import 'dotenv/config';
import fs from 'fs';
import path from 'path';
import { createDeepAgent, FilesystemBackend, CompositeBackend } from "deepagents";
import { ChatOpenAI } from "@langchain/openai";
import { AIMessageChunk, ToolMessage } from "langchain";
import { HumanMessage } from "@langchain/core/messages";
import { ChatDeepSeek } from "@langchain/deepseek";
import config from '../../conf.json' with { type: 'json' };
import logger from '../../utils/logger.js';

// 密钥由 conf.json 统一提供；百度地图 skill 通过 env_get 读环境变量，此处桥接
process.env.TAVILY_API_KEY ??= config.agent.tavily?.apiKey;
process.env.BAIDU_MAP_AUTH_TOKEN ??= config.agent.baiduMap?.authToken;
import Prompts from "./prompts.js";
import {
  getEnvTool, webFetchTool, webSearchTool, getCalendarInfoTool,
  getLunarCalendarInfoTool, getYearHolidaysTool, getYearTermsTool, getLatLngTool,
  httpGetTool, httpPostTool, createEscortRecordQueryTool
} from "./tools/index.js";

export default class EscortAgent {
  // 历史消息字符数上限，超出时从头部丢弃完整轮次
  static MAX_HISTORY_CHARS = config.agent.maxHistoryChars || 40000;

  constructor() {
    this.messages = [];
  }

  clearMessages() {
    this.messages = [];
  }

  // 按字符数裁剪历史：只以 HumanMessage 为界从头部删除完整轮次，
  // 避免切断 AI(tool_calls) -> Tool 的链式结构；永远保留最新一轮
  _trimHistory() {
    const size = (msgs) => msgs.reduce((sum, m) => sum + (m.text?.length ?? 0), 0);
    if (size(this.messages) <= EscortAgent.MAX_HISTORY_CHARS) {
      return;
    }

    const starts = [];
    this.messages.forEach((m, i) => {
      if (HumanMessage.isInstance(m)) starts.push(i);
    });
    if (starts.length < 2) {
      return;
    }

    let cut = 0;
    for (let i = 0; i < starts.length - 1; i++) {
      cut = starts[i + 1];
      if (size(this.messages.slice(cut)) <= EscortAgent.MAX_HISTORY_CHARS) {
        break;
      }
    }
    this.messages = this.messages.slice(cut);
    logger.info(`History trimmed to ${this.messages.length} messages, ${size(this.messages)} chars`);
  }

  // msg: { ts: "2023-08-01 10:00:00", content: "你好" }
  async streamChat(userInfo, msgs, callback) {
    if (!msgs.length) {
      return;
    }

    msgs.forEach(msg => {
      if (msg.type === "clear") {
        this.messages = [];
        this.agent = null;
      } else {
        this.messages.push(new HumanMessage(`${msg.ts} - ${msg.content}`));
      }
    });

    if (this.messages.length === 0) {
      return;
    }

    this._trimHistory();

    // 在处理完 clear 消息后再生成 agent，确保清空后使用新实例
    const agent = this._genAgent(userInfo);
    const INTERESTING_NODES = new Set(["model_request", "tools"]);
    for await (const [namespace, mode, data] of await agent.stream(
      { messages: this.messages },
      {
        recursion_limit: 50,
        streamMode: ["updates", "messages", "custom"], subgraphs: true,
        configurable: {
          thread_id: msgs[0].userId || msgs[0].appId
        }
      })) {
      const isSubagent = namespace.some(s => s.startsWith("tools:"));
      const source = isSubagent ? "subagent" : "main";
      if (mode === "updates") {
        // Main agent updates (empty namespace)
        if (namespace.length === 0) {
          for (const [nodeName, data_] of Object.entries(data)) {
            if (!INTERESTING_NODES.has(nodeName)) continue;
            if (nodeName === "tools") {
              // 工具结果必须并入历史，否则下一轮会出现 tool_calls 缺少对应 tool 结果的断链
              for (const msg of data_.messages ?? []) {
                if (msg.type === "tool") {
                  this.messages.push(msg);
                  logger.info(`Tool complete: ${msg.name}, Result: ${String(msg.content).slice(0, 200)}`);
                }
              }
            } else if (nodeName === "model_request") {
              this.messages.push(...data_.messages);
            }
          }
        } else {
          // Subagent updates (non-empty namespace)
          for (const nodeName of Object.keys(data)) {
            if (!INTERESTING_NODES.has(nodeName)) continue;
            logger.info(`[${namespace[0]}] step: ${nodeName}`);
          }
        }
      } else if (mode === "messages") {
        const [message, metadata] = data;
        if (message.tool_call_chunks?.length) {
          continue;
        }
        if (metadata?.lcSource === "summarization" || metadata?.lc_source === "summarization") {
          continue;
        }
        if (AIMessageChunk.isInstance(message)) {
          if (message.text) {
            callback(source, "ai", message.text, message.id);
          }
          if (message.additional_kwargs.reasoning_content) {
            callback(source, "reasoning", message.additional_kwargs.reasoning_content, message.id);
          }
        }
        if (ToolMessage.isInstance(message) && message.text) {
          callback(source, "tool", message.text, message.id);
        }
      } else if (mode === "custom") {
        logger.info("custom: ", data);
      }
    }
  }

  _genAgent(userInfo) {
    const rootDir = process.cwd();
    const memoryFile = userInfo
      ? path.join(rootDir, "data", userInfo._id, "memories", "user_memory.txt")
      : null;

    // 会话中记忆文件被更新后重建 agent，使 systemPrompt 中的用户记忆保持最新
    if (this.agent && this._memoryMtime !== this._statMemory(memoryFile)) {
      this.agent = null;
    }
    if (this.agent) {
      return this.agent;
    }

    let backend = new FilesystemBackend({ rootDir });

    if (userInfo) {
      const userMemoryPath = path.join(rootDir, "data", userInfo._id, "memories");
      backend = new CompositeBackend(
        new FilesystemBackend({ rootDir }),
        {
          "/memories/": new FilesystemBackend({
            rootDir: userMemoryPath,
            virtualMode: true
          })
        },
      )
    }

    this.flashModel = new ChatDeepSeek({
      model: config.agent.deepseek.flashModel,
      apiKey: config.agent.deepseek.apiKey,
      temperature: 0.0
    });

    this._memoryMtime = this._statMemory(memoryFile);

    this.agent = createDeepAgent({
      name: "deep-agent",
      model: this.flashModel,
      systemPrompt: Prompts.buildSystemPrompt(userInfo),
      memory: ["./agent/escort/AGENTS.md"],
      backend,
      tools: [getEnvTool, webFetchTool, webSearchTool, getLatLngTool, httpGetTool, httpPostTool,
        getCalendarInfoTool, getLunarCalendarInfoTool, getYearHolidaysTool, getYearTermsTool,
        createEscortRecordQueryTool(userInfo)],
      skills: ["./agent/escort/skills/"],
    });

    return this.agent;
  }

  // 返回记忆文件 mtime，文件不存在时返回 null
  _statMemory(memoryFile) {
    if (!memoryFile) return null;
    try {
      return fs.statSync(memoryFile).mtimeMs;
    } catch {
      return null;
    }
  }
}