test-repo/scripts/build/build-license.js

import path from "node:path";
import { promises as fs } from "node:fs";
import { outdent } from "outdent";
import { DIST_DIR, PROJECT_ROOT } from "../utils/index.mjs";

const PROJECT_LICENSE_FILE = path.join(PROJECT_ROOT, "LICENSE");
const LICENSE_FILE = path.join(DIST_DIR, "LICENSE");
const separator = `\n${"-".repeat(40)}\n\n`;

async function getLicenseText(files) {
  let dependencies = files.flatMap((file) => file.dependencies);

  dependencies = dependencies.filter(
    (dependency, index) =>
      // Exclude ourself
      dependency.name !== "prettier" &&
      // Unique by `name` and `version`
      index ===
        dependencies.findIndex(
          ({ name, version }) =>
            dependency.name === name && dependency.version === version
        )
  );

  dependencies.sort(
    (dependencyA, dependencyB) =>
      dependencyA.name.localeCompare(dependencyB.name) ||
      dependencyA.version.localeCompare(dependencyB.version)
  );

  const prettierLicense = await fs.readFile(PROJECT_LICENSE_FILE, "utf8");

  const licenses = [
    ...new Set(
      dependencies
        .filter(({ license }) => license)
        .map(({ license }) => license)
    ),
  ];

  const text = outdent`
    # Prettier license

    Prettier is released under the MIT license:

    ${prettierLicense.trim()}
  `;

  if (licenses.length === 0) {
    return text;
  }

  const parts = [
    text,
    outdent`
      ## Licenses of bundled dependencies

      The published Prettier artifact additionally contains code with the following licenses:
      ${licenses.join(", ")}
    `,
  ];

  const content = dependencies
    .map((dependency) => {
      let text = `### ${dependency.name}@v${dependency.version}\n`;

      const meta = [];

      if (dependency.license) {
        meta.push(`License: ${dependency.license}`);
      }
      if (dependency.author?.name) {
        meta.push(`By: ${dependency.author.name}`);
      }
      if (dependency.repository?.url) {
        meta.push(`Repository: <${dependency.repository.url}>`);
      }

      if (meta.length > 0) {
        text += "\n" + meta.join("\n") + "\n";
      }

      if (dependency.licenseText) {
        text +=
          "\n" +
          dependency.licenseText
            .trim()
            .split("\n")
            .map((line) => (line ? `> ${line}` : ">"))
            .join("\n") +
          "\n";
      }
      return text;
    })
    .join(separator);

  return [
    ...parts,
    outdent`
      ## Bundled dependencies

      ${content}
    `,
  ].join("\n\n");
}

async function buildLicense({ file, files, shouldCollectLicenses }) {
  if (files.indexOf(file) !== files.length - 1) {
    throw new Error("license should be last file to build.");
  }

  if (!shouldCollectLicenses) {
    return;
  }

  const javascriptFiles = files.filter((file) => !file.isMetaFile);
  if (javascriptFiles.some((file) => !Array.isArray(file.dependencies))) {
    return { skipped: true };
  }

  const text = await getLicenseText(javascriptFiles);

  await fs.writeFile(LICENSE_FILE, text);
}

export default buildLicense;