%% @copyright 2016 Hinagiku Soranoba All Rights Reserved.
%%
%% @doc Automatically generate the .appup files from the beam file.
%%
-module(erlup_appup).

-include("erlup.hrl").

%%----------------------------------------------------------------------------------------------------------------------
%% Exported API
%%----------------------------------------------------------------------------------------------------------------------
-export([
         do/4
        ]).

%%----------------------------------------------------------------------------------------------------------------------
%% 'provider' Callback API
%%----------------------------------------------------------------------------------------------------------------------
-export([init/1, do/1, format_error/1]).

%%----------------------------------------------------------------------------------------------------------------------
%% Macros and Types
%%----------------------------------------------------------------------------------------------------------------------

-type instruction() :: tuple().

%%----------------------------------------------------------------------------------------------------------------------
%% Exported Functions
%%----------------------------------------------------------------------------------------------------------------------

%% @doc Automatically generate the .appup files from the beam file.
-spec do([file:filename()], string() | [string()], string(), erlup_state:t()) -> ok.
do(Dirs, [X | _] = PreviousVsns, CurrentVsn, State0) when is_list(X) ->
    lists:foreach(fun(P) -> do(Dirs, P, CurrentVsn, State0) end, PreviousVsns);
do(Dirs, PreviousVsn, CurrentVsn, State0) ->
    ?INFO("previous = ~p, current = ~p", [PreviousVsn, CurrentVsn]),
    State1 = lists:foldl(fun({Before, After}, Acc) -> erlup_state:set_sedargs(Before, After, Acc) end,
                         State0, [{'$from', PreviousVsn}, {'$to', CurrentVsn}]),
    State2 = case erlup_state:get(rels, State1, undefined) of
                 undefined -> erlup_state:put(rels, Rels = erlup_utils:find_rels(Dirs), State1);
                 Rels      -> State1
             end,

    Fun = fun(Vsn) ->
                  case lists:keyfind(Vsn, 2, Rels) of
                      false           -> ?throw("Can not find a rel file. (" ++ Vsn ++ ")");
                      {_, _, RelFile} ->
                          case erlup_utils:lookup_include_libs(RelFile) of
                              {ok, AppVsns} ->
                                  [begin
                                       EbinDir = filename:join([erlup_utils:base_dir(RelFile), "lib",
                                                                atom_to_list(App) ++ "-" ++ AppVsn, "ebin"]),
                                       {App, AppVsn, EbinDir}
                                   end || {App, AppVsn} <- AppVsns];
                              {error, Reason} ->
                                  ?throw(Reason)
                          end
                  end
          end,
    rewrite_appups(Fun(CurrentVsn), Fun(PreviousVsn), State2).

%%----------------------------------------------------------------------------------------------------------------------
%% 'provider' Callback Functions
%%----------------------------------------------------------------------------------------------------------------------

%% @private
-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
init(State) ->
    Provider = providers:create([
                                 {name, appup},
                                 {namespace, erlup},
                                 {module, ?MODULE},
                                 {bare, true},
                                 {deps, []},
                                 {opts, erlup_rebar3:opts("appup")},
                                 {short_desc, "Generate the .appup file"}
                                ]),
    {ok, rebar_state:add_provider(State, Provider)}.

%% @private
-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
do(State) ->
    erlup_rebar3:do("appup", State).

%% @private
-spec format_error(iodata()) -> iolist().
format_error(Reason) ->
    io_lib:format("~s", [Reason]).

%%----------------------------------------------------------------------------------------------------------------------
%% Internal Functions
%%----------------------------------------------------------------------------------------------------------------------

%% @doc Rewrite the appup files.
-spec rewrite_appups(To, From, erlup_state:t()) -> ok when
      To       :: AppInfos,
      From     :: AppInfos,
      AppInfos :: [{App :: atom(), Vsn :: string(), EbinDir :: file:filename_all()}].
rewrite_appups([], _, _) ->
    ok;
rewrite_appups([{App, ToVsn, ToEbinDir} | ToRest], From, State0) ->
    case lists:keyfind(App, 1, From) of
        false ->
            ?DEBUG("~s (~p) is added application.", [App, ToVsn]),
            rewrite_appups(ToRest, From, State0);
        {_, ToVsn, _} ->
            ?DEBUG("~s (~p) is not changed.", [App, ToVsn]),
            rewrite_appups(ToRest, From, State0);
        {_, FromVsn, FromEbinDir} ->
            ?DEBUG("~s (~p => ~p) is changed. ebin : ~s => ~s", [App, FromVsn, ToVsn, FromEbinDir, ToEbinDir]),
            State = lists:foldl(fun({Before, After}, Acc) -> erlup_state:set_sedargs(Before, After, Acc) end,
                                State0, [{'$from_vsn', FromVsn}, {'$to_vsn', ToVsn}]),

            AppupPath = filename:join(ToEbinDir, atom_to_list(App) ++ ".appup"),
            {Up, Down} = case file:consult(AppupPath) of
                             {ok, [{ToVsn, Up0, Down0}]} when is_list(Up0), is_list(Down0) ->
                                 %% NOTE: If an exact match, delete here, because want to overwrite.
                                 {proplists:delete(FromVsn, Up0), proplists:delete(FromVsn, Down0)};
                             {ok, _} ->
                                 ?WARN("the appup (~s) is invalid format. to overwrite.", [AppupPath]),
                                 {[], []};
                             _ ->
                                 {[], []}
                         end,
            case {find_appup_instructions(FromVsn, Up), find_appup_instructions(FromVsn, Down)} of
                {Res1, Res2} when Res1 =/= error, Res2 =/= error ->
                    ?INFO("Skip that rewrite the appup (~s), because ~s is already exists.", [AppupPath, FromVsn]);
                {Res1, Res2} ->
                    Instructions = case Res1 of
                                       {ok, Instructions0} -> Instructions0;
                                       error               ->
                                           ?IF(Res2 =/= error,
                                               ?WARN("Down instructions exist, but up instructions doesn't exist. (~s)",
                                                     [AppupPath])),
                                           application_instructions(ToEbinDir, FromEbinDir, State)
                                   end,
                    Up2   = [{FromVsn, Instructions} | Up],
                    Down2 = [{FromVsn, revert_instructions(Instructions, State)} | Down],
                    case file:write_file(AppupPath, format_appup(ToVsn, Up2, Down2)) of
                        ok              -> ok;
                        {error, Reason} -> ?throw(file:format_error(Reason) ++ " " ++ AppupPath)
                    end,
                    ?INFO("rewrite the appup (~s).", [AppupPath])
            end,
            rewrite_appups(ToRest, From, State)
    end.

%% @doc Find the instructions that is matching vsn pattern.
-spec find_appup_instructions(Vsn, [{VsnPattern, [instruction()]}]) -> {ok, [instruction()]} | error when
      Vsn          :: string(),
      VsnPattern   :: binary() | string().
find_appup_instructions(_, []) ->
    error;
find_appup_instructions(Vsn, [{VsnPattern, Instructions} | Rest]) when is_binary(VsnPattern) ->
    case re:run(Vsn, VsnPattern) of
        nomatch    -> find_appup_instructions(Vsn, Rest);
        {match, _} -> {ok, Instructions}
    end;
find_appup_instructions(Vsn, [{VsnPattern, Instructions} | _]) when Vsn =:= VsnPattern ->
    {ok, Instructions};
find_appup_instructions(Vsn, [_ | Rest]) ->
    find_appup_instructions(Vsn, Rest).

%% @doc Given instructions at the time of upgrade, returns instructions at the time of downgrade.
-spec revert_instructions([instruction()], erlup_state:t()) -> [instruction()].
revert_instructions(Insts, State) ->
    revert_instructions(Insts, State, []).

%% @see revert_instructions/2
-spec revert_instructions([instruction()], erlup_state:t(), [instruction()]) -> [instruction()].
revert_instructions([], _, Acc) ->
    Acc; % keep the reversing list
revert_instructions([Inst | RestInsts], State, Acc) when element(1, Inst) =:= add_module ->
    %% {add_module, Mod}, {add_module, Mod, DepMods} -> {delete_module, ...}
    revert_instructions(RestInsts, State, [setelement(1, Inst, delete_module) | Acc]);
revert_instructions([Inst | RestInsts], State, Acc) when element(1, Inst) =:= delete_module ->
    %% {delete_module, Mod}, {delete_module, Mod, DepMods} -> {add_module, ...}
    revert_instructions(RestInsts, State, [setelement(1, Inst, add_module) | Acc]);
revert_instructions([{apply, {M, F, _}} | RestInsts], State, Acc) ->
    %% {apply, {M, F, A}}: Args changed.
    A = proplists:get_value(F, erlup_state:applies(down, State)),
    revert_instructions(RestInsts, State, [{apply, {M, F, A}} | Acc]);
revert_instructions([Inst | RestInsts], State, Acc) when
      element(1, Inst) =:= update, element(1, element(3, Inst)) =:= advanced ->
    %% {update, Mod, {advanced, Extra}, ...}: Extra changed.
    Extra = erlup_state:extra(down, State),
    revert_instructions(RestInsts, State, [setelement(3, Inst, {advanced, Extra}) | Acc]);
revert_instructions([Inst | RestInsts], State, Acc) ->
    revert_instructions(RestInsts, State, [Inst | Acc]).

%% @doc Returns the instructions of the application at the time of upgrade.
-spec application_instructions(file:filename(), file:filename(), erlup_state:t()) -> [instruction()].
application_instructions(ToEbinDir, FromEbinDir, State) ->
    {Added, Deleted, Differents} = beam_lib:cmp_dirs(ToEbinDir, FromEbinDir),
    CmpFiles = lists:map(fun(X) -> {added, X} end, Added)
        ++ lists:map(fun({X, _}) -> {changed, X} end, Differents)
        ++ lists:map(fun(X) -> {deleted, X} end, Deleted),
    %% TODO: ordering
    application_instructions_1(CmpFiles, State, []).

%% @see application_instructions/3
-spec application_instructions_1([{Cmp, file:filename()}], erlup_state:t(), _) -> [instruction()] when
      Cmp :: added | deleted | changed.
application_instructions_1([], _, Acc) ->
    lists:flatten(Acc);
application_instructions_1([{Cmp, File} | Rest], State, Acc) ->
    {ok, Chunks} = beam_lib:chunks(File, [attributes, exports]),
    application_instructions_1(Rest, State, [module_instructions(Cmp, Chunks, State) | Acc]).

%% @doc Returns the instructions of the module at the time of upgrade.
-spec module_instructions(Cmp, {module(), beam_lib:chunkdata()}, erlup_state:t()) -> [instruction()] when
      Cmp :: added | deleted | changed.
module_instructions(added, {Module, _}, _) ->
    [{add_module, Module}];
module_instructions(deleted, {Module, _}, _) ->
    [{delete_module, Module}];
module_instructions(changed, {Module, ChunkData}, State) ->
    ModDeps = proplists:get_value(Module, erlup_state:mod_deps(State), []),
    Insts = ?IIF(is_supervisor(ChunkData), [{update, Module, supervisor}], [])
            ++ ?IIF(is_special_process(ChunkData),
                    [{update, Module, {advanced, erlup_state:extra(up, State)}, ModDeps}], []),
    ?IIF(Insts =:= [], [{load_module, Module, ModDeps}], Insts)
        ++ lists:map(fun(X) -> {apply, X} end, get_applies({Module, ChunkData}, State)).

%% @doc Get the functions that be called at the time of upgrade.
-spec get_applies({module(), [beam_lib:chunkdata()]}, erlup_state:t()) -> [{module(), Function :: atom(), Args :: term()}].
get_applies({Module, ChunkData}, State) ->
    Exports = proplists:get_value(exports, ChunkData, []),
    lists:filter(fun({Function, Args}) when is_list(Args) ->
                         case lists:member({Function, length(Args)}, Exports) of
                             true  -> {true, {Module, Function, Args}};
                             false -> false
                         end;
                    (_) -> false
                 end, erlup_state:applies(up, State)).

%% @doc Return the behaviour modules
-spec get_behaviour([beam_lib:chunkdata()]) -> [module()].
get_behaviour(ChunkData) ->
    Attributes = proplists:get_value(attributes, ChunkData),
    proplists:get_value(behavior, Attributes, []) ++ proplists:get_value(behaviour, Attributes, []).

%% @doc Return true, if it is special process. Otherwise false.
-spec is_special_process([beam_lib:chunkdata()]) -> boolean().
is_special_process(ChunkData) ->
    Exports = proplists:get_value(exports, ChunkData, []),
    proplists:is_defined(code_change, Exports) orelse proplists:is_defined(system_code_change, Exports).

%% @doc Return true, if it is supervisor. Otherwise, false.
-spec is_supervisor([beam_lib:chunkdata()]) -> boolean().
is_supervisor(ChunkData) ->
    lists:member(supervisor, get_behaviour(ChunkData)).

%% @doc Returns the data of appup formats in human readable format.
-spec format_appup(string(), [{FromVsn, [instruction()]}], [{FromVsn, [instruction()]}]) -> iodata() when
      FromVsn :: string().
format_appup(ToVsn, Up, Down) ->
    io_lib:format("{~p,~n [~n~s ],~n [~n~s ]}.~n",
                  [ToVsn, format_vsn_instructions(Up), format_vsn_instructions(Down)]).

%% @see format_appup/3
-spec format_vsn_instructions([{FromVsn, [instruction()]}]) -> iodata() when
      FromVsn :: string().
format_vsn_instructions(VsnInstructions) ->
    string:join(lists:map(fun({FromVsn, Instructions}) ->
                                  io_lib:format("  {~p,~n   [~n~s   ]}",
                                                [FromVsn, format_instructions(Instructions)])
                          end, VsnInstructions), [$,,$\n]) ++ [$\n].

%% @see format_appup/3
-spec format_instructions([instruction()]) -> iodata().
format_instructions([]) ->
    [];
format_instructions(Instructions) ->
    string:join(lists:map(fun(X) -> io_lib:format("    ~p", [X]) end, Instructions), [$,,$\n]) ++ [$\n].