%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% ex: ts=4 sw=4 et

-module(rebar_plugins).

-export([install/1, handle_plugins/2]).

-include("rebar.hrl").

%% ===================================================================
%% Public API
%% ===================================================================

-spec install(rebar_state:t()) -> rebar_state:t().
install(State) ->
    Plugins = rebar_state:get(State, plugins, []),

    ProjectApps = rebar_state:project_apps(State),

    OtherPlugins = lists:flatmap(fun(App) ->
                                         AppDir = rebar_app_info:dir(App),
                                         C = rebar_config:consult(AppDir),
                                         S = rebar_state:new(rebar_state:new(), C, AppDir),
                                         rebar_state:get(S, plugins, [])
                                 end, ProjectApps),

    handle_plugins(Plugins++OtherPlugins, State).

-spec handle_plugins([rebar_prv_install_deps:dep()], rebar_state:t()) -> rebar_state:t().
handle_plugins(Plugins, State) ->
    PluginProviders = lists:flatmap(fun(Plugin) ->
                                            handle_plugin(Plugin, State)
                                    end, Plugins),
    rebar_state:create_logic_providers(PluginProviders, State).

handle_plugin(Plugin, State) ->
    try
        %% Set deps dir to plugins dir so apps are installed there
        State1 = rebar_state:set(State, deps_dir, ?DEFAULT_PLUGINS_DIR),
        {ok, _, State2} = rebar_prv_install_deps:handle_deps(default, State1, [Plugin]),

        Apps = rebar_state:all_deps(State2),
        ToBuild = lists:dropwhile(fun rebar_app_info:valid/1, Apps),
        [build_plugin(AppInfo) || AppInfo <- ToBuild],
        [true = code:add_patha(filename:join(rebar_app_info:dir(AppInfo), "ebin")) || AppInfo <- Apps],
        plugin_providers(Plugin)
    catch
        C:T ->
            ?DEBUG("~p ~p", [C, T]),
            ?WARN("Plugin ~p not available. It will not be used.", [Plugin]),
            []
    end.

build_plugin(AppInfo) ->
    AppDir = rebar_app_info:dir(AppInfo),
    C = rebar_config:consult(AppDir),
    S = rebar_state:new(rebar_state:new(), C, AppDir),
    rebar_prv_compile:compile(S, AppInfo).

plugin_providers({Plugin, _, _}) when is_atom(Plugin) ->
    validate_plugin(Plugin);
plugin_providers({Plugin, _}) when is_atom(Plugin) ->
    validate_plugin(Plugin);
plugin_providers(Plugin) when is_atom(Plugin) ->
    validate_plugin(Plugin).

validate_plugin(Plugin) ->
    _ = application:load(Plugin),
    case application:get_env(Plugin, providers) of
        {ok, Providers} ->
            Providers;
        undefined ->
            Exports = Plugin:module_info(exports),
            case lists:member({init,1}, Exports) of
                false ->
                    ?WARN("Plugin ~p does not export init/1. It will not be used.", [Plugin]),
                    [];
                true ->
                    [Plugin]
            end
    end.