import * as plugins from '../plugins.js';
import { BaseUpstream } from '../upstream/classes.baseupstream.js';
import type {
  IProtocolUpstreamConfig,
  IUpstreamFetchContext,
  IUpstreamRegistryConfig,
} from '../upstream/interfaces.upstream.js';
import type { IMavenCoordinate } from './interfaces.maven.js';

/**
 * Maven-specific upstream implementation.
 *
 * Handles:
 * - Artifact fetching (JAR, POM, WAR, etc.)
 * - Metadata fetching (maven-metadata.xml)
 * - Checksum files (.md5, .sha1, .sha256, .sha512)
 * - SNAPSHOT version handling
 * - Content-addressable caching for release artifacts
 */
export class MavenUpstream extends BaseUpstream {
  protected readonly protocolName = 'maven';

  constructor(
    config: IProtocolUpstreamConfig,
    logger?: plugins.smartlog.Smartlog,
  ) {
    super(config, logger);
  }

  /**
   * Fetch an artifact from upstream registries.
   */
  public async fetchArtifact(
    groupId: string,
    artifactId: string,
    version: string,
    extension: string,
    classifier?: string,
  ): Promise<Buffer | null> {
    const path = this.buildArtifactPath(groupId, artifactId, version, extension, classifier);
    const resource = `${groupId}:${artifactId}`;

    const context: IUpstreamFetchContext = {
      protocol: 'maven',
      resource,
      resourceType: 'artifact',
      path,
      method: 'GET',
      headers: {},
      query: {},
    };

    const result = await this.fetch(context);

    if (!result || !result.success) {
      return null;
    }

    return Buffer.isBuffer(result.body) ? result.body : Buffer.from(result.body);
  }

  /**
   * Fetch maven-metadata.xml from upstream.
   */
  public async fetchMetadata(groupId: string, artifactId: string, version?: string): Promise<string | null> {
    const groupPath = groupId.replace(/\./g, '/');
    let path: string;

    if (version) {
      // Version-level metadata (for SNAPSHOTs)
      path = `/${groupPath}/${artifactId}/${version}/maven-metadata.xml`;
    } else {
      // Artifact-level metadata (lists all versions)
      path = `/${groupPath}/${artifactId}/maven-metadata.xml`;
    }

    const resource = `${groupId}:${artifactId}`;

    const context: IUpstreamFetchContext = {
      protocol: 'maven',
      resource,
      resourceType: 'metadata',
      path,
      method: 'GET',
      headers: {
        'accept': 'application/xml, text/xml',
      },
      query: {},
    };

    const result = await this.fetch(context);

    if (!result || !result.success) {
      return null;
    }

    if (Buffer.isBuffer(result.body)) {
      return result.body.toString('utf8');
    }

    return typeof result.body === 'string' ? result.body : null;
  }

  /**
   * Fetch a checksum file from upstream.
   */
  public async fetchChecksum(
    groupId: string,
    artifactId: string,
    version: string,
    extension: string,
    checksumType: 'md5' | 'sha1' | 'sha256' | 'sha512',
    classifier?: string,
  ): Promise<string | null> {
    const basePath = this.buildArtifactPath(groupId, artifactId, version, extension, classifier);
    const path = `${basePath}.${checksumType}`;
    const resource = `${groupId}:${artifactId}`;

    const context: IUpstreamFetchContext = {
      protocol: 'maven',
      resource,
      resourceType: 'checksum',
      path,
      method: 'GET',
      headers: {
        'accept': 'text/plain',
      },
      query: {},
    };

    const result = await this.fetch(context);

    if (!result || !result.success) {
      return null;
    }

    if (Buffer.isBuffer(result.body)) {
      return result.body.toString('utf8').trim();
    }

    return typeof result.body === 'string' ? result.body.trim() : null;
  }

  /**
   * Check if an artifact exists in upstream (HEAD request).
   */
  public async headArtifact(
    groupId: string,
    artifactId: string,
    version: string,
    extension: string,
    classifier?: string,
  ): Promise<{ exists: boolean; size?: number; lastModified?: string } | null> {
    const path = this.buildArtifactPath(groupId, artifactId, version, extension, classifier);
    const resource = `${groupId}:${artifactId}`;

    const context: IUpstreamFetchContext = {
      protocol: 'maven',
      resource,
      resourceType: 'artifact',
      path,
      method: 'HEAD',
      headers: {},
      query: {},
    };

    const result = await this.fetch(context);

    if (!result) {
      return null;
    }

    if (!result.success) {
      return { exists: false };
    }

    return {
      exists: true,
      size: result.headers['content-length'] ? parseInt(result.headers['content-length'], 10) : undefined,
      lastModified: result.headers['last-modified'],
    };
  }

  /**
   * Build the path for a Maven artifact.
   */
  private buildArtifactPath(
    groupId: string,
    artifactId: string,
    version: string,
    extension: string,
    classifier?: string,
  ): string {
    const groupPath = groupId.replace(/\./g, '/');
    let filename = `${artifactId}-${version}`;
    if (classifier) {
      filename += `-${classifier}`;
    }
    filename += `.${extension}`;

    return `/${groupPath}/${artifactId}/${version}/${filename}`;
  }

  /**
   * Override URL building for Maven-specific handling.
   */
  protected buildUpstreamUrl(
    upstream: IUpstreamRegistryConfig,
    context: IUpstreamFetchContext,
  ): string {
    let baseUrl = upstream.url;

    // Remove trailing slash
    if (baseUrl.endsWith('/')) {
      baseUrl = baseUrl.slice(0, -1);
    }

    return `${baseUrl}${context.path}`;
  }
}