import { director, Director } from 'cc';

type PendingWait = {
    framesLeft: number;
    done: () => void;
};

/**
 * 业务层帧等待：走 Director 帧事件，不受 Component.unscheduleAllCallbacks 影响；
 * 支持并发排队，避免后一次 waitFrames 覆盖前一次回调。
 */
export class FrameFlowHost {
    private _pending: PendingWait[] = [];
    private _listening = false;
    private readonly _onFrame: () => void;

    constructor() {
        this._onFrame = this._tick.bind(this);
    }

    waitFrames(frames: number, done: () => void): void {
        if (frames <= 0) {
            done();
            return;
        }
        this._pending.push({ framesLeft: frames, done });
        if (!this._listening) {
            this._listening = true;
            director.on(Director.EVENT_AFTER_UPDATE, this._onFrame, this);
        }
    }

    dispose(): void {
        if (this._listening) {
            director.off(Director.EVENT_AFTER_UPDATE, this._onFrame, this);
            this._listening = false;
        }
        this._pending.length = 0;
    }

    private _tick(): void {
        if (this._pending.length === 0) {
            this.dispose();
            return;
        }
        const current = this._pending;
        this._pending = [];
        for (let i = 0; i < current.length; i++) {
            const item = current[i];
            item.framesLeft--;
            if (item.framesLeft <= 0) {
                item.done();
            } else {
                this._pending.push(item);
            }
        }
        if (this._pending.length === 0) {
            this.dispose();
        }
    }
}