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

#include "pwyazh.h"
#include "pwyazh_GL.h"

#include "common.h"

#define LIGHT_COUNT 200
#define CUBE_COUNT  1000

int main(void)
{
    /* NOTE(pryazha): GLFW init */
    glfwSetErrorCallback(error_callback);
    if (glfwInit() == GLFW_FALSE)
        return 1;
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
    S32 width = 1600;
    S32 height = 900;
    GLFWwindow *window = glfwCreateWindow(width, height, "deferred", 0, 0);
    if (!window)
        return 1;
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
    glfwMakeContextCurrent(window);
    if (glewInit() != GLEW_OK)
        return 1;
    glEnable(GL_DEPTH_TEST);

    /* NOTE(pryazha): Program init */
    State state = {0};
    state.arena = arena_alloc(Kilobytes(256));
    state.input.first_mouse = 1;
    state.camera = (Camera){ v3f(0.0f, 2.0f, 5.0f), 90.0f, 0.1f, 100.0f, 0.0f, 0.0f };

    /* NOTE(pryazha): Textures */
    U32 woood_texture = load_texture("../../data/textures/wood.png");

    /* NOTE(pryazha): Meshes */
    Mesh *quad = mesh_gen_quad(state.arena);
    Mesh *cube = mesh_load_obj(state.arena, "../../data/models/cube.obj");

    /* NOTE(pryazha): Framebuffers */
    U32 gbuffer;
    glGenFramebuffers(1, &gbuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, gbuffer);

    // position color buffer
    U32 gpositions;
    glGenTextures(1, &gpositions);
    glBindTexture(GL_TEXTURE_2D, gpositions);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, width, height, 0, GL_RGBA, GL_FLOAT, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gpositions, 0);
    // normal
    U32 gnormals;
    glGenTextures(1, &gnormals);
    glBindTexture(GL_TEXTURE_2D, gnormals);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, width, height, 0, GL_RGBA, GL_FLOAT, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, gnormals, 0);
    // color + specular
    U32 gcolor_specular;
    glGenTextures(1, &gcolor_specular);
    glBindTexture(GL_TEXTURE_2D, gcolor_specular);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, gcolor_specular, 0);
    U32 attachments[3] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2};
    glDrawBuffers(3, attachments);
    U32 rbo; 
    glGenRenderbuffers(1, &rbo);
    glBindRenderbuffer(GL_RENDERBUFFER, rbo);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rbo);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        fprintf(stderr, "error: gbuffer not complete\n");
    fprintf(stdout, "info: gbuffer complete\n");

    /* NOTE(pryazha): Shaders */
    U32 shader_gbuffer = load_shader("shaders/gbuffer.vert", "shaders/gbuffer.frag");
    U32 shader_screen = load_shader("shaders/screen.vert", "shaders/screen.frag");
    U32 shader_specular = load_shader("shaders/screen.vert", "shaders/specular.frag");
    U32 shader_deferred = load_shader("shaders/screen.vert", "shaders/deferred.frag");
    U32 shader_light = load_shader("shaders/light.vert", "shaders/light.frag");

    glUseProgram(shader_deferred);
    shader_set_1i(shader_deferred, "positions", 0);
    shader_set_1i(shader_deferred, "normals", 1);
    shader_set_1i(shader_deferred, "color_specular", 2);
    glUseProgram(0);

    V3F cube_positions[CUBE_COUNT];
    S32 cols = 30;
    F32 spacing = 3.0f;
    for (S32 i = 0; i < CUBE_COUNT; i++) {
        S32 col = i % cols;
        S32 row = i / cols;
        cube_positions[i] = v3f(col * spacing, 0.0f, row * spacing);
    }

    light_t lights[LIGHT_COUNT];
#if 0
    V3F origin = {50.0f, 3.0f, 50.0f};
    F32 da = 2.0f*pi_F32/LIGHT_COUNT;
    F32 a = 0.0f;
    F32 radius = 20.0f;
    for (S32 i = 0; i < LIGHT_COUNT; i++, a += da) {
        lights[i].position = v3f_add(v3f(f32_sin(a) * radius, 0.0f, f32_cos(a) * radius), origin);
        F32 r = (F32)(rand() % 100) / 100.0f;
        F32 g = (F32)(rand() % 100) / 100.0f;
        F32 b = (F32)(rand() % 100) / 100.0f;
        lights[i].color = v3f(r, g, b);
    }
#else
    V3F origin = {0.0f, 3.0f, 0.0f};
    cols = 30;
    spacing = 3.0f;
    for (S32 i = 0; i < LIGHT_COUNT; i++) {
        S32 col = i % cols;
        S32 row = i / cols;
        lights[i].position = v3f_add(v3f(col * spacing, 0.0f, row * spacing), origin);
        F32 r = (F32)(rand() % 100) / 100.0f;
        F32 g = (F32)(rand() % 100) / 100.0f;
        F32 b = (F32)(rand() % 100) / 100.0f;
        lights[i].color = v3f(r, g, b);
    }
#endif

    S32 show_gbuffer = 0;

    F64 last_time = glfwGetTime();
    while (!glfwWindowShouldClose(window)) {
        F64 time = glfwGetTime();
        state.dt = time - last_time;
        last_time = time;

        input_update_last_state(&state.input);

        glfwPollEvents();
        glfwGetFramebufferSize(window, &width, &height);
        process_glfw_keyboard(window, &state.input);
        process_glfw_mouse_pos(window, &state.input);

        if (key_first_press(state.input.exit))
            glfwSetWindowShouldClose(window, GLFW_TRUE);

        F32 speed = 2.0f;
        V3F dv = get_dv_camera_first_person(&state.input, &state.camera, speed, state.dt);
        state.camera_dp = v3f_add(state.camera_dp, dv);
        state.camera_dp = v3f_scalef(state.camera_dp, 0.8f);
        state.camera.pos = v3f_add(state.camera.pos, state.camera_dp);

        F32 sensitivity = 0.1f;
        state.input.mouse_offset = v2f_scalef(state.input.mouse_offset, sensitivity);
        state.camera.yaw += state.input.mouse_offset.x;
        state.camera.pitch += state.input.mouse_offset.y;
        if (state.camera.pitch > 89.0f)
            state.camera.pitch = 89.0f;
        if (state.camera.pitch < -89.0f)
            state.camera.pitch = -89.0f;

        /* NOTE(pryazha): Update */
        for (S32 i = 0; i < LIGHT_COUNT; i++)
            lights[i].position.y = origin.y + f32_sin(glfwGetTime() + i);

        if (key_first_press(state.input.jump)) {
            show_gbuffer = !show_gbuffer;
        }

        /* NOTE(pryazha): Render */
        F32 ar = (F32)width/(F32)height;
        MAT4 projection = camera_persp(state.camera, ar);
        MAT4 view = get_view_matrix(&state.camera);

        glBindFramebuffer(GL_FRAMEBUFFER, gbuffer);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glUseProgram(shader_gbuffer);
        shader_set_mat4fv(shader_gbuffer, "projection", projection);
        shader_set_mat4fv(shader_gbuffer, "view", view);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, woood_texture);

        for (S32 i = 0; i < CUBE_COUNT; i++) {
            MAT4 model = mat4_make_translate(cube_positions[i]);
            shader_set_mat4fv(shader_gbuffer, "model", model);
            mesh_draw(cube);
        }

        glUseProgram(0);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        if (show_gbuffer) {
            glDisable(GL_DEPTH_TEST);
            glUseProgram(shader_screen);
            MAT4 model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
            model = mat4_translate(model, v3f(-0.5f, 0.5f, 0.0f));
            shader_set_mat4fv(shader_screen, "model", model);
            glBindTexture(GL_TEXTURE_2D, gpositions);
            mesh_draw(quad);

            model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
            model = mat4_translate(model, v3f(0.5f, 0.5f, 0.0f));
            shader_set_mat4fv(shader_screen, "model", model);
            glBindTexture(GL_TEXTURE_2D, gnormals);
            mesh_draw(quad);

            model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
            model = mat4_translate(model, v3f(-0.5f, -0.5f, 0.0f));
            shader_set_mat4fv(shader_screen, "model", model);
            glBindTexture(GL_TEXTURE_2D, gcolor_specular);
            mesh_draw(quad);
            glUseProgram(0);

            glUseProgram(shader_specular);
            model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
            model = mat4_translate(model, v3f(0.5f, -0.5f, 0.0f));
            shader_set_mat4fv(shader_specular, "model", model);
            glBindTexture(GL_TEXTURE_2D, gcolor_specular);
            mesh_draw(quad);
            glUseProgram(0);
            glEnable(GL_DEPTH_TEST);
        } else {
            glUseProgram(shader_deferred);
            glActiveTexture(GL_TEXTURE0);
            glBindTexture(GL_TEXTURE_2D, gpositions);
            glActiveTexture(GL_TEXTURE1);
            glBindTexture(GL_TEXTURE_2D, gnormals);
            glActiveTexture(GL_TEXTURE2);
            glBindTexture(GL_TEXTURE_2D, gcolor_specular);
            shader_set_3fv(shader_deferred, "view_position", state.camera.pos);
            for (S32 i = 0; i < LIGHT_COUNT; i++) {
                char light_string[512];
                snprintf(light_string, 512, "lights[%d].position", i);
                shader_set_3fv(shader_deferred, light_string, lights[i].position);
                snprintf(light_string, 512, "lights[%d].color", i);
                shader_set_3fv(shader_deferred, light_string, lights[i].color);
            }
            MAT4 model = mat4_identity();
            shader_set_mat4fv(shader_deferred, "model", model);
            mesh_draw(quad);
            glUseProgram(0);
            glEnable(GL_DEPTH_TEST);

            glBindFramebuffer(GL_READ_FRAMEBUFFER, gbuffer);
            glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
            glBlitFramebuffer(0, 0, width, height, 0, 0, width, height,
                              GL_DEPTH_BUFFER_BIT, GL_NEAREST);
            glBindFramebuffer(GL_FRAMEBUFFER, 0);

            glUseProgram(shader_light);
            shader_set_mat4fv(shader_light, "projection", projection);
            shader_set_mat4fv(shader_light, "view", view);
            for (S32 i = 0; i < LIGHT_COUNT; i++) {
                shader_set_3fv(shader_light, "light_color", lights[i].color);
                model = mat4_make_scale(v3f(0.2f, 0.2f, 0.2f));
                model = mat4_translate(model, lights[i].position);
                shader_set_mat4fv(shader_light, "model", model);
                mesh_draw(cube);
            }
            glUseProgram(0);
        }

        glfwSwapBuffers(window);
    }

    return 0;
}