-module(rumBkdFile).

%% @doc File backend for lager, with multiple file support.
%% Multiple files are supported, each with the path and the loglevel being configurable.
%% The configuration paramter for this backend is a list of key-value 2-tuples. See the init() function for the available options.
%% This backend supports external and internal log rotation and will re-open handles to files if the inode changes.
%% It will also rotate the files itself if the size of the file exceeds the `size' and keep `count' rotated files.
%% `date' is an alternate rotation trigger, based on time. See the README for documentation.
%% For performance, the file backend does delayed writes, although it will sync at specific log levels, configured via the `sync_on' option.
%% By default the error level or above will trigger a sync.

-include("rumDef.hrl").
-include_lib("kernel/include/file.hrl").

-behaviour(gen_emm).

-export([configToId/1]).

-export([
   init/1
   , handleCall/2
   , handleEvent/2
   , handleInfo/2
   , terminate/2
   , code_change/3
]).

-record(state, {
   fileName :: string(),
   level :: rumMaskLevel(),
   fd :: file:io_device() | undefined,
   inode :: integer() | undefined,
   ctime :: file:date_time() | undefined,
   flap = false :: boolean(),
   size = 0 :: integer(),
   date :: undefined | string(),
   count = 10 :: integer(),
   rotator = lager_util :: atom(),
   shaper :: rumShaper(),
   formatter :: atom(),
   formatterConfig :: any(),
   syncOn :: integer(),
   checkInterval = ?RumDefCheckInterval :: non_neg_integer(),   %% 单位毫秒
   syncInterval = ?RumDefSyncInterval :: non_neg_integer(),
   syncSize = ?RumDefSyncSize :: non_neg_integer(),
   lastCheck = rumTime:nowMs() :: erlang:timestamp(),   %% 单位毫秒
   osType :: atom()
}).

-spec init([rumFileOpt(), ...]) -> {ok, #state{}} | {error, atom()}.
init(Opts) ->
   true = checkOpts(Opts, false),
   RelName = rumUtil:get_opt(file, Opts, undefined),
   CfgLevel = rumUtil:get_opt(level, Opts, ?RumDefLogLevel),
   CfgDate = rumUtil:get_opt(date, Opts, ?RumDefRotateDate),
   Size = rumUtil:get_opt(size, Opts, ?RumDefRotateSize),
   Count = rumUtil:get_opt(count, Opts, ?RumDefRotateCnt),
   Rotator = rumUtil:get_opt(rotator, Opts, ?RumDefRotateMod),
   HighWaterMark = rumUtil:get_opt(high_water_mark, Opts, ?RumDefCheckHWM),
   Flush = rumUtil:get_opt(flush_queue, Opts, ?RumDefFlushQueue),
   FlushThr = rumUtil:get_opt(flush_threshold, Opts, ?RumDefFlushThreshold),
   SyncInterval = rumUtil:get_opt(sync_interval, Opts, ?RumDefSyncInterval),
   CfgCheckInterval = rumUtil:get_opt(check_interval, Opts, ?RumDefCheckInterval),
   SyncSize = rumUtil:get_opt(sync_size, Opts, ?RumDefSyncSize),
   CfgSyncOn = rumUtil:get_opt(sync_on, Opts, ?RumDefSyncLevel),
   Formatter = rumUtil:get_opt(formatter, Opts, ?RumDefFormatter),
   FormatterConfig = rumUtil:get_opt(formatter_config, Opts, ?RumDefFormatterCfg),

   %% 需要二次转换的配置在这里处理
   Level = rumUtil:configToMask(CfgLevel),
   SyncOn = rumUtil:configToMask(CfgSyncOn),
   CheckInterval = ?IIF(CfgCheckInterval == always, 0, CfgCheckInterval),
   {ok, Date} = rumUtil:parseRotateSpec(CfgDate),
   FileName = rumUtil:parsePath(RelName),

   scheduleRotation(Date, FileName),
   Shaper = rumUtil:maybeFlush(Flush, #rumShaper{hwm = HighWaterMark, flushThreshold = FlushThr, id = FileName}),
   TemState = #state{
      fileName = FileName, level = Level, size = Size, date = Date
      , count = Count, rotator = Rotator, shaper = Shaper
      , formatter = Formatter, formatterConfig = FormatterConfig
      , syncOn = SyncOn, syncInterval = SyncInterval
      , syncSize = SyncSize, checkInterval = CheckInterval
   },
   case Rotator:createLogFile(FileName, {SyncSize, SyncInterval}) of
      {ok, Fd, Inode, CTime, _Size} ->
         {ok, TemState#state{fd = Fd, inode = Inode, ctime = CTime}};
      {error, Reason} ->
         ?INT_LOG(error, "Failed to open log file ~ts with error ~s", [FileName, file:format_error(Reason)]),
         {ok, TemState#state{flap = true}}
   end.

handleCall(mGetLogLevel, #state{level = Level} = State) ->
   {reply, Level, State};
handleCall({mSetLogLevel, Level}, #state{fileName = Ident} = State) ->
   case rumUtil:validateLogLevel(Level) of
      false ->
         {reply, {error, bad_loglevel}, State};
      LevelMask ->
         ?INT_LOG(notice, "Changed loglevel of ~s to ~p", [Ident, Level]),
         {reply, ok, State#state{level = LevelMask}}
   end;

handleCall({mSetLogHwm, Hwm}, #state{shaper = Shaper, fileName = FileName} = State) ->
   case checkOpts([{high_water_mark, Hwm}], true) of
      false ->
         {reply, {error, bad_log_hwm}, State};
      _ ->
         NewShaper = Shaper#rumShaper{hwm = Hwm},
         ?INT_LOG(notice, "Changed loghwm of ~ts to ~p", [FileName, Hwm]),
         {reply, {last_loghwm, Shaper#rumShaper.hwm}, State#state{shaper = NewShaper}}
   end;
handleCall(mRotate, State = #state{fileName = File}) ->
   {ok, NewState} = handleInfo({mRotate, File}, State),
   {reply, ok, NewState};
handleCall(_Msg, State) ->
   ?ERR("~p call receive unexpect msg ~p ~n ", [?MODULE, _Msg]),
   {reply, ok, State}.

handleEvent({mWriteLog, Message}, #state{fileName = FileName, level = Level, shaper = Shaper, formatter = Formatter, formatterConfig = FormatConfig} = State) ->
   case rumUtil:isLoggAble(Message, Level, {rumBkdFile, FileName}) of
      true ->
         case rumUtil:checkHwm(Shaper) of
            {true, _Drop, NewShaper} ->
               {ok, writeLog(State#state{shaper = NewShaper}, rumMsg:timestamp(Message), rumMsg:severity_as_int(Message), Formatter:format(Message, FormatConfig))};
            {drop, Drop, NewShaper} ->
               TemState =
                  case Drop =< 0 of
                     true ->
                        State;
                     _ ->
                        Report = eFmt:format(<<"rumBkdFile dropped ~p messages in the last second that exceeded the limit of ~p messages/sec">>, [Drop, NewShaper#rumShaper.hwm]),
                        ReportMsg = rumMsg:new(Report, warning, [], []),
                        writeLog(State, rumMsg:timestamp(ReportMsg), rumMsg:severity_as_int(ReportMsg), Formatter:format(ReportMsg, FormatConfig))
                  end,
               {ok, writeLog(TemState#state{shaper = NewShaper}, rumMsg:timestamp(Message), rumMsg:severity_as_int(Message), Formatter:format(Message, FormatConfig))};
            {false, _, NewShaper} ->
               {ok, State#state{shaper = NewShaper}}
         end;
      _ ->
         kpS
   end;
handleEvent(_Msg, _State) ->
   ?ERR("~p event receive unexpect msg ~p ~n ", [?MODULE, _Msg]),
   kpS.

handleInfo({mRotate, File}, #state{fileName = File, count = Count, date = Date, rotator = Rotator} = State) ->
   NewState = closeFile(State),
   _ = Rotator:rotateLogFile(File, Count),
   scheduleRotation(File, Date),
   {ok, NewState};
handleInfo({mShaperExpired, Name}, #state{shaper = Shaper, fileName = Name, formatter = Formatter, formatterConfig = FormatConfig} = State) ->
   case Shaper#rumShaper.dropped of
      0 ->
         ignore;
      Dropped ->
         Report = eFmt:format(<<"rumBkdFile dropped ~p messages in the last second that exceeded the limit of ~p messages/sec">>, [Dropped, Shaper#rumShaper.hwm]),
         ReportMsg = rumMsg:new(Report, warning, [], []),
         writeLog(State, rumMsg:timestamp(ReportMsg), rumMsg:severity_as_int(ReportMsg), Formatter:format(ReportMsg, FormatConfig))
   end,
   {ok, State#state{shaper = Shaper#rumShaper{dropped = 0, mps = 0, lastTime = rumTime:now()}}};
handleInfo(_Msg, _State) ->
   ?ERR("~p info receive unexpect msg ~p ~n ", [?MODULE, _Msg]),
   kpS.

terminate(_Reason, State) ->
   %% leaving this function call unmatched makes dialyzer cranky
   _ = closeFile(State),
   ok.

code_change(_OldVsn, State, _Extra) ->
   {ok, State}.

writeLog(#state{fileName = FileName, fd = Fd, inode = Inode, ctime = CTime, flap = Flap, size = RotSize, count = Count, rotator = Rotator, lastCheck = LastCheck, checkInterval = CheckInterval, syncSize = SyncSize, syncInterval = SyncInterval} = State, Timestamp, Level, Msg) ->
   case isWriteCheck(Fd, LastCheck, CheckInterval, FileName, Inode, CTime, Timestamp) of
      true ->
         %% need to check for rotation
         case Rotator:ensureLogFile(FileName, Fd, Inode, CTime, {SyncSize, SyncInterval}) of
            {ok, NewFD, NewInode, NewCTime, FileSize} ->
               case RotSize > 0 andalso FileSize > RotSize of
                  true ->
                     TemState = closeFile(State),
                     case Rotator:rotateLogFile(FileName, Count) of
                        ok ->
                           %% go around the loop again, we'll do another rotation check and hit the next clause of ensureLogFile
                           writeLog(TemState, Timestamp, Level, Msg);
                        {error, Reason} ->
                           ?IIF(Flap, State, begin ?INT_LOG(error, "Failed to rotate log file ~ts with error ~s", [FileName, file:format_error(Reason)]),  State#state{flap = true} end)
                     end;
                  _ ->
                     %% update our last check and try again
                     TemState = State#state{lastCheck = Timestamp, fd = NewFD, inode = NewInode, ctime = NewCTime},
                     writeFile(TemState, Level, Msg)
               end;
            {error, Reason} ->
               ?IIF(Flap, State, begin ?INT_LOG(error, "Failed to reopen log file ~ts with error ~s", [FileName, file:format_error(Reason)]),  State#state{flap = true} end)
         end;
      _ ->
         writeFile(State, Level, Msg)
   end.

writeFile(#state{fd = Fd, fileName = FileName, flap = Flap, syncOn = SyncOn} = State, Level, Msg) ->
   %% delayed_write doesn't report errors
   _ = file:write(Fd, unicode:characters_to_binary(Msg)),
   case (Level band SyncOn) =/= 0 of
      true ->
         %% force a sync on any message that matches the 'syncOn' bitmask
         NewFlap =
            case file:datasync(Fd) of
               {error, Reason} when Flap == false ->
                  ?INT_LOG(error, "Failed to write log message to file ~ts: ~s", [FileName, file:format_error(Reason)]),
                  true;
               ok ->
                  false;
               _ ->
                  Flap
            end,
         State#state{flap = NewFlap};
      _ ->
         State
   end.

isWriteCheck(Fd, LastCheck, CheckInterval, Name, Inode, CTime, Timestamp) ->
   DiffTime = abs(Timestamp - LastCheck),
   case DiffTime >= CheckInterval orelse Fd == undefined of
      true ->
         true;
      _ ->
         % We need to know if the file has changed "out from under lager" so we don't write to an invalid Fd
         {Result, _FInfo} = rumUtil:isFileChanged(Name, Inode, CTime),
         Result
   end.

%% Convert the config into a gen_event handler ID
configToId(Config) ->
   case rumUtil:get_opt(file, Config, undefined) of
      undefined ->
         erlang:error(no_file);
      File ->
         {?MODULE, File}
   end.

checkOpts([], IsFile) ->
   ?IIF(IsFile, true, {error, no_file_name});
checkOpts([{file, _File} | Tail], _IsFile) ->
   checkOpts(Tail, true);
checkOpts([{level, Level} | Tail], IsFile) ->
   ?IIF(rumUtil:validateLogLevel(Level) /= false, checkOpts(Tail, IsFile), {error, {invalid_log_level, Level}});
checkOpts([{size, Size} | Tail], IsFile) when is_integer(Size), Size >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([{count, Count} | Tail], IsFile) when is_integer(Count), Count >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([{rotator, Rotator} | Tail], IsFile) when is_atom(Rotator) ->
   checkOpts(Tail, IsFile);
checkOpts([{high_water_mark, HighWaterMark} | Tail], IsFile) when is_integer(HighWaterMark), HighWaterMark >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([{date, _Date} | Tail], IsFile) ->
   checkOpts(Tail, IsFile);
checkOpts([{sync_interval, SyncInt} | Tail], IsFile) when is_integer(SyncInt), SyncInt >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([{sync_size, SyncSize} | Tail], IsFile) when is_integer(SyncSize), SyncSize >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([{check_interval, CheckInt} | Tail], IsFile) when is_integer(CheckInt), CheckInt >= 0; CheckInt == always ->
   checkOpts(Tail, IsFile);
checkOpts([{sync_on, Level} | Tail], IsFile) ->
   ?IIF(rumUtil:validateLogLevel(Level) /= false, checkOpts(Tail, IsFile), {error, {invalid_sync_on, Level}});
checkOpts([{formatter, Fmt} | Tail], IsFile) when is_atom(Fmt) ->
   checkOpts(Tail, IsFile);
checkOpts([{formatter_config, FmtCfg} | Tail], IsFile) when is_list(FmtCfg) ->
   checkOpts(Tail, IsFile);
checkOpts([{flush_queue, FlushCfg} | Tail], IsFile) when is_boolean(FlushCfg) ->
   checkOpts(Tail, IsFile);
checkOpts([{flush_threshold, Thr} | Tail], IsFile) when is_integer(Thr), Thr >= 0 ->
   checkOpts(Tail, IsFile);
checkOpts([Other | _Tail], _IsFile) ->
   {error, {invalid_opt, Other}}.

scheduleRotation(undefined, _FileName) ->
   ok;
scheduleRotation(Date, Name) ->
   erlang:send_after(rumUtil:calcNextRotateMs(Date), self(), {mRotate, Name}),
   ok.

closeFile(#state{fd = Fd} = State) ->
   case Fd of
      undefined -> State;
      _ ->
         %% Flush and close any file handles.
         %% delayed write can cause file:close not to do a close
         _ = file:datasync(Fd),
         _ = file:close(Fd),
         _ = file:close(Fd),
         State#state{fd = undefined}
   end.