slime/src/core/Entity.ts

import { Component } from './Component.ts';

/**
 * Entity class - represents a game object with a unique ID.
 * Entities are containers for components.
 */
export class Entity {
  private static nextId = 0;

  readonly id: number;
  private components: Map<string, Component>;
  active: boolean;

  owner?: number;
  startX?: number;
  startY?: number;
  maxRange?: number;
  lifetime?: number;
  damage?: number;
  deathTime?: number;

  constructor() {
    this.id = Entity.nextId++;
    this.components = new Map();
    this.active = true;
  }

  /**
   * Add a component to this entity.
   * @param component - The component to add
   * @returns This entity for chaining
   */
  addComponent(component: Component): Entity {
    this.components.set(component.type, component);
    return this;
  }

  /**
   * Get a component by type.
   * @param type - The component type name
   * @returns The component instance if found
   */
  getComponent<T extends Component>(type: string): T | undefined {
    return this.components.get(type) as T | undefined;
  }

  /**
   * Check if entity has a component.
   * @param type - The component type name
   * @returns True if the component exists
   */
  hasComponent(type: string): boolean {
    return this.components.has(type);
  }

  /**
   * Check if entity has all specified components.
   * @param types - List of component type names
   * @returns True if all components exist
   */
  hasComponents(...types: string[]): boolean {
    return types.every((type) => this.components.has(type));
  }

  /**
   * Remove a component.
   * @param type - The component type name
   * @returns This entity for chaining
   */
  removeComponent(type: string): Entity {
    this.components.delete(type);
    return this;
  }

  /**
   * Get all components attached to this entity.
   * @returns Array of components
   */
  getAllComponents(): Component[] {
    return Array.from(this.components.values());
  }
}