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

#include "pwyazh.h"

#include "common.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_Q: {
                    global_input.move_down.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_E: {
                    global_input.move_up.state = KeyState_PRESS;
                } break;
                case GLFW_KEY_SPACE: {
                    global_input.jump.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_Q: {
                    global_input.move_down.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_E: {
                    global_input.move_up.state = KeyState_RELEASE;
                } break;
                case GLFW_KEY_SPACE: {
                    global_input.jump.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);
    }
    
    U32 shader = create_shader_program("shaders/default.vs", "shaders/default.fs");
    
    Arena *arena = arena_alloc(Megabytes(512));
    
    Mesh *what_cube_mesh = mesh_load_obj(arena, "what_cube/what_cube.obj");
    U32 what_cube_texture = load_texture("what_cube/pryazha.jpg");
    
    F32 target_fps = 60.0f;
    F32 target_spf = 1.0f/target_fps;
    F32 dt = 0.0f;
    F32 last_time = glfwGetTime();
    F32 time = last_time;
    
    MAT4 projection, view, model;
    projection = perspective(90.0f, (F32)WIDTH/(F32)HEIGHT, 0.1f, 100.0f);
    model = mat4_identity();
    
    V3F camera_pos = v3f(0.0f, 0.0f, 3.0f);
    
    glEnable(GL_DEPTH_TEST);
    
    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();
        
        /* NOTE(pryazha): Update */
        V3F f = v3f_norm(v3f_sub(v3f(0.0f, 0.0f, 0.0f), camera_pos));
        V3F l = v3f_norm(v3f_cross(v3f(0.0f, 1.0f, 0.0f), f));
        V3F u = v3f_cross(f, l);
        
        V3F dp = v3f_zero();
        F32 speed = 2.0f;
        if (key_is_pressed(global_input.move_right))
            dp = v3f_sub(dp, l);
        if (key_is_pressed(global_input.move_forward))
            dp = v3f_add(dp, f);
        if (key_is_pressed(global_input.move_left))
            dp = v3f_add(dp, l);
        if (key_is_pressed(global_input.move_backward))
            dp = v3f_sub(dp, f);
        if (key_is_pressed(global_input.move_up))
            dp = v3f_add(dp, u);
        if (key_is_pressed(global_input.move_down))
            dp = v3f_sub(dp, u);
        
        camera_pos = v3f_add(camera_pos, v3f_scalef(dp, speed*dt));
        
        view = look_at(camera_pos, v3f_zero(), v3f(0.0f, 1.0f, 0.0f));
        
        input_update_last_state(&global_input);
        
        /* NOTE(pryazha): Render */
        glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        
        glUseProgram(shader);
        shader_set_mat4fv(shader, "projection", projection);
        shader_set_mat4fv(shader, "view", view);
        shader_set_mat4fv(shader, "model", model);
        glBindTexture(GL_TEXTURE_2D, what_cube_texture);
        mesh_draw(what_cube_mesh);
        
        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;
        time += dt;
        last_time = current_time;
    }
    
    arena_release(arena);
    glfwTerminate();
    return(0);
}