const { execFileSync } = require('node:child_process');

const { readFileSync, writeFileSync } = require('node:fs');

const feature = /^feat(?:\([^\r\n)]+\))?!?:\s*(.+)$/;

const git = (...args) => execFileSync('git', args, { encoding: 'utf8' }).trim();

const escape = (value) =>

String(value)

.replace(/[\\`*_[\]<>|]/g, (char) => `\\${char}`)

.replace(/[\r\n]+/g, ' ');

function replaceUpdates(readme, rows) {

const section = /^## Recent updates\r?\n[\s\S]*?(?=^## |$(?![\s\S]))/m;

if (!section.test(readme)) throw Error('README.md must contain a Recent updates section.');

return readme.replace(

section,

() =>

`## Recent updates\n\n| Date | Feature | Contributor |\n| --- | --- | --- |\n${rows.join('\n')}\n\n`,

);

}

module.exports = async ({ github, context, core }) => {

const { before, after, created, deleted } = context.payload;

if (deleted) return;

const range = created || !before || /^0+$/.test(before) ? [after] : [`${before}..${after}`];

// A multi-commit push can contain feat even when its newest commit is a fix.

const subjects = git('log', '--format=%s', ...range).split('\n');

if (!subjects.some((subject) => feature.test(subject))) {

core.info('No feat commits in this push.');

return;

}

const readme = readFileSync('README.md', 'utf8');

const previous = new Map(

[...readme.matchAll(/\[([^\n]+?)\]\(https:\/\/[^\s)]+\/commit\/([a-f0-9]{40})\)/g)].map(

(match) => [match[2], match[1]],

),

);

const history = git('log', '--format=%H%x00%aI%x00%s')

.split('\n')

.map((line) => line.split('\0'));

const updates = [];

for (const [sha, date, subject] of history) {

const match = subject.match(feature);

if (!match) continue;

// Badge/documentation-only commits do not describe an application feature.

const files = git('diff-tree', '--root', '--no-commit-id', '--name-only', '-r', sha)

.split('\n')

.filter(Boolean);

if (!files.some((file) => !file.endsWith('.md') && !file.startsWith('doc/'))) continue;

updates.push({ sha, date, subject: match[1] });

}

updates.sort((a, b) => Date.parse(b.date) - Date.parse(a.date));

const rows = await Promise.all(

updates.slice(0, 7).map(async ({ sha, date, subject }) => {

const { data } = await github.rest.repos.getCommit({ ...context.repo, ref: sha });

const author = data.author;

const contributor = author

? `[@${escape(author.login)}](${author.html_url})`

: `[${escape(data.commit.author.name)}](${data.html_url})`;

// Use the calendar date recorded by Git; display no time or timezone.

return `| ${date.slice(0, 10)} | [${previous.get(sha) || escape(subject)}](${data.html_url}) | ${contributor} |`;

}),

);

const updated = replaceUpdates(readme, rows);

if (updated === readme) {

core.info('Recent updates already current.');

return;

}

writeFileSync('README.md', updated);

core.setOutput('changed', 'true');

};

module.exports.replaceUpdates = replaceUpdates;