import { System } from '../core/System.ts';
import { SkillRegistry } from '../skills/SkillRegistry.ts';
import { SystemName, ComponentType } from '../core/Constants.ts';
import { Events } from '../core/EventBus.ts';
import type { Entity } from '../core/Entity.ts';
import type { Skills } from '../components/Skills.ts';
import type { Intent } from '../components/Intent.ts';

/**
 * System responsible for managing skill cooldowns and activating skills based on entity intent.
 */
export class SkillSystem extends System {
  constructor() {
    super(SystemName.SKILL);
    this.requiredComponents = [ComponentType.SKILLS];
    this.priority = 30;
  }

  /**
   * Process all entities with skills, updating cooldowns and activating skills if intended.
   * @param deltaTime - Time elapsed since last frame in seconds
   * @param entities - Entities matching system requirements
   */
  process(deltaTime: number, entities: Entity[]): void {
    entities.forEach((entity) => {
      const skills = entity.getComponent<Skills>(ComponentType.SKILLS);
      const intent = entity.getComponent<Intent>(ComponentType.INTENT);
      if (!skills) return;

      skills.updateCooldowns(deltaTime);

      if (intent && intent.action === 'skill_use') {
        const skillId = intent.data.skillId;
        if (skillId && !skills.isOnCooldown(skillId)) {
          this.activateSkill(entity, skillId);
        }
        intent.clear();
      }
    });
  }

  /**
   * Activate a specific skill for an entity.
   * @param entity - The entity performing the skill
   * @param skillId - The ID of the skill to activate
   */
  activateSkill(entity: Entity, skillId: string): void {
    const skill = SkillRegistry.get(skillId);
    if (!skill) {
      console.warn(`Skill not found: ${skillId}`);
      return;
    }

    if (skill.activate(entity, this.engine)) {
      const skills = entity.getComponent<Skills>(ComponentType.SKILLS);
      if (skills) {
        skills.setCooldown(skillId, skill.cooldown);
      }
      this.engine.emit(Events.SKILL_COOLDOWN_STARTED, { skillId });
    }
  }
}