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

/**
 * RubyGems-specific upstream implementation.
 *
 * Handles:
 * - Compact Index format (/versions, /info/{gem}, /names)
 * - Gem file (.gem) downloading
 * - Gem spec fetching
 * - HTTP Range requests for incremental updates
 */
export class RubygemsUpstream extends BaseUpstream {
  protected readonly protocolName = 'rubygems';

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

  /**
   * Fetch the /versions file (master list of all gems).
   */
  public async fetchVersions(etag?: string): Promise<{ data: string; etag?: string } | null> {
    const headers: Record<string, string> = {
      'accept': 'text/plain',
    };

    if (etag) {
      headers['if-none-match'] = etag;
    }

    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: '*',
      resourceType: 'versions',
      path: '/versions',
      method: 'GET',
      headers,
      query: {},
    };

    const result = await this.fetch(context);

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

    let data: string;
    if (Buffer.isBuffer(result.body)) {
      data = result.body.toString('utf8');
    } else if (typeof result.body === 'string') {
      data = result.body;
    } else {
      return null;
    }

    return {
      data,
      etag: result.headers['etag'],
    };
  }

  /**
   * Fetch gem info file (/info/{gemname}).
   */
  public async fetchInfo(gemName: string): Promise<string | null> {
    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: gemName,
      resourceType: 'info',
      path: `/info/${gemName}`,
      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');
    }

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

  /**
   * Fetch the /names file (list of all gem names).
   */
  public async fetchNames(): Promise<string | null> {
    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: '*',
      resourceType: 'names',
      path: '/names',
      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');
    }

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

  /**
   * Fetch a gem file.
   */
  public async fetchGem(gemName: string, version: string): Promise<Buffer | null> {
    const path = `/gems/${gemName}-${version}.gem`;

    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: gemName,
      resourceType: 'gem',
      path,
      method: 'GET',
      headers: {
        'accept': 'application/octet-stream',
      },
      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 gem spec (quick spec).
   */
  public async fetchQuickSpec(gemName: string, version: string): Promise<Buffer | null> {
    const path = `/quick/Marshal.4.8/${gemName}-${version}.gemspec.rz`;

    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: gemName,
      resourceType: 'spec',
      path,
      method: 'GET',
      headers: {
        'accept': 'application/octet-stream',
      },
      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 gem versions JSON from API.
   */
  public async fetchVersionsJson(gemName: string): Promise<any[] | null> {
    const path = `/api/v1/versions/${gemName}.json`;

    const context: IUpstreamFetchContext = {
      protocol: 'rubygems',
      resource: gemName,
      resourceType: 'versions-json',
      path,
      method: 'GET',
      headers: {
        'accept': 'application/json',
      },
      query: {},
    };

    const result = await this.fetch(context);

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

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

    return Array.isArray(result.body) ? result.body : null;
  }

  /**
   * Override URL building for RubyGems-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}`;
  }
}