feat: add poc

src/systems/InputSystem.js

@@ -0,0 +1,153 @@
+import { System } from '../core/System.js';
+
+export class InputSystem extends System {
+  constructor() {
+    super('InputSystem');
+    this.requiredComponents = []; // No required components - handles input globally
+    this.priority = 0; // Run first
+
+    this.keys = {};
+    this.keysPrevious = {}; // Track previous frame key states
+    this.mouse = {
+      x: 0,
+      y: 0,
+      buttons: {},
+      buttonsPrevious: {}
+    };
+  }
+
+  init(engine) {
+    super.init(engine);
+    this.setupEventListeners();
+  }
+
+  setupEventListeners() {
+    window.addEventListener('keydown', (e) => {
+      const key = e.key.toLowerCase();
+      const code = e.code.toLowerCase();
+
+      // Store by key name
+      this.keys[key] = true;
+      this.keys[code] = true;
+
+      // Handle special keys
+      if (key === ' ') {
+        this.keys['space'] = true;
+      }
+      if (code === 'space') {
+        this.keys['space'] = true;
+      }
+
+      // Arrow keys
+      if (code === 'arrowup') this.keys['arrowup'] = true;
+      if (code === 'arrowdown') this.keys['arrowdown'] = true;
+      if (code === 'arrowleft') this.keys['arrowleft'] = true;
+      if (code === 'arrowright') this.keys['arrowright'] = true;
+
+      // Prevent default for game keys
+      if ([' ', 'w', 'a', 's', 'd', '1', '2', '3', '4', '5', '6', '7', '8', '9'].includes(key)) {
+        e.preventDefault();
+      }
+    });
+
+    window.addEventListener('keyup', (e) => {
+      const key = e.key.toLowerCase();
+      const code = e.code.toLowerCase();
+
+      this.keys[key] = false;
+      this.keys[code] = false;
+
+      // Handle special keys
+      if (key === ' ') {
+        this.keys['space'] = false;
+      }
+      if (code === 'space') {
+        this.keys['space'] = false;
+      }
+
+      // Arrow keys
+      if (code === 'arrowup') this.keys['arrowup'] = false;
+      if (code === 'arrowdown') this.keys['arrowdown'] = false;
+      if (code === 'arrowleft') this.keys['arrowleft'] = false;
+      if (code === 'arrowright') this.keys['arrowright'] = false;
+    });
+
+    window.addEventListener('mousemove', (e) => {
+      if (this.engine && this.engine.canvas) {
+        const canvas = this.engine.canvas;
+        const rect = canvas.getBoundingClientRect();
+        this.mouse.x = e.clientX - rect.left;
+        this.mouse.y = e.clientY - rect.top;
+      }
+    });
+
+    window.addEventListener('mousedown', (e) => {
+      this.mouse.buttons[e.button] = true;
+    });
+
+    window.addEventListener('mouseup', (e) => {
+      this.mouse.buttons[e.button] = false;
+    });
+  }
+
+  process(_deltaTime, _entities) {
+    // Don't update previous states here - that happens at end of frame
+    // This allows other systems to check isKeyJustPressed during the frame
+  }
+
+  /**
+     * Update previous states - called at end of frame
+     */
+  updatePreviousStates() {
+    // Deep copy current states to previous for next frame
+    this.keysPrevious = {};
+    for (const key in this.keys) {
+      this.keysPrevious[key] = this.keys[key];
+    }
+    this.mouse.buttonsPrevious = {};
+    for (const button in this.mouse.buttons) {
+      this.mouse.buttonsPrevious[button] = this.mouse.buttons[button];
+    }
+  }
+
+  /**
+     * Check if a key is currently pressed
+     */
+  isKeyPressed(key) {
+    return this.keys[key.toLowerCase()] === true;
+  }
+
+  /**
+     * Check if a key was just pressed (not held from previous frame)
+     */
+  isKeyJustPressed(key) {
+    const keyLower = key.toLowerCase();
+    const isPressed = this.keys[keyLower] === true;
+    const wasPressed = this.keysPrevious[keyLower] === true;
+    return isPressed && !wasPressed;
+  }
+
+  /**
+     * Get mouse position
+     */
+  getMousePosition() {
+    return { x: this.mouse.x, y: this.mouse.y };
+  }
+
+  /**
+     * Check if mouse button is pressed
+     */
+  isMouseButtonPressed(button = 0) {
+    return this.mouse.buttons[button] === true;
+  }
+
+  /**
+     * Check if mouse button was just pressed
+     */
+  isMouseButtonJustPressed(button = 0) {
+    const isPressed = this.mouse.buttons[button] === true;
+    const wasPressed = this.mouse.buttonsPrevious[button] === true;
+    return isPressed && !wasPressed;
+  }
+}
+