pigallery2/common/event/EventLimit.ts

export class EventLimit<T> {

    private lastTriggerValue:T = null;

    private handlers:Array<EventLimitHandler<T>> = [];

    public on(limit:T, handler:{ (data?:T): void }) {
        this.handlers.push(new EventLimitHandler(limit, handler));
        if (this.lastTriggerValue != null) {
            this.trigger(this.lastTriggerValue);
        }
    }

    public onSingle(limit:T, handler:{ (data?:T): void }) {
        this.handlers.push(new SingleFireEventLimitHandler(limit, handler));
        if (this.lastTriggerValue != null) {
            this.trigger(this.lastTriggerValue);
        }
    }

    public off(limit:T, handler:{ (data?:T): void }) {
        this.handlers = this.handlers.filter(h => h.handler !== handler && h.limit !== limit);
    }

    public allOff() {
        this.handlers = [];
    }

    public trigger = (data?:T) => {
        if (this.handlers) {
            this.handlers.slice(0).forEach(h => {
                if (h.limit <= data && (h.lastTriggerValue < h.limit || h.lastTriggerValue == null)) {
                    h.fire(data);
                }
                h.lastTriggerValue = data;
            });
            this.handlers = this.handlers.filter(h => h.isValid());
        }
        this.lastTriggerValue = data;
    };
}

class EventLimitHandler<T> {
    public lastTriggerValue:T = null;
    constructor(public limit:T, public handler:{ (data?:T): void }) {
    }
    public fire(data?: T){
        this.handler(data);
    }
    public isValid():boolean{
        return true;
    }
}
class SingleFireEventLimitHandler<T> extends EventLimitHandler<T>{
    public fired = false;
    constructor(public limit:T, public handler:{ (data?:T): void }) {
        super(limit,handler);
    }

    public fire(data?: T){
        if(this.fired == false) {
            this.handler(data);
        }
        this.fired = true
    }

    public isValid():boolean{
        return this.fired === false;
    }
}