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

#include "pwyazh.h"

#include "pwyazh_GL.h"

#include "common.h"

#include <unistd.h>

#define WIDTH 1280
#define HEIGHT 720

static V3F camera_pos;
static F32 dt;
static Input 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: {
                    input.move_right.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_W: {
                    input.move_forward.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_A: {
                    input.move_left.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_S: {
                    input.move_backward.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_E: {
                    input.move_up.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_Q: {
                    input.move_down.state = KeyState_PRESS;
                } break;
            }
        } break;
        
        case GLFW_RELEASE: {
            switch (key)
            {
                case GLFW_KEY_D: {
                    input.move_right.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_W: {
                    input.move_forward.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_A: {
                    input.move_left.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_S: {
                    input.move_backward.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_E: {
                    input.move_up.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_Q: {
                    input.move_down.state = KeyState_RELEASE;
                } break;
            }
        } break;
    }
}

int
main(void)
{
    GLFWwindow *window;
    
    if (glfwInit() == GLFW_FALSE)
    {
        fprintf(stderr, "[ERROR] Failed to initialize glfw.\n");
        return(1);
    }
    
    glfwWindowHint(GLFW_RESIZABLE, 0);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    window = glfwCreateWindow(WIDTH, HEIGHT, "depth testing", 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);
    }
    
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    
    U32 shader = create_shader_program("shaders/depth.vs", "shaders/depth.fs");
    U32 marble_texture = load_texture("../../data/textures/marble.jpg");
    U32 metal_texture = load_texture("../../data/textures/metal.png");
    
    F32 a = 0.5f;
    F32 vertices[] = {
        -a, -a, -a, 0.0f,  0.0f,
        a, -a, -a, 1.0f,  0.0f,
        a,  a, -a, 1.0f,  1.0f,
        a,  a, -a, 1.0f,  1.0f,
        -a,  a, -a, 0.0f,  1.0f,
        -a, -a, -a, 0.0f,  0.0f,
        
        -a, -a,  a, 0.0f,  0.0f,
        a, -a,  a, 1.0f,  0.0f,
        a,  a,  a, 1.0f,  1.0f,
        a,  a,  a, 1.0f,  1.0f,
        -a,  a,  a, 0.0f,  1.0f,
        -a, -a,  a, 0.0f,  0.0f,
        
        -a,  a,  a, 1.0f,  0.0f,
        -a,  a, -a, 1.0f,  1.0f,
        -a, -a, -a, 0.0f,  1.0f,
        -a, -a, -a, 0.0f,  1.0f,
        -a, -a,  a, 0.0f,  0.0f,
        -a,  a,  a, 1.0f,  0.0f,
        
        a,  a,  a, 1.0f,  0.0f,
        a,  a, -a, 1.0f,  1.0f,
        a, -a, -a, 0.0f,  1.0f,
        a, -a, -a, 0.0f,  1.0f,
        a, -a,  a, 0.0f,  0.0f,
        a,  a,  a, 1.0f,  0.0f,
        
        -a, -a, -a, 0.0f,  1.0f,
        a, -a, -a, 1.0f,  1.0f,
        a, -a,  a, 1.0f,  0.0f,
        a, -a,  a, 1.0f,  0.0f,
        -a, -a,  a, 0.0f,  0.0f,
        -a, -a, -a, 0.0f,  1.0f,
        
        -a,  a, -a, 0.0f,  1.0f,
        a,  a, -a, 1.0f,  1.0f,
        a,  a,  a, 1.0f,  0.0f,
        a,  a,  a, 1.0f,  0.0f,
        -a,  a,  a, 0.0f,  0.0f,
        -a,  a, -a,  0.0f,  1.0f
    };
    
    Transform cube_positions[] = {
        transform_default(),
        transform_make_translate(v3f(a, 0.0f, -4*a))
    };
    
    Transform platform_position =
        transform_make_scale_translate(v3f(10.0f, 0.2f, 10.0f),
                                       v3f(0.0f, -(a+(a*0.2f)+0.01f), 0.0f));
    
    U32 VAO, VBO;
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);
    
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), 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);
    
    F32 target_fps = 60.0f;
    F32 target_spf = 1.0f/target_fps;
    camera_pos = v3f(0.0f, 0.0f, 3.0f);
    
    /* glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); */
    
    F32 last_time = glfwGetTime();
    
    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();
        
        /* INFO(pryazha): update */
        V3F left, up, forward;
        V3F world_up = v3f(0.0f, 1.0f, 0.0f);
        
        forward = v3f_norm(v3f_sub(v3f(0.0f, 0.0f, 0.0f), camera_pos));
        left = v3f_norm(v3f_cross(world_up, forward));
        up = v3f_cross(forward, left);
        
        V3F dp = v3f_zero();
        
        F32 speed = 2.0f;
        if (key_is_pressed(input.move_right))
            dp = v3f_add(dp, v3f_scalef(left, -speed*dt));
        if (key_is_pressed(input.move_forward))
            dp = v3f_add(dp, v3f_scalef(forward, speed*dt));
        if (key_is_pressed(input.move_left))
            dp = v3f_add(dp, v3f_scalef(left, speed*dt));
        if (key_is_pressed(input.move_backward))
            dp = v3f_add(dp, v3f_scalef(forward, -speed*dt));
        if (key_is_pressed(input.move_up))
            dp = v3f_add(dp, v3f_scalef(up, speed*dt));
        if (key_is_pressed(input.move_down))
            dp = v3f_add(dp, v3f_scalef(up, -speed*dt));
        
        input_update_last_state(&input);
        
        camera_pos = v3f_add(camera_pos, dp);
        
        /* INFO(pryazha): render */
        glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        
        glUseProgram(shader);
        MAT4 model, view, projection;
        
        view = look_at(camera_pos, v3f(0.0f, 0.0f, 0.0f), v3f(0.0f, 1.0f, 0.0f));
        shader_set_mat4fv(shader, "view", view);
        
        /* projection = ortho(-5.0f, 5.0f, -5.0f, 5.0f, 0.1f, 100.0f); */
        F32 fovx = 90.0f;
        F32 near = 0.1f;
        F32 far = 100.0f;
        projection = perspective(fovx, (F32)WIDTH/(F32)HEIGHT, near, far);
        
        shader_set_mat4fv(shader, "projection", projection);
        
        glBindTexture(GL_TEXTURE_2D, marble_texture);
        glBindVertexArray(VAO);
        for (S32 transform_index = 0;
             transform_index < (S32)ArrayCount(cube_positions);
             ++transform_index)
        {
            model = transform_apply(cube_positions[transform_index]);
            shader_set_mat4fv(shader, "model", model);
            glDrawArrays(GL_TRIANGLES, 0, 36);
        }
        
        glBindTexture(GL_TEXTURE_2D, metal_texture);
        model = transform_apply(platform_position);
        shader_set_mat4fv(shader, "model", model);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        
        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;
    }
    
    glfwTerminate();
    return(0);
}