From 09b505861f7ad05fcfdbe16f62d5acc5610f678e Mon Sep 17 00:00:00 2001
From: Roberto Aloi <robertoaloi@users.noreply.github.com>
Date: Tue, 16 Jul 2019 15:41:10 +0200
Subject: [PATCH] [#22] Convert indexer into gen_server

---
 src/erlang_ls_indexer.erl | 87 ++++++++++++++++++++++++++++++++++++---
 src/erlang_ls_sup.erl     |  4 ++
 2 files changed, 86 insertions(+), 5 deletions(-)

diff --git a/src/erlang_ls_indexer.erl b/src/erlang_ls_indexer.erl
index f09b554c2..fba199510 100644
--- a/src/erlang_ls_indexer.erl
+++ b/src/erlang_ls_indexer.erl
@@ -1,16 +1,92 @@
+%%==============================================================================
+%% The Buffer Server
+%%==============================================================================
 -module(erlang_ls_indexer).
 
--export([ index/1 ]).
+%%==============================================================================
+%% Behaviours
+%%==============================================================================
+-behaviour(gen_server).
 
--spec index(string()) -> map().
-index(Path) ->
-  {ok, IoDevice} = file:open(Path, [read]),
+%%==============================================================================
+%% Exports
+%%==============================================================================
+%% API
+-export([ start_link/0
+        , index/1
+        , stop/0
+        ]).
+
+%% gen_server callbacks
+-export([ init/1
+        , handle_call/3
+        , handle_cast/2
+        ]).
+
+%%==============================================================================
+%% Includes
+%%==============================================================================
+-include("erlang_ls.hrl").
+
+%%==============================================================================
+%% Defines
+%%==============================================================================
+-define(SERVER, ?MODULE).
+
+%%==============================================================================
+%% Record Definitions
+%%==============================================================================
+-record(state, {}).
+
+%%==============================================================================
+%% Type Definitions
+%%==============================================================================
+-type state()  :: #state{}.
+
+%%%=============================================================================
+%%% API
+%%%=============================================================================
+-spec start_link() -> {ok, pid()}.
+start_link() ->
+  gen_server:start_link({local, ?SERVER}, ?MODULE, {}, []).
+
+-spec index(uri()) -> ok.
+index(Uri) ->
+  gen_server:call(?SERVER, {index, Uri}).
+
+-spec stop() -> ok.
+stop() ->
+  gen_server:stop(?SERVER).
+
+%%==============================================================================
+%% gen_server Callback Functions
+%%==============================================================================
+-spec init({}) -> {ok, state()}.
+init({}) ->
+  {ok, #state{}}.
+
+-spec handle_call(any(), any(), state()) -> {reply, ok, state()}.
+handle_call({index, Uri}, _From, State) ->
+  ok = do_index(Uri),
+  {reply, ok, State}.
+
+-spec handle_cast(any(), state()) -> {noreply, state()}.
+handle_cast(_Msg, State) -> {noreply, State}.
+
+%%==============================================================================
+%% Internal Functions
+%%==============================================================================
+-spec do_index(uri()) -> ok.
+do_index(Uri) ->
+  {ok, IoDevice} = file:open(Uri, [read]),
   {ok, Forms} = epp_dodger:parse(IoDevice, {1, 1}),
   erl_syntax_lib:mapfold(fun analyze_form/2, #{ module => undefined
                                               , macros => []
                                               , variables => []
                                               , applications => []
-                                              }, erl_syntax:form_list(Forms)).
+                                              }, erl_syntax:form_list(Forms)),
+  ok = file:close(IoDevice),
+  ok.
 
 -spec analyze_form(erl_syntax:syntax_tree(), map()) -> map().
 analyze_form(Form, Acc) ->
@@ -71,3 +147,4 @@ analyze_tree(_Form, _Type, Acc) ->
 %% TODO: Assume OTP structure on init
 %% TODO: Function to append to map field
 %% TODO: We should input binaries, not files. Could we patch epp?
+%% TODO: Avoid epp parsing twice
diff --git a/src/erlang_ls_sup.erl b/src/erlang_ls_sup.erl
index 281f38810..e2034e28f 100644
--- a/src/erlang_ls_sup.erl
+++ b/src/erlang_ls_sup.erl
@@ -47,5 +47,9 @@ init([]) ->
                   , start    => {erlang_ls_buffer_sup, start_link, []}
                   , shutdown => brutal_kill
                   }
+               , #{ id       => erlang_ls_indexer
+                  , start    => {erlang_ls_indexer, start_link, []}
+                  , shutdown => brutal_kill
+                  }
                ],
   {ok, {SupFlags, ChildSpecs}}.