export type TNpmRequestRoute =
  | { type: 'root' }
  | { type: 'search' }
  | { type: 'userAuth'; username: string }
  | { type: 'tokens'; path: string }
  | { type: 'distTags'; packageName: string; tag?: string }
  | { type: 'tarball'; packageName: string; filename: string }
  | { type: 'unpublishVersion'; packageName: string; version: string }
  | { type: 'unpublishPackage'; packageName: string; rev: string }
  | { type: 'packageVersion'; packageName: string; version: string }
  | { type: 'package'; packageName: string };

function decodePackageName(rawPackageName: string): string {
  return decodeURIComponent(rawPackageName);
}

export function parseNpmRequestRoute(path: string, method: string): TNpmRequestRoute | null {
  if (path === '/' || path === '') {
    return { type: 'root' };
  }

  if (path.startsWith('/-/v1/search')) {
    return { type: 'search' };
  }

  const userMatch = path.match(/^\/-\/user\/org\.couchdb\.user:(.+)$/);
  if (userMatch) {
    return {
      type: 'userAuth',
      username: userMatch[1],
    };
  }

  if (path.startsWith('/-/npm/v1/tokens')) {
    return {
      type: 'tokens',
      path,
    };
  }

  const distTagsMatch = path.match(/^\/-\/package\/(@?[^\/]+(?:\/[^\/]+)?)\/dist-tags(?:\/(.+))?$/);
  if (distTagsMatch) {
    const [, rawPackageName, tag] = distTagsMatch;
    return {
      type: 'distTags',
      packageName: decodePackageName(rawPackageName),
      tag,
    };
  }

  const tarballMatch = path.match(/^\/(@?[^\/]+(?:\/[^\/]+)?)\/-\/(.+\.tgz)$/);
  if (tarballMatch) {
    const [, rawPackageName, filename] = tarballMatch;
    return {
      type: 'tarball',
      packageName: decodePackageName(rawPackageName),
      filename,
    };
  }

  if (method === 'DELETE') {
    const unpublishVersionMatch = path.match(/^\/(@?[^\/]+(?:\/[^\/]+)?)\/-\/([^\/]+)$/);
    if (unpublishVersionMatch) {
      const [, rawPackageName, version] = unpublishVersionMatch;
      return {
        type: 'unpublishVersion',
        packageName: decodePackageName(rawPackageName),
        version,
      };
    }

    const unpublishPackageMatch = path.match(/^\/(@?[^\/]+(?:\/[^\/]+)?)\/-rev\/([^\/]+)$/);
    if (unpublishPackageMatch) {
      const [, rawPackageName, rev] = unpublishPackageMatch;
      return {
        type: 'unpublishPackage',
        packageName: decodePackageName(rawPackageName),
        rev,
      };
    }
  }

  const unencodedScopedPackageMatch = path.match(/^\/@[^\/]+\/[^\/]+$/);
  if (unencodedScopedPackageMatch) {
    return {
      type: 'package',
      packageName: decodePackageName(path.substring(1)),
    };
  }

  const versionMatch = path.match(/^\/(@?[^\/]+(?:\/[^\/]+)?)\/([^\/]+)$/);
  if (versionMatch) {
    const [, rawPackageName, version] = versionMatch;
    return {
      type: 'packageVersion',
      packageName: decodePackageName(rawPackageName),
      version,
    };
  }

  const packageMatch = path.match(/^\/(@?[^\/]+(?:\/[^\/]+)?)$/);
  if (packageMatch) {
    return {
      type: 'package',
      packageName: decodePackageName(packageMatch[1]),
    };
  }

  return null;
}