#include "config.h"
#include <iostream>

#include <cmath>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <functional>
#include <utility>
#include <iterator>
#include <memory>
#include <utility>
#include <SDL.h>

#ifdef ENABLE_NCURSES
#include <ncurses.h>
#endif

#include "fb/chfb.h"
#include "fb/pixfb.h"
#include "o3d/scene.h"
#include "o3d/mesh.h"
#include "o3d/obj3d.h"
#include "o3d/vertex.h"
#include "o3d/vertex_data.h"
#include "o3d/tri_vertex.h"
#include "o3d/camera.h"
#include "math/vector.h"
#include "math/mat4.h"
#include "renderer.h"

#define FPS 60

#define PI 3.1415926535f

#define MODE_HELP      0
#define MODE_TERM      1
#define MODE_GRAPHICAL 2

static void print_usage(std::ostream& output_stream) {
    output_stream << "Usage: ./engine [-htg] [--help] [--term] [--graphical]\n"
                  << "  -h, --help        show usage (this)\n"
                  << "  -t, --term        terminal mode\n"
                  << "  -g, --graphical   graphical mode (default)\n"
                  << std::flush;
}

[[noreturn]]
static void usage_error_exit() {
    print_usage(std::cerr);
    std::exit(EXIT_FAILURE);
}

static void scene_main(engine::Renderer& renderer, engine::math::Matrix4 final_transform_mat, std::function<bool()> update_frame) {
    float dist = 4.f;
    float rad = 5.f;
    bool cont = true;
    engine::o3d::Scene scene{
        {{0.f, 0.f, rad * dist}, 0.f, 0.f, 0.f}, // camera
        { // objects
            engine::o3d::Object3D{
                engine::o3d::Mesh::cube(),
                -rad * engine::math::Vector3(.5f, .5f, .5f),
                rad, 0.f, 0.f, 0.f
            },
            engine::o3d::Object3D{
                engine::o3d::Mesh::cube(),
                +rad * engine::math::Vector3(.5f, .5f, .5f),
                rad, 0.f, 0.f, 0.f
            },
        }
    };
    auto scale_mat = engine::math::Matrix4::scale(rad);
    while (cont) {
        scene.camera.rot_x += .0050f;
        scene.camera.rot_y += .0065f;
        scene.camera.rot_z += .0080f;

        renderer.clear();
        auto transform_mat =
            engine::math::Matrix4::translate(-scene.camera.loc)
            * engine::math::Matrix4::rot_x(-scene.camera.rot_x)
            * engine::math::Matrix4::rot_y(-scene.camera.rot_y)
            * engine::math::Matrix4::rot_z(-scene.camera.rot_z);
        std::array<engine::math::Matrix4, 2> mats{{
            transform_mat * engine::math::Matrix4::translate(engine::math::Vector3{-.5f * rad, -.5f * rad, -.5f * rad}) * scale_mat,
            transform_mat * engine::math::Matrix4::translate(engine::math::Vector3{+.5f * rad, +.5f * rad, +.5f * rad}) * scale_mat,
        }};
        auto pre_final_mat = final_transform_mat
            * engine::math::Matrix4::projection(static_cast<float>(renderer.height()) / static_cast<float>(renderer.width()), 2.f, 50.f);
        for (int i = 0; i < 2; i++) {
            auto final_mat = pre_final_mat * mats[i];
            const auto& mesh = scene.objs[i].mesh;
            std::vector<engine::o3d::Vertex4> pts;
            for (const auto& vert : mesh.pts)
                pts.push_back({ final_mat * engine::math::Vector4{vert.point}, vert.data });
            for (auto face : mesh.faces)
                renderer.draw_triangle({pts[face[0]], pts[face[1]], pts[face[2]]});
        }
        cont = update_frame();
    }
}

#ifdef ENABLE_NCURSES
#define MKEY_Z   122 
#define MKEY_Q   113
#define MKEY_S   115
#define MKEY_D   100

#define MKEY_ESC 27

static int main_term() {
    // init
    setlocale(LC_ALL, "");
    initscr();
    cbreak();
    noecho();
    intrflush(stdscr, FALSE);
    keypad(stdscr, TRUE);
    set_escdelay(0);
    curs_set(0);

    int w, h;
    getmaxyx(stdscr, h, w);
    engine::Renderer renderer{
        std::make_unique<engine::fb::CharacterFrameBuffer>(static_cast<unsigned int>(w), static_cast<unsigned int>(h))};

    scene_main(renderer, engine::math::Matrix4::scale(engine::math::Vector3(2.f, 1.f, 1.f)), [&]() {
        mvaddnstr(0, 0,
            static_cast<engine::fb::CharacterFrameBuffer*>(renderer.fb.get())->chars(),
            renderer.width() * renderer.height());

        bool cont = true;
        //timeout(1000 / FPS);
        timeout(10);
        int c = getch();

        if (c == MKEY_ESC) return false;
        switch (c) {
        case KEY_UP:
            // a.x += 0.1f;
            // dist += .1f;
            break;
        case KEY_DOWN:
            // a.x -= 0.1f;
            // dist -= .1f;
            break;
        case KEY_LEFT:
            // a.y += 0.1f;
            break;
        case KEY_RIGHT:
            // a.y -= 0.1f;
            break;
        case MKEY_Q:
            // a.z += 0.1f;
            break;
        case MKEY_D:
            // a.z -= 0.1f;
            break;
        }

        getmaxyx(stdscr, h, w);
        renderer.resize(static_cast<unsigned int>(w), static_cast<unsigned int>(h));

        return cont;
    });

    // terminate
    endwin();

    return EXIT_SUCCESS;
}
#endif

#define SCREEN_WIDTH  640
#define SCREEN_HEIGHT 480

static int main_graphical() {
    SDL_Window* window = NULL;
    SDL_Renderer* renderer = NULL;
    SDL_Texture* texture = NULL;

    // init
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        std::cerr << "Error: SDL_Init error: " << SDL_GetError() << std::endl;
        return EXIT_FAILURE;
    }
    window = SDL_CreateWindow("Engine", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    if (window == NULL) {
        SDL_Quit();
        std::cerr << "Error: SDL_CreateWindow error: " << SDL_GetError() << std::endl;
        return EXIT_FAILURE;
    }
    renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, SCREEN_WIDTH, SCREEN_HEIGHT);
    engine::Renderer engine_renderer{
        std::make_unique<engine::fb::PixelFrameBuffer>(SCREEN_WIDTH, SCREEN_HEIGHT)};

    SDL_Event e;

    scene_main(engine_renderer, engine::math::Matrix4::idty(), [&]() {
        SDL_UpdateTexture(texture, NULL,
            static_cast<engine::fb::PixelFrameBuffer*>(engine_renderer.fb.get())->pixels(),
            SCREEN_WIDTH * 4);
        SDL_RenderClear(renderer);
        SDL_RenderCopy(renderer, texture, NULL, NULL);
        SDL_RenderPresent(renderer);
        SDL_UpdateWindowSurface(window);
        bool cont = true;
        if (SDL_WaitEventTimeout(&e, 10)) {
            do {
                if (e.type == SDL_QUIT) {
                    cont = false;
                }
            } while (SDL_PollEvent(&e));
        }
        return cont;
    });

    // terminate
    SDL_DestroyTexture(texture);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return EXIT_SUCCESS;
}

static std::vector<std::string_view> convert_args(int argc, char *argv[]) {
    std::vector<std::string_view> args(argc);
    for (int i = 0; i < argc; i++)
        args[i] = argv[i];
    return args;
}

static void parse_args(const std::vector<std::string_view>& args, int& mode) {
    for (auto args_iter = std::next(args.begin()); args_iter != args.end(); args_iter++) {
        const auto& arg = *args_iter;
        if (arg.size() >= 1 && arg[0] == '-') {
            if (arg.size() >= 2 && arg[1] == '-') {
                auto long_opt = arg.substr(2);
                if (long_opt == "help") {
                    mode = MODE_HELP;
                } else if (long_opt == "term") {
                    mode = MODE_TERM;
                } else if (long_opt == "graphical") {
                    mode = MODE_GRAPHICAL;
                } else {
                    std::cerr << "Error: Unexpected option `--" << long_opt << "'." << std::endl;
                    usage_error_exit();
                }
            } else {
                std::size_t arg_len = arg.size();
                if (arg_len == 1) {
                    std::cerr << "Error: Unexpected argument `-'." << std::endl;
                    usage_error_exit();
                }
                for (auto arg_iter = std::next(arg.begin()); arg_iter != arg.end(); arg_iter++) {
                    const auto& opt = *arg_iter;
                    switch (opt) {
                    case 'h':
                        mode = MODE_HELP;
                        break;
                    case 't':
                        mode = MODE_TERM;
                        break;
                    case 'g':
                        mode = MODE_GRAPHICAL;
                        break;
                    default:
                        std::cerr << "Error: Unexpected option `-" << opt << "'." << std::endl;
                        usage_error_exit();
                    }
                }
            }
        } else {
            std::cerr << "Error: Unexpected argument `" << arg << "'." << std::endl;
            usage_error_exit();
        }
    }
}

int main(int argc, char *argv[]) {
    int mode = MODE_GRAPHICAL;
    parse_args(convert_args(argc, argv), mode);
    switch (mode) {
    case MODE_HELP:
        print_usage(std::cout);
        return EXIT_SUCCESS;
    case MODE_TERM:
#ifdef ENABLE_NCURSES
        return main_term();
#else
        std::cerr << "Error: ncurses was not enabled during compilation." << std::endl;
        return EXIT_FAILURE;
#endif
    case MODE_GRAPHICAL:
        return main_graphical();
    default:
        ; // unreachable
    }
    return EXIT_SUCCESS; // unreachable
}