%%% -*- mode: Erlang; fill-column: 80; comment-column: 75; -*-
%%% Copyright 2012 Erlware, LLC. All Rights Reserved.
%%%
%%% This file is provided to you under the Apache License,
%%% Version 2.0 (the "License"); you may not use this file
%%% except in compliance with the License.  You may obtain
%%% a copy of the License at
%%%
%%%   http://www.apache.org/licenses/LICENSE-2.0
%%%
%%% Unless required by applicable law or agreed to in writing,
%%% software distributed under the License is distributed on an
%%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%%% KIND, either express or implied.  See the License for the
%%% specific language governing permissions and limitations
%%% under the License.
%%%---------------------------------------------------------------------------
%%% @author Eric Merritt <ericbmerritt@gmail.com>
%%% @copyright (C) 2012 Erlware, LLC.
%%% @doc
-module(relcool).

-export([main/1,
         do/7,
         do/8,
         format_error/1,
         opt_spec_list/0]).

-export_type([error/0]).

-include_lib("relcool/include/relcool.hrl").

%%============================================================================
%% types
%%============================================================================

-type error() :: {error, {Module::module(), Reason::term()}}.

%%============================================================================
%% API
%%============================================================================
-spec main([string()]) -> ok | error() | {ok, rcl_state:t()}.
main(Args) ->
    OptSpecList = opt_spec_list(),
    case rcl_cmd_args:args2state(getopt:parse(OptSpecList, Args)) of
        {ok, {State, _Target}} ->
            run_relcool_process(rcl_state:caller(State, command_line));
        Error={error, _} ->
            report_error(rcl_state:caller(rcl_state:new([], []),
                                          command_line), Error)
    end.

%% @doc provides an API to run the Relcool process from erlang applications
%%
%% @param RelName - The release name to build (maybe `undefined`)
%% @param RelVsn - The release version to build (maybe `undefined`)
%% @param Goals - The release goals for the system in depsolver or Relcool goal
%% format
%% @param LibDirs - The library dirs that should be used for the system
%% @param OutputDir - The directory where the release should be built to
%% @param Configs - The list of config files for the system
do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Configs) ->
    do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, [], Configs).

%% @doc provides an API to run the Relcool process from erlang applications
%%
%% @param RelName - The release name to build (maybe `undefined`)
%% @param RelVsn - The release version to build (maybe `undefined`)
%% @param Goals - The release goals for the system in depsolver or Relcool goal
%% format
%% @param LibDirs - The library dirs that should be used for the system
%% @param OutputDir - The directory where the release should be built to
%% @param Overrides - A list of overrides for the system
%% @param Configs - The list of config files for the system
do(RelName, RelVsn, Goals, LibDirs, LogLevel, OutputDir, Overrides, Configs) ->
    State = rcl_state:new([{relname, RelName},
                           {relvsn, RelVsn},
                           {goals, Goals},
                           {overrides, Overrides},
                           {output_dir, OutputDir},
                           {lib_dirs, LibDirs},
                           {log, rcl_log:new(LogLevel)}],
                          Configs),
    run_relcool_process(rcl_state:caller(State, api)).


-spec opt_spec_list() -> [getopt:option_spec()].
opt_spec_list() ->
    [
     {relname,  $n, "relname",  string,  "Specify the name for the release that will be generated"},
     {relvsn, $v, "relvsn", string, "Specify the version for the release"},
     {goals, $g, "goal", string, "Specify a target constraint on the system. These are "
      "usually the OTP"},
     {output_dir, $o, "output-dir", string, "The output directory for the release. This is `./` by default."},
     {lib_dir, $l, "lib-dir", string, "Additional dirs that should be searched for OTP Apps"},
     {log_level, $V, "verbose", {integer, 2}, "Verbosity level, maybe between 0 and 2"}
    ].

-spec format_error(Reason::term()) -> iolist().
format_error({invalid_return_value, Provider, Value}) ->
    [rcl_provider:format(Provider), " returned an invalid value ",
     io_lib:format("~p", [Value])];
format_error({error, {Module, Reason}}) ->
    io_lib:format("~s~n", [Module:format_error(Reason)]).


%%============================================================================
%% internal api
%%============================================================================
run_relcool_process(State) ->
    rcl_log:info(rcl_state:log(State), "Starting relcool build process ..."),
    rcl_log:debug(rcl_state:log(State),
                  fun() ->
                          rcl_state:format(State)
                  end),
    run_providers(State).

%% @doc for now the 'config' provider is special in that it generates the
%% providers used by the rest of the system. We expect the config provider to be
%% the first provider in the system. Once the config provider is run, we get the
%% providers again and run the rest of them (because they could have been
%% updated by the config process).
run_providers(State0) ->
    [ConfigProvider | _] = rcl_state:providers(State0),
    case run_provider(ConfigProvider, {ok, State0}) of
        Err = {error, _} ->
            Err;
        {ok, State1} ->
            Providers = rcl_state:providers(State1),
            Result = run_providers(ConfigProvider, Providers, State1),
            case rcl_state:caller(State1) of
                command_line ->
                    init:stop(0);
                api ->
                    Result
            end
    end.

run_providers(ConfigProvider, Providers, State0) ->
    case Providers of
        [ConfigProvider | Rest] ->
            %% IF the config provider is still the first provider do not run it
            %% again just run the rest.
            lists:foldl(fun run_provider/2, {ok, State0}, Rest);
        _ ->
            lists:foldl(fun run_provider/2, {ok, State0}, Providers)
    end.

-spec run_provider(rcl_provider:t(), {ok, rcl_state:t()} | error()) ->
                          {ok, rcl_state:t()} | error().
run_provider(_Provider, Error = {error, _}) ->
    Error;
run_provider(Provider, {ok, State0}) ->
    case rcl_provider:do(Provider, State0) of
        {ok, State1} ->
            {ok, State1};
        E={error, _} ->
            E
    end.

-spec usage() -> ok.
usage() ->
    getopt:usage(opt_spec_list(), "relcool", "[*release-specification-file*]").


-spec report_error(rcl_state:t(), error()) -> none() | error().
report_error(State, Error) ->
    io:format(format_error(Error)),
    usage(),
    case rcl_state:caller(State) of
        command_line ->
            erlang:halt(127);
        api ->
            Error
    end.