import "server-only";

/**
 * 本地千问模型 Provider
 * 支持千问2.5-VL-3B-Instruct 本地部署模型
 */

interface LocalQwenConfig {
  baseURL: string;
  apiKey: string;
  timeout?: number;
}

interface QwenMessage {
  role: string;
  content: Array<{ type: string; text?: string; image?: string }>;
}

interface QwenChatRequest {
  messages: QwenMessage[];
  max_new_tokens?: number;
  temperature?: number;
  top_p?: number;
  do_sample?: boolean;
}

interface QwenChatResponse {
  response: string;
  usage: {
    tokens: number;
  };
  processing_time: number;
}

/**
 * 创建本地千问模型客户端
 */
export function createLocalQwen(config: LocalQwenConfig) {
  const { baseURL, apiKey, timeout = 30000 } = config;

  // 使用 fetch API 的辅助函数
  async function fetchAPI(endpoint: string, options: RequestInit = {}) {
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), timeout);

    try {
      const response = await fetch(`${baseURL}${endpoint}`, {
        ...options,
        signal: controller.signal,
        headers: {
          "X-API-Key": apiKey,
          "Content-Type": "application/json",
          ...options.headers,
        },
      });

      clearTimeout(timeoutId);

      if (!response.ok) {
        const error = await response.json().catch(() => ({ detail: response.statusText }));
        throw new Error(error.detail || `HTTP ${response.status}`);
      }

      return await response.json();
    } finally {
      clearTimeout(timeoutId);
    }
  }

  /**
   * 转换 AI SDK 消息格式到千问格式
   */
  function convertMessages(messages: any[]): QwenMessage[] {
    return messages.map((msg) => {
      // 如果消息是字符串，转换为标准格式
      if (typeof msg.content === "string") {
        return {
          role: msg.role,
          content: [
            {
              type: "text",
              text: msg.content,
            },
          ],
        };
      }
      
      // 如果消息已经是数组格式，直接返回
      if (Array.isArray(msg.content)) {
        return {
          role: msg.role,
          content: msg.content,
        };
      }
      
      // 默认转换
      return {
        role: msg.role,
        content: [
          {
            type: "text",
            text: String(msg.content),
          },
        ],
      };
    });
  }

  /**
   * 生成聊天响应
   */
  async function chat(
    messages: any[],
    options: {
      maxTokens?: number;
      temperature?: number;
      topP?: number;
    } = {}
  ): Promise<string> {
    try {
      console.log("[LocalQwen] Sending chat request to:", baseURL);
      console.log("[LocalQwen] Messages count:", messages.length);

      const requestBody: QwenChatRequest = {
        messages: convertMessages(messages),
        max_new_tokens: options.maxTokens || 512,
        temperature: options.temperature || 0.7,
        top_p: options.topP || 0.9,
        do_sample: true,
      };

      const response = await fetchAPI("/chat/text", {
        method: "POST",
        body: JSON.stringify(requestBody),
      });

      console.log("[LocalQwen] Response received:", {
        tokens: response.usage.tokens,
        processingTime: response.processing_time,
      });

      return response.response;
    } catch (error: unknown) {
      console.error("[LocalQwen] Chat error:", error);
      const errorMsg = error instanceof Error ? error.message : String(error);
      throw new Error(`本地千问模型请求失败: ${errorMsg}`);
    }
  }

  /**
   * 创建流式响应（本地模型暂不支持流式，模拟流式效果）
   */
  async function* chatStream(
    messages: any[],
    options: {
      maxTokens?: number;
      temperature?: number;
      topP?: number;
    } = {}
  ): AsyncGenerator<string> {
    const response = await chat(messages, options);
    
    // 模拟流式输出，每次输出几个字符
    const chunkSize = 5;
    for (let i = 0; i < response.length; i += chunkSize) {
      yield response.slice(i, i + chunkSize);
      // 添加小延迟使流式效果更自然
      await new Promise((resolve) => setTimeout(resolve, 50));
    }
  }

  /**
   * 健康检查
   */
  async function healthCheck(): Promise<boolean> {
    try {
      const response = await fetchAPI("/health");
      return response.status === "healthy";
    } catch (error: unknown) {
      console.error("[LocalQwen] Health check failed:", error);
      return false;
    }
  }

  // 返回类似 AI SDK LanguageModel 的接口
  return {
    chat: (modelId: string) => ({
      doGenerate: async (options: any) => {
        const response = await chat(options.prompt, {
          maxTokens: options.maxTokens,
          temperature: options.temperature,
          topP: options.topP,
        });

        return {
          text: response,
          finishReason: "stop" as const,
          usage: {
            promptTokens: 0,
            completionTokens: 0,
          },
        };
      },
      doStream: async function* (options: any) {
        for await (const chunk of chatStream(options.prompt, {
          maxTokens: options.maxTokens,
          temperature: options.temperature,
          topP: options.topP,
        })) {
          yield {
            type: "text-delta" as const,
            textDelta: chunk,
          };
        }
        
        yield {
          type: "finish" as const,
          finishReason: "stop" as const,
          usage: {
            promptTokens: 0,
            completionTokens: 0,
          },
        };
      },
      modelId,
      provider: "local-qwen",
      specificationVersion: "v1" as const,
      defaultObjectGenerationMode: "json" as const,
    }),
    healthCheck,
  };
}