import type { CurvePiece } from "../mat/curve-piece.js";
import { evalDeCasteljau } from 'flo-bezier3';
import { squaredDistanceBetween } from 'flo-vector2d';

const { min } = Math;


const TOLERANCE = 1 + 2**-20;


/**
 * Finds an initial distance such that the closest point can not be further than 
 * this distance away.
 * 
 * @internal
 */ 
function getBestDistanceSquared(
        curvePieces: CurvePiece[], 
        xO: number[]) {

    let bestSquaredDistance = Infinity;
    for (let i=0; i<curvePieces.length; i++) {
        const curvePiece = curvePieces[i];

        const { curve: { ps }, ts } = curvePiece;
        
        const p1 = evalDeCasteljau(ps, ts[0]);
        const p2 = evalDeCasteljau(ps, ts[1]);
        
        bestSquaredDistance = min(
            bestSquaredDistance,
            squaredDistanceBetween(xO, p1),
            squaredDistanceBetween(xO, p2)
        ); 
    }

    // The extra multiplier is to account for floating point precision.
    return TOLERANCE*bestSquaredDistance;
}


export { getBestDistanceSquared }