#include "common.hh"

#include "args.hh"
#include "timer_state.hh"
#include "xcb_atoms.hh"
#include "xcb_colors.hh"
#include "xcb_connection.hh"
#include "xcb_event.hh"
#include "xcb_resource.hh"
#include "xcb_resources.hh"
#include "xcb_xkb.hh"
#include "xdg.hh"

#include <algorithm>
#include <condition_variable>
#include <deque>
#include <errno.h>
#include <iostream>
#include <limits>
#include <mutex>
#include <optional>
#include <string.h>
#include <thread>
#include <xcb/xcb_icccm.h>

#ifndef VERSION
# warning No version defined
# define VERSION
#endif

namespace {

constexpr char const kTitle[] = "Timer";
constexpr char const kClass[] = "org.the_jk.timer";

constexpr std::chrono::seconds const kRedrawInterval{36};

class Timer : public TimerState::Delegate {
public:
  explicit Timer(std::filesystem::path state_file)
    : state_file_(std::move(state_file)),
      state_(TimerState::create(state_file_, this)) {}

  bool good() const {
    return state_ != nullptr;
  }

  bool run(Option const* display, std::optional<std::string> font_name) {
    int screen_index = 0;
    if (display->is_set()) {
      conn_ = xcb::make_shared_conn(xcb_connect(display->arg().c_str(),
                                                &screen_index));
    } else {
      conn_ = xcb::make_shared_conn(xcb_connect(nullptr, &screen_index));
    }

    {
      auto err = xcb_connection_has_error(conn_.get());
      if (err) {
        std::cerr << "Unable to connect to X display: " << err << std::endl;
        return false;
      }
    }

    auto atoms = xcb::Atoms::create(conn_);
    string_atom_ = atoms->get("STRING");
    wm_protocols_ = atoms->get("WM_PROTOCOLS");
    wm_delete_window_ = atoms->get("WM_DELETE_WINDOW");

    auto* screen = xcb::get_screen(conn_.get(), screen_index);
    assert(screen);

    auto colors = xcb::Colors::create(conn_, screen->default_colormap);
    background_inactive_ =
      colors->get_with_fallback(0x80, 0x80, 0x80, screen->white_pixel);
    foreground_inactive_ =
      colors->get_with_fallback(0x00, 0x00, 0x00, screen->black_pixel);
    background_active_ =
      colors->get_with_fallback(0x80, 0xff, 0x80, screen->white_pixel);
    foreground_active_ =
      colors->get_with_fallback(0x00, 0x00, 0x00, screen->black_pixel);

    keyboard_ = xcb::Keyboard::create(conn_.get());
    if (!keyboard_) {
      std::cerr << "Failed to initialize XKB." << std::endl;
      return EXIT_FAILURE;
    }

    wnd_ = xcb::make_unique_wnd(conn_);
    gc_ = xcb::make_unique_gc(conn_);
    font_ = xcb::make_unique_font(conn_);

    if (!font_name) {
      auto resources = xcb::Resources::create(conn_);
      font_name = resources->get_string("timer.font", "");
      if (!font_name) {
        font_name = "fixed";
      }
    }

    auto font_cookie = xcb_open_font_checked(conn_.get(), font_->id(),
                                             font_name->size(),
                                             font_name->data());

    if (!atoms->sync()) {
      std::cerr << "Failed to get X atoms." << std::endl;
      return EXIT_FAILURE;
    }
    if (!colors->sync()) {
      std::cerr << "Failed to get X colors." << std::endl;
      return EXIT_FAILURE;
    }

    uint32_t value_list[3];
    uint32_t value_mask = 0;
    value_mask |= XCB_CW_BACK_PIXEL;
    value_list[0] = screen->black_pixel;
    value_mask |= XCB_CW_EVENT_MASK;
    value_list[1] = XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS |
      XCB_EVENT_MASK_BUTTON_PRESS | XCB_EVENT_MASK_STRUCTURE_NOTIFY;
    xcb_create_window(conn_.get(), XCB_COPY_FROM_PARENT, wnd_->id(),
                      screen->root, 0, 0, wnd_width_, wnd_height_, 0,
                      XCB_WINDOW_CLASS_INPUT_OUTPUT,
                      screen->root_visual, value_mask, value_list);

    xcb_icccm_set_wm_name(conn_.get(), wnd_->id(), string_atom_->get(),
                          8, sizeof(kTitle) - 1, kTitle);
    xcb_icccm_set_wm_class(conn_.get(), wnd_->id(), sizeof(kClass) - 1, kClass);
    xcb_atom_t atom_list[1];
    atom_list[0] = wm_delete_window_->get();
    xcb_icccm_set_wm_protocols(conn_.get(), wnd_->id(),
                               wm_protocols_->get(), 1, atom_list);

    value_mask = XCB_GC_FONT;
    value_list[0] = font_->id();
    xcb_create_gc(conn_.get(), gc_->id(), wnd_->id(), value_mask, value_list);

    {
      xcb::generic_error error(xcb_request_check(conn_.get(), font_cookie));
      if (error) {
        std::cerr << "Failed to load font " << *font_name << ": "
                  << static_cast<int>(error->error_code) << std::endl;
        return false;
      }
    }

    update_text();

    xcb_map_window(conn_.get(), wnd_->id());
    xcb_flush(conn_.get());

    std::thread xcb_thread(&Timer::run_xcb, this);

    bool quit = false;
    std::chrono::steady_clock::time_point next_redraw;
    if (active_) {
      next_redraw = std::chrono::steady_clock::now() + kRedrawInterval;
    }
    while (!quit) {
      ActionData action;
      {
        std::unique_lock<std::mutex> lock(action_lock_);
        while (action_.empty()) {
          if (active_) {
            if (action_cond_.wait_until(lock, next_redraw)
                == std::cv_status::timeout) {
              next_redraw = std::chrono::steady_clock::now() + kRedrawInterval;
              update_text();
              draw();
            }
          } else {
            action_cond_.wait(lock);
          }
        }
        action = action_.front();
        action_.pop_front();
      }

      switch (action.action) {
      case Action::QUIT:
        quit = true;
        break;
      case Action::DRAW:
        if (action.b) {
          draw();
        }
        break;
      case Action::RESIZE:
        wnd_width_ = action.rect.width;
        wnd_height_ = action.rect.height;
        break;
      case Action::TOGGLE:
        if (active_) {
          state_->stop();
        } else {
          state_->start();
        }
        break;
      case Action::SEND_RESET:
        state_->reset();
        break;
      case Action::RECV_RESET:
        total_ = std::chrono::minutes::zero();
        update_text();
        draw();
        break;
      case Action::START:
        active_ = true;
        next_redraw = std::chrono::steady_clock::now() + kRedrawInterval;
        total_ = action.duration;
        epoch_ = action.point;
        update_text();
        draw();
        break;
      case Action::STOP:
        active_ = false;
        total_ = action.duration;
        update_text();
        draw();
        break;
      case Action::RESTART:
        state_ = TimerState::create(state_file_, this);
        if (!state_) {
          std::cerr << "Timer state failed and unable to restart." << std::endl;
          quit = true;
          conn_.reset();
          break;
        }
      }
    }

    xcb_thread.join();
    return true;
  }

  void start(
      std::chrono::minutes total,
      std::chrono::time_point<std::chrono::system_clock> epoch) override {
    post(Action::START, total, epoch);
  }

  void stop(std::chrono::minutes total) override {
    post(Action::STOP, total);
  }

  void reset() override {
    post(Action::RECV_RESET);
  }

  void restart() override {
    post(Action::RESTART);
  }

private:
  enum class Action {
    QUIT,
    DRAW,
    RESIZE,
    TOGGLE,
    START,
    STOP,
    SEND_RESET,
    RECV_RESET,
    RESTART,
  };

  struct ActionData {
    Action action;
    xcb_rectangle_t rect;
    bool b{false};
    std::chrono::minutes duration;
    std::chrono::time_point<std::chrono::system_clock> point;

    ActionData() = default;

    explicit ActionData(Action action)
      : action(action) {
      assert(action == Action::QUIT || action == Action::TOGGLE ||
             action == Action::SEND_RESET || action == Action::RECV_RESET ||
             action == Action::RESTART);
    }

    ActionData(Action action, xcb_rectangle_t rect, bool last)
      : action(action), rect(rect), b(last) {
      assert(action == Action::DRAW);
    }

    ActionData(Action action, uint16_t width, uint16_t height)
      : action(action), rect({0, 0, width, height}) {
      assert(action == Action::RESIZE);
    }

    ActionData(Action action, std::chrono::minutes total,
               std::chrono::time_point<std::chrono::system_clock> epoch)
      : action(action), duration(total), point(epoch) {
      assert(action == Action::START);
    }

    ActionData(Action action, std::chrono::minutes total)
      : action(action), duration(total) {
      assert(action == Action::STOP);
    }
  };

  void run_xcb() {
    while (true) {
      xcb::generic_event event(xcb_wait_for_event(conn_.get()));
      if (!event) {
        auto err = xcb_connection_has_error(conn_.get());
        if (err) {
          std::cerr << "X connection had fatal error: " << err << std::endl;
        } else {
          std::cerr << "X connection had fatal I/O error." << std::endl;
        }
        break;
      }
      auto response_type = XCB_EVENT_RESPONSE_TYPE(event.get());
      if (response_type == XCB_EXPOSE) {
        auto* e = reinterpret_cast<xcb_expose_event_t*>(event.get());
        if (e->window == wnd_->id()) {
          xcb_rectangle_t rect;
          rect.x = e->x;
          rect.y = e->y;
          rect.width = e->width;
          rect.height = e->height;
          post(Action::DRAW, rect, e->count == 0);
        }
        continue;
      } else if (response_type == XCB_KEY_PRESS) {
        auto* e = reinterpret_cast<xcb_key_press_event_t*>(event.get());
        if (e->event == wnd_->id()) {
          auto str = keyboard_->get_utf8(e);
          if (str == "q" || str == "\x1b" /* Escape */) {
            break;
          } else if (str == " ") {
            post(Action::TOGGLE);
          } else if ((e->state & XCB_MOD_MASK_CONTROL) &&
                     str == "\x12" /* Ctrl + R */) {
            post(Action::SEND_RESET);
          }
        }
        continue;
      } else if (response_type == XCB_BUTTON_PRESS) {
        auto* e = reinterpret_cast<xcb_button_press_event_t*>(event.get());
        if (e->event == wnd_->id()) {
          if (e->detail == 1 /* Left button */) {
            post(Action::TOGGLE);
          }
        }
        continue;
      } else if (response_type == XCB_CONFIGURE_NOTIFY) {
        auto* e = reinterpret_cast<xcb_configure_notify_event_t*>(event.get());
        if (e->window == wnd_->id()) {
          post(Action::RESIZE, e->width, e->height);
        }
        continue;
      } else if (response_type == XCB_REPARENT_NOTIFY) {
        // Ignored, part of XCB_EVENT_MASK_STRUCTURE_NOTIFY
        continue;
      } else if (response_type == XCB_MAP_NOTIFY) {
        // Ignored, part of XCB_EVENT_MASK_STRUCTURE_NOTIFY
        continue;
      } else if (keyboard_->handle_event(conn_.get(), event.get())) {
        continue;
      } else if (response_type == XCB_CLIENT_MESSAGE) {
        auto* e = reinterpret_cast<xcb_client_message_event_t*>(event.get());
        if (e->window == wnd_->id() && e->type == wm_protocols_->get() &&
            e->format == 32) {
          if (e->data.data32[0] == wm_delete_window_->get()) {
            break;
          }
        }
        continue;
      }

#ifndef NDEBUG
      if (response_type == 0) {
        auto* e = reinterpret_cast<xcb_generic_error_t*>(event.get());
        std::cout << "Unhandled error: "
                  << xcb_event_get_error_label(e->error_code) << std::endl;
      } else {
        std::cout << "Unhandled event: " << xcb_event_get_label(response_type)
                  << std::endl;
      }
#endif
    }

    post(Action::QUIT);
  }

  template<class... Args>
  void post(Args&&... args) {
    bool notify;
    {
      std::lock_guard<std::mutex> lock(action_lock_);
      notify = action_.empty();
      action_.emplace_back(std::forward<Args>(args)...);
    }
    if (notify)
      action_cond_.notify_one();
  }

  void update_text() {
    char tmp[50];
    int len;

    using hours = std::chrono::duration<float, std::ratio<60 * 60>>;

    if (active_) {
      auto diff = std::chrono::duration_cast<std::chrono::minutes>(
          std::chrono::system_clock::now() - epoch_);

      len = snprintf(tmp, sizeof(tmp), "%.2f (%.2f)", hours(diff).count(),
                     hours(total_ + diff).count());
    } else {
      len = snprintf(tmp, sizeof(tmp), "(%.2f)", hours(total_).count());
    }
    if (len < 0 || len == sizeof(tmp))
      return;

    text_.resize(len);
    for (int i = 0; i < len; ++i) {
      text_[i].byte1 = 0;
      text_[i].byte2 = tmp[i];
    }

    text_extents_cookie_ = xcb_query_text_extents(conn_.get(), font_->id(),
                                                  text_.size(), text_.data());
    text_extents_width_ = 0;
  }

  void draw() {
    xcb_rectangle_t r{0, 0, wnd_width_, wnd_height_};

    uint32_t values[2];
    values[0] =
      active_ ? background_active_->get() : background_inactive_->get();
    xcb_change_gc(conn_.get(), gc_->id(), XCB_GC_FOREGROUND, values);
    xcb_poly_fill_rectangle(conn_.get(), wnd_->id(), gc_->id(), 1, &r);

    values[0] =
      active_ ? foreground_active_->get() : foreground_inactive_->get();
    values[1] =
      active_ ? background_active_->get() : background_inactive_->get();
    xcb_change_gc(conn_.get(), gc_->id(),
                  XCB_GC_FOREGROUND | XCB_GC_BACKGROUND, values);

    if (text_extents_width_ == 0) {
      xcb::reply<xcb_query_text_extents_reply_t> reply(
          xcb_query_text_extents_reply(conn_.get(), text_extents_cookie_,
                                       nullptr));
      if (reply) {
        text_extents_width_ = reply->overall_width;
        text_extents_height_ = reply->font_ascent;
      } else {
        text_extents_width_ = 1;
        text_extents_height_ = 0;
      }
    }

    auto x = (text_extents_width_ < wnd_width_) ?
      (wnd_width_ - text_extents_width_) / 2 : 0;
    auto y = wnd_height_ / 2 + text_extents_height_ / 2;

    xcb_image_text_16(conn_.get(), text_.size(), wnd_->id(), gc_->id(), x, y,
                      text_.data());

    xcb_flush(conn_.get());
  }

  xcb::shared_conn conn_;
  std::optional<xcb::Atoms::Reference> string_atom_;
  std::optional<xcb::Atoms::Reference> wm_protocols_;
  std::optional<xcb::Atoms::Reference> wm_delete_window_;
  std::optional<xcb::Colors::Color> background_inactive_;
  std::optional<xcb::Colors::Color> background_active_;
  std::optional<xcb::Colors::Color> foreground_inactive_;
  std::optional<xcb::Colors::Color> foreground_active_;
  std::unique_ptr<xcb::Keyboard> keyboard_;
  xcb::unique_wnd wnd_;
  xcb::unique_gc gc_;
  xcb::unique_font font_;
  uint16_t wnd_width_{100};
  uint16_t wnd_height_{50};

  bool active_{false};
  std::chrono::minutes total_{0};
  std::chrono::time_point<std::chrono::system_clock> epoch_;

  std::vector<xcb_char2b_t> text_;
  xcb_query_text_extents_cookie_t text_extents_cookie_;
  uint16_t text_extents_width_{0};
  uint16_t text_extents_height_{0};

  std::mutex action_lock_;
  std::condition_variable action_cond_;
  std::deque<ActionData> action_;

  std::filesystem::path const state_file_;
  std::unique_ptr<TimerState> state_;
};

}  // namespace

int main(int argc, char** argv) {
  auto args = Args::create();
  auto* help = args->add_option('h', "help", "display this text and exit.");
  auto* version = args->add_option('V', "version", "display version and exit.");
  auto* opt_state_file = args->add_option_with_arg(
      'S', "state", "load state from FILE instead of default.", "FILE");
  auto* opt_font_name = args->add_option_with_arg(
      'F', "font", "use font named FONT instead of default or Xresources.",
      "FONT");
  auto* display = args->add_option_with_arg(
      'D', "display", "connect to DISPLAY instead of default.", "DISPLAY");
  std::vector<std::string> arguments;
  if (!args->run(argc, argv, "timer", std::cerr, &arguments)) {
    std::cerr << "Try `timer --help` for usage." << std::endl;
    return EXIT_FAILURE;
  }
  if (help->is_set()) {
    std::cout << "Usage: `timer [OPTIONS]`\n"
              << "Timer is a timekeeping tool.\n"
              << "\n";
    args->print_descriptions(std::cout, 80);
    return EXIT_SUCCESS;
  }
  if (version->is_set()) {
    std::cout << "Timer " VERSION " written by "
              << "Joel Klinghed <the_jk@spawned.biz>" << std::endl;
    std::cout << "Icon by Free Preloaders [https://freeicons.io/profile/726]"
              << " on https://freeicons.io" << std::endl;
    return EXIT_SUCCESS;
  }
  if (!arguments.empty()) {
    std::cerr << "Unexpected arguments after options.\n"
              << "Try `timer --help` for usage." << std::endl;
    return EXIT_FAILURE;
  }

  std::filesystem::path state_file;
  if (opt_state_file->is_set()) {
    state_file = opt_state_file->arg();
  } else {
    state_file = xdg::path_to_write(xdg::Type::DATA, "timer.state");
  }

  Timer timer(state_file);
  if (!timer.good())
    return EXIT_FAILURE;
  return timer.run(display,
                   opt_font_name->is_set() ? opt_font_name->arg() :
                   std::optional<std::string>())
    ? EXIT_SUCCESS : EXIT_FAILURE;
}