export interface IPosition {
    x: number;
    y: number;
}

export class Position implements IPosition {
    constructor(public x: number, public y: number) { }

    static fromEvent(e: MouseEvent | TouchEvent, el: any = null) {
        /**
         * Fix issue: Resize doesn't work on Windows10 IE11 (and on some windows 7 IE11)
         * https://github.com/xieziyu/angular2-draggable/issues/164
         * e instanceof MouseEvent check returns false on IE11
         */
        if (this.isMouseEvent(e)) {
            return new Position(e.clientX, e.clientY);
        } else {
            if (el === null || e.changedTouches.length === 1) {
                return new Position(e.changedTouches[0].clientX, e.changedTouches[0].clientY);
            }

            /**
             * Fix issue: Multiple phone draggables at the same time
             * https://github.com/xieziyu/angular2-draggable/issues/128
             */
            for (let i = 0; i < e.changedTouches.length; i++) {
                if (e.changedTouches[i].target === el) {
                    return new Position(e.changedTouches[i].clientX, e.changedTouches[i].clientY);
                }
            }
        }
    }

    static isMouseEvent(e: MouseEvent | TouchEvent): e is MouseEvent {
        return Object.prototype.toString.apply(e).indexOf('MouseEvent') === 8;
    }

    static isIPosition(obj): obj is IPosition {
        return !!obj && ('x' in obj) && ('y' in obj);
    }

    static getCurrent(el: Element) {
        let pos = new Position(0, 0);

        if (window) {
            const computed = window.getComputedStyle(el);
            if (computed) {
                let x = parseInt(computed.getPropertyValue('left'), 10);
                let y = parseInt(computed.getPropertyValue('top'), 10);
                pos.x = isNaN(x) ? 0 : x;
                pos.y = isNaN(y) ? 0 : y;
            }
            return pos;
        } else {
            console.error('Not Supported!');
            return null;
        }
    }

    static copy(p: IPosition) {
        return new Position(0, 0).set(p);
    }

    get value(): IPosition {
        return { x: this.x, y: this.y };
    }

    add(p: IPosition) {
        this.x += p.x;
        this.y += p.y;
        return this;
    }

    subtract(p: IPosition) {
        this.x -= p.x;
        this.y -= p.y;
        return this;
    }

    multiply(n: number) {
        this.x *= n;
        this.y *= n;
    }

    divide(n: number) {
        this.x /= n;
        this.y /= n;
    }

    reset() {
        this.x = 0;
        this.y = 0;
        return this;
    }

    set(p: IPosition) {
        this.x = p.x;
        this.y = p.y;
        return this;
    }
}