import * as plugins from '../plugins.js';
import { Readable } from 'stream';

/**
 * Multipart upload metadata
 */
export interface IMultipartUpload {
  uploadId: string;
  bucket: string;
  key: string;
  initiated: Date;
  parts: Map<number, IPartInfo>;
  metadata: Record<string, string>;
}

/**
 * Part information
 */
export interface IPartInfo {
  partNumber: number;
  etag: string;
  size: number;
  lastModified: Date;
}

/**
 * Manages multipart upload state and storage
 */
export class MultipartUploadManager {
  private uploads: Map<string, IMultipartUpload> = new Map();
  private uploadDir: string;

  constructor(private rootDir: string) {
    this.uploadDir = plugins.path.join(rootDir, '.multipart');
  }

  /**
   * Initialize multipart uploads directory
   */
  public async initialize(): Promise<void> {
    await plugins.smartfs.directory(this.uploadDir).recursive().create();
  }

  /**
   * Generate a unique upload ID
   */
  private generateUploadId(): string {
    return plugins.crypto.randomBytes(16).toString('hex');
  }

  /**
   * Initiate a new multipart upload
   */
  public async initiateUpload(
    bucket: string,
    key: string,
    metadata: Record<string, string>
  ): Promise<string> {
    const uploadId = this.generateUploadId();

    this.uploads.set(uploadId, {
      uploadId,
      bucket,
      key,
      initiated: new Date(),
      parts: new Map(),
      metadata,
    });

    // Create directory for this upload's parts
    const uploadPath = plugins.path.join(this.uploadDir, uploadId);
    await plugins.smartfs.directory(uploadPath).recursive().create();

    return uploadId;
  }

  /**
   * Upload a part
   */
  public async uploadPart(
    uploadId: string,
    partNumber: number,
    stream: Readable
  ): Promise<IPartInfo> {
    const upload = this.uploads.get(uploadId);
    if (!upload) {
      throw new Error('No such upload');
    }

    const partPath = plugins.path.join(this.uploadDir, uploadId, `part-${partNumber}`);

    // Write part to disk
    const webWriteStream = await plugins.smartfs.file(partPath).writeStream();
    const writer = webWriteStream.getWriter();

    let size = 0;
    const hash = plugins.crypto.createHash('md5');

    for await (const chunk of stream) {
      const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);
      await writer.write(new Uint8Array(buffer));
      hash.update(buffer);
      size += buffer.length;
    }

    await writer.close();

    const etag = hash.digest('hex');

    const partInfo: IPartInfo = {
      partNumber,
      etag,
      size,
      lastModified: new Date(),
    };

    upload.parts.set(partNumber, partInfo);

    return partInfo;
  }

  /**
   * Complete multipart upload - combine all parts
   */
  public async completeUpload(
    uploadId: string,
    parts: Array<{ PartNumber: number; ETag: string }>
  ): Promise<{ etag: string; size: number }> {
    const upload = this.uploads.get(uploadId);
    if (!upload) {
      throw new Error('No such upload');
    }

    // Verify all parts are uploaded
    for (const part of parts) {
      const uploadedPart = upload.parts.get(part.PartNumber);
      if (!uploadedPart) {
        throw new Error(`Part ${part.PartNumber} not uploaded`);
      }
      // Normalize ETag format (remove quotes if present)
      const normalizedETag = part.ETag.replace(/"/g, '');
      if (uploadedPart.etag !== normalizedETag) {
        throw new Error(`Part ${part.PartNumber} ETag mismatch`);
      }
    }

    // Sort parts by part number
    const sortedParts = parts.sort((a, b) => a.PartNumber - b.PartNumber);

    // Combine parts into final object
    const finalPath = plugins.path.join(this.uploadDir, uploadId, 'final');
    const webWriteStream = await plugins.smartfs.file(finalPath).writeStream();
    const writer = webWriteStream.getWriter();

    const hash = plugins.crypto.createHash('md5');
    let totalSize = 0;

    for (const part of sortedParts) {
      const partPath = plugins.path.join(this.uploadDir, uploadId, `part-${part.PartNumber}`);

      // Read part and write to final file
      const partContent = await plugins.smartfs.file(partPath).read();
      const buffer = Buffer.isBuffer(partContent) ? partContent : Buffer.from(partContent as string);

      await writer.write(new Uint8Array(buffer));
      hash.update(buffer);
      totalSize += buffer.length;
    }

    await writer.close();

    const etag = hash.digest('hex');

    return { etag, size: totalSize };
  }

  /**
   * Get the final combined file path
   */
  public getFinalPath(uploadId: string): string {
    return plugins.path.join(this.uploadDir, uploadId, 'final');
  }

  /**
   * Get upload metadata
   */
  public getUpload(uploadId: string): IMultipartUpload | undefined {
    return this.uploads.get(uploadId);
  }

  /**
   * Abort multipart upload - clean up parts
   */
  public async abortUpload(uploadId: string): Promise<void> {
    const upload = this.uploads.get(uploadId);
    if (!upload) {
      throw new Error('No such upload');
    }

    // Delete upload directory
    const uploadPath = plugins.path.join(this.uploadDir, uploadId);
    await plugins.smartfs.directory(uploadPath).recursive().delete();

    // Remove from memory
    this.uploads.delete(uploadId);
  }

  /**
   * Clean up upload after completion
   */
  public async cleanupUpload(uploadId: string): Promise<void> {
    const uploadPath = plugins.path.join(this.uploadDir, uploadId);
    await plugins.smartfs.directory(uploadPath).recursive().delete();
    this.uploads.delete(uploadId);
  }

  /**
   * List all in-progress uploads for a bucket
   */
  public listUploads(bucket?: string): IMultipartUpload[] {
    const uploads = Array.from(this.uploads.values());
    if (bucket) {
      return uploads.filter((u) => u.bucket === bucket);
    }
    return uploads;
  }

  /**
   * List parts for an upload
   */
  public listParts(uploadId: string): IPartInfo[] {
    const upload = this.uploads.get(uploadId);
    if (!upload) {
      throw new Error('No such upload');
    }
    return Array.from(upload.parts.values()).sort((a, b) => a.partNumber - b.partNumber);
  }
}