#include "GL/glew.h"
#include "GLFW/glfw3.h"

#include "pwyazh.h"

#include "pwyazh_GL.h"

#include "common.h"

#include <unistd.h>

#define WIDTH 1024
#define HEIGHT 768
static Input global_input;

void
key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    switch (action)
    {
        case GLFW_PRESS: {
            switch (key)
            {
                case GLFW_KEY_D: {
                    global_input.move_right.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_W: {
                    global_input.move_forward.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_A: {
                    global_input.move_left.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_S: {
                    global_input.move_backward.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_E: {
                    global_input.move_up.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_Q: {
                    global_input.move_down.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_SPACE: {
                    global_input.jump.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_RIGHT: {
                    global_input.action_right.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_LEFT: {
                    global_input.action_left.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_ESCAPE: {
                    global_input.exit.state = KeyState_PRESS;
                } break;
            }
        } break;
        
        case GLFW_RELEASE: {
            switch (key)
            {
                case GLFW_KEY_D: {
                    global_input.move_right.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_W: {
                    global_input.move_forward.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_A: {
                    global_input.move_left.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_S: {
                    global_input.move_backward.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_E: {
                    global_input.move_up.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_Q: {
                    global_input.move_down.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_SPACE: {
                    global_input.jump.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_RIGHT: {
                    global_input.action_right.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_LEFT: {
                    global_input.action_left.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_ESCAPE: {
                    global_input.exit.state = KeyState_RELEASE;
                } break;
            }
        } break;
    }
}

int
main(void)
{
    GLFWwindow *window;
    Arena *arena = 0;
    F32 target_fps, target_spf,
    last_time, dt;
    MAT4 projection, view, model;
    V3F camera_pos;
    F32 camera_speed, fovx, near, far;
    U32 fbo, intermediate_fbo, color_tex,
    screen_texture, rbo,
    quad_vao, vbo,
    color_shader, screen_shader;
    
    if (glfwInit() == GLFW_FALSE)
    {
        fprintf(stderr, "[ERROR] Failed to initialize glfw.\n");
        return(1);
    }
    
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    window = glfwCreateWindow(WIDTH, HEIGHT, "Anti Aliasing (Off-screen)", 0, 0);
    if (!window)
    {
        fprintf(stderr, "[ERROR] Failed to create window.\n");
        glfwTerminate();
        return(1);
    }
    
    glfwMakeContextCurrent(window);
    
    glfwSetKeyCallback(window, key_callback);
    
    if (glewInit() != GLEW_OK)
    {
        fprintf(stderr, "[ERROR] Failed to initialize glew.\n");
        glfwTerminate();
        return(1);
    }
    
    arena = arena_alloc(Megabytes(64));
    
    Mesh *cube_mesh = mesh_load_obj(arena, "../../data/models/cube.obj");
    color_shader = create_shader_program("shaders/color.vs",
                                         "shaders/color.fs");
    screen_shader = create_shader_program("shaders/screen.vs",
                                          "shaders/screen.fs");
    glGenFramebuffers(1, &fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glGenTextures(1, &color_tex);
    glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, color_tex);
    glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB,
                            WIDTH, HEIGHT, GL_TRUE);
    glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                           GL_TEXTURE_2D_MULTISAMPLE, color_tex, 0);
    glGenRenderbuffers(1, &rbo);
    glBindRenderbuffer(GL_RENDERBUFFER, rbo);
    glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8,
                                     WIDTH, HEIGHT);
    glBindRenderbuffer(GL_RENDERBUFFER, 0);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
                              GL_RENDERBUFFER, rbo);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        fprintf(stderr, "[ERROR]: Framebuffer is not complete.\n");
    fprintf(stdout, "[INFO]: Multisample fbo complete.\n");
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    
    glGenFramebuffers(1, &intermediate_fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, intermediate_fbo);
    glGenTextures(1, &screen_texture);
    glBindTexture(GL_TEXTURE_2D, screen_texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WIDTH, HEIGHT,
                 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                           GL_TEXTURE_2D, screen_texture, 0);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        fprintf(stderr, "[ERROR]: Framebuffer is not complete.\n");
    fprintf(stdout, "[INFO]: Intermediate fbo complete.\n");
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    
    F32 quad_vertices[] = {
        -1.0f, -1.0f, 0.0f,  0.0f, 0.0f,
        1.0f, -1.0f, 0.0f,  1.0f, 0.0f,
        1.0f,  1.0f, 0.0f,  1.0f, 1.0f,
        -1.0f, -1.0f, 0.0f,  0.0f, 0.0f,
        1.0f,  1.0f, 0.0f,  1.0f, 1.0f,
        -1.0f,  1.0f, 0.0f,  0.0f, 1.0f
    };
    
    glGenVertexArrays(1, &quad_vao);
    glBindVertexArray(quad_vao);
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(quad_vertices), quad_vertices, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5*sizeof(F32), (void *)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5*sizeof(F32), (void *)(3*sizeof(F32)));
    glBindVertexArray(0);
    
    target_fps = 60.0f;
    target_spf = 1.0f/target_fps;
    
    camera_pos = v3f(0.0f, 0.0f, 3.0f);
    camera_speed = 2.0f;
    fovx = 90.0f;
    near = 0.1f;
    far = 1000.0f;
    
    last_time = glfwGetTime();
    
    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();
        
        /* NOTE(pryazha): Update */
        if (key_is_pressed(global_input.exit))
            glfwSetWindowShouldClose(window, GLFW_TRUE);
        
        V3F camera_dv = get_dv_camera_orbital(&global_input, camera_pos,
                                              v3f_zero(), dt, camera_speed);
        camera_pos = v3f_add(camera_pos, camera_dv);
        
        projection = perspective(fovx, (F32)WIDTH/(F32)HEIGHT, near, far);
        view = look_at(camera_pos, v3f_zero(), v3f(0.0f, 1.0f, 0.0f));
        model = mat4_identity();
        
        input_update_last_state(&global_input);
        
        /* NOTE(pryazha): Render */
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glEnable(GL_DEPTH_TEST);
        glUseProgram(color_shader);
        shader_set_mat4fv(color_shader, "projection", projection);
        shader_set_mat4fv(color_shader, "view", view);
        shader_set_mat4fv(color_shader, "model", model);
        mesh_draw(cube_mesh);
        
        glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, intermediate_fbo);
        /* TODO(pryazha): Update width and height */
        glBlitFramebuffer(0, 0, WIDTH, HEIGHT,
                          0, 0, WIDTH, HEIGHT,
                          GL_COLOR_BUFFER_BIT, GL_NEAREST);
        
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        glUseProgram(screen_shader);
        glDisable(GL_DEPTH_TEST);
        glBindTexture(GL_TEXTURE_2D, screen_texture);
        glBindVertexArray(quad_vao);
        glDrawArrays(GL_TRIANGLES, 0, 6);
        glBindVertexArray(0);
        
        glfwSwapBuffers(window);
        
        F32 elapsed = glfwGetTime()-last_time;
        if (elapsed < target_spf)
        {
            U32 sleep_time = (U32)(target_spf-elapsed);
            if (sleep_time > 0)
                sleep(sleep_time);
        }
        F32 current_time = glfwGetTime();
        dt = current_time-last_time;
        last_time = current_time;
    }
    
    arena_release(arena);
    glfwTerminate();
    return(0);
}