import { S3Client, PutObjectCommand, GetObjectCommand, DeleteObjectCommand, HeadObjectCommand, ListObjectsV2Command } from '@aws-sdk/client-s3';
import { getSignedUrl } from '@aws-sdk/s3-request-presigner';
import { v4 as uuidv4 } from 'uuid';
import fs from 'fs/promises';
import path from 'path';

export interface S3Config {
  endpoint: string;
  accessKeyId: string;
  secretAccessKey: string;
  bucketName: string;
  region: string;
  useSSL?: boolean;
}

export interface UploadResult {
  key: string;
  url: string;
  size: number;
  contentType: string;
}

export interface S3FileInfo {
  key: string;
  size: number;
  lastModified: Date;
  contentType?: string;
}

export class S3Service {
  private client: S3Client;
  private bucketName: string;

  constructor(config: S3Config) {
    this.client = new S3Client({
      endpoint: config.endpoint,
      region: config.region,
      credentials: {
        accessKeyId: config.accessKeyId,
        secretAccessKey: config.secretAccessKey,
      },
      forcePathStyle: true, // Required for MinIO
    });
    this.bucketName = config.bucketName;
  }

  /**
   * Load S3 configuration from s3-config.json file
   */
  static async loadConfig(): Promise<S3Config> {
    try {
      const configPath = path.join(process.cwd(), 's3-config.json');
      const configData = await fs.readFile(configPath, 'utf-8');
      return JSON.parse(configData);
    } catch (error) {
      console.warn('Failed to load s3-config.json, using environment variables as fallback');
      return {
        endpoint: process.env.S3_ENDPOINT || 'http://localhost:9000',
        accessKeyId: process.env.S3_ACCESS_KEY_ID || 'minioadmin',
        secretAccessKey: process.env.S3_SECRET_ACCESS_KEY || 'minioadmin',
        bucketName: process.env.S3_BUCKET_NAME || 'music-files',
        region: process.env.S3_REGION || 'us-east-1',
        useSSL: process.env.S3_USE_SSL !== 'false',
      };
    }
  }

  /**
   * Create S3Service instance with configuration from file
   */
  static async createFromConfig(): Promise<S3Service> {
    const config = await this.loadConfig();
    return new S3Service(config);
  }

  /**
   * Upload a file to S3
   */
  async uploadFile(
    file: Buffer,
    originalName: string,
    contentType: string
  ): Promise<UploadResult> {
    const fileExtension = originalName.split('.').pop();
    const key = `music/${uuidv4()}.${fileExtension}`;

    const command = new PutObjectCommand({
      Bucket: this.bucketName,
      Key: key,
      Body: file,
      ContentType: contentType,
      Metadata: {
        originalName,
        uploadedAt: new Date().toISOString(),
      },
    });

    await this.client.send(command);

    return {
      key,
      url: `${this.bucketName}/${key}`,
      size: file.length,
      contentType,
    };
  }

  /**
   * Recursively list all files in the S3 bucket
   */
  async listAllFiles(prefix: string = ''): Promise<S3FileInfo[]> {
    const files: S3FileInfo[] = [];
    let continuationToken: string | undefined;

    do {
      const command = new ListObjectsV2Command({
        Bucket: this.bucketName,
        Prefix: prefix,
        ContinuationToken: continuationToken,
      });

      const response = await this.client.send(command);
      
      if (response.Contents) {
        for (const object of response.Contents) {
          if (object.Key && !object.Key.endsWith('/')) { // Skip directories
            files.push({
              key: object.Key,
              size: object.Size || 0,
              lastModified: object.LastModified || new Date(),
            });
          }
        }
      }

      continuationToken = response.NextContinuationToken;
    } while (continuationToken);

    return files;
  }

  /**
   * Generate a presigned URL for secure file access
   */
  async getPresignedUrl(key: string, expiresIn: number = 3600): Promise<string> {
    const command = new GetObjectCommand({
      Bucket: this.bucketName,
      Key: key,
    });

    return await getSignedUrl(this.client, command, { expiresIn });
  }

  /**
   * Delete a file from S3
   */
  async deleteFile(key: string): Promise<void> {
    const command = new DeleteObjectCommand({
      Bucket: this.bucketName,
      Key: key,
    });

    await this.client.send(command);
  }

  /**
   * Check if a file exists
   */
  async fileExists(key: string): Promise<boolean> {
    try {
      const command = new HeadObjectCommand({
        Bucket: this.bucketName,
        Key: key,
      });
      await this.client.send(command);
      return true;
    } catch (error) {
      return false;
    }
  }

  /**
   * Get file metadata
   */
  async getFileMetadata(key: string) {
    const command = new HeadObjectCommand({
      Bucket: this.bucketName,
      Key: key,
    });
    return await this.client.send(command);
  }

  /**
   * Get file content as buffer
   */
  async getFileContent(key: string): Promise<Buffer> {
    const command = new GetObjectCommand({
      Bucket: this.bucketName,
      Key: key,
    });

    const response = await this.client.send(command);
    
    if (!response.Body) {
      throw new Error('File has no content');
    }

    // Convert stream to buffer
    const chunks: Uint8Array[] = [];
    const stream = response.Body as any;
    
    return new Promise((resolve, reject) => {
      stream.on('data', (chunk: Uint8Array) => chunks.push(chunk));
      stream.on('error', reject);
      stream.on('end', () => resolve(Buffer.concat(chunks)));
    });
  }

  /**
   * Get streaming URL for a file
   */
  async getStreamingUrl(key: string): Promise<string> {
    return `${process.env.S3_ENDPOINT}/${this.bucketName}/${key}`;
  }
}