import TarObject, {
  TAR_OBJECT_TYPE_GNU_NEXT_LINK_NAME,
  TAR_OBJECT_TYPE_GNU_NEXT_NAME,
  TAR_OBJECT_TYPE_PAX_GLOBAL,
  TAR_OBJECT_TYPE_PAX_NEXT,
} from './TarObject';
import TarPaxParser, { TAR_PAX_KEY_LINK_NAME, TAR_PAX_KEY_NAME } from './TarPaxParser';

/**
 * Applies the extended protocols: ustar, pax, gnu.
 */
export default class TarExtender {
  protected globalOverrides: Map<string, string> = new Map();

  protected nextOverrides: Map<string, string> = new Map();

  extend() {
    return new TransformStream<TarObject, TarObject>({
      transform: (obj, controller) => {
        if (obj.header.magicBytes === 'ustar') {
          switch (obj.header.type) {
            case TAR_OBJECT_TYPE_PAX_GLOBAL:
              return this.parsePax(obj, true);
            case TAR_OBJECT_TYPE_PAX_NEXT:
              return this.parsePax(obj, false);
            case TAR_OBJECT_TYPE_GNU_NEXT_LINK_NAME:
              return this.parseGnuNextLinkName(obj);
            case TAR_OBJECT_TYPE_GNU_NEXT_NAME:
              return this.parseGnuNextName(obj);
            default:
              this.override(obj);
              break;
          }
        }
        controller.enqueue(obj);
      },
    });
  }

  /**
   * @link https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_01
   */
  protected override(obj: TarObject) {
    for (const overrides of [this.globalOverrides, this.nextOverrides]) {
      for (const [key, value] of overrides) {
        switch (key) {
          case 'gid':
            obj.header.groupId = parseInt(value, 10);
            break;
          case 'gname':
            obj.header.groupName = value;
            break;
          case 'mtime':
            obj.header.modifiedTime = Number(value);
            break;
          case 'size':
            obj.header.size = parseInt(value, 10);
            break;
          case 'uid':
            obj.header.userId = parseInt(value, 10);
            break;
          case 'uname':
            obj.header.userName = value;
            break;
          case TAR_PAX_KEY_LINK_NAME:
            obj.header.linkName = value;
            break;
          case TAR_PAX_KEY_NAME:
            obj.header.name = value;
            obj.header.prefix = '';
            break;
          default:
            obj.header.attrs[key] = value;
            break;
        }
      }
    }
    this.nextOverrides.clear();
    // https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
    if (obj.header.prefix) {
      obj.header.name = `${obj.header.prefix}/${obj.header.name}`;
      obj.header.prefix = '';
    }
  }

  protected async parsePax(obj: TarObject, isGlobal: boolean) {
    if (obj.body) {
      const paxParser = new TarPaxParser();
      const stream = obj.body
        .pipeThrough(new TextDecoderStream())
        .pipeThrough(paxParser.parse());
      for await (const { key, value } of stream) {
        (isGlobal ? this.globalOverrides : this.nextOverrides).set(key, value);
      }
    }
  }

  protected async parseGnuNextLinkName(obj: TarObject) {
    if (obj.body) {
      const stream = obj.body.pipeThrough(new TextDecoderStream());
      let linkName = '';
      for await (const str of stream) {
        linkName += str;
      }
      this.nextOverrides.set(TAR_PAX_KEY_LINK_NAME, linkName);
    }
  }

  protected async parseGnuNextName(obj: TarObject) {
    if (obj.body) {
      const stream = obj.body.pipeThrough(new TextDecoderStream());
      let name = '';
      for await (const str of stream) {
        name += str;
      }
      this.nextOverrides.set(TAR_PAX_KEY_NAME, name);
    }
  }
}