#include "../include/RenderBackend/OpenGL/opengl.hpp"
#include "../include/RenderBackend/OpenGL/Shader.hpp"
#include "../include/RenderBackend/OpenGL/ShaderProgram.hpp"
#include "../include/RenderBackend/OpenGL/DeviceMemory.hpp"
#include "../include/RenderBackend/OpenGL/DeviceFrame.hpp"
#include "../include/Triangle.hpp"

#include <cstdio>
#include <chrono>

// TODO: Creating buffers etc should be somehow created/drawn using the window object, since they are associated with the window
// opengl context

using namespace amalgine;
using namespace std;

static void glfwErrorHandler(int errorCode, const char *errorDescription);
static void initGlfw();
static void initGlew();
static GLFWwindow *createWindow();
static std::unique_ptr<Shader> load_shader_from_file(const char *filepath, Shader::Type shader_type);
static std::unique_ptr<ShaderProgram> build_shader_program_from_shaders(const std::vector<Shader*> &shaders);

int main()
{
    initGlfw();
    glfwSetErrorCallback(glfwErrorHandler);
    GLFWwindow *window = createWindow();
    int window_width = 1;
    int window_height = 1;
    glfwGetWindowSize(window, &window_width, &window_height);
    
    DeviceFrame frame;
    
    std::array<Triangle3D, 2> cpuTriangle = {
        Triangle3D(
            Vertex3D(0.0f, 0.0f, 0.0f),
            Vertex3D(1.0f, 0.0f, 0.0f),
            Vertex3D(0.0f, 1.0f, 0.0f)
        ),
        Triangle3D(
            Vertex3D(1.0f, 0.0f, 0.0f),
            Vertex3D(1.0f, 1.0f, 0.0f),
            Vertex3D(0.0f, 1.0f, 0.0f)
        ),
    };
    DataView<Triangle3D> cpuTriangles(cpuTriangle.data(), cpuTriangle.size());
    DeviceMemory *gpuTriangle = frame.alloc();
    gpuTriangle->copy(cpuTriangles, DeviceMemory::StorageType::STATIC);

    std::unique_ptr<Shader> vertex_shader = load_shader_from_file("shaders/vertex.vert", Shader::Type::VERTEX);
    std::unique_ptr<Shader> pixel_shader = load_shader_from_file("shaders/fragment.frag", Shader::Type::PIXEL);
    std::unique_ptr<ShaderProgram> shader_program = build_shader_program_from_shaders({ vertex_shader.get(), pixel_shader.get() });

    shader_program->set_vertex_input("position", *gpuTriangle);

    Result<Uniform> proj_uniform = shader_program->get_uniform_by_name("proj");
    glm::mat4 proj = glm::perspective(glm::radians(75.0f), (float)window_width / (float)window_height, 0.2f, 1000.0f);
    proj_uniform->set(proj);

    Result<Uniform> triangle_color_uniform = shader_program->get_uniform_by_name("triangle_color");
    triangle_color_uniform->set(vec3f{ 1.0f, 0.0f, 0.0f });

    Result<Uniform> view_uniform = shader_program->get_uniform_by_name("view");
    Result<Uniform> model_uniform = shader_program->get_uniform_by_name("model");

    glm::vec3 character_pos(0.0f, 3.0f, 3.0f);
    auto t_start = std::chrono::high_resolution_clock::now();
    
    while(!glfwWindowShouldClose(window)) {
        glfwPollEvents();
        if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
            glfwSetWindowShouldClose(window, GL_TRUE);

        auto t_now = std::chrono::high_resolution_clock::now();
        float time_delta = std::chrono::duration_cast<std::chrono::duration<float>>(t_now - t_start).count();
        t_start = t_now;

        if(glfwGetKey(window, GLFW_KEY_W))
            character_pos.y -= time_delta;
        if(glfwGetKey(window, GLFW_KEY_S))
            character_pos.y += time_delta;

        glm::mat4 view = glm::lookAt(
            character_pos,
            character_pos - glm::vec3(0.0f, 3.0f, 3.0f),
            glm::vec3(0.0f, 0.0f, 1.0f)
        );
        view_uniform->set(view);

        glm::mat4 model = glm::mat4(1.0f);
        model = glm::rotate(
            model,
            0.0f,
            glm::vec3(0.0f, 0.0f, 1.0f)
        );
        model_uniform->set(model);

        // Set color for clearing
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        // Do the actual screen clearing, using the color set using glClearColor
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        frame.draw(shader_program.get());
        glfwSwapBuffers(window);
    }

    glfwTerminate();
    return 0;
}

void glfwErrorHandler(int errorCode, const char *errorDescription)
{
    printf("GLFW error code: %d, description: %s\n", errorCode, errorDescription);
}

void initGlfw()
{
    if(!glfwInit())
    {
        fprintf(stderr, "Failed to initialize GLFW\n");
        exit(-1);
    }

    glfwWindowHint(GLFW_SAMPLES, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 5);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
}

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

GLFWwindow* createWindow() {
    GLFWwindow *window = glfwCreateWindow(1280, 720, "Amalgine", nullptr, nullptr);
    if(!window)
    {
        fprintf(stderr, "Failed to open GLFW window\n");
        glfwTerminate();
        exit(10);
    }

    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_FALSE);
    glfwMakeContextCurrent(window);
    glfwSwapInterval(0);
    initGlew();
    return window;
}

static int file_read_all(const char *filepath, std::string &result) {
    FILE *file = fopen(filepath, "rb");
    if(!file) {
        perror("file_read_all");
        return errno;
    }

    fseek(file, 0, SEEK_END);
    size_t file_size = ftell(file);
    fseek(file, 0, SEEK_SET);
    result.resize(file_size);
    fread(&result[0], 1, result.size(), file);
    fclose(file);
    return 0;
}

std::unique_ptr<Shader> load_shader_from_file(const char *filepath, Shader::Type shader_type) {
    std::string file_content;
    if(file_read_all(filepath, file_content) != 0)
        exit(13);

    Result<std::unique_ptr<Shader>> vertex_shader_result = Shader::compile(shader_type, file_content.data(), file_content.size());
    if(!vertex_shader_result) {
        fprintf(stderr, "Failed to compile shader, error: %s\n", vertex_shader_result.getErrorMsg().c_str());
        exit(12);
    }
    return std::move(vertex_shader_result.unwrap());
}

std::unique_ptr<ShaderProgram> build_shader_program_from_shaders(const std::vector<Shader*> &shaders) {
    Result<std::unique_ptr<ShaderProgram>> shader_program_result = ShaderProgram::build(shaders);
    if(!shader_program_result) {
        fprintf(stderr, "Failed to link shaders, error: %s\n", shader_program_result.getErrorMsg().c_str());
        exit(13);
    }
    return std::move(shader_program_result.unwrap());
}