/*******************************************************************************************
*
*   raylib example - loading thread
*
*   NOTE: This example requires linking with pthreads library,
*   on MinGW, it can be accomplished passing -static parameter to compiler
*
*   This example has been created using raylib 2.5 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2014-2019 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

#include "pthread.h"                        // POSIX style threads management

#include <time.h>                           // Required for: clock()

#if defined(PLATFORM_WEB)
    #include <emscripten/emscripten.h>
#endif

// Using C11 atomics for synchronization
// NOTE: A plain bool (or any plain data type for that matter) can't be used for inter-thread synchronization
static bool dataLoaded = false;             // Data Loaded completion indicator
static void *LoadDataThread(void *arg);     // Loading data thread function declaration

static int dataProgress = 0;                // Data progress accumulator

//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;

// NOTE: Textures MUST be loaded after Window initialization (OpenGL context is required)

pthread_t threadId;             // Loading data thread id

enum { STATE_WAITING, STATE_LOADING, STATE_FINISHED } state = STATE_WAITING;
int framesCounter = 0;

//----------------------------------------------------------------------------------
// Module Functions Declaration
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void);     // Update and Draw one frame

//----------------------------------------------------------------------------------
// Program Main Entry Point
//----------------------------------------------------------------------------------
int main(void)
{
    // Initialization
    //--------------------------------------------------------------------------------------
    InitWindow(screenWidth, screenHeight, "raylib [core] example - loading thread");

#if defined(PLATFORM_WEB)
    emscripten_set_main_loop(UpdateDrawFrame, 0, 1);
#else
    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        UpdateDrawFrame();
    }
#endif

    // De-Initialization
    //--------------------------------------------------------------------------------------
    CloseWindow();        // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}

//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void)
{
    // Update
    //----------------------------------------------------------------------------------
    switch (state)
    {
        case STATE_WAITING:
        {
            if (IsKeyPressed(KEY_ENTER))
            {
                int error = pthread_create(&threadId, NULL, &LoadDataThread, NULL);
                if (error != 0) TraceLog(LOG_ERROR, "Error creating loading thread");
                else TraceLog(LOG_INFO, "Loading thread initialized successfully");

                state = STATE_LOADING;
            }
        } break;
        case STATE_LOADING:
        {
            framesCounter++;
            if (dataLoaded)
            {
                framesCounter = 0;
                state = STATE_FINISHED;
            }
        } break;
        case STATE_FINISHED:
        {
            if (IsKeyPressed(KEY_ENTER))
            {
                // Reset everything to launch again
                dataLoaded = false;
                dataProgress = 0;
                state = STATE_WAITING;
            }
        } break;
        default: break;
    }
    //----------------------------------------------------------------------------------

    // Draw
    //----------------------------------------------------------------------------------
    BeginDrawing();

        ClearBackground(RAYWHITE);

        switch (state)
        {
            case STATE_WAITING: DrawText("PRESS ENTER to START LOADING DATA", 150, 170, 20, DARKGRAY); break;
            case STATE_LOADING:
            {
                DrawRectangle(150, 200, dataProgress, 60, SKYBLUE);
                if ((framesCounter/15)%2) DrawText("LOADING DATA...", 240, 210, 40, DARKBLUE);

            } break;
            case STATE_FINISHED:
            {
                DrawRectangle(150, 200, 500, 60, LIME);
                DrawText("DATA LOADED!", 250, 210, 40, GREEN);

            } break;
            default: break;
        }

        DrawRectangleLines(150, 200, 500, 60, DARKGRAY);

    EndDrawing();
    //----------------------------------------------------------------------------------
}


// Loading data thread function definition
static void *LoadDataThread(void *arg)
{
    int timeCounter = 0;            // Time counted in ms
    clock_t prevTime = clock();     // Previous time

    // We simulate data loading with a time counter for 5 seconds
    while (timeCounter < 5000)
    {
        clock_t currentTime = clock() - prevTime;
        timeCounter = currentTime*1000/CLOCKS_PER_SEC;

        // We accumulate time over a global variable to be used in
        // main thread as a progress bar
        dataProgress = timeCounter/10;
    }

    // When data has finished loading, we set global variable
    dataLoaded = true;

    return NULL;
}