import type { World, EntityId } from 'db://assets/mx/module/ecs';
import { BattleEventFactory } from '../events/BattleEvents';
import type { BattleEventBus } from '../events/BattleEventBus';
import type { GridMap } from '../battlefield/GridMap';
import type { SpatialGrid } from '../battlefield/SpatialGrid';
import type { AbilitySystem } from './AbilitySystem';

/** 暂缓 kill 判定（还魂丹等：死亡特效播完再复活或真死） */
export type TryDeferEntityKillFn = (victim: EntityId, killer: EntityId, hpBeforeKill: number) => boolean;

/** 实体生命周期 */
export class LifecycleSystem {
    private _tryDeferKill: TryDeferEntityKillFn | null = null;

    constructor(
        private readonly _world: World,
        private readonly _grid: GridMap,
        private readonly _spatial: SpatialGrid,
        private readonly _events: BattleEventBus,
        private readonly _abilities: AbilitySystem,
    ) {}

    /** 注册暂缓 kill 回调（BattleSession.tryDeferEntityKill 桥接） */
    setTryDeferKillPredicate(fn: TryDeferEntityKillFn | null): void {
        this._tryDeferKill = fn;
    }

    /**
     * @param victim 被击杀实体 ID
     * @param killer 击杀者实体 ID
     * @param hpBeforeKill 致死前血量（还魂丹等复活继承用）
     * @param damageType 致死伤害类型
     * @param fromPassiveResult 是否来自被动 result
     */
    kill(victim: EntityId, killer: EntityId, hpBeforeKill = 0, damageType?: string, fromPassiveResult = false): void {
        if (!this._world.isAlive(victim)) return;
        if (this._tryDeferKill?.(victim, killer, hpBeforeKill)) return;

        // 先解绑触发器，避免后续 fireEvent('OnKill') 仍把 victim 当作施法者
        this._abilities.unbindEntity(victim);

        this._grid.clearOccupant(victim);
        this._spatial.removeEntity(victim);

        // 立即派发：金币/飞桃需在 destroy 前读到 UnitMeta / 怪物节点
        this._events.emit(BattleEventFactory.entityKilled(killer, victim, damageType, fromPassiveResult), true);
        this._world.destroy(victim);
        this._abilities.fireEvent('OnKill', { killer, victim });
    }

    /** 无击杀结算移除（复活回收上场怪等） */
    despawn(entity: EntityId): void {
        if (!this._world.isAlive(entity)) return;
        this._abilities.unbindEntity(entity);
        this._grid.clearOccupant(entity);
        this._spatial.removeEntity(entity);
        this._events.emit(BattleEventFactory.unitDespawned(entity), true);
        this._world.destroy(entity);
    }
}