// Converts coverage/lcov.info (Bun) to HTML and Cobertura. Run: bun scripts/coverage-reports.mjs
// shortcut: line coverage only, Bun's lcov has no usable branch/function data; revisit if Bun adds it.
// Totals here sum lines (8351/8578); Bun's text table averages per-file percentages, so it reads lower.
import { readdirSync, readFileSync, writeFileSync } from 'node:fs';
import { join, resolve } from 'node:path';
import libCoverage from 'istanbul-lib-coverage';
import libReport from 'istanbul-lib-report';
import reports from 'istanbul-reports';

const map = libCoverage.createCoverageMap({});
const loc = (line) => ({ start: { line, column: 0 }, end: { line, column: 1 } });
for (const record of readFileSync('coverage/lcov.info', 'utf8').split('end_of_record')) {
	const file = /^SF:(.+)$/m.exec(record)?.[1];
	if (!file) continue;
	const statementMap = {};
	const s = {};
	for (const [, line, hits] of record.matchAll(/^DA:(\d+),(\d+)/gm)) {
		statementMap[line] = loc(+line);
		s[line] = +hits;
	}
	map.addFileCoverage({
		path: resolve(file),
		statementMap,
		s,
		fnMap: {},
		f: {},
		branchMap: {},
		b: {},
	});
}
const context = libReport.createContext({ dir: 'coverage', coverageMap: map });
for (const name of ['html', 'cobertura']) reports.create(name).execute(context);

// Istanbul reports 0 branches/functions as 100%; relabel them instead of claiming coverage.
const rewrite = (file, edit) => writeFileSync(file, edit(readFileSync(file, 'utf8')));
for (const page of readdirSync('coverage', { recursive: true }).filter((f) => f.endsWith('.html')))
	rewrite(join('coverage', page), (html) =>
		html
			.replace(
				/<span class="strong">100% <\/span>(\s*<span class="quiet">(?:Branches|Functions)<\/span>\s*<span class='fraction'>)0\/0</g,
				'<span class="strong">n/a </span>$1not collected<',
			)
			.replace(
				/<td data-value="100" class="pct \w+">100%<\/td>(\s*)<td data-value="0" class="abs \w+">0\/0<\/td>/g,
				'<td data-value="0" class="pct">n/a</td>$1<td data-value="0" class="abs">not collected</td>',
			),
	);
rewrite('coverage/cobertura-coverage.xml', (xml) =>
	xml
		.replaceAll('branch-rate="1"', 'branch-rate="0"')
		.replace(
			'<coverage ',
			'<!-- Line coverage only: bun test does not collect branch or function coverage. -->\n<coverage ',
		),
);