release.js

// Thanks to Vercel/Next.js -> https://github.com/vercel/next.js/blob/canary/release.js

// section -> label
const conventionalNamingMap = {
    Features: "feat",
    "Bug Fixes": "fix",
    "Refactoring Changes": "refactor",
    "Reverted Changes": "revert",
    "Style Changes": "style",
    "Documentation Changes": "docs",
};

const fallbackSection = "Misc Changes";

// --------------------------------------------------

const prNumberRegex = /\(#([-0-9]+)\)$/;

const getCommitPullRequest = async (commit, github) => {
    const match = prNumberRegex.exec(commit.title);

    if (!match) {
        return null;
    }

    const number = parseInt(match[1], 10);

    if (!number) {
        return null;
    }

    const { data } = await github.connection.pullRequests.get({
        owner: github.repoDetails.user,
        repo: github.repoDetails.repo,
        number,
    });

    return data;
};

const getSectionForPullRequest = (pullRequest) => {
    const { title } = pullRequest;

    // sections defined first will take priority
    for (const [section, label] of Object.entries(conventionalNamingMap)) {
        if (title.startsWith(label)) {
            return section;
        }
    }

    return null;
};

const groupByConventionalNaming = async (commits, github) => {
    // Initialize the sections object with empty arrays
    const sections = Object.keys(conventionalNamingMap).reduce(
        (sections, section) => {
            sections[section] = [];
            return sections;
        },
        {},
    );
    sections.__fallback = [];

    for (const commit of commits) {
        const pullRequest = await getCommitPullRequest(commit, github);

        if (pullRequest) {
            const section = getSectionForPullRequest(pullRequest);

            if (section) {
                // Add the change to the respective section
                sections[section].push({
                    title: pullRequest.title,
                    number: pullRequest.number,
                });

                continue;
            }

            // No section found, add it to the fallback section
            sections.__fallback.push({
                title: pullRequest.title,
                number: pullRequest.number,
            });

            continue;
        }

        // No Pull Request found, add it to the fallback section but without the number
        sections.__fallback.push({
            title: commit.title,
        });
    }

    return sections;
};

function cleanupPRTitle(title) {
    const regexp = new RegExp(
        `^(${Object.values(conventionalNamingMap).join(
            "|",
        )})(\\s)?((\\(|\\[).*(\\)|\\]))?:`,
        "i",
    );

    return title.replace(regexp, "**$1**");
}

const buildChangelog = (sections, authors) => {
    let text = "";

    for (const section in sections) {
        const changes = sections[section];

        // No changes in this section? Don't render it
        if (changes.length === 0) {
            continue;
        }

        const title = section === "__fallback" ? fallbackSection : section;
        text += `### ${title}\n\n`;

        for (const change of changes) {
            const numberText =
                change.number != null ? `: #${change.number}` : "";

            text += `- ${cleanupPRTitle(change.title)}${numberText}\n`;
        }

        text += "\n";
    }

    if (authors.size > 0) {
        text += "### Credits \n\n";
        text += "Huge thanks to ";

        let index = 1;
        authors.forEach((author) => {
            // GitHub links usernames if prefixed with @
            text += `@${author}`;

            const penultimate = index === authors.size - 1;
            const notLast = index !== authors.size;

            if (penultimate) {
                // Oxford comma is applied when list is bigger than 2 names
                if (authors.size > 2) {
                    text += ",";
                }

                text += " and ";
            } else if (notLast) {
                text += ", ";
            }

            index += 1;
        });

        text += " for helping!";
        text += "\n";
    }

    return text;
};

module.exports = async (markdown, metadata) => {
    const { commits, authors, githubConnection, repoDetails } = metadata;

    const github = { connection: githubConnection, repoDetails };

    const sections = await groupByConventionalNaming(commits.all, github);
    const changelog = buildChangelog(sections, authors);

    return changelog;
};