#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

#include <math.h>

#include <GL/glew.h>

#include <GLFW/glfw3.h>
GLFWwindow* window;

#include <cglm/struct.h>

#include "worldgen.h"

#define WINW 800
#define WINH 450

#define FOV 1.4f

#define SHADER_BUF_SIZE 1000

GLuint loadShaders(const char*, const char*);
static GLfloat vertexBufferData[1000];

void setVertexBufferData(GLfloat*, unsigned int*, unsigned int);

int main()
{
    glewExperimental = true;
    if( !glfwInit() )
    {
        fprintf( stderr, "Failed to initialize GLFW :(\n" );
        return -1;
    }
    glfwWindowHint(GLFW_SAMPLES, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow(WINW, WINH, "Planet Miner", NULL, NULL);
    if( window == NULL )
    {
        fprintf( stderr, "Failed to create window. If you are using an Intel GPU, please note that they are not compatible with OpenGL 3.3\n" );
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    glewExperimental = true;
    if( glewInit() != GLEW_OK )
    {
        fprintf( stderr, "Failed to initialize GLEW\n" );
        getchar();
        glfwTerminate();
        return -1;
    }

    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    GLuint vertexArrayID;
    glGenVertexArrays(1, &vertexArrayID);
    glBindVertexArray(vertexArrayID);


    GLuint programID = loadShaders( "src/shader.vert", "src/shader.frag" );

    GLuint matrixID = glGetUniformLocation(programID, "MVP");

    mat4s projection = glms_perspective(FOV, 16.0f / 9.0f, 0.1f, 100.0f);

    vec3s eye = {0.0f, 0.0f, 5.0f};
    vec3s center = {0.0f, 0.0f, 0.0f};
    vec3s up = {0.0f, 1.0f, 0.0f};
    
    vec3s planetPos = {0.0f, 0.0f, 0.0f};
    worldMesh* mesh = generateWorld(planetPos);
    setVertexBufferData(mesh->vertices, mesh->triangles, mesh->triangleArrayCount);

    GLuint vertexbuffer;
    glGenBuffers(1, &vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexBufferData), vertexBufferData, GL_STATIC_DRAW);
    
    vec3s direction = {0.0f, 0.0f, -5.0f};

    printf("Entering main loop\n");

    do
    {
        glClear( GL_COLOR_BUFFER_BIT );

        mat4s view = glms_lookat(eye, center, up);
        mat4s model = glms_mat4_identity();
        mat4s mvp = glms_mat4_mul(glms_mat4_mul(projection, view), model);

        glUseProgram(programID);

        glUniformMatrix4fv(matrixID, 1, GL_FALSE, &mvp);

        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);

        glVertexAttribPointer(
            0,
            3,
            GL_FLOAT,
            GL_FALSE,
            0,
            (void*)0
        );

        glDrawArrays(GL_TRIANGLES, 0, 20*3);
        glDisableVertexAttribArray(0);

        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    while( (glfwGetKey(window, GLFW_KEY_Q) != GLFW_PRESS 
            && glfwGetKey(window, GLFW_KEY_ESCAPE) != GLFW_PRESS)
            && !glfwWindowShouldClose(window));

    glDeleteBuffers(1, &vertexbuffer);
    glDeleteProgram(programID);
    glDeleteVertexArrays(1, &vertexArrayID);

    glfwTerminate();

    return 0;
}

GLuint loadShaders(const char* vertexShaderPath, const char* fragmentShaderPath)
{
    char* vertexShaderCode = readTextFile( vertexShaderPath );
    char* fragmentShaderCode = readTextFile( fragmentShaderPath );

    GLuint vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
	GLuint fragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);

    GLint result = GL_FALSE;
    int infoLogLength;

    printf("Compiling vertex shader...\n");
    glShaderSource(vertexShaderID, 1, &vertexShaderCode, NULL);
    glCompileShader(vertexShaderID);

    glGetShaderiv(vertexShaderID, GL_COMPILE_STATUS, &result);
    glGetShaderiv(vertexShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
    if( infoLogLength > 0 )
    {
        char vertexShaderErrorMessage[infoLogLength + 1];
        glGetShaderInfoLog(vertexShaderID, infoLogLength, NULL, &vertexShaderErrorMessage);
        printf("%s\n", &vertexShaderErrorMessage);
    }

    printf("Compiling fragment shader...\n");
    glShaderSource(fragmentShaderID, 1, &fragmentShaderCode, NULL);
    glCompileShader(fragmentShaderID);

    glGetShaderiv(fragmentShaderID, GL_COMPILE_STATUS, &result);
    glGetShaderiv(fragmentShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
    if( infoLogLength > 0 )
    {
        char fragmentShaderErrorMessage[infoLogLength + 1];
        glGetShaderInfoLog(fragmentShaderID, infoLogLength, NULL, &fragmentShaderErrorMessage);
        printf("%s\n", &fragmentShaderErrorMessage);
    }

    printf("Linking program\n");
    GLuint programID = glCreateProgram();
    glAttachShader(programID, vertexShaderID);
    glAttachShader(programID, fragmentShaderID);
    glLinkProgram(programID);

    glGetProgramiv(programID, GL_LINK_STATUS, &result);
    glGetProgramiv(programID, GL_INFO_LOG_LENGTH, &infoLogLength);
    if( infoLogLength > 0 )
    {
        char programErrorMessage[infoLogLength + 1];
        glGetProgramInfoLog(programID, infoLogLength, NULL, &programErrorMessage);
        printf("%s\n", &programErrorMessage);
    }

    free( vertexShaderCode );
    free( fragmentShaderCode );

    glDetachShader( programID, vertexShaderID );
    glDetachShader( programID, fragmentShaderID );

    glDeleteShader( vertexShaderID );
    glDeleteShader( fragmentShaderID );
    return programID;
}

void setVertexBufferData(GLfloat* vertices, unsigned int* triangles, unsigned int triangleCount)
{
    for( int i = 0; i < triangleCount; ++i )
    {
        vertexBufferData[i*3] = vertices[triangles[i]*3];
        vertexBufferData[i*3 + 1] = vertices[triangles[i]*3 + 1];
        vertexBufferData[i*3 + 2] = vertices[triangles[i]*3 + 2];
    }
}