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

#include "pwyazh.h"

#include "common.h"

#include <unistd.h>

#define WIDTH 1024
#define HEIGHT 768

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_SPACE: {
                    input.jump.state = KeyState_PRESS;
                } break;
            }
        } break;

        case GLFW_RELEASE: {
            switch (key)
            {
                case GLFW_KEY_SPACE: {
                    input.jump.state = KeyState_RELEASE;
                } break;
            }
        } break;
    }
}

void
draw_cube(U32 cube_vao, U32 texture)
{
    glBindVertexArray(cube_vao);
    glBindTexture(GL_TEXTURE_2D, texture);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    glBindTexture(GL_TEXTURE_2D, 0);
    glBindVertexArray(0);
}

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);
    
    U32 shader = create_shader_program_geom("shaders/base.vs",
                                            "shaders/base.fs",
                                            "shaders/base.gs");
    U32 explosion_shader = create_shader_program_geom("shaders/explosion.vs",
                                                      "shaders/explosion.fs",
                                                      "shaders/explosion.gs");
    U32 normals_shader = create_shader_program_geom("shaders/normals.vs",
                                                    "shaders/normals.fs",
                                                    "shaders/normals.gs");
    U32 basic_shader = create_shader_program("shaders/basic.vs", "shaders/basic.fs");

    U32 grid_texture = load_texture("../data/textures/grid.png");

    F32 points[] = {
        -0.5f,  0.5f, 1.0f, 0.0f, 0.0f,
         0.5f,  0.5f, 0.0f, 1.0f, 0.0f,
         0.5f, -0.5f, 0.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, 1.0f, 1.0f, 0.0f
    };

    GLuint points_vao, vbo;
    glGenVertexArrays(1, &points_vao);
    glBindVertexArray(points_vao);
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 5*sizeof(F32), (void *)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5*sizeof(F32), (void *)(2*sizeof(F32)));
    glBindVertexArray(0);

    F32 a = 0.5f;
    /* NOTE(pryazha): Counter-clockwise order */
    F32 cube_vertices[] = {
        /* NOTE(pryazha): Back face */
         a, -a, -a,  0.0f, 0.0f, /* bottom-left */
        -a,  a, -a,  1.0f, 1.0f, /* top-right */
         a,  a, -a,  0.0f, 1.0f, /* top-left */
         a, -a, -a,  0.0f, 0.0f, /* bottom-left */
        -a, -a, -a,  1.0f, 0.0f, /* bottom-right */
        -a,  a, -a,  1.0f, 1.0f, /* top-right */

         /* NOTE(pryazha): Front face */
        -a, -a,  a,  0.0f, 0.0f, /* bottom-left */
         a,  a,  a,  1.0f, 1.0f, /* top-right */
        -a,  a,  a,  0.0f, 1.0f, /* top-left */
        -a, -a,  a,  0.0f, 0.0f, /* bottom-left */
         a, -a,  a,  1.0f, 0.0f, /* bottom-right */
         a,  a,  a,  1.0f, 1.0f, /* top-right */
         
         /* NOTE(pryazha): Left face */
        -a, -a, -a,  0.0f, 0.0f, /* bottom-left */
        -a,  a,  a,  1.0f, 1.0f, /* top-right */
        -a,  a, -a,  0.0f, 1.0f, /* top-left */
        -a, -a, -a,  0.0f, 0.0f, /* bottom-left */
        -a, -a,  a,  1.0f, 0.0f, /* bottom-right */
        -a,  a,  a,  1.0f, 1.0f, /* top-right */

         /* NOTE(pryazha): Right face */
         a, -a,  a,  0.0f, 0.0f, /* bottom-left */
         a,  a, -a,  1.0f, 1.0f, /* top-right */
         a,  a,  a,  0.0f, 1.0f, /* top-left */
         a, -a,  a,  0.0f, 0.0f, /* bottom-left */
         a, -a, -a,  1.0f, 0.0f, /* bottom-right */
         a,  a, -a,  1.0f, 1.0f, /* top-right */

         /* NOTE(pryazha): Top face */
        -a,  a,  a,  0.0f, 0.0f, /* bottom-left */
         a,  a, -a,  1.0f, 1.0f, /* top-right */
        -a,  a, -a,  0.0f, 1.0f, /* top-left */
        -a,  a,  a,  0.0f, 0.0f, /* bottom-left */
         a,  a,  a,  1.0f, 0.0f, /* bottom-right */
         a,  a, -a,  1.0f, 1.0f, /* top-right */

         /* NOTE(pryazha): Bottom face */
        -a, -a, -a,  0.0f, 0.0f, /* bottom-left */
         a, -a,  a,  1.0f, 1.0f, /* top-right */
        -a, -a,  a,  0.0f, 1.0f, /* top-left */
        -a, -a, -a,  0.0f, 0.0f, /* bottom-left */
         a, -a, -a,  1.0f, 0.0f, /* bottom-right */
         a, -a,  a,  1.0f, 1.0f, /* top-right */
    };

    U32 cube_vao;
    glGenVertexArrays(1, &cube_vao);
    glBindVertexArray(cube_vao);
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(cube_vertices), cube_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 vertices[] = {
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,
         0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  0.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,

        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,
         0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,

        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
        -0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  0.0f,
        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,

         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,
         0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,

        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  1.0f,
         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,
         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,

        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  1.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f
    };

    U32 normals_cube_vao;
    glGenVertexArrays(1, &normals_cube_vao);
    glBindVertexArray(normals_cube_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, 8*sizeof(F32), (void *)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8*sizeof(F32), (void *)(3*sizeof(F32)));
    glEnableVertexAttribArray(2);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8*sizeof(F32), (void *)(6*sizeof(F32)));
    glBindVertexArray(0);

    F32 target_fps = 60.0f;
    F32 target_spf = 1.0f/target_fps;
    
    F32 last_time = glfwGetTime();
    F32 time = last_time;

    S32 scene = 0;

    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();

        /* NOTE(pryazha): Update */
        if (key_first_press(input.jump))
        {
            scene++;
            scene %= 3;
        }

        input_update_last_state(&input);
        
        /* NOTE(pryazha): Render */
        glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        if (scene == 0)
        {
            glUseProgram(shader);
            glBindVertexArray(points_vao);
            glDrawArrays(GL_POINTS, 0, 4);
            glBindVertexArray(0);
        }
        else if (scene == 1)
        {
            F32 radius = 2.0f;
            F32 x = f32_sin(0.5*time)*radius;
            F32 z = f32_cos(0.5*time)*radius;
            MAT4 projection = perspective(90.0f, (F32)WIDTH/(F32)HEIGHT, 0.1f, 100.0f);
            MAT4 view = look_at(v3f(x, 1.0f, z), v3f_zero(), v3f(0.0f, 1.0f, 0.0f));
            MAT4 model = mat4_identity();
            glUseProgram(explosion_shader);
            shader_set_mat4fv(explosion_shader, "projection", projection);
            shader_set_mat4fv(explosion_shader, "view", view);
            shader_set_mat4fv(explosion_shader, "model", model);
            shader_set_1f(explosion_shader, "time", time);
            glBindVertexArray(cube_vao);
            glBindTexture(GL_TEXTURE_2D, grid_texture);
            glDrawArrays(GL_TRIANGLES, 0, 36);
            glBindVertexArray(0);
        }
        else
        {
            MAT4 projection, view, model;
            F32 radius, x, z;
            
            radius = 2.0f;
            x = f32_sin(0.5*time)*radius;
            z = f32_cos(0.5*time)*radius;

            projection = perspective(90.0f, (F32)WIDTH/(F32)HEIGHT, 0.1f, 100.0f);
            view = look_at(v3f(x, 1.0f, z), v3f_zero(), v3f(0.0f, 1.0f, 0.0f));
            model = mat4_identity();

            glUseProgram(basic_shader);
            shader_set_mat4fv(basic_shader, "projection", projection);
            shader_set_mat4fv(basic_shader, "view", view);
            shader_set_mat4fv(basic_shader, "model", model);
            draw_cube(normals_cube_vao, grid_texture);

            glUseProgram(normals_shader);
            shader_set_mat4fv(normals_shader, "projection", projection);
            shader_set_mat4fv(normals_shader, "view", view);
            shader_set_mat4fv(normals_shader, "model", model);
            draw_cube(normals_cube_vao, grid_texture);
        }

        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;
    }

    glDeleteBuffers(1, &vbo);
    glDeleteVertexArrays(1, &points_vao);

    glfwTerminate();
    return(0);
}