init_revisions(&rev, NULL);
rev.abbrev = 0;
rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
if (diff_setup_done(&rev.diffopt) < 0)
die("diff_setup_done failed");
add_pending_object(&rev, head, NULL);
run_diff_index(&rev, 0);
}

static void describe_detached_head(char *msg, struct commit *commit)
{
struct strbuf sb = STRBUF_INIT;
struct pretty_print_context ctx = {0};
parse_commit(commit);
pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, &ctx);
fprintf(stderr, "%s %s... %s\n", msg,
find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
strbuf_release(&sb);
}

static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
{
struct unpack_trees_options opts;
struct tree_desc tree_desc;

memset(&opts, 0, sizeof(opts));
opts.head_idx = -1;
opts.update = worktree;
opts.skip_unmerged = !worktree;
opts.reset = 1;
opts.merge = 1;
opts.fn = oneway_merge;
opts.verbose_update = !o->quiet;
opts.src_index = &the_index;
opts.dst_index = &the_index;
parse_tree(tree);
init_tree_desc(&tree_desc, tree->buffer, tree->size);
switch (unpack_trees(1, &tree_desc, &opts)) {
case -2:
o->writeout_error = 1;
/*
* We return 0 nevertheless, as the index is all right
* and more importantly we have made best efforts to
* update paths in the work tree, and we cannot revert
* them.
*/
case 0:
return 0;
default:
return 128;
}
}

struct branch_info {
const char *name; /* The short name used */
const char *path; /* The full name of a real branch */
struct commit *commit; /* The named commit */
};

static void setup_branch_path(struct branch_info *branch)
{
struct strbuf buf = STRBUF_INIT;

strbuf_branchname(&buf, branch->name);
if (strcmp(buf.buf, branch->name))
branch->name = xstrdup(buf.buf);
strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
branch->path = strbuf_detach(&buf, NULL);
}

static int merge_working_tree(struct checkout_opts *opts,
struct branch_info *old, struct branch_info *new)
{
int ret;
struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
int newfd = hold_locked_index(lock_file, 1);

if (read_cache_preload(NULL) < 0)
return error("corrupt index file");

if (opts->force) {
ret = reset_tree(new->commit->tree, opts, 1);
if (ret)
return ret;
} else {
struct tree_desc trees[2];
struct tree *tree;
struct unpack_trees_options topts;

memset(&topts, 0, sizeof(topts));
topts.head_idx = -1;
topts.src_index = &the_index;
topts.dst_index = &the_index;

topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";

refresh_cache(REFRESH_QUIET);

if (unmerged_cache()) {
error("you need to resolve your current index first");
return 1;
}

/* 2-way merge to the new branch */
topts.initial_checkout = is_cache_unborn();
topts.update = 1;
topts.merge = 1;
topts.gently = opts->merge;
topts.verbose_update = !opts->quiet;
topts.fn = twoway_merge;
topts.dir = xcalloc(1, sizeof(*topts.dir));
topts.dir->flags |= DIR_SHOW_IGNORED;
topts.dir->exclude_per_dir = ".gitignore";
tree = parse_tree_indirect(old->commit ?
old->commit->object.sha1 :
(unsigned char *)EMPTY_TREE_SHA1_BIN);
init_tree_desc(&trees[0], tree->buffer, tree->size);
tree = parse_tree_indirect(new->commit->object.sha1);
init_tree_desc(&trees[1], tree->buffer, tree->size);

ret = unpack_trees(2, trees, &topts);
if (ret == -1) {
/*
* Unpack couldn't do a trivial merge; either
* give up or do a real merge, depending on
* whether the merge flag was used.
*/
struct tree *result;
struct tree *work;
struct merge_options o;
if (!opts->merge)
return 1;
parse_commit(old->commit);

/* Do more real merge */

/*
* We update the index fully, then write the
* tree from the index, then merge the new
* branch with the current tree, with the old
* branch as the base. Then we reset the index
* (but not the working tree) to the new
* branch, leaving the working tree as the
* merged version, but skipping unmerged
* entries in the index.
*/

add_files_to_cache(NULL, NULL, 0);
init_merge_options(&o);
o.verbosity = 0;
work = write_tree_from_memory(&o);

ret = reset_tree(new->commit->tree, opts, 1);
if (ret)
return ret;
o.branch1 = new->name;
o.branch2 = "local";
merge_trees(&o, new->commit->tree, work,
old->commit->tree, &result);
ret = reset_tree(new->commit->tree, opts, 0);
if (ret)
return ret;
}
}

if (write_cache(newfd, active_cache, active_nr) ||
commit_locked_index(lock_file))
die("unable to write new index file");

if (!opts->force && !opts->quiet)
show_local_changes(&new->commit->object);

return 0;
}

static void report_tracking(struct branch_info *new)
{
struct strbuf sb = STRBUF_INIT;
struct branch *branch = branch_get(new->name);

if (!format_tracking_info(branch, &sb))
return;
fputs(sb.buf, stdout);
strbuf_release(&sb);
}

static void update_refs_for_switch(struct checkout_opts *opts,
struct branch_info *old,
struct branch_info *new)
{
struct strbuf msg = STRBUF_INIT;
const char *old_desc;
if (opts->new_branch) {
create_branch(old->name, opts->new_branch, new->name, 0,
opts->new_branch_log, opts->track);
new->name = opts->new_branch;
setup_branch_path(new);
}

old_desc = old->name;
if (!old_desc && old->commit)
old_desc = sha1_to_hex(old->commit->object.sha1);
strbuf_addf(&msg, "checkout: moving from %s to %s",
old_desc ? old_desc : "(invalid)", new->name);

if (new->path) {
create_symref("HEAD", new->path, msg.buf);
if (!opts->quiet) {
if (old->path && !strcmp(new->path, old->path))
fprintf(stderr, "Already on '%s'\n",
new->name);
else
fprintf(stderr, "Switched to%s branch '%s'\n",
opts->new_branch ? " a new" : "",
new->name);
}
} else if (strcmp(new->name, "HEAD")) {
update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
REF_NODEREF, DIE_ON_ERR);
if (!opts->quiet) {
if (old->path)
fprintf(stderr, "Note: moving to '%s' which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n git checkout -b <new_branch_name>\n", new->name);
describe_detached_head("HEAD is now at", new->commit);
}
}
remove_branch_state();
strbuf_release(&msg);
if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
report_tracking(new);
}

static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
{
int ret = 0;
struct branch_info old;
unsigned char rev[20];
int flag;
memset(&old, 0, sizeof(old));
old.path = resolve_ref("HEAD", rev, 0, &flag);
old.commit = lookup_commit_reference_gently(rev, 1);
if (!(flag & REF_ISSYMREF))
old.path = NULL;

if (old.path && !prefixcmp(old.path, "refs/heads/"))
old.name = old.path + strlen("refs/heads/");

if (!new->name) {
new->name = "HEAD";
new->commit = old.commit;
if (!new->commit)
die("You are on a branch yet to be born");
parse_commit(new->commit);
}

ret = merge_working_tree(opts, &old, new);
if (ret)
return ret;

/*
* If we were on a detached HEAD, but have now moved to
* a new commit, we want to mention the old commit once more
* to remind the user that it might be lost.
*/
if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
describe_detached_head("Previous HEAD position was", old.commit);

update_refs_for_switch(opts, &old, new);

ret = post_checkout_hook(old.commit, new->commit, 1);
return ret || opts->writeout_error;
}

static int git_checkout_config(const char *var, const char *value, void *cb)
{
return git_xmerge_config(var, value, cb);
}

static int interactive_checkout(const char *revision, const char **pathspec,
struct checkout_opts *opts)
{
return run_add_interactive(revision, "--patch=checkout", pathspec);
}

struct tracking_name_data {
const char *name;
char *remote;
int unique;
};

static int check_tracking_name(const char *refname, const unsigned char *sha1,
int flags, void *cb_data)
{
struct tracking_name_data *cb = cb_data;
const char *slash;

if (prefixcmp(refname, "refs/remotes/"))
return 0;
slash = strchr(refname + 13, '/');
if (!slash || strcmp(slash + 1, cb->name))
return 0;
if (cb->remote) {
cb->unique = 0;
return 0;
}
cb->remote = xstrdup(refname);
return 0;
}

static const char *unique_tracking_name(const char *name)
{
struct tracking_name_data cb_data = { name, NULL, 1 };
for_each_ref(check_tracking_name, &cb_data);
if (cb_data.unique)
return cb_data.remote;
free(cb_data.remote);
return NULL;
}

int cmd_checkout(int argc, const char **argv, const char *prefix)
{
struct checkout_opts opts;
unsigned char rev[20];
const char *arg;
struct branch_info new;
struct tree *source_tree = NULL;
char *conflict_style = NULL;
int patch_mode = 0;
int dwim_new_local_branch = 1;
struct option options[] = {
OPT__QUIET(&opts.quiet),
OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
OPT_SET_INT('t', "track", &opts.track, "track",
BRANCH_TRACK_EXPLICIT),
OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
2),
OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
3),
OPT_BOOLEAN('f', "force", &opts.force, "force"),
OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
OPT_STRING(0, "conflict", &conflict_style, "style",
"conflict style (merge or diff3)"),
OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
{ OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
"second guess 'git checkout no-such-branch'",
PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
OPT_END(),
};
int has_dash_dash;

memset(&opts, 0, sizeof(opts));
memset(&new, 0, sizeof(new));

git_config(git_checkout_config, NULL);

opts.track = BRANCH_TRACK_UNSPECIFIED;

argc = parse_options(argc, argv, prefix, options, checkout_usage,
PARSE_OPT_KEEP_DASHDASH);

if (patch_mode && (opts.track > 0 || opts.new_branch
|| opts.new_branch_log || opts.merge || opts.force))
die ("--patch is incompatible with all other options");

/* --track without -b should DWIM */
if (0 < opts.track && !opts.new_branch) {
const char *argv0 = argv[0];
if (!argc || !strcmp(argv0, "--"))
die ("--track needs a branch name");
if (!prefixcmp(argv0, "refs/"))
argv0 += 5;
if (!prefixcmp(argv0, "remotes/"))
argv0 += 8;
argv0 = strchr(argv0, '/');
if (!argv0 || !argv0[1])
die ("Missing branch name; try -b");
opts.new_branch = argv0 + 1;
}

if (conflict_style) {
opts.merge = 1; /* implied */
git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
}

if (opts.force && opts.merge)
die("git checkout: -f and -m are incompatible");

/*
* case 1: git checkout <ref> -- [<paths>]
*
* <ref> must be a valid tree, everything after the '--' must be
* a path.
*
* case 2: git checkout -- [<paths>]
*
* everything after the '--' must be paths.
*
* case 3: git checkout <something> [<paths>]
*
* With no paths, if <something> is a commit, that is to
* switch to the branch or detach HEAD at it.
*
* With no paths, if <something> is _not_ a commit, no -t nor -b
* was given, and there is a tracking branch whose name is
* <something> in one and only one remote, then this is a short-hand
* to fork local <something> from that remote tracking branch.
*
* Otherwise <something> shall not be ambiguous.
* - If it's *only* a reference, treat it like case (1).
* - If it's only a path, treat it like case (2).
* - else: fail.
*
*/
if (argc) {
if (!strcmp(argv[0], "--")) { /* case (2) */
argv++;
argc--;
goto no_reference;
}

arg = argv[0];
has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");

if (!strcmp(arg, "-"))
arg = "@{-1}";

if (get_sha1(arg, rev)) {
if (has_dash_dash) /* case (1) */
die("invalid reference: %s", arg);
if (!patch_mode &&
dwim_new_local_branch &&
opts.track == BRANCH_TRACK_UNSPECIFIED &&
!opts.new_branch &&
!check_filename(NULL, arg) &&
argc == 1) {
const char *remote = unique_tracking_name(arg);
if (!remote || get_sha1(remote, rev))
goto no_reference;
opts.new_branch = arg;
arg = remote;
/* DWIMmed to create local branch */
}
else
goto no_reference;
}

/* we can't end up being in (2) anymore, eat the argument */
argv++;
argc--;

new.name = arg;
if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
setup_branch_path(&new);
if (resolve_ref(new.path, rev, 1, NULL))
new.commit = lookup_commit_reference(rev);
else
new.path = NULL;
parse_commit(new.commit);
source_tree = new.commit->tree;
} else
source_tree = parse_tree_indirect(rev);

if (!source_tree) /* case (1): want a tree */
die("reference is not a tree: %s", arg);
if (!has_dash_dash) {/* case (3 -> 1) */
/*
* Do not complain the most common case
* git checkout branch
* even if there happen to be a file called 'branch';
* it would be extremely annoying.
*/
if (argc)
verify_non_filename(NULL, arg);
}
else {
argv++;
argc--;
}
}

no_reference:

if (opts.track == BRANCH_TRACK_UNSPECIFIED)
opts.track = git_branch_track;

if (argc) {
const char **pathspec = get_pathspec(prefix, argv);

if (!pathspec)
die("invalid path specification");

if (patch_mode)
return interactive_checkout(new.name, pathspec, &opts);

/* Checkout paths */
if (opts.new_branch) {
if (argc == 1) {
die("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
} else {
die("git checkout: updating paths is incompatible with switching branches.");
}
}

if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");

return checkout_paths(source_tree, pathspec, &opts);
}

if (patch_mode)
return interactive_checkout(new.name, NULL, &opts);

if (opts.new_branch) {
struct strbuf buf = STRBUF_INIT;
if (strbuf_check_branch_ref(&buf, opts.new_branch))
die("git checkout: we do not like '%s' as a branch name.",
opts.new_branch);
if (!get_sha1(buf.buf, rev))
die("git checkout: branch %s already exists", opts.new_branch);
strbuf_release(&buf);
}

if (new.name && !new.commit) {
die("Cannot switch branch to a non-commit.");
}
if (opts.writeout_stage)
die("--ours/--theirs is incompatible with switching branches.");

return switch_branches(&opts, &new);
}
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