import { readFile } from 'node:fs/promises';
import { pathToFileURL } from 'node:url';

// One labeled field per row, including omissions and rule failures.
// eligible means your non-score checks passed, not that the value is correct.
type Row = { confidence: number | null; eligible: boolean; correct: boolean };

export function summarize(input: unknown, threshold: number) {
	if (!Number.isFinite(threshold) || threshold < 0 || threshold > 1) {
		throw new Error('Threshold must be in [0, 1]');
	}
	if (!Array.isArray(input) || input.length === 0) throw new Error('Expected labeled rows');
	const rows: Row[] = input.map((row: unknown) => {
		if (typeof row !== 'object' || row === null) throw new Error('Invalid row');
		const r = row as Record<string, unknown>;
		if (
			typeof r.correct !== 'boolean' ||
			typeof r.eligible !== 'boolean' ||
			(r.confidence !== null &&
				(typeof r.confidence !== 'number' ||
					!Number.isFinite(r.confidence) ||
					r.confidence < 0 ||
					r.confidence > 1))
		) {
			throw new Error('Each row needs correct, eligible and confidence (number or null)');
		}
		return { correct: r.correct, eligible: r.eligible, confidence: r.confidence };
	});
	const accepted = rows.filter(
		(r) => r.eligible && r.confidence !== null && r.confidence >= threshold,
	);
	const errors = accepted.filter((r) => !r.correct).length;
	return {
		threshold,
		total: rows.length,
		accepted: accepted.length,
		errors,
		coverage: accepted.length / rows.length,
		empiricalRisk: accepted.length === 0 ? null : errors / accepted.length,
	};
}

if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
	const path = process.argv[2];
	if (!path) throw new Error('Usage: npx tsx thresholds.ts labeled-fields.json');
	const rows: unknown = JSON.parse(await readFile(path, 'utf8'));
	// Candidate thresholds for exploration only; none is a recommended policy.
	console.table([0.5, 0.7, 0.9, 0.95].map((t) => summarize(rows, t)));
}