/*
    Copyright 2016-2019 Arisotura

    This file is part of melonDS.

    melonDS is free software: you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with melonDS. If not, see http://www.gnu.org/licenses/.
*/

#include <GL/gl.h>
#include <GL/glext.h>

#include <stdio.h>
#include <string.h>
#include "NDS.h"
#include "GPU.h"
#include "Platform.h"

namespace GPU3D
{
namespace GLRenderer43
{

PFNGLGENFRAMEBUFFERSPROC        glGenFramebuffers;
PFNGLDELETEFRAMEBUFFERSPROC     glDeleteFramebuffers;
PFNGLBINDFRAMEBUFFERPROC        glBindFramebuffer;
PFNGLFRAMEBUFFERTEXTUREPROC     glFramebufferTexture;

PFNGLGENBUFFERSPROC             glGenBuffers;
PFNGLDELETEBUFFERSPROC          glDeleteBuffers;
PFNGLBINDBUFFERPROC             glBindBuffer;
PFNGLMAPBUFFERPROC              glMapBuffer;
PFNGLMAPBUFFERRANGEPROC         glMapBufferRange;
PFNGLUNMAPBUFFERPROC            glUnmapBuffer;
PFNGLBUFFERDATAPROC             glBufferData;

PFNGLCREATESHADERPROC           glCreateShader;
PFNGLSHADERSOURCEPROC           glShaderSource;
PFNGLCOMPILESHADERPROC          glCompileShader;
PFNGLCREATEPROGRAMPROC          glCreateProgram;
PFNGLATTACHSHADERPROC           glAttachShader;
PFNGLLINKPROGRAMPROC            glLinkProgram;
PFNGLUSEPROGRAMPROC             glUseProgram;
PFNGLGETSHADERIVPROC            glGetShaderiv;
PFNGLGETSHADERINFOLOGPROC       glGetShaderInfoLog;
PFNGLGETPROGRAMIVPROC           glGetProgramiv;
PFNGLGETPROGRAMINFOLOGPROC      glGetProgramInfoLog;
PFNGLDELETESHADERPROC           glDeleteShader;
PFNGLDELETEPROGRAMPROC          glDeleteProgram;


const char* kRenderVS = R"(#version 400

in vec4 vPosition;

void main()
{
    // burp
    gl_Position = vPosition;
}
)";

const char* kRenderFS = R"(#version 400

out vec4 oColor;

void main()
{
    oColor = vec4(0,1,1,1);
}
)";


GLuint RenderShader[3];

GLuint FramebufferID, PixelbufferID;
u8 Framebuffer[256*192*4];
u8 CurLine[256*4];


bool InitGLExtensions()
{
#define LOADPROC(type, name)  \
    name = (PFN##type##PROC)Platform::GL_GetProcAddress(#name); \
    if (!name) { printf("OpenGL: " #name " not found\n"); return false; }

    LOADPROC(GLGENFRAMEBUFFERS, glGenFramebuffers);
    LOADPROC(GLDELETEFRAMEBUFFERS, glDeleteFramebuffers);
    LOADPROC(GLBINDFRAMEBUFFER, glBindFramebuffer);
    LOADPROC(GLFRAMEBUFFERTEXTURE, glFramebufferTexture);

    LOADPROC(GLGENBUFFERS, glGenBuffers);
    LOADPROC(GLDELETEBUFFERS, glDeleteBuffers);
    LOADPROC(GLBINDBUFFER, glBindBuffer);
    LOADPROC(GLMAPBUFFER, glMapBuffer);
    LOADPROC(GLMAPBUFFERRANGE, glMapBufferRange);
    LOADPROC(GLUNMAPBUFFER, glUnmapBuffer);
    LOADPROC(GLBUFFERDATA, glBufferData);

    LOADPROC(GLCREATESHADER, glCreateShader);
    LOADPROC(GLSHADERSOURCE, glShaderSource);
    LOADPROC(GLCOMPILESHADER, glCompileShader);
    LOADPROC(GLCREATEPROGRAM, glCreateProgram);
    LOADPROC(GLATTACHSHADER, glAttachShader);
    LOADPROC(GLLINKPROGRAM, glLinkProgram);
    LOADPROC(GLUSEPROGRAM, glUseProgram);
    LOADPROC(GLGETSHADERIV, glGetShaderiv);
    LOADPROC(GLGETSHADERINFOLOG, glGetShaderInfoLog);
    LOADPROC(GLGETPROGRAMIV, glGetProgramiv);
    LOADPROC(GLGETPROGRAMINFOLOG, glGetProgramInfoLog);
    LOADPROC(GLDELETESHADER, glDeleteShader);
    LOADPROC(GLDELETEPROGRAM, glDeleteProgram);

#undef LOADPROC
    return true;
}

bool BuildShaderProgram(const char* vs, const char* fs, GLuint* ids, const char* name)
{
    int len;
    int res;

    ids[0] = glCreateShader(GL_VERTEX_SHADER);
    len = strlen(vs);
    glShaderSource(ids[0], 1, &vs, &len);
    glCompileShader(ids[0]);

    glGetShaderiv(ids[0], GL_COMPILE_STATUS, &res);
    if (res != GL_TRUE)
    {
        glGetShaderiv(ids[0], GL_INFO_LOG_LENGTH, &res);
        if (res < 1) res = 1024;
        char* log = new char[res+1];
        glGetShaderInfoLog(ids[0], res+1, NULL, log);
        printf("OpenGL: failed to compile vertex shader %s: %s\n", name, log);
        delete[] log;

        glDeleteShader(ids[0]);

        return false;
    }

    ids[1] = glCreateShader(GL_FRAGMENT_SHADER);
    len = strlen(vs);
    glShaderSource(ids[1], 1, &fs, &len);
    glCompileShader(ids[1]);

    glGetShaderiv(ids[1], GL_COMPILE_STATUS, &res);
    if (res != GL_TRUE)
    {
        glGetShaderiv(ids[1], GL_INFO_LOG_LENGTH, &res);
        if (res < 1) res = 1024;
        char* log = new char[res+1];
        glGetShaderInfoLog(ids[1], res+1, NULL, log);
        printf("OpenGL: failed to compile fragment shader %s: %s\n", name, log);
        delete[] log;

        glDeleteShader(ids[0]);
        glDeleteShader(ids[1]);

        return false;
    }

    ids[2] = glCreateProgram();
    glAttachShader(ids[2], ids[0]);
    glAttachShader(ids[2], ids[1]);
    glLinkProgram(ids[2]);

    glGetProgramiv(ids[2], GL_LINK_STATUS, &res);
    if (res != GL_TRUE)
    {
        glGetProgramiv(ids[2], GL_INFO_LOG_LENGTH, &res);
        if (res < 1) res = 1024;
        char* log = new char[res+1];
        glGetProgramInfoLog(ids[2], res+1, NULL, log);
        printf("OpenGL: failed to link program %s: %s\n", name, log);
        delete[] log;

        glDeleteShader(ids[0]);
        glDeleteShader(ids[1]);
        glDeleteProgram(ids[2]);

        return false;
    }

    return true;
}

bool Init()
{
    if (!InitGLExtensions()) return false;

    const GLubyte* renderer = glGetString(GL_RENDERER); // get renderer string
    const GLubyte* version = glGetString(GL_VERSION); // version as a string
    printf("OpenGL: renderer: %s\n", renderer);
    printf("OpenGL: version: %s\n", version);


    if (!BuildShaderProgram(kRenderVS, kRenderFS, RenderShader, "RenderShader"))
        return false;


    u8* test_tex = new u8[256*192*4];
    u8* ptr = test_tex;
    for (int y = 0; y < 192; y++)
    {
        for (int x = 0; x < 256; x++)
        {
            if ((x & 0x10) ^ (y & 0x10))
            {
                *ptr++ = 0x3F;
                *ptr++ = 0x00;
                *ptr++ = 0;
                *ptr++ = 0x1F;
            }
            else
            {
                *ptr++ = 0x3F;
                *ptr++ = y>>2;
                *ptr++ = 0;
                *ptr++ = 0x1F;
            }
        }
    }

    glGenFramebuffers(1, &FramebufferID);
    glBindFramebuffer(GL_FRAMEBUFFER, FramebufferID);

    GLuint frametex;
    glGenTextures(1, &frametex);
    glBindTexture(GL_TEXTURE_2D, frametex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 192, 0, GL_RGBA, GL_UNSIGNED_BYTE, test_tex);
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, frametex, 0);

    glGenBuffers(1, &PixelbufferID);
    glBindBuffer(GL_PIXEL_PACK_BUFFER, PixelbufferID);
    //glBufferData(GL_PIXEL_PACK_BUFFER, 256*48*4, NULL, GL_DYNAMIC_READ);
    glBufferData(GL_PIXEL_PACK_BUFFER, 256*192*4, NULL, GL_DYNAMIC_READ);

    return true;
}

void DeInit()
{
    //
}

void Reset()
{
    //
}


void VCount144()
{
}

void RenderFrame()
{
    // render shit here

    glBindFramebuffer(GL_FRAMEBUFFER, FramebufferID);
    glReadBuffer(GL_COLOR_ATTACHMENT0);
    //glReadPixels(0, 0, 256, 48, GL_RGBA, GL_UNSIGNED_BYTE, Framebuffer);
    glBindBuffer(GL_PIXEL_PACK_BUFFER, PixelbufferID);
    //glReadPixels(0, 0, 256, 48, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
    glReadPixels(0, 0, 256, 192, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
}

void RequestLine(int line)
{
    if (line == 0)
    {
        u8* data = (u8*)glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
        //if (data) memcpy(&Framebuffer[4*256*0], data, 4*256*48);
        if (data) memcpy(&Framebuffer[4*256*0], data, 4*256*192);
        glUnmapBuffer(GL_PIXEL_PACK_BUFFER);

        //glReadPixels(0, 48, 256, 48, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
    }
    /*else if (line == 48)
    {
        u8* data = (u8*)glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
        if (data) memcpy(&Framebuffer[4*256*48], data, 4*256*48);
        glUnmapBuffer(GL_PIXEL_PACK_BUFFER);

        glReadPixels(0, 96, 256, 48, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
    }
    else if (line == 96)
    {
        u8* data = (u8*)glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
        if (data) memcpy(&Framebuffer[4*256*96], data, 4*256*48);
        glUnmapBuffer(GL_PIXEL_PACK_BUFFER);

        glReadPixels(0, 144, 256, 48, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
    }
    else if (line == 144)
    {
        u8* data = (u8*)glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
        if (data) memcpy(&Framebuffer[4*256*144], data, 4*256*48);
        glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
    }*/
}

u32* GetLine(int line)
{
    return (u32*)&Framebuffer[256*4 * line];
}

}
}