#!/usr/bin/env node
/**
 * Fase 17.4.3 — CHANGELOG.md linter.
 *
 * Validates three things and exits non-zero on the first failure:
 *
 *   1. Keep-a-Changelog header line is present.
 *   2. Every release heading matches `## [vX.Y.Z] — YYYY-MM-DD` or the
 *      placeholder `## [Unreleased]`. Pre-release / build-metadata
 *      suffixes are allowed on the version (e.g. `v0.0.0-beta`,
 *      `v1.0.0-rc.0`).
 *   3. Every bullet inside a release section starts with one of the
 *      three prefixes `[new] / [fix] / [tweak]`. Bullets that introduce
 *      a sub-grouping header (lines ending in `:`) are exempted so the
 *      area-by-area structure of the beta backfill can use plain bullets
 *      as section titles.
 *
 * Wired into `just check` and runnable standalone:
 *   node scripts/check-changelog.mjs [path]
 *
 * Exit codes:
 *   0 — file passes all three checks
 *   1 — usage error (missing file)
 *   2 — validation failure (one or more issues printed to stderr)
 */
import { readFileSync } from 'node:fs';
import { resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const __filename = fileURLToPath(import.meta.url);
const repoRoot = resolve(__filename, '..', '..');

const target = resolve(process.argv[2] ?? resolve(repoRoot, 'CHANGELOG.md'));

let raw;
try {
	raw = readFileSync(target, 'utf8');
} catch (err) {
	console.error(`check-changelog: cannot read ${target}: ${err.message}`);
	process.exit(1);
}

const lines = raw.split('\n');
const errors = [];

// Check 1 — Keep-a-Changelog header.
if (!raw.includes('Keep a Changelog')) {
	errors.push('Missing Keep-a-Changelog reference in the header.');
}

// Walk through lines. Track when we are inside a release section.
const RELEASE_HEADING = /^## \[(.+?)\](?:\s+—\s+(.+))?$/;
const VERSION_RE = /^v\d+\.\d+\.\d+(?:[-+][0-9A-Za-z.-]+)?$/;
const DATE_RE = /^\d{4}-\d{2}-\d{2}/;
const BULLET = /^[-*]\s+(.*)$/;
const ALLOWED_PREFIXES = ['[new]', '[fix]', '[tweak]'];

let insideRelease = false;
let currentRelease = null;

for (let i = 0; i < lines.length; i++) {
	const line = lines[i];
	const m = line.match(RELEASE_HEADING);
	if (m) {
		const [, label, rest] = m;
		currentRelease = label;
		insideRelease = true;
		if (label === 'Unreleased') {
			// no further checks
			continue;
		}
		if (!VERSION_RE.test(label)) {
			errors.push(
				`Line ${i + 1}: release label "${label}" does not match vX.Y.Z (semver-with-optional-prerelease).`
			);
		}
		if (!rest || !DATE_RE.test(rest)) {
			errors.push(
				`Line ${i + 1}: release heading "${label}" is missing the "— YYYY-MM-DD" date segment.`
			);
		}
		continue;
	}

	if (!insideRelease) continue;

	const bm = line.match(BULLET);
	if (!bm) continue;

	const body = bm[1].trim();
	if (!body) continue;

	// Sub-grouping bullets end with ":" and carry no prefix (e.g. "- Auth + identity:").
	if (body.endsWith(':')) continue;

	const ok = ALLOWED_PREFIXES.some((p) => body.toLowerCase().startsWith(p));
	if (!ok) {
		errors.push(
			`Line ${i + 1} (in "${currentRelease}"): bullet missing [new]/[fix]/[tweak] prefix — "${body.slice(0, 80)}".`
		);
	}
}

if (errors.length > 0) {
	for (const e of errors) console.error(`check-changelog: ${e}`);
	process.exit(2);
}

console.log(`check-changelog: ${target} OK`);