import { Body, Controller, Get, Param, Post, Put, Query, Res } from "@nestjs/common";
import { ApiOperation, ApiResponse } from "@nestjs/swagger";
import { FastifyReply } from "fastify";

import { CreateChatSessionDto } from "./DTO/create-chat-session.dto";
import { SendMessageDto } from "./DTO/send-message.dto";
import { SessionIdParamDto } from "./DTO/session-id.param.dto";
import { ChatbotService } from "./providers/chatbot.service";
import { AuthGuards } from "../../common/decorators/auth-guard.decorator";
import { UserDec } from "../../common/decorators/user.decorator";
import { PaginationDto } from "../../common/DTO/pagination.dto";

@Controller("chatbot")
@AuthGuards()
export class ChatbotController {
  constructor(private chatbotService: ChatbotService) {}

  @Post("sessions")
  @ApiOperation({ summary: "Create a new chat session" })
  @ApiResponse({ status: 201, description: "Chat session created successfully" })
  createSession(@UserDec("id") userId: string, @Body() createDto: CreateChatSessionDto) {
    return this.chatbotService.createChatSession(userId, createDto);
  }

  @Get("sessions")
  @ApiOperation({ summary: "Get user's chat sessions" })
  @ApiResponse({ status: 200, description: "Chat sessions retrieved successfully" })
  getUserSessions(@UserDec("id") userId: string, @Query() queryDto: PaginationDto) {
    return this.chatbotService.getUserChatSessions(userId, queryDto.limit);
  }

  @Get("sessions/:sessionId")
  @ApiOperation({ summary: "Get a specific chat session with messages" })
  @ApiResponse({ status: 200, description: "Chat session retrieved successfully" })
  getSession(@UserDec("id") userId: string, @Param() param: SessionIdParamDto) {
    return this.chatbotService.getChatSession(param.sessionId, userId);
  }

  @Post("messages")
  @ApiOperation({ summary: "Send a message in a chat session (Enhanced with LangChain + Fallback)" })
  @ApiResponse({ status: 201, description: "Message sent successfully with enhanced AI" })
  sendMessage(@UserDec("id") userId: string, @Body() sendDto: SendMessageDto) {
    return this.chatbotService.sendMessage(userId, sendDto);
  }

  @Post("messages/stream")
  @ApiOperation({ summary: "Send a message and get streaming response (Enhanced with LangChain + Fallback)" })
  @ApiResponse({ status: 200, description: "Enhanced streaming response initiated" })
  async sendMessageStream(@UserDec("id") userId: string, @Body() sendDto: SendMessageDto, @Res() res: FastifyReply): Promise<void> {
    try {
      // Now uses LangChain by default with automatic Gemini fallback
      const { userMessage, streamGenerator } = await this.chatbotService.sendMessageStream(userId, sendDto);

      // Set headers for Server-Sent Events
      res.header("Content-Type", "text/event-stream");
      res.header("Cache-Control", "no-cache");
      res.header("Connection", "keep-alive");
      res.header("Access-Control-Allow-Origin", "*");

      // Send initial user message
      res.raw.write(`data: ${JSON.stringify({ type: "user_message", data: userMessage, enhanced: true })}\n\n`);

      // Start streaming bot response
      res.raw.write(`data: ${JSON.stringify({ type: "bot_response_start", provider: "enhanced" })}\n\n`);

      const stream = await streamGenerator();
      for await (const chunk of stream) {
        if (chunk) {
          res.raw.write(`data: ${JSON.stringify({ type: "bot_response_chunk", data: chunk })}\n\n`);
        }
      }

      // End streaming
      res.raw.write(`data: ${JSON.stringify({ type: "bot_response_end" })}\n\n`);
      res.raw.end();
    } catch (error) {
      console.error(error);
      res.raw.write(
        `data: ${JSON.stringify({ type: "error", data: "خطا در تولید پاسخ هوشمند. LangChain با خطا مواجه شد و به Gemini بازگشت ⚠️" })}\n\n`,
      );
      res.raw.end();
    }
  }

  @Post("training/refresh")
  @ApiOperation({ summary: "Refresh LangChain training data from database" })
  @ApiResponse({ status: 200, description: "Training data refreshed successfully" })
  refreshTrainingData(@UserDec("id") _userId: string) {
    return this.chatbotService.refreshLangChainData();
  }

  @Put("sessions/:sessionId/close")
  @ApiOperation({ summary: "Close a chat session" })
  @ApiResponse({ status: 200, description: "Chat session closed successfully" })
  closeSession(@UserDec("id") userId: string, @Param() param: SessionIdParamDto) {
    return this.chatbotService.closeChatSession(param.sessionId, userId);
  }

  @Put("sessions/:sessionId/messages/read")
  @ApiOperation({ summary: "Mark messages as read" })
  @ApiResponse({ status: 200, description: "Messages marked as read successfully" })
  markMessagesAsRead(@UserDec("id") userId: string, @Param() param: SessionIdParamDto, @Body() body: { messageIds: string[] }) {
    return this.chatbotService.markMessagesAsRead(param.sessionId, userId, body.messageIds);
  }

  // @Post("messages/langchain")
  // @ApiOperation({ summary: "Send a message using LangChain with enhanced RAG capabilities" })
  // @ApiResponse({ status: 201, description: "Message sent successfully with LangChain", type: ChatMessageResponseDto })
  // sendMessageWithLangChain(@UserDec("id") userId: string, @Body() sendDto: SendMessageDto): Promise<ChatMessageResponseDto> {
  //   return this.chatbotService.sendMessageWithLangChain(userId, sendDto);
  // }

  // @Post("messages/langchain/stream")
  // @ApiOperation({ summary: "Send a message and get streaming response using LangChain" })
  // @ApiResponse({ status: 200, description: "Streaming response initiated with LangChain" })
  // async sendMessageStreamWithLangChain(@UserDec("id") userId: string, @Body() sendDto: SendMessageDto, @Res() res: FastifyReply): Promise<void> {
  //   try {
  //     const { userMessage, streamGenerator } = await this.chatbotService.sendMessageStreamWithLangChain(userId, sendDto);

  //     // Set headers for Server-Sent Events
  //     res.header("Content-Type", "text/event-stream");
  //     res.header("Cache-Control", "no-cache");
  //     res.header("Connection", "keep-alive");
  //     res.header("Access-Control-Allow-Origin", "*");

  //     // Send initial user message
  //     res.raw.write(`data: ${JSON.stringify({ type: "user_message", data: userMessage })}\n\n`);

  //     // Start streaming bot response
  //     res.raw.write(`data: ${JSON.stringify({ type: "bot_response_start", provider: "langchain" })}\n\n`);

  //     const stream = await streamGenerator();
  //     for await (const chunk of stream) {
  //       if (chunk) {
  //         res.raw.write(`data: ${JSON.stringify({ type: "bot_response_chunk", data: chunk })}\n\n`);
  //       }
  //     }

  //     // End streaming
  //     res.raw.write(`data: ${JSON.stringify({ type: "bot_response_end" })}\n\n`);
  //     res.raw.end();
  //   } catch (error) {
  //     console.error(error);
  //     res.raw.write(`data: ${JSON.stringify({ type: "error", data: "خطا در تولید پاسخ با LangChain. لطفاً دوباره تلاش کنید. ⚠️" })}\n\n`);
  //     res.raw.end();
  //   }
  // }
}