import { System } from '../core/System.js';

/**
 * System to handle game menus (start, pause)
 */
export class MenuSystem extends System {
  constructor(engine) {
    super('MenuSystem');
    this.requiredComponents = []; // No required components
    this.priority = 1; // Run early
    this.engine = engine;
    this.ctx = engine.ctx;
    this.gameState = 'start'; // 'start', 'playing', 'paused'
    this.paused = false;
  }

  init(engine) {
    super.init(engine);
    this.setupInput();
  }

  setupInput() {
    window.addEventListener('keydown', (e) => {
      if (e.key === 'Escape' || e.key === 'p' || e.key === 'P') {
        if (this.gameState === 'playing') {
          this.togglePause();
        }
      }
      if (e.key === 'Enter' || e.key === ' ') {
        if (this.gameState === 'start') {
          this.startGame();
        } else if (this.gameState === 'paused') {
          this.resumeGame();
        }
      }
    });
  }

  startGame() {
    this.gameState = 'playing';
    this.paused = false;
    if (!this.engine.running) {
      this.engine.start();
    }
  }

  togglePause() {
    if (this.gameState === 'playing') {
      this.gameState = 'paused';
      this.paused = true;
    } else if (this.gameState === 'paused') {
      this.resumeGame();
    }
  }

  resumeGame() {
    this.gameState = 'playing';
    this.paused = false;
  }

  process(_deltaTime, _entities) {
    // Don't update game systems if paused or at start menu
    if (this.gameState === 'paused' || this.gameState === 'start') {
      // Pause all other systems
      this.engine.systems.forEach(system => {
        if (system !== this && system.name !== 'MenuSystem' && system.name !== 'UISystem') {
          // Systems will check game state themselves
        }
      });
    }
  }

  drawMenu() {
    const ctx = this.ctx;
    const width = this.engine.canvas.width;
    const height = this.engine.canvas.height;

    // Dark overlay
    ctx.fillStyle = 'rgba(0, 0, 0, 0.7)';
    ctx.fillRect(0, 0, width, height);

    ctx.fillStyle = '#ffffff';
    ctx.font = 'bold 48px Courier New';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';

    if (this.gameState === 'start') {
      ctx.fillText('SLIME GENESIS', width / 2, height / 2 - 100);
      ctx.font = '24px Courier New';
      ctx.fillText('Press ENTER or SPACE to Start', width / 2, height / 2);
      ctx.font = '16px Courier New';
      ctx.fillText('WASD: Move | Mouse: Aim | Click/Space: Attack', width / 2, height / 2 + 50);
      ctx.fillText('Shift: Stealth | 1-9: Skills | ESC: Pause', width / 2, height / 2 + 80);
    } else if (this.gameState === 'paused') {
      ctx.fillText('PAUSED', width / 2, height / 2 - 50);
      ctx.font = '24px Courier New';
      ctx.fillText('Press ENTER or SPACE to Resume', width / 2, height / 2);
      ctx.fillText('Press ESC to Pause/Unpause', width / 2, height / 2 + 40);
    }
  }

  getGameState() {
    return this.gameState;
  }

  isPaused() {
    return this.paused || this.gameState === 'start';
  }
}