import { IDisposable } from 'ts-toolset';

/** 实例工厂接口 */
export interface IInstanceFactory<T extends IDisposable> extends IDisposable {

    /** 获取实例 */
    getInstance(target: { new(...params: any[]): T }, ...params: any[]): T;

    /** 获取实例，返回实例和标识（标识实例是否是新建的） */
    getInstanceAndSign(target: { new(...params: any[]): T }, ...params: any[]): [T, boolean];

    /** 回收所有实例 */
    recycle(): void;

    /** 回收指定实例 */
    recycle(instance: T): void;

    /** 回收指定实例集合 */
    recycle(instances: T[]): void;

}

/** 实例工厂 */
export class InstanceFactory<T extends IDisposable> implements IInstanceFactory<T>{

    /** 可用复用实例 */
    private _spareInstances: T[] = [];

    /** 已被使用的实例 */
    private _workingInstances: T[] = [];

    private _recycleInstance(instance: T) {
        let index = this._workingInstances.indexOf(instance);
        if (index > -1) {
            instance.dispose();
            this._workingInstances.splice(index, 1);
            this._spareInstances.push(instance);
        }
    }

    private _getInstance(target: { new(...params: any[]): T }, params: any[]): [T, boolean] {
        let isNew = this._spareInstances.length === 0;
        const instance = isNew
            ? new target(...params)
            : this._spareInstances.pop() as T;

        this._workingInstances.push(instance);
        return [instance, isNew];
    }

    getInstance(target: { new(...params: any[]): T }, ...params: any[]) {
        return this._getInstance(target, params)[0];
    }

    getInstanceAndSign(target: { new(...params: any[]): T }, ...params: any[]) {
        return this._getInstance(target, params);
    }

    recycle(): void;
    recycle(instances: T): void;
    recycle(instances: T[]): void;
    recycle(instances: T | T[] = this._workingInstances) {
        Array.isArray(instances)
            ? instances.forEach(ins => this._recycleInstance(ins))
            : this._recycleInstance(instances);
    }

    /** 释放实例 */
    dispose() {
        this._spareInstances.splice(0, this._spareInstances.length);
        this._workingInstances.splice(0, this._workingInstances.length);
    }
}