#include "find_desktop.hh"

#include "xcb_atoms.hh"
#include "xcb_connection.hh"
#include "xcb_event.hh"
#include "xcb_resource.hh"

#include <cassert>
#include <charconv>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <optional>
#include <string>
#include <system_error>
#include <xcb/xproto.h>

namespace {

int get_from_e17_using_window(xcb_connection_t* conn, xcb_window_t wnd,
                              xcb_atom_t e_window_desk) {
  if (e_window_desk == XCB_ATOM_NONE) {
    return -1;
  }

  for (int i = 0; i < 2; ++i) {
    auto cookie =
        xcb_get_property(conn, 0, wnd, e_window_desk, XCB_ATOM_CARDINAL, 0, 2);
    xcb::reply<xcb_get_property_reply_t> reply(
        xcb_get_property_reply(conn, cookie, nullptr));

    if (reply && reply->format == 32 &&
        xcb_get_property_value_length(reply.get()) >= 8) {
      auto* data = static_cast<uint32_t*>(xcb_get_property_value(reply.get()));
      auto x = data[0];
      auto y = data[1];
      return static_cast<int>((x * 256) + y);
    }

    xcb_flush(conn);
    struct timespec ts = {.tv_sec = 0, .tv_nsec = 250000000};  // 250ms
    nanosleep(&ts, nullptr);
  }
  return -1;
}

std::string create_desktop(std::string const& prefix, int desktop,
                           bool use_prefix) {
  std::string ret;
  if (use_prefix) {
    ret.append(prefix);
    ret.push_back('_');
  }
  auto const offset = ret.size();
  ret.resize(offset + 10);
  auto [ptr, ec] =
      std::to_chars(ret.data() + offset, ret.data() + ret.size(), desktop);
  if (ec == std::errc()) {
    ret.resize(ptr - ret.data());
  } else {
    assert(false);
    ret.resize(offset);
  }
  return ret;
}

}  // namespace

std::optional<std::string> find_desktop(std::optional<std::string> display,
                                        bool use_prefix) {
  int screen_num = 0;
  auto conn = xcb::make_shared_conn(xcb_connect(
      display.has_value() ? display.value().c_str() : nullptr, &screen_num));
  if (!conn || xcb_connection_has_error(conn.get())) {
    return std::nullopt;
  }

  auto atoms = xcb::Atoms::create(conn);
  if (!atoms) {
    return std::nullopt;
  }

  auto* screen = xcb::get_screen(conn.get(), screen_num);
  if (!screen) {
    return std::nullopt;
  }

  xcb_window_t root = screen->root;

  auto net_current_desktop_atom = atoms->get("_NET_CURRENT_DESKTOP");
  auto e_window_desk_atom = atoms->get("__E_WINDOW_DESK");

  if (!atoms->sync()) {
    return std::nullopt;
  }

  auto* desktop_env = getenv("DESKTOP");
  if (!desktop_env || strncmp(desktop_env, "Enlightenment-0.17", 18) != 0) {
    /* Skip _NET_CURRENT_DESKTOP if we're in e17 */
    /* Try to read the _NET_CURRENT_DESKTOP property */
    auto net_current_desktop = net_current_desktop_atom.get();
    if (net_current_desktop != XCB_ATOM_NONE) {
      auto cookie = xcb_get_property(conn.get(), 0, root, net_current_desktop,
                                     XCB_ATOM_CARDINAL, 0, 1);
      xcb::reply<xcb_get_property_reply_t> reply(
          xcb_get_property_reply(conn.get(), cookie, nullptr));

      if (reply && reply->format == 32 &&
          xcb_get_property_value_length(reply.get()) >= 4) {
        auto* data =
            static_cast<uint32_t*>(xcb_get_property_value(reply.get()));
        return create_desktop("ewmh", static_cast<int>(data[0]), use_prefix);
      }
    }
  }

  /* Failing that, let's see if our owner knows */
  auto* windowid_env = getenv("WINDOWID");
  if (windowid_env) {
    auto* const end = windowid_env + strlen(windowid_env);
    unsigned long windowid;
    auto [ptr, ec] = std::from_chars(windowid_env, end, windowid);
    if (ptr == end && ec == std::errc{}) {
      auto ret = get_from_e17_using_window(conn.get(),
                                           static_cast<xcb_window_t>(windowid),
                                           e_window_desk_atom.get());
      if (ret != -1) {
        return create_desktop("enlightenment", ret, use_prefix);
      }
    }
  }

  /* Try creating a bogus window then */
  {
    auto wnd = xcb::make_unique_wnd(conn);
    xcb_create_window(conn.get(), XCB_COPY_FROM_PARENT, wnd->id(), root, 0, 0,
                      1, 1, 0, XCB_WINDOW_CLASS_INPUT_OUTPUT,
                      XCB_COPY_FROM_PARENT, 0, nullptr);
    xcb_map_window(conn.get(), wnd->id());
    xcb_flush(conn.get());

    auto ret = get_from_e17_using_window(conn.get(), wnd->id(),
                                         e_window_desk_atom.get());
    if (ret != -1) {
      return create_desktop("enlightenment", ret, use_prefix);
    }
  }

  /* Don't know what else to do */
  return std::nullopt;
}