export class UI {
  constructor() {
    this.loadingScreen = document.getElementById('loading-screen');
    this.mainMenu = document.getElementById('main-menu');
    this.pauseMenu = document.getElementById('pause-menu');
    this.controlsScreen = document.getElementById('controls-screen');
    this.quitScreen = document.getElementById('quit-screen');
    this.progressBar = document.getElementById('progress-bar');
    this.loadingMessage = document.getElementById('loading-message');
    this.menuItems = document.querySelectorAll('#menu-items .menu-item');
    this.pauseItems = document.querySelectorAll('#pause-items .menu-item');
    this.currentMenuItem = 0;
    this.currentPauseItem = 0;
    this.onNewFlight = null;
    this.onResume = null;
    this.onMainMenu = null;
    this.onQuit = null;
    this.menuActive = false;
    this.controlsActive = false;
  }

  delay(ms) {
    return new Promise(r => setTimeout(r, ms));
  }

  async showLoading(onStep) {
    const steps = [
      { label: 'GENERATING TERRAIN...', duration: 600 },
      { label: 'BUILDING AIRPORT...', duration: 500 },
      { label: 'LOADING AIRCRAFT...', duration: 400 },
      { label: 'CALIBRATING INSTRUMENTS...', duration: 400 },
      { label: 'READY', duration: 300 },
    ];

    for (let i = 0; i < steps.length; i++) {
      const step = steps[i];
      this.loadingMessage.textContent = step.label;
      this.progressBar.style.width = `${((i + 1) / steps.length) * 100}%`;
      if (onStep) onStep(i);
      await this.delay(step.duration);
    }

    this.loadingScreen.style.display = 'none';
    this.showMainMenu();
  }

  showMainMenu() {
    this.mainMenu.style.display = 'flex';
    this.currentMenuItem = 0;
    this.updateMenuHighlight();
    this.menuActive = true;
  }

  hideMainMenu() {
    this.mainMenu.style.display = 'none';
    this.menuActive = false;
  }

  handleMenuInput(key) {
    if (!this.menuActive) return false;
    if (key === 'ArrowUp' || key === 'ArrowDown') {
      const items = this.menuItems;
      if (key === 'ArrowUp') {
        this.currentMenuItem = (this.currentMenuItem - 1 + items.length) % items.length;
      } else {
        this.currentMenuItem = (this.currentMenuItem + 1) % items.length;
      }
      this.updateMenuHighlight();
      return true;
    } else if (key === 'Enter' || key === ' ') {
      const action = this.menuItems[this.currentMenuItem].dataset.action;
      if (action === 'new-flight' && this.onNewFlight) this.onNewFlight();
      else if (action === 'controls') this.showControls();
      else if (action === 'quit' && this.onQuit) this.onQuit();
      return true;
    }
    return false;
  }

  updateMenuHighlight() {
    this.menuItems.forEach((item, i) => {
      item.classList.toggle('selected', i === this.currentMenuItem);
    });
  }

  showControls() {
    this.controlsScreen.style.display = 'flex';
    this.controlsActive = true;
  }

  hideControls() {
    this.controlsScreen.style.display = 'none';
    this.controlsActive = false;
  }

  handleControlsInput() {
    if (!this.controlsActive) return false;
    this.hideControls();
    return true;
  }

  showPauseMenu() {
    this.pauseMenu.style.display = 'flex';
    this.currentPauseItem = 0;
    this.updatePauseHighlight();
  }

  hidePauseMenu() {
    this.pauseMenu.style.display = 'none';
  }

  handlePauseInput(key) {
    if (this.pauseMenu.style.display === 'none') return false;
    if (key === 'ArrowUp' || key === 'ArrowDown') {
      const items = this.pauseItems;
      if (key === 'ArrowUp') {
        this.currentPauseItem = (this.currentPauseItem - 1 + items.length) % items.length;
      } else {
        this.currentPauseItem = (this.currentPauseItem + 1) % items.length;
      }
      this.updatePauseHighlight();
      return true;
    } else if (key === 'Enter' || key === ' ') {
      const action = this.pauseItems[this.currentPauseItem].dataset.action;
      if (action === 'resume' && this.onResume) this.onResume();
      else if (action === 'main-menu' && this.onMainMenu) this.onMainMenu();
      return true;
    }
    return false;
  }

  updatePauseHighlight() {
    this.pauseItems.forEach((item, i) => {
      item.classList.toggle('selected', i === this.currentPauseItem);
    });
  }

  showQuitScreen() {
    this.quitScreen.style.display = 'flex';
    this.mainMenu.style.display = 'none';
  }
}