smartarchive/ts/classes.archiveanalyzer.ts

import type { SmartArchive } from './classes.smartarchive.js';
import type { TSupportedMime } from './interfaces.js';
import * as plugins from './plugins.js';

/**
 * Type for decompression streams
 */
export type TDecompressionStream =
  | plugins.stream.Transform
  | plugins.stream.Duplex
  | plugins.tarStream.Extract;

/**
 * Result of archive analysis
 */
export interface IAnalyzedResult {
  fileType: plugins.fileType.FileTypeResult | undefined;
  isArchive: boolean;
  resultStream: plugins.smartstream.SmartDuplex<Buffer, Buffer>;
  decompressionStream: TDecompressionStream;
}

/**
 * Analyzes archive streams to detect format and provide decompression
 */
export class ArchiveAnalyzer {
  private smartArchiveRef: SmartArchive;

  constructor(smartArchiveRefArg: SmartArchive) {
    this.smartArchiveRef = smartArchiveRefArg;
  }

  /**
   * Check if a MIME type represents an archive format
   */
  private async mimeTypeIsArchive(mimeType: string | undefined): Promise<boolean> {
    if (!mimeType) return false;

    const archiveMimeTypes: Set<string> = new Set([
      'application/zip',
      'application/x-rar-compressed',
      'application/x-tar',
      'application/gzip',
      'application/x-7z-compressed',
      'application/x-bzip2',
    ]);

    return archiveMimeTypes.has(mimeType);
  }

  /**
   * Get the appropriate decompression stream for a MIME type
   */
  private async getDecompressionStream(mimeTypeArg: TSupportedMime): Promise<TDecompressionStream> {
    switch (mimeTypeArg) {
      case 'application/gzip':
        return this.smartArchiveRef.gzipTools.getDecompressionStream();
      case 'application/zip':
        return this.smartArchiveRef.zipTools.getDecompressionStream();
      case 'application/x-bzip2':
        return this.smartArchiveRef.bzip2Tools.getDecompressionStream();
      case 'application/x-tar':
        return this.smartArchiveRef.tarTools.getDecompressionStream();
      default:
        // Handle unsupported formats or no decompression needed
        return plugins.smartstream.createPassThrough();
    }
  }

  /**
   * Create an analyzed stream that detects archive type and provides decompression
   * Emits a single IAnalyzedResult object
   */
  public getAnalyzedStream(): plugins.smartstream.SmartDuplex<Buffer, IAnalyzedResult> {
    let firstRun = true;
    const resultStream = plugins.smartstream.createPassThrough();

    const analyzerstream = new plugins.smartstream.SmartDuplex<Buffer, IAnalyzedResult>({
      readableObjectMode: true,
      writeFunction: async (chunkArg: Buffer, streamtools) => {
        if (firstRun) {
          firstRun = false;
          const fileType = await plugins.fileType.fileTypeFromBuffer(chunkArg);
          const decompressionStream = await this.getDecompressionStream(fileType?.mime as TSupportedMime);

          const result: IAnalyzedResult = {
            fileType,
            isArchive: await this.mimeTypeIsArchive(fileType?.mime),
            resultStream,
            decompressionStream,
          };
          await streamtools.push(result);
        }
        await resultStream.backpressuredPush(chunkArg);
        return null;
      },
      finalFunction: async () => {
        resultStream.push(null);
        return null;
      },
    });

    return analyzerstream;
  }
}