ddg-service.ts

import { generateVqdHash } from "./vm.ts";
import { userAgent } from "./utils.ts";
import { CONFIG, getHash, setHash } from "./utils.ts";
import { ChatMessage } from "./types.ts";
import { errorResponse } from "./response.ts";

export class DDGService {
  private hash: string | null = null;

  async getVqdHash(): Promise<string | Response> {
    // 优先使用环境变量中的hash
    const envHash = getHash();
    if (envHash) {
      return envHash;
    }

    try {
      const response = await fetch(CONFIG.DDG_STATUS_URL, {
        method: "GET",
        headers: {
          "User-Agent": userAgent,
          "x-vqd-accept": "1",
        },
      });

      if (!response.ok) {
        return errorResponse(`hash初始化请求失败: ${response.status}`, 502);
      }

      const hash = response.headers.get("x-vqd-hash-1");

      if (!hash) {
        return errorResponse(`未找到hash头部，状态码: ${response.status}`, 502);
      }

      let decryptedHash: string;
      try {
        decryptedHash = generateVqdHash(hash);
      } catch (decryptError) {
        return errorResponse(`hash解密失败: ${decryptError.message}`, 502);
      }

      if (!decryptedHash || decryptedHash.trim() === "") {
        return errorResponse(`hash解密结果为空`, 502);
      }
      setHash(decryptedHash);
      return decryptedHash;
    } catch (error) {
      return errorResponse(`获取hash失败: ${error.message}`, 502);
    }
  }

  // 内部发送消息方法，返回具体的错误信息
  private async sendMessage(
    model: string,
    messages: ChatMessage[]
  ): Promise<{
    success: boolean;
    response?: Response;
    error?: string;
    status?: number;
  }> {
    const hash = await this.getVqdHash();
    if (hash instanceof Response) {
      return { success: false, error: "获取hash失败", status: hash.status };
    }

    const payload = {
      model,
      messages,
      canUseTools: false,
      canUseApproxLocation: false,
    };

    try {
      const response = await fetch(CONFIG.DDG_CHAT_URL, {
        method: "POST",
        headers: {
          "User-Agent": userAgent,
          "x-vqd-hash-1": hash,
          "Content-Type": "application/json",
        },
        body: JSON.stringify(payload),
      });

      if (!response.ok) {
        const errorText = await response.text();
        return {
          success: false,
          error: `上游错误: ${response.status} - ${errorText}`,
          status: response.status,
        };
      }

      return { success: true, response };
    } catch (error) {
      return {
        success: false,
        error: `请求失败: ${error.message}`,
        status: 502,
      };
    }
  }

  // 带重试机制的发送消息方法 - 只对418错误重试
  async sendMessageWithRetry(
    model: string,
    messages: ChatMessage[],
    maxRetries = 1
  ): Promise<Response> {
    let lastResult: {
      success: boolean;
      response?: Response;
      error?: string;
      status?: number;
    } | null = null;

    for (let attempt = 0; attempt <= maxRetries; attempt++) {
      if (attempt > 0) {
        setHash(""); // 重置hash，强制重新获取
      }

      const result = await this.sendMessage(model, messages);

      if (result.success && result.response) {
        return result.response;
      }

      lastResult = result;

      // 只有418错误才重试
      if (result.status === 418 || 429) {
        continue;
      } else {
        // 其他错误直接返回，不重试
        break;
      }
    }

    // 返回最后一次的错误
    return errorResponse(
      lastResult?.error || "发送消息失败",
      lastResult?.status || 502
    );
  }
}