import { BaseRegistry } from '../core/classes.baseregistry.js';
import { RegistryStorage } from '../core/classes.registrystorage.js';
import { AuthManager } from '../core/classes.authmanager.js';
import type { IRequestContext, IResponse, IAuthToken, IRegistryError } from '../core/interfaces.core.js';
import type {
  IUploadSession,
  IOciManifest,
  IOciImageIndex,
  ITagList,
  IReferrersResponse,
  IPaginationOptions,
} from './interfaces.oci.js';

/**
 * OCI Distribution Specification v1.1 compliant registry
 */
export class OciRegistry extends BaseRegistry {
  private storage: RegistryStorage;
  private authManager: AuthManager;
  private uploadSessions: Map<string, IUploadSession> = new Map();
  private basePath: string = '/oci';
  private cleanupInterval?: NodeJS.Timeout;

  constructor(storage: RegistryStorage, authManager: AuthManager, basePath: string = '/oci') {
    super();
    this.storage = storage;
    this.authManager = authManager;
    this.basePath = basePath;
  }

  public async init(): Promise<void> {
    // Start cleanup of stale upload sessions
    this.startUploadSessionCleanup();
  }

  public getBasePath(): string {
    return this.basePath;
  }

  public async handleRequest(context: IRequestContext): Promise<IResponse> {
    // Remove base path from URL
    const path = context.path.replace(this.basePath, '');

    // Extract token from Authorization header
    const authHeader = context.headers['authorization'] || context.headers['Authorization'];
    const tokenString = authHeader?.replace(/^Bearer\s+/i, '');
    const token = tokenString ? await this.authManager.validateToken(tokenString, 'oci') : null;

    // Route to appropriate handler
    if (path === '/v2/' || path === '/v2') {
      return this.handleVersionCheck();
    }

    // Manifest operations: /v2/{name}/manifests/{reference}
    const manifestMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/manifests\/([^\/]+)$/);
    if (manifestMatch) {
      const [, name, reference] = manifestMatch;
      return this.handleManifestRequest(context.method, name, reference, token, context.body, context.headers);
    }

    // Blob operations: /v2/{name}/blobs/{digest}
    const blobMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/blobs\/(sha256:[a-f0-9]{64})$/);
    if (blobMatch) {
      const [, name, digest] = blobMatch;
      return this.handleBlobRequest(context.method, name, digest, token, context.headers);
    }

    // Blob upload operations: /v2/{name}/blobs/uploads/
    const uploadInitMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/blobs\/uploads\/?$/);
    if (uploadInitMatch && context.method === 'POST') {
      const [, name] = uploadInitMatch;
      return this.handleUploadInit(name, token, context.query, context.body);
    }

    // Blob upload operations: /v2/{name}/blobs/uploads/{uuid}
    const uploadMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/blobs\/uploads\/([^\/]+)$/);
    if (uploadMatch) {
      const [, name, uploadId] = uploadMatch;
      return this.handleUploadSession(context.method, uploadId, token, context);
    }

    // Tags list: /v2/{name}/tags/list
    const tagsMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/tags\/list$/);
    if (tagsMatch) {
      const [, name] = tagsMatch;
      return this.handleTagsList(name, token, context.query);
    }

    // Referrers: /v2/{name}/referrers/{digest}
    const referrersMatch = path.match(/^\/v2\/([^\/]+(?:\/[^\/]+)*)\/referrers\/(sha256:[a-f0-9]{64})$/);
    if (referrersMatch) {
      const [, name, digest] = referrersMatch;
      return this.handleReferrers(name, digest, token, context.query);
    }

    return {
      status: 404,
      headers: { 'Content-Type': 'application/json' },
      body: this.createError('NOT_FOUND', 'Endpoint not found'),
    };
  }

  protected async checkPermission(
    token: IAuthToken | null,
    resource: string,
    action: string
  ): Promise<boolean> {
    if (!token) return false;
    return this.authManager.authorize(token, `oci:repository:${resource}`, action);
  }

  // ========================================================================
  // REQUEST HANDLERS
  // ========================================================================

  private handleVersionCheck(): IResponse {
    return {
      status: 200,
      headers: {
        'Content-Type': 'application/json',
        'Docker-Distribution-API-Version': 'registry/2.0',
      },
      body: {},
    };
  }

  private async handleManifestRequest(
    method: string,
    repository: string,
    reference: string,
    token: IAuthToken | null,
    body?: Buffer | any,
    headers?: Record<string, string>
  ): Promise<IResponse> {
    switch (method) {
      case 'GET':
        return this.getManifest(repository, reference, token, headers);
      case 'HEAD':
        return this.headManifest(repository, reference, token);
      case 'PUT':
        return this.putManifest(repository, reference, token, body, headers);
      case 'DELETE':
        return this.deleteManifest(repository, reference, token);
      default:
        return {
          status: 405,
          headers: {},
          body: this.createError('UNSUPPORTED', 'Method not allowed'),
        };
    }
  }

  private async handleBlobRequest(
    method: string,
    repository: string,
    digest: string,
    token: IAuthToken | null,
    headers: Record<string, string>
  ): Promise<IResponse> {
    switch (method) {
      case 'GET':
        return this.getBlob(repository, digest, token, headers['range'] || headers['Range']);
      case 'HEAD':
        return this.headBlob(repository, digest, token);
      case 'DELETE':
        return this.deleteBlob(repository, digest, token);
      default:
        return {
          status: 405,
          headers: {},
          body: this.createError('UNSUPPORTED', 'Method not allowed'),
        };
    }
  }

  private async handleUploadInit(
    repository: string,
    token: IAuthToken | null,
    query: Record<string, string>,
    body?: Buffer | any
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'push')) {
      return this.createUnauthorizedResponse(repository, 'push');
    }

    // Check for monolithic upload (digest + body provided)
    const digest = query.digest;
    if (digest && body) {
      // Monolithic upload: complete upload in single POST
      const blobData = Buffer.isBuffer(body) ? body : Buffer.from(JSON.stringify(body));

      // Verify digest
      const calculatedDigest = await this.calculateDigest(blobData);
      if (calculatedDigest !== digest) {
        return {
          status: 400,
          headers: {},
          body: this.createError('DIGEST_INVALID', 'Provided digest does not match uploaded content'),
        };
      }

      // Store the blob
      await this.storage.putOciBlob(digest, blobData);

      return {
        status: 201,
        headers: {
          'Location': `${this.basePath}/v2/${repository}/blobs/${digest}`,
          'Docker-Content-Digest': digest,
        },
        body: null,
      };
    }

    // Standard chunked upload: create session
    const uploadId = this.generateUploadId();
    const session: IUploadSession = {
      uploadId,
      repository,
      chunks: [],
      totalSize: 0,
      createdAt: new Date(),
      lastActivity: new Date(),
    };

    this.uploadSessions.set(uploadId, session);

    return {
      status: 202,
      headers: {
        'Location': `${this.basePath}/v2/${repository}/blobs/uploads/${uploadId}`,
        'Docker-Upload-UUID': uploadId,
      },
      body: null,
    };
  }

  private async handleUploadSession(
    method: string,
    uploadId: string,
    token: IAuthToken | null,
    context: IRequestContext
  ): Promise<IResponse> {
    const session = this.uploadSessions.get(uploadId);
    if (!session) {
      return {
        status: 404,
        headers: {},
        body: this.createError('BLOB_UPLOAD_INVALID', 'Upload session not found'),
      };
    }

    if (!await this.checkPermission(token, session.repository, 'push')) {
      return this.createUnauthorizedResponse(session.repository, 'push');
    }

    switch (method) {
      case 'PATCH':
        return this.uploadChunk(uploadId, context.body, context.headers['content-range']);
      case 'PUT':
        return this.completeUpload(uploadId, context.query['digest'], context.body);
      case 'GET':
        return this.getUploadStatus(uploadId);
      default:
        return {
          status: 405,
          headers: {},
          body: this.createError('UNSUPPORTED', 'Method not allowed'),
        };
    }
  }

  // Continuing with the actual OCI operations implementation...
  // (The rest follows the same pattern as before, adapted to return IResponse objects)

  private async getManifest(
    repository: string,
    reference: string,
    token: IAuthToken | null,
    headers?: Record<string, string>
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return {
        status: 401,
        headers: {
          'WWW-Authenticate': `Bearer realm="${this.basePath}/v2/token",service="registry",scope="repository:${repository}:pull"`,
        },
        body: this.createError('DENIED', 'Insufficient permissions'),
      };
    }

    // Resolve tag to digest if needed
    let digest = reference;
    if (!reference.startsWith('sha256:')) {
      const tags = await this.getTagsData(repository);
      digest = tags[reference];
      if (!digest) {
        return {
          status: 404,
          headers: {},
          body: this.createError('MANIFEST_UNKNOWN', 'Manifest not found'),
        };
      }
    }

    const manifestData = await this.storage.getOciManifest(repository, digest);
    if (!manifestData) {
      return {
        status: 404,
        headers: {},
        body: this.createError('MANIFEST_UNKNOWN', 'Manifest not found'),
      };
    }

    return {
      status: 200,
      headers: {
        'Content-Type': 'application/vnd.oci.image.manifest.v1+json',
        'Docker-Content-Digest': digest,
      },
      body: manifestData,
    };
  }

  private async headManifest(
    repository: string,
    reference: string,
    token: IAuthToken | null
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return this.createUnauthorizedHeadResponse(repository, 'pull');
    }

    // Similar logic as getManifest but return headers only
    let digest = reference;
    if (!reference.startsWith('sha256:')) {
      const tags = await this.getTagsData(repository);
      digest = tags[reference];
      if (!digest) {
        return { status: 404, headers: {}, body: null };
      }
    }

    const exists = await this.storage.ociManifestExists(repository, digest);
    if (!exists) {
      return { status: 404, headers: {}, body: null };
    }

    const manifestData = await this.storage.getOciManifest(repository, digest);

    return {
      status: 200,
      headers: {
        'Content-Type': 'application/vnd.oci.image.manifest.v1+json',
        'Docker-Content-Digest': digest,
        'Content-Length': manifestData ? manifestData.length.toString() : '0',
      },
      body: null,
    };
  }

  private async putManifest(
    repository: string,
    reference: string,
    token: IAuthToken | null,
    body?: Buffer | any,
    headers?: Record<string, string>
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'push')) {
      return {
        status: 401,
        headers: {
          'WWW-Authenticate': `Bearer realm="${this.basePath}/v2/token",service="registry",scope="repository:${repository}:push"`,
        },
        body: this.createError('DENIED', 'Insufficient permissions'),
      };
    }

    if (!body) {
      return {
        status: 400,
        headers: {},
        body: this.createError('MANIFEST_INVALID', 'Manifest body is required'),
      };
    }

    const manifestData = Buffer.isBuffer(body) ? body : Buffer.from(JSON.stringify(body));
    const contentType = headers?.['content-type'] || headers?.['Content-Type'] || 'application/vnd.oci.image.manifest.v1+json';

    // Calculate manifest digest
    const digest = await this.calculateDigest(manifestData);

    // Store manifest by digest
    await this.storage.putOciManifest(repository, digest, manifestData, contentType);

    // If reference is a tag (not a digest), update tags mapping
    if (!reference.startsWith('sha256:')) {
      const tags = await this.getTagsData(repository);
      tags[reference] = digest;
      const tagsPath = `oci/tags/${repository}/tags.json`;
      await this.storage.putObject(tagsPath, Buffer.from(JSON.stringify(tags), 'utf-8'));
    }

    return {
      status: 201,
      headers: {
        'Location': `${this.basePath}/v2/${repository}/manifests/${digest}`,
        'Docker-Content-Digest': digest,
      },
      body: null,
    };
  }

  private async deleteManifest(
    repository: string,
    digest: string,
    token: IAuthToken | null
  ): Promise<IResponse> {
    if (!digest.startsWith('sha256:')) {
      return {
        status: 400,
        headers: {},
        body: this.createError('UNSUPPORTED', 'Must use digest for deletion'),
      };
    }

    if (!await this.checkPermission(token, repository, 'delete')) {
      return this.createUnauthorizedResponse(repository, 'delete');
    }

    await this.storage.deleteOciManifest(repository, digest);

    return {
      status: 202,
      headers: {},
      body: null,
    };
  }

  private async getBlob(
    repository: string,
    digest: string,
    token: IAuthToken | null,
    range?: string
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return this.createUnauthorizedResponse(repository, 'pull');
    }

    const data = await this.storage.getOciBlob(digest);
    if (!data) {
      return {
        status: 404,
        headers: {},
        body: this.createError('BLOB_UNKNOWN', 'Blob not found'),
      };
    }

    return {
      status: 200,
      headers: {
        'Content-Type': 'application/octet-stream',
        'Docker-Content-Digest': digest,
      },
      body: data,
    };
  }

  private async headBlob(
    repository: string,
    digest: string,
    token: IAuthToken | null
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return this.createUnauthorizedHeadResponse(repository, 'pull');
    }

    const exists = await this.storage.ociBlobExists(digest);
    if (!exists) {
      return { status: 404, headers: {}, body: null };
    }

    const blob = await this.storage.getOciBlob(digest);

    return {
      status: 200,
      headers: {
        'Content-Length': blob ? blob.length.toString() : '0',
        'Docker-Content-Digest': digest,
      },
      body: null,
    };
  }

  private async deleteBlob(
    repository: string,
    digest: string,
    token: IAuthToken | null
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'delete')) {
      return this.createUnauthorizedResponse(repository, 'delete');
    }

    await this.storage.deleteOciBlob(digest);

    return {
      status: 202,
      headers: {},
      body: null,
    };
  }

  private async uploadChunk(
    uploadId: string,
    data: Buffer,
    contentRange: string
  ): Promise<IResponse> {
    const session = this.uploadSessions.get(uploadId);
    if (!session) {
      return {
        status: 404,
        headers: {},
        body: this.createError('BLOB_UPLOAD_INVALID', 'Upload session not found'),
      };
    }

    session.chunks.push(data);
    session.totalSize += data.length;
    session.lastActivity = new Date();

    return {
      status: 202,
      headers: {
        'Location': `${this.basePath}/v2/${session.repository}/blobs/uploads/${uploadId}`,
        'Range': `0-${session.totalSize - 1}`,
        'Docker-Upload-UUID': uploadId,
      },
      body: null,
    };
  }

  private async completeUpload(
    uploadId: string,
    digest: string,
    finalData?: Buffer
  ): Promise<IResponse> {
    const session = this.uploadSessions.get(uploadId);
    if (!session) {
      return {
        status: 404,
        headers: {},
        body: this.createError('BLOB_UPLOAD_INVALID', 'Upload session not found'),
      };
    }

    const chunks = [...session.chunks];
    if (finalData) chunks.push(finalData);
    const blobData = Buffer.concat(chunks);

    // Verify digest
    const calculatedDigest = await this.calculateDigest(blobData);
    if (calculatedDigest !== digest) {
      return {
        status: 400,
        headers: {},
        body: this.createError('DIGEST_INVALID', 'Digest mismatch'),
      };
    }

    await this.storage.putOciBlob(digest, blobData);
    this.uploadSessions.delete(uploadId);

    return {
      status: 201,
      headers: {
        'Location': `${this.basePath}/v2/${session.repository}/blobs/${digest}`,
        'Docker-Content-Digest': digest,
      },
      body: null,
    };
  }

  private async getUploadStatus(uploadId: string): Promise<IResponse> {
    const session = this.uploadSessions.get(uploadId);
    if (!session) {
      return {
        status: 404,
        headers: {},
        body: this.createError('BLOB_UPLOAD_INVALID', 'Upload session not found'),
      };
    }

    return {
      status: 204,
      headers: {
        'Location': `${this.basePath}/v2/${session.repository}/blobs/uploads/${uploadId}`,
        'Range': session.totalSize > 0 ? `0-${session.totalSize - 1}` : '0-0',
        'Docker-Upload-UUID': uploadId,
      },
      body: null,
    };
  }

  private async handleTagsList(
    repository: string,
    token: IAuthToken | null,
    query: Record<string, string>
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return this.createUnauthorizedResponse(repository, 'pull');
    }

    const tags = await this.getTagsData(repository);
    const tagNames = Object.keys(tags);

    const response: ITagList = {
      name: repository,
      tags: tagNames,
    };

    return {
      status: 200,
      headers: { 'Content-Type': 'application/json' },
      body: response,
    };
  }

  private async handleReferrers(
    repository: string,
    digest: string,
    token: IAuthToken | null,
    query: Record<string, string>
  ): Promise<IResponse> {
    if (!await this.checkPermission(token, repository, 'pull')) {
      return this.createUnauthorizedResponse(repository, 'pull');
    }

    const response: IReferrersResponse = {
      schemaVersion: 2,
      mediaType: 'application/vnd.oci.image.index.v1+json',
      manifests: [],
    };

    return {
      status: 200,
      headers: { 'Content-Type': 'application/json' },
      body: response,
    };
  }

  // ========================================================================
  // HELPER METHODS
  // ========================================================================

  private async getTagsData(repository: string): Promise<Record<string, string>> {
    const path = `oci/tags/${repository}/tags.json`;
    const data = await this.storage.getObject(path);
    return data ? JSON.parse(data.toString('utf-8')) : {};
  }

  private async putTagsData(repository: string, tags: Record<string, string>): Promise<void> {
    const path = `oci/tags/${repository}/tags.json`;
    const data = Buffer.from(JSON.stringify(tags, null, 2), 'utf-8');
    await this.storage.putObject(path, data);
  }

  private generateUploadId(): string {
    return `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
  }

  private async calculateDigest(data: Buffer): Promise<string> {
    const crypto = await import('crypto');
    const hash = crypto.createHash('sha256').update(data).digest('hex');
    return `sha256:${hash}`;
  }

  private createError(code: string, message: string, detail?: any): IRegistryError {
    return {
      errors: [{ code, message, detail }],
    };
  }

  /**
   * Create an unauthorized response with proper WWW-Authenticate header.
   * Per OCI Distribution Spec, 401 responses MUST include WWW-Authenticate header.
   */
  private createUnauthorizedResponse(repository: string, action: string): IResponse {
    return {
      status: 401,
      headers: {
        'WWW-Authenticate': `Bearer realm="${this.basePath}/v2/token",service="registry",scope="repository:${repository}:${action}"`,
      },
      body: this.createError('DENIED', 'Insufficient permissions'),
    };
  }

  /**
   * Create an unauthorized HEAD response (no body per HTTP spec).
   */
  private createUnauthorizedHeadResponse(repository: string, action: string): IResponse {
    return {
      status: 401,
      headers: {
        'WWW-Authenticate': `Bearer realm="${this.basePath}/v2/token",service="registry",scope="repository:${repository}:${action}"`,
      },
      body: null,
    };
  }

  private startUploadSessionCleanup(): void {
    this.cleanupInterval = setInterval(() => {
      const now = new Date();
      const maxAge = 60 * 60 * 1000; // 1 hour

      for (const [uploadId, session] of this.uploadSessions.entries()) {
        if (now.getTime() - session.lastActivity.getTime() > maxAge) {
          this.uploadSessions.delete(uploadId);
        }
      }
    }, 10 * 60 * 1000);
  }

  public destroy(): void {
    if (this.cleanupInterval) {
      clearInterval(this.cleanupInterval);
      this.cleanupInterval = undefined;
    }
  }
}