dangerfile.ts

import { markdown, danger, warn, fail } from "danger";

const BIG_PR_THRESHOLD = 1000;
const LONG_COMMIT_MESSAGE_THRESHOLD = 125;

function generateCollapsibleList(items: string[], summary: string): string {
  return `
  <details>
    <summary>${summary}</summary>
    <ul>
      ${items.map((item) => `<li>${danger.github.utils.fileLinks([item], false)}</li>`).join("\n")}
    </ul>
  </details>
  `;
}

function getPrefixSymbol(val: number) {
  return val > 0 ? "🔴 " : val < 0 ? "🟢 " : "🟡 ";
}

function formatByteStr(bytes: number, addPrefix = false) {
  const [kiloBytes, megaBytes, gigaBytes] = [1, 2, 3].map((exp) => 1e3 ** exp);

  const outputStr =
    bytes < kiloBytes
      ? bytes + " B"
      : bytes < megaBytes
      ? (bytes / kiloBytes).toFixed(2) + " KB"
      : bytes < gigaBytes
      ? (bytes / megaBytes).toFixed(2) + " MB"
      : (bytes / gigaBytes).toFixed(2) + " GB";

  return `${addPrefix ? getPrefixSymbol(bytes) : ""}${outputStr}`;
}

(async function () {
  const packageChanged = danger.git.modified_files.includes("package.json");
  const lockfileChanged = danger.git.modified_files.includes("pnpm-lock.yaml");
  const PACKAGE_CHECK_MESSAGE = `Changes found in package.json, but not in pnpm-lock.yaml - <i>'Forgot to run \`pnpm i\`?'</i>`;

  const linesAdded = danger.github.pr.additions;
  const linesDeleted = danger.github.pr.deletions;
  const BIG_PR_MESSAGE = `Big PR (# added: <b>${linesAdded}</b>, # deleted: <b>${linesDeleted}</b>), please keep your PR small to make it easier to review`;

  const malformedCommits = danger.git.commits.filter((commit) => {
    const subject = commit.message.split("\n")[0];

    return (
      (!subject.match(/^(feat|fix|build|chore|ci|style|refactor|perf|test|docs)(\(.+?\))?:/i) &&
        !subject.includes("Merge pull request")) ||
      subject.length > LONG_COMMIT_MESSAGE_THRESHOLD
    );
  });

  const MALFORMED_COMMIT_MESSAGE = `
  Some commit messages do not match the expected format (helps us generate changelogs).

  <details>
      <summary>Violating Commits</summary>
      <ul>
        ${malformedCommits
          .map((item) => `<li>${item.message.split("\n")[0]} (${item.sha.slice(0, 7)})</li>`)
          .join("\n")}
      </ul>
  </details>

  See ${danger.utils.href(
    "https://www.conventionalcommits.org/en/v1.0.0/",
    "Conventional Commits"
  )} for expected formatting.
  `;

  const filesChanged = [...danger.git.modified_files, ...danger.git.created_files, ...danger.git.deleted_files];

  const fileSizeMapper: Record<"filename" | "base" | "current" | "diff" | "percent", string>[] = [];
  const totalChange: Record<"base" | "current" | "diff", number> = { base: 0, current: 0, diff: 0 };
  for (const file of filesChanged) {
    if (file !== "pnpm-lock.yaml") {
      const { before, after } = await danger.git.diffForFile(file);

      const unMinifiedSizeDiffInBytes = after.length - before.length;
      const percentageChanged = before.length === 0 ? 100 : (unMinifiedSizeDiffInBytes * 100) / before.length;

      totalChange.base += before.length;
      totalChange.current += after.length;
      totalChange.diff += unMinifiedSizeDiffInBytes;

      fileSizeMapper.push({
        filename: file,
        base: formatByteStr(before.length),
        current: formatByteStr(after.length),
        diff: formatByteStr(unMinifiedSizeDiffInBytes, true),
        percent: `${getPrefixSymbol(percentageChanged)}${percentageChanged.toFixed(2)}%`
      });
    }
  }

  const totalPercentage = (totalChange.diff * 100) / totalChange.base;

  // MESSAGES

  if (packageChanged && !lockfileChanged) warn(PACKAGE_CHECK_MESSAGE);

  if (linesAdded + linesDeleted > BIG_PR_THRESHOLD && !lockfileChanged) warn(BIG_PR_MESSAGE);

  if (malformedCommits.length > 0) fail(MALFORMED_COMMIT_MESSAGE);

  markdown(`
  ## PR Snapshot

  Comparing: ${danger.git.base.slice(0, 7)}...${danger.git.head.slice(0, 7)}

  <details>
  <summary>Insights</summary>

  <b>Note:</b> the following excludes changes to \`pnpm-lock.yaml\` due to its volatile nature.

  | Filename | Base | Current | +/- |  %  |
  |---------:|:----:|:-------:|:---|:---|
  ${fileSizeMapper
    .map(
      (item) =>
        `| ${danger.github.utils.fileLinks([item.filename], false)} | ${item.base} | ${item.current} | ${item.diff} | ${
          item.percent
        } |`
    )
    .join("\n")}
  | Total | ${formatByteStr(totalChange.base)} | ${formatByteStr(totalChange.current)} | ${formatByteStr(
    totalChange.diff,
    true
  )} | ${getPrefixSymbol(totalPercentage)}${totalPercentage.toFixed(2)}% |

  </details>

  ### Summary
  ${generateCollapsibleList(danger.git.modified_files, "Changed Files")}

  ${generateCollapsibleList(danger.git.created_files, "Created Files")}

  ${generateCollapsibleList(danger.git.deleted_files, "Deleted Files")}
  `);
})();