import { Point } from "./Polygon";

/**
 * Concatenates two arrays component wise.
 * a[i], b[i+offset] => [a[i], b[i+offset]]
 */
export function zip<S,T>(a:S[], b:T[], offset:number = 0): Array<[S, T]>
{
    if(offset < 0)
    {
        throw new Error("The offset is negative.");
    }
    if(offset % 1 !== 0)
    {
        throw new Error("The offset is not an integer.");
    }
    if(a.length !== b.length)
    {
        throw new Error("Input arrays have different lengths.");
    }
    const output:Array<[S, T]> = [];
    const length = a.length;
    for(let i=0;i<length;i++)
    {
        output.push([
            a[i],
            b[(i+offset)%length],
        ]);
    }
    return output;
}

export function midPoint(a:Point, b:Point, scalar:number): Point
{
    const cx = scalar * (b.x - a.x) + a.x;
    const cy = scalar * (b.y - a.y) + a.y;

    return new Point(cx, cy);
}

export function clamp(value:number, lowerBound:number|null = 0, upperBound:number|null = 1): number
{
    if(lowerBound != null)
    {
        value = Math.max(lowerBound, value);
    }
    if(upperBound != null)
    {
        value = Math.min(upperBound, value);
    }
    return value;
}

export function randomizeScalar(
    baseValue:number,
    randomizeAmplitude:number,
    lowerBound:number | null,
    upperBound:number | null,
): number
{
    if(randomizeAmplitude !== 0)
    {
        baseValue += 2 * randomizeAmplitude * (Math.random() - 0.5);
    }
    return clamp(baseValue, lowerBound, upperBound);
}