// Interface for point data structure used e.g. in SignaturePad#fromData method
export interface BasicPoint {
    x: number;
    y: number;
    pressure: number;
    time: number;
}

export class Point implements BasicPoint {
    public x: number;
    public y: number;
    public pressure: number;
    public time: number;

    public constructor(x: number, y: number, pressure?: number, time?: number) {
        if (isNaN(x) || isNaN(y)) {
            throw new Error(`Point is invalid: (${x}, ${y})`);
        }
        this.x = +x;
        this.y = +y;
        this.pressure = pressure || 0;
        this.time = time || Date.now();
    }

    public distanceTo(start: BasicPoint): number {
        return Math.sqrt(
            Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2),
        );
    }

    public equals(other: BasicPoint): boolean {
        return (
            this.x === other.x &&
            this.y === other.y &&
            this.pressure === other.pressure &&
            this.time === other.time
        );
    }

    public velocityFrom(start: BasicPoint): number {
        return this.time !== start.time
            ? this.distanceTo(start) / (this.time - start.time)
            : 0;
    }
}