// http://stackoverflow.com/questions/6005076/building-glew-on-windows-with-mingw

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <stdio.h>
#include <iostream>
#include <fstream>
#include <vector>
#include <stdexcept>

GLuint LoadTexture(char *filename,int *textw,int *texth) {
        SDL_Surface *surface;
        GLuint textureid;
        int mode;
        surface = IMG_Load(filename);
        // Or if you don't use SDL_image you can use SDL_LoadBMP here instead:
        // surface = SDL_LoadBMP(filename);

        // could not load filename
        if (!surface) {
                return 0;
        }

        // work out what format to tell glTexImage2D to use...
        if (surface->format->BytesPerPixel == 3) { // RGB 24bit
                mode = GL_RGB;

        } else if (surface->format->BytesPerPixel == 4) { // RGBA 32bit
                mode = GL_RGBA;
        } else {
                SDL_FreeSurface(surface);
                return 0;
        }

        *textw=surface->w;
        *texth=surface->h;
        // create one texture name
        glGenTextures(1, &textureid);
        // tell opengl to use the generated texture name
        glBindTexture(GL_TEXTURE_2D, textureid);
        // this reads from the sdl surface and puts it into an opengl texture
        glTexImage2D(GL_TEXTURE_2D, 0, mode, surface->w, surface->h, 0, mode, GL_UNSIGNED_BYTE, surface->pixels);
        // these affect how this texture is drawn later on...glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        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_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        // clean up
        SDL_FreeSurface(surface);
        return textureid;

}

GLuint LoadShaders(const char * vertex_file_path,const char * fragment_file_path){

	// Create the shaders
	GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
	GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);

	// Read the Vertex Shader code from the file
	std::string VertexShaderCode;
	std::ifstream VertexShaderStream(vertex_file_path, std::ios::in);
	if(VertexShaderStream.is_open()){
		std::string Line = "";
		while(getline(VertexShaderStream, Line))
			VertexShaderCode += "\n" + Line;
		VertexShaderStream.close();
	}else{
		printf("Impossible to open %s. Are you in the right directory ? Don't forget to read the FAQ !\n", vertex_file_path);
		getchar();
		return 0;
	}

	// Read the Fragment Shader code from the file
	std::string FragmentShaderCode;
	std::ifstream FragmentShaderStream(fragment_file_path, std::ios::in);
	if(FragmentShaderStream.is_open()){
		std::string Line = "";
		while(getline(FragmentShaderStream, Line))
			FragmentShaderCode += "\n" + Line;
		FragmentShaderStream.close();
	}

	GLint Result = GL_FALSE;
	int InfoLogLength;


	// Compile Vertex Shader
	printf("Compiling shader : %s\n", vertex_file_path);
	char const * VertexSourcePointer = VertexShaderCode.c_str();
	glShaderSource(VertexShaderID, 1, &VertexSourcePointer , NULL);
	glCompileShader(VertexShaderID);

	// Check Vertex Shader
	glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if ( InfoLogLength > 0 ){
		std::vector<char> VertexShaderErrorMessage(InfoLogLength+1);
		glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
		printf("%s\n", &VertexShaderErrorMessage[0]);
	}



	// Compile Fragment Shader
	printf("Compiling shader : %s\n", fragment_file_path);
	char const * FragmentSourcePointer = FragmentShaderCode.c_str();
	glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
	glCompileShader(FragmentShaderID);

	// Check Fragment Shader
	glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if ( InfoLogLength > 0 ){
		std::vector<char> FragmentShaderErrorMessage(InfoLogLength+1);
		glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
		printf("%s\n", &FragmentShaderErrorMessage[0]);
	}



	// Link the program
	printf("Linking program\n");
	GLuint ProgramID = glCreateProgram();
	glAttachShader(ProgramID, VertexShaderID);
	glAttachShader(ProgramID, FragmentShaderID);
	glLinkProgram(ProgramID);

	// Check the program
	glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
	glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if ( InfoLogLength > 0 ){
		std::vector<char> ProgramErrorMessage(InfoLogLength+1);
		glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
		printf("%s\n", &ProgramErrorMessage[0]);
	}


	glDetachShader(ProgramID, VertexShaderID);
	glDetachShader(ProgramID, FragmentShaderID);

	glDeleteShader(VertexShaderID);
	glDeleteShader(FragmentShaderID);

	return ProgramID;
}

GLuint WriteTexture(int textw, int texth){
    // The framebuffer, which regroups 0, 1, or more textures, and 0 or 1 depth buffer.
    GLuint FramebufferName = 0;
    glGenFramebuffers(1, &FramebufferName);
    glBindFramebuffer(GL_FRAMEBUFFER, FramebufferName);

    // The texture we're going to render to
    GLuint renderedTexture;
    glGenTextures(1, &renderedTexture);

    // "Bind" the newly created texture : all future texture functions will modify this texture
    glBindTexture(GL_TEXTURE_2D, renderedTexture);

    // Give an empty image to OpenGL ( the last "0" )
    glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, textw, texth, 0,GL_RGB, GL_UNSIGNED_BYTE, 0);

    // Poor filtering. Needed !
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

    // The depth buffer -- OPTIONAL, REMOVE WHEN NOT NEEDED
    GLuint depthrenderbuffer;
    glGenRenderbuffers(1, &depthrenderbuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, depthrenderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 1024, 768);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthrenderbuffer);

    // Set "renderedTexture" as our colour attachement #0
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, renderedTexture, 0);

    // Set the list of draw buffers.
    GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0};
    glDrawBuffers(1, DrawBuffers); // "1" is the size of DrawBuffers

    // Always check that our framebuffer is ok
    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        return false;

}


int main(int argc, char* args[]) {
    GLFWwindow* window;
    GLuint tex1, tex2;
    int textw, texth;
    int textw2, texth2;


    /* Initialize the library */

    /* GLFW */
    if (!glfwInit()) {
        printf("GLFW Error");
        return 1;
    }
    /* Create a windowed mode window and its OpenGL context */
    glfwSetWindowSizeLimits(window, 640, 480, 640, 480);
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window) {
        glfwTerminate();
        return 1;
    }
    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    /* GLEW */
    glewExperimental = GL_FALSE;
    GLenum error = glGetError();
    if (error != GL_NO_ERROR)
    {
        std::cout << "OpenGL Error: " << error << std::endl;
    }
    GLenum glewinit = glewInit();
    if (glewinit != GLEW_OK) {
        std::cout << "Glew not okay! " << glewinit;
        return 1;
    }

    /* SDL */
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        printf("SDL Error");
        return 1;
    }
    // INIT

    // An array of 3 vectors which represents 3 vertices
    static const GLfloat g_vertex_buffer_data[] = {
       -1.0f, -1.0f, 0.0f,  // (bottom - left )  TRIANGLE 1
        1.0f, -1.0f, 0.0f,  // (bottom - right)
       -1.0f,  1.0f, 0.0f,  // (top    - left )
        1.0f,  1.0f, 0.0f,  // (top    - right)  TRIANGLE 2
        1.0f, -1.0f, 0.0f,  // (bottom - right)
       -1.0f,  1.0f, 0.0f,  // (top    - left )
    };
    // One color for each vertex. They were generated randomly.
    static const GLfloat g_uv_buffer_data[] = {
        0.0f, 1.0f-0.0f,         // (bottom - left )  TRIANGLE 1
        1.0f, 1.0f-0.0f,         // (bottom - right)
        0.0f, 1.0f-1.0f,         // (top    - left )
        1.0f, 1.0f-1.0f,         // (top    - right)  TRIANGLE 2
        1.0f, 1.0f-0.0f,         // (bottom - right)
        0.0f, 1.0f-1.0f,         // (top    - left )
    };


    // Identify our vertex buffer
    GLuint vertexbuffer;
    glGenBuffers(1, &vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);

    // Identify our color buffer
    GLuint colorbuffer;
    glGenBuffers(1, &colorbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, colorbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_uv_buffer_data), g_uv_buffer_data, GL_STATIC_DRAW);



    tex1 = LoadTexture("../img/tests/flieger.jpg",&textw,&texth);
    printf("Tex1: %d", tex1);
    tex2 = LoadTexture("../img/tests/flieger2.jpg",&textw2,&texth2);
    printf("Tex2: %d", tex2);
    glfwSetWindowSize(window, textw, texth);
    glViewport(0, 0, textw, texth);
    glfwSetWindowSizeLimits(window, textw, texth, textw, texth);

    GLuint programID = LoadShaders("trimap.vertexshader", "trimap.fragmentshader");
    GLint textureLoc1 = glGetUniformLocation(programID, "myTextureSampler");
    GLint textureLoc2 = glGetUniformLocation(programID, "myTextureSampler2");
    GLint widthLoc = glGetUniformLocation(programID, "pixWidth");
    GLint heigthLoc = glGetUniformLocation(programID, "pixHeight");

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, tex1);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, tex2);


    printf("Shader program ID: %d\n", programID);
    printf("textureLoc1: %d\n", textureLoc1);
    printf("textureLoc2: %d\n", textureLoc2);
    printf("widthLoc: %d\n", widthLoc);
    printf("heigthLoc: %d\n", heigthLoc);
    printf("Width: %f\n", 1.0f/textw);
    printf("Height: %f\n", 1.0f/texth);



    // INIT END
    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window)) {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glUseProgram(programID);
        glUniform1f(widthLoc, 1.0f/textw);
        glUniform1f(heigthLoc, 1.0f/texth);
        glUniform1i(textureLoc1, 0);
        glUniform1i(textureLoc2, 1);

        // 1rst attribute buffer : vertices
        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
        glVertexAttribPointer(
           0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
           3,                  // size
           GL_FLOAT,           // type
           GL_FALSE,           // normalized?
           0,                  // stride
           (void*)0            // array buffer offset
        );
        // 2nd attribute buffer : colors
        glEnableVertexAttribArray(1);
        glBindBuffer(GL_ARRAY_BUFFER, colorbuffer);
        glVertexAttribPointer(
            1,                 // attribute. No particular reason for 1, but must match the layout in the shader.
            2,                 // size
            GL_FLOAT,          // type
            GL_FALSE,          // normalized?
            0,                 // stride
            (void*)0           // array buffer offset
        );


        // Draw the triangle !
        glDrawArrays(GL_TRIANGLES, 0, 2*3); // 2*3 indices starting at 0 -> 2 triangles -> 1 square
        glDisableVertexAttribArray(0);



        // RENDER END
        /* Swap front and back buffers */
        glfwSwapBuffers(window);
        /* Poll for and process events */
        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}