// scoring.js — accuracy calculation

const Scoring = (() => {
	/**
	 * Calculate a score from the drawn path points.
	 * NOTE: Currently uses an effort-based approximation.
	 * TODO: Replace with real polygon comparison (IoU or Hausdorff distance).
	 * @param {{ x: number, y: number }[]} drawnPoints
	 * @returns {number} Score between 0 and 100.
	 */
	function calculateScore(drawnPoints) {
		if (!drawnPoints || drawnPoints.length < 10) return 0;

		const effort = Math.min(drawnPoints.length / 300, 1); // 0–1
		const base = 40 + Math.round(effort * 45); // 40–85
		const jitter = Math.round((Math.random() - 0.5) * 14); // ±7
		return Math.max(0, Math.min(100, base + jitter));
	}

	/**
	 * Compare a drawn polygon against a reference polygon.
	 * Stub — reserved for future IoU / Hausdorff implementation.
	 * @param {{ x: number, y: number }[]} _drawnPoints
	 * @param {{ x: number, y: number }[]} _referencePolygon - Normalised 0–1 coords.
	 * @returns {number} Score between 0 and 100.
	 */
	function compareShapes(_drawnPoints, _referencePolygon) {
		// TODO: implement real shape comparison
		return 0;
	}

	/**
	 * Map a numeric score to a letter grade with colour.
	 * @param {number} score
	 * @returns {{ label: string, color: string }}
	 */
	function getGrade(score) {
		if (score >= 90) return { label: "S", color: "#f0b429" };
		if (score >= 75) return { label: "A", color: "#41b869" };
		if (score >= 60) return { label: "B", color: "#1a7fc4" };
		if (score >= 40) return { label: "C", color: "#7a9aaa" };
		return { label: "D", color: "#e05c5c" };
	}

	return { calculateScore, compareShapes, getGrade };
})();