Plugin templates enabled

This lets a plugin define templates to be loaded:

    $ rebar3 new
    ...
    proper (plugin): A basic PropEr suite for an OTP application
    ...
    $ rebar3 new help proper
    proper:
            plugin template (...)
            Description: A basic PropEr suite for an OTP application
            Variables:
                    name="suite" (...)
                    ...
    → rebar3 new proper fakesuite
    ===> Writing test/prop_fakesuite.erl

In this case, proper is a fake template file I've put by hand in
_build/default/plugins/rebar3_proper/priv/<somename>/, meaning it will
only work as far as it's called from the project's root.

The priority order of plugins is now .config > plugin > built-in, such
that someone could ensure plugins do not crush their own private
templates, but also that custom or plugin templates do overtake built-in
ones. It used to be Built-in > .config only.

Templates are searched for recursively in the priv/ directory of
plugins.

14 files changed, 181 insertions, 8 deletions

diff --git a/src/rebar_app_info.erl b/src/rebar_app_info.erl
index 95b4624..9fee4e0 100644
--- a/src/rebar_app_info.erl
+++ b/src/rebar_app_info.erl
@@ -23,6 +23,7 @@
          original_vsn/1,
          original_vsn/2,
          ebin_dir/1,
+         priv_dir/1,
          applications/1,
          applications/2,
          profiles/1,
@@ -361,6 +362,10 @@ out_dir(AppInfo=#app_info_t{}, OutDir) ->
 ebin_dir(#app_info_t{out_dir=OutDir}) ->
     ec_cnv:to_list(filename:join(OutDir, "ebin")).
 
+-spec priv_dir(t()) -> file:name().
+priv_dir(#app_info_t{out_dir=OutDir}) ->
+    ec_cnv:to_list(filename:join(OutDir, "priv")).
+
 -spec resource_type(t(), pkg | src) -> t().
 resource_type(AppInfo=#app_info_t{}, Type) ->
     AppInfo#app_info_t{resource_type=Type}.
diff --git a/src/rebar_prv_new.erl b/src/rebar_prv_new.erl
index 71560d5..064315e 100644
--- a/src/rebar_prv_new.erl
+++ b/src/rebar_prv_new.erl
@@ -132,10 +132,13 @@ show_template({Name, Type, Location, Description, Vars}) ->
                format_vars(Vars)]).
 
 format_type(escript) -> "built-in";
+format_type(plugin) -> "plugin";
 format_type(file) -> "custom".
 
 format_type(escript, _) ->
     "built-in template";
+format_type(plugin, Loc) ->
+    io_lib:format("plugin template (~s)", [Loc]);
 format_type(file, Loc) ->
     io_lib:format("custom template (~s)", [Loc]).
 
diff --git a/src/rebar_templater.erl b/src/rebar_templater.erl
index f0b2ce8..f687637 100644
--- a/src/rebar_templater.erl
+++ b/src/rebar_templater.erl
@@ -239,6 +239,7 @@ replace_var([H|T], Acc, Vars) ->
 %% Load a list of all the files in the escript and on disk
 find_templates(State) ->
     DiskTemplates = find_disk_templates(State),
+    PluginTemplates = find_plugin_templates(State),
     {MainTemplates, Files} =
         case rebar_state:escript_path(State) of
             undefined ->
@@ -249,19 +250,23 @@ find_templates(State) ->
                 F = cache_escript_files(State),
                 {find_escript_templates(F), F}
         end,
-    AvailTemplates = find_available_templates(DiskTemplates,
-                                              MainTemplates),
+    AvailTemplates = find_available_templates([MainTemplates,
+                                               PluginTemplates,
+                                               DiskTemplates]),
     ?DEBUG("Available templates: ~p\n", [AvailTemplates]),
     {AvailTemplates, Files}.
 
-find_available_templates(TemplateList1, TemplateList2) ->
-    AvailTemplates = prioritize_templates(
-                       tag_names(TemplateList1),
-                       tag_names(TemplateList2)),
-
+find_available_templates(TemplateListList) ->
+    AvailTemplates = prioritize_templates(TemplateListList),
     ?DEBUG("Available templates: ~p\n", [AvailTemplates]),
     AvailTemplates.
 
+prioritize_templates([TemplateList]) ->
+    tag_names(TemplateList);
+prioritize_templates([TemplateList | TemplateListList]) ->
+    prioritize_templates(tag_names(TemplateList),
+                         prioritize_templates(TemplateListList)).
+
 %% Scan the current escript for available files
 cache_escript_files(State) ->
     {ok, Files} = rebar_utils:escript_foldl(
@@ -299,6 +304,14 @@ find_other_templates(State) ->
             rebar_utils:find_files(TemplateDir, ?TEMPLATE_RE)
     end.
 
+%% Fetch template indexes that sit on disk in plugins
+find_plugin_templates(State) ->
+    [{plugin, File}
+     || App <- rebar_state:all_plugin_deps(State),
+        Priv <- [rebar_app_info:priv_dir(App)],
+        Priv =/= undefined,
+        File <- rebar_utils:find_files(Priv, ?TEMPLATE_RE)].
+
 %% Take an existing list of templates and tag them by name the way
 %% the user would enter it from the CLI
 tag_names(List) ->
@@ -316,6 +329,10 @@ prioritize_templates([{Name, Type, File} | Rest], Valid) ->
             ?DEBUG("Skipping template ~p, due to presence of a built-in "
                    "template with the same name", [Name]),
             prioritize_templates(Rest, Valid);
+        {_, plugin, _} ->
+            ?DEBUG("Skipping template ~p, due to presence of a plugin "
+                   "template with the same name", [Name]),
+            prioritize_templates(Rest, Valid);
         {_, file, _} ->
             ?DEBUG("Skipping template ~p, due to presence of a custom "
                    "template at ~s", [Name, File]),
@@ -327,6 +344,9 @@ prioritize_templates([{Name, Type, File} | Rest], Valid) ->
 load_file(Files, escript, Name) ->
     {Name, Bin} = lists:keyfind(Name, 1, Files),
     Bin;
+load_file(_Files, plugin, Name) ->
+    {ok, Bin} = file:read_file(Name),
+    Bin;
 load_file(_Files, file, Name) ->
     {ok, Bin} = file:read_file(Name),
     Bin.
diff --git a/test/rebar_new_SUITE.erl b/test/rebar_new_SUITE.erl
index b514a2b..1971be6 100644
--- a/test/rebar_new_SUITE.erl
+++ b/test/rebar_new_SUITE.erl
@@ -7,9 +7,25 @@
 -include_lib("eunit/include/eunit.hrl").
 
 all() -> [app_git_user, app_hg_user, app_with_fallbacks,
-          app_with_flags1, app_with_flags2].
+          app_with_flags1, app_with_flags2, plugin_tpl].
 
 
+init_per_testcase(plugin_tpl, Config) ->
+    application:load(rebar),
+    DataDir = ?config(data_dir, Config),
+    PrivDir = ?config(priv_dir, Config),
+    Name = rebar_test_utils:create_random_name("plugin_tpl"),
+    AppsDir = filename:join([PrivDir, rebar_test_utils:create_random_name(Name)]),
+    ec_file:copy(filename:join([DataDir, "plugin_tpl"]), AppsDir, [recursive]),
+    Verbosity = rebar3:log_level(),
+    rebar_log:init(command_line, Verbosity),
+    GlobalDir = filename:join([DataDir, "cache"]),
+    State = rebar_state:new([{base_dir, filename:join([AppsDir, "_build"])}
+                            ,{global_rebar_dir, GlobalDir}
+                            ,{root_dir, AppsDir}]),
+    mock_home_dir(DataDir),
+    mock_empty_escript_templates(),
+    [{apps, AppsDir}, {state, State}, {name, Name} | Config];
 init_per_testcase(Case, Config0) ->
     Config = rebar_test_utils:init_rebar_state(Config0),
     Name = rebar_test_utils:create_random_name(atom_to_list(Case)),
@@ -132,11 +148,24 @@ app_with_flags2(Config) ->
        {filename:join(["src", Name++"_app.erl"]), [Name]}
       ]).
 
+plugin_tpl(Config) ->
+    Name = ?config(name, Config),
+    rebar_test_utils:run_and_check(
+      Config, [],
+      ["new", "-f", "tpl", Name],
+      {ok, []}
+     ),
+    Result = filename:join(["src", Name++".erl"]), % In CWD
+    {ok, Bin} = file:read_file(Result),
+    {match, _} = re:run(Bin, Name, [multiline,global]).
+
 validate_files(_Config, Name, Checks) ->
     [begin
         Path = filename:join([Name, File]),
+        ct:pal("validating ~s for content", [Path]),
         {ok, Bin} = file:read_file(Path),
         [{match, _} = re:run(Bin, Pattern, [multiline,global])
          || Pattern <- Patterns]
      end || {File, Patterns} <- Checks],
     ok.
+
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore
new file mode 100644
index 0000000..a939dce
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore
@@ -0,0 +1,19 @@
+.rebar3
+_*
+.eunit
+*.o
+*.beam
+*.plt
+*.swp
+*.swo
+.erlang.cookie
+ebin
+log
+erl_crash.dump
+.rebar
+_rel
+_deps
+_plugins
+_tdeps
+logs
+_build
\ No newline at end of file
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl
new file mode 100644
index 0000000..9129961
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl
@@ -0,0 +1,2 @@
+-module({{name}}).
+
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template
new file mode 100644
index 0000000..7fa4caf
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template
@@ -0,0 +1,7 @@
+{description, "A basic template"}.
+{variables, [
+    {name, "mod", "Name of the module"}
+]}.
+
+{dir, "test"}.
+{template, "module.erl.dtl", "src/{{name}}.erl"}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config
new file mode 100644
index 0000000..f618f3e
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config
@@ -0,0 +1,2 @@
+{erl_opts, [debug_info]}.
+{deps, []}.
\ No newline at end of file
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src
new file mode 100644
index 0000000..6c6d811
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src
@@ -0,0 +1,15 @@
+{application, 'tpl',
+ [{description, "A rebar plugin"},
+  {vsn, "0.1.0"},
+  {registered, []},
+  {applications,
+   [kernel,
+    stdlib
+   ]},
+  {env,[]},
+  {modules, []},
+
+  {contributors, []},
+  {licenses, []},
+  {links, []}
+ ]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl
new file mode 100644
index 0000000..529bcb8
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl
@@ -0,0 +1,8 @@
+-module('tpl').
+
+-export([init/1]).
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    {ok, State1} = 'tpl_prv':init(State),
+    {ok, State1}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl
new file mode 100644
index 0000000..c68ffa3
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl
@@ -0,0 +1,32 @@
+-module('tpl_prv').
+
+-export([init/1, do/1, format_error/1]).
+
+-define(PROVIDER, 'tpl').
+-define(DEPS, [app_discovery]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    Provider = providers:create([
+            {name, ?PROVIDER},            % The 'user friendly' name of the task
+            {module, ?MODULE},            % The module implementation of the task
+            {bare, true},                 % The task can be run by the user, always true
+            {deps, ?DEPS},                % The list of dependencies
+            {example, "rebar3 tpl"}, % How to use the plugin
+            {opts, []},                   % list of options understood by the plugin
+            {short_desc, "A rebar plugin"},
+            {desc, "A rebar plugin"}
+    ]),
+    {ok, rebar_state:add_provider(State, Provider)}.
+
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    {ok, State}.
+
+-spec format_error(any()) ->  iolist().
+format_error(Reason) ->
+    io_lib:format("~p", [Reason]).
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/rebar.config b/test/rebar_new_SUITE_data/plugin_tpl/rebar.config
new file mode 100644
index 0000000..74d1fc5
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/rebar.config
@@ -0,0 +1,3 @@
+{erl_opts, [debug_info]}.
+{deps, []}.
+{plugins, [tpl]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src
new file mode 100644
index 0000000..8f18874
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src
@@ -0,0 +1,15 @@
+{application, 'plugin_tpl',
+ [{description, "An OTP library"},
+  {vsn, "0.1.0"},
+  {registered, []},
+  {applications,
+   [kernel,
+    stdlib
+   ]},
+  {env,[]},
+  {modules, []},
+
+  {contributors, []},
+  {licenses, []},
+  {links, []}
+ ]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl
new file mode 100644
index 0000000..406bd97
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl
@@ -0,0 +1,13 @@
+-module('plugin_tpl').
+
+%% API exports
+-export([]).
+
+%%====================================================================
+%% API functions
+%%====================================================================
+
+
+%%====================================================================
+%% Internal functions
+%%====================================================================