import type { CpNode } from '../cp-node/cp-node.js';
import type { CurvePiece } from '../mat/curve-piece.js';
import { circumCenter } from 'flo-vector2d';
import { getCloseBoundaryPointsCertified } from '../closest-boundary-point/get-close-boundary-points-certified.js';


/**
 * Finds an initial 3-prong circle center point from which to iterate. The point 
 * must be within the shape. 
 * 
 * @param maxCoordPowerOf2
 * @param δ3s the three boundary pieces of which we need to find the three 
 * 3-prong points.
 * @param curvePiece3s 
 * 
 * @internal
 */
function calcInitial3ProngCenter(
        δ3s: CpNode[][], 
        curvePiece3s: CurvePiece[][]) {

    const circle = δ3s[0][0].pointOnShape.circle;
    const twoProngCircleCenter = circle.center;

    const pos = getCloseBoundaryPointsCertified(
        curvePiece3s[1],
        twoProngCircleCenter
    )[0];

    const meanPoints = [
        δ3s[0][0].pointOnShape.p, 
        pos.p,
        δ3s[2][1].pointOnShape.p,
    ];

    return circumCenter(meanPoints);
}


export { calcInitial3ProngCenter }