////////////////////////////////
//~ Global state

P_SharedLogCtx P_shared_log_ctx = ZI;

////////////////////////////////
//~ Startup

void P_LogStartup(String logfile_path)
{
    __prof;
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    ctx->callbacks_arena = AllocArena(Mebi(8));
    if (logfile_path.len > 0)
    {
        /* Create / wipe log file */
        P_CloseFIle(P_OpenFileWrite(logfile_path));
        /* Keep log file open for appending */
        if (P_IsFile(logfile_path))
        {
            ctx->file = P_OpenFileAppend(logfile_path);
            ctx->file_valid = 1;
        }
    }
    Atomic32FetchSet(&ctx->initialized, 1);
}

////////////////////////////////
//~ Callback registration

void P_RegisterLogCallback(P_LogEventCallbackFunc *func, i32 level)
{
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }
    P_Lock lock = P_LockE(&ctx->callbacks_mutex);
    {
        LogEventCallback *callback = PushStruct(ctx->callbacks_arena, LogEventCallback);
        callback->func = func;
        callback->level = level;
        if (ctx->last_callback)
        {
            ctx->last_callback->next = callback;
        }
        else
        {
            ctx->first_callback = callback;
        }
        ctx->last_callback = callback;
    }
    P_Unlock(&lock);
}

////////////////////////////////
//~ Append

void P__LogAppend(String msg)
{
    __prof;
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }

    if (ctx->file_valid)
    {
        TempArena scratch = BeginScratchNoConflict();
        String msg_line = CatString(scratch.arena, msg, Lit("\n"));
        P_WriteFile(ctx->file, msg_line);
        EndScratch(scratch);
    }
}

////////////////////////////////
//~ Panic

/* Panic log function is separate to enforce zero side effects other than
 * writing to log file. */
void P__LogPanic(String msg)
{
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }

    if (ctx->file_valid)
    {
        P_WriteFile(ctx->file, Lit("******** PANICKING ********\n"));
        P_WriteFile(ctx->file, msg);
        P_WriteFile(ctx->file, Lit("\n***************************\n"));
    }
}

////////////////////////////////
//~ Logfv

#if P_IncludeLogSourceLocation
void P__LogFV(i32 level, String file, u32 line, String fmt, va_list args)
#else
void P__LogFV(i32 level, String fmt, va_list args)
#endif
{
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }
    TempArena scratch = BeginScratchNoConflict();
    String msg = StringFormatV(scratch.arena, fmt, args);
#if P_IncludeLogSourceLocation
    P__log(level, file, line, msg);
#else
    P__log(level, msg);
#endif
    EndScratch(scratch);
}

////////////////////////////////
//~ Logf

#if P_IncludeLogSourceLocation
void P__LogF(i32 level, String file, u32 line, String fmt, ...)
#else
void P__LogF(i32 level, String fmt, ...)
#endif
{
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }
    va_list args;
    va_start(args, fmt);
#if P_IncludeLogSourceLocation
    P__LogFV(level, file, line, fmt, args);
#else
    P__LogFV(level, fmt, args);
#endif
    va_end(args);
}

////////////////////////////////
//~ Log

#if P_IncludeLogSourceLocation
void P__log(i32 level, String file, u32 line, String msg)
#else
void P__log(i32 level, String msg)
#endif
{
    __prof;
    P_SharedLogCtx *ctx = &P_shared_log_ctx;
    if (!Atomic32Fetch(&ctx->initialized)) { return; }
    TempArena scratch = BeginScratchNoConflict();

    P_LogLevelSettings settings = P_log_settings[level];
    if (level < 0 || level >= P_LogLevel_Count)
    {
        P_Panic(Lit("Invalid log level"));
    }


    u32 tid = P_GetThreadId();


    //- Format message
    P_DateTime datetime = P_LocalTime();
    i64 time_ns = P_TimeNs();
    String shorthand = settings.shorthand;

#if P_IncludeLogSourceLocation
    String msg_formatted = StringFormat(
        scratch.arena,
        Lit("[%F:%F:%F.%F] |%F| [%F] <%F:%F> %F"),

        /* Time */
        FmtUintZ(datetime.hour, 2),
        FmtUintZ(datetime.minute, 2),
        FmtUintZ(datetime.second, 2),
        FmtUintZ(datetime.milliseconds, 3),

        /* TID */
        FmtUintZ(tid, 5),

        /* Level */
        FmtString(shorthand),

        /* Source location */
        FmtString(file),
        FmtSint(line),

        /* Message */
        FmtString(msg)
    );
#else
    String msg_formatted = StringFormat(
        scratch.arena,
        Lit("[%F:%F:%F.%F] |%F| [%F] %F"),

        /* Time */
        FmtUintZ(datetime.hour, 2),
        FmtUintZ(datetime.minute, 2),
        FmtUintZ(datetime.second, 2),
        FmtUintZ(datetime.milliseconds, 3),

        /* TID */
        FmtUintZ(tid, 5),

        /* Level */
        FmtString(shorthand),

        /* Message */
        FmtString(msg)
    );
#endif

    __profmsg((char *)msg.text, msg.len, settings.color);
    P__LogAppend(msg_formatted);

    //- Run callbacks
    P_LogEvent event = ZI;
    event.level = level;
    event.msg = msg;
    event.datetime = datetime;
    event.time_ns = time_ns;
#if P_IncludeLogSourceLocation
    event.file = file;
    event.line = line;
#endif
    {
        P_Lock lock = P_LockS(&ctx->callbacks_mutex);
        for (LogEventCallback *callback = ctx->first_callback; callback; callback = callback->next)
        {
            if (level <= callback->level)
            {
                __profn("Run log callback");
                callback->func(event);
            }
        }
        P_Unlock(&lock);
    }

    EndScratch(scratch);
}