package handler

import (
	"bufio"
	"bytes"
	"chatplus/core"
	"chatplus/core/types"
	"chatplus/store/model"
	"chatplus/store/vo"
	"chatplus/utils"
	"chatplus/utils/param"
	"chatplus/utils/resp"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
	"gorm.io/gorm"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"
	"unicode/utf8"
)

const ErrorMsg = "抱歉，AI 助手开小差了，请马上联系管理员去盘它。"

type ChatHandler struct {
	BaseHandler
	db *gorm.DB
}

func NewChatHandler(config *types.AppConfig,
	app *core.AppServer,
	db *gorm.DB) *ChatHandler {
	handler := ChatHandler{db: db}
	handler.app = app
	handler.config = config
	return &handler
}

// ChatHandle 处理聊天 WebSocket 请求
func (h *ChatHandler) ChatHandle(c *gin.Context) {
	ws, err := (&websocket.Upgrader{CheckOrigin: func(r *http.Request) bool { return true }}).Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		logger.Error(err)
		return
	}
	sessionId := c.Query("sessionId")
	roleId := param.GetInt(c, "roleId", 0)
	chatId := c.Query("chatId")
	chatModel := c.Query("model")
	session, ok := h.app.ChatSession[sessionId]
	if !ok {
		logger.Info("用户未登录")
		c.Abort()
		return
	}

	// use old chat data override the chat model and role ID
	var chat model.ChatItem
	res := h.db.Where("chat_id=?", chatId).First(&chat)
	if res.Error == nil {
		chatModel = chat.Model
		roleId = int(chat.RoleId)
	}

	session.ChatId = chatId
	session.Model = chatModel
	logger.Infof("New websocket connected, IP: %s, Username: %s", c.Request.RemoteAddr, session.Username)
	client := core.NewWsClient(ws)
	var chatRole model.ChatRole
	res = h.db.First(&chatRole, roleId)
	if res.Error != nil || !chatRole.Enable {
		replyMessage(client, "当前聊天角色不存在或者未启用！！！")
		c.Abort()
		return
	}

	// 保存会话连接
	h.app.ChatClients[chatId] = client
	go func() {
		for {
			_, message, err := client.Receive()
			if err != nil {
				logger.Error(err)
				client.Close()
				delete(h.app.ChatClients, chatId)
				delete(h.app.ReqCancelFunc, chatId)
				return
			}
			logger.Info("Receive a message: ", string(message))
			//replyMessage(client, "这是一条测试消息！")
			ctx, cancel := context.WithCancel(context.Background())
			h.app.ReqCancelFunc[chatId] = cancel
			// 回复消息
			err = h.sendMessage(ctx, session, chatRole, string(message), client)
			if err != nil {
				logger.Error(err)
			} else {
				replyChunkMessage(client, types.WsMessage{Type: types.WsEnd})
				logger.Info("回答完毕: " + string(message))
			}

		}
	}()
}

// 将消息发送给 ChatGPT 并获取结果，通过 WebSocket 推送到客户端
func (h *ChatHandler) sendMessage(ctx context.Context, session types.ChatSession, role model.ChatRole, prompt string, ws core.Client) error {
	promptCreatedAt := time.Now() // 记录提问时间

	var user model.User
	res := h.db.Model(&model.User{}).First(&user, session.UserId)
	if res.Error != nil {
		replyMessage(ws, "非法用户，请联系管理员！")
		return res.Error
	}
	var userVo vo.User
	err := utils.CopyObject(user, &userVo)
	userVo.Id = user.Id
	if err != nil {
		return errors.New("User 对象转换失败，" + err.Error())
	}

	if userVo.Status == false {
		replyMessage(ws, "您的账号已经被禁用，如果疑问，请联系管理员！")
		replyMessage(ws, "![](images/wx.png)")
		return nil
	}

	if userVo.Calls <= 0 {
		replyMessage(ws, "您的对话次数已经用尽，请联系管理员充值！")
		replyMessage(ws, "![](images/wx.png)")
		return nil
	}

	if userVo.ExpiredTime > 0 && userVo.ExpiredTime <= time.Now().Unix() {
		replyMessage(ws, "您的账号已经过期，请联系管理员！")
		replyMessage(ws, "![](images/wx.png)")
		return nil
	}
	var req = types.ApiRequest{
		Model:       session.Model,
		Temperature: userVo.ChatConfig.Temperature,
		MaxTokens:   userVo.ChatConfig.MaxTokens,
		Stream:      true,
	}

	// 加载聊天上下文
	var chatCtx []types.Message
	if userVo.ChatConfig.EnableContext {
		if v, ok := h.app.ChatContexts[session.ChatId]; ok {
			chatCtx = v
		} else {
			// 加载角色信息
			var messages []types.Message
			err := utils.JsonDecode(role.Context, &messages)
			if err == nil {
				chatCtx = messages
			}
			// TODO: 这里默认加载最近 4 条聊天记录作为上下文，后期应该做成可配置的
			var historyMessages []model.HistoryMessage
			res := h.db.Where("chat_id = ?", session.ChatId).Limit(4).Order("created_at desc").Find(&historyMessages)
			if res.Error == nil {
				for _, msg := range historyMessages {
					ms := types.Message{Role: "user", Content: msg.Content}
					if msg.Type == types.ReplyMsg {
						ms.Role = "assistant"
					}
					chatCtx = append(chatCtx, ms)
				}
			}
		}
		logger.Info("聊天上下文：", chatCtx)
	}
	req.Messages = append(chatCtx, types.Message{
		Role:    "user",
		Content: prompt,
	})
	var apiKey string
	response, err := h.doRequest(ctx, userVo, &apiKey, req)
	if err != nil {
		if strings.Contains(err.Error(), "context canceled") {
			logger.Info("用户取消了请求：", prompt)
			return nil
		} else {
			logger.Error(err)
		}

		replyMessage(ws, ErrorMsg)
		replyMessage(ws, "![](images/wx.png)")
		return err
	} else {
		defer response.Body.Close()
	}

	contentType := response.Header.Get("Content-Type")
	if strings.Contains(contentType, "text/event-stream") {
		replyCreatedAt := time.Now()
		// 循环读取 Chunk 消息
		var message = types.Message{}
		var contents = make([]string, 0)
		var responseBody = types.ApiResponse{}
		reader := bufio.NewReader(response.Body)
		for {
			line, err := reader.ReadString('\n')
			if err != nil {
				if strings.Contains(err.Error(), "context canceled") {
					logger.Info("用户取消了请求：", prompt)
				} else {
					logger.Error(err)
				}
				break
			}
			if !strings.Contains(line, "data:") {
				continue
			}

			err = json.Unmarshal([]byte(line[6:]), &responseBody)
			if err != nil { // 数据解析出错
				logger.Error(err, line)
				replyMessage(ws, ErrorMsg)
				replyMessage(ws, "![](images/wx.png)")
				break
			}

			// 初始化 role
			if responseBody.Choices[0].Delta.Role != "" && message.Role == "" {
				message.Role = responseBody.Choices[0].Delta.Role
				replyChunkMessage(ws, types.WsMessage{Type: types.WsStart})
				continue
			} else if responseBody.Choices[0].FinishReason != "" {
				break // 输出完成或者输出中断了
			} else {
				content := responseBody.Choices[0].Delta.Content
				contents = append(contents, content)
				replyChunkMessage(ws, types.WsMessage{
					Type:    types.WsMiddle,
					Content: responseBody.Choices[0].Delta.Content,
				})
			}
		} // end for

		// 消息发送成功
		if len(contents) > 0 {
			// 更新用户的对话次数
			res := h.db.Model(&user).UpdateColumn("calls", gorm.Expr("calls - ?", 1))
			if res.Error != nil {
				return res.Error
			}

			if message.Role == "" {
				message.Role = "assistant"
			}
			message.Content = strings.Join(contents, "")
			useMsg := types.Message{Role: "user", Content: prompt}

			// 更新上下文消息
			if userVo.ChatConfig.EnableContext {
				chatCtx = append(chatCtx, useMsg)  // 提问消息
				chatCtx = append(chatCtx, message) // 回复消息
				h.app.ChatContexts[session.ChatId] = chatCtx
			}

			// 追加聊天记录
			if userVo.ChatConfig.EnableHistory {
				// for prompt
				token, err := utils.CalcTokens(prompt, req.Model)
				if err != nil {
					logger.Error(err)
				}
				historyUserMsg := model.HistoryMessage{
					UserId:  userVo.Id,
					ChatId:  session.ChatId,
					RoleId:  role.Id,
					Type:    types.PromptMsg,
					Icon:    user.Avatar,
					Content: prompt,
					Tokens:  token,
				}
				historyUserMsg.CreatedAt = promptCreatedAt
				historyUserMsg.UpdatedAt = promptCreatedAt
				res := h.db.Save(&historyUserMsg)
				if res.Error != nil {
					logger.Error("failed to save prompt history message: ", res.Error)
				}

				// for reply
				token, err = utils.CalcTokens(message.Content, req.Model)
				if err != nil {
					logger.Error(err)
				}
				historyReplyMsg := model.HistoryMessage{
					UserId:  userVo.Id,
					ChatId:  session.ChatId,
					RoleId:  role.Id,
					Type:    types.ReplyMsg,
					Icon:    role.Icon,
					Content: message.Content,
					Tokens:  token,
				}
				historyReplyMsg.CreatedAt = replyCreatedAt
				historyReplyMsg.UpdatedAt = replyCreatedAt
				res = h.db.Create(&historyReplyMsg)
				if res.Error != nil {
					logger.Error("failed to save reply history message: ", res.Error)
				}
			}

			// 保存当前会话
			var chatItem model.ChatItem
			res = h.db.Where("chat_id = ?", session.ChatId).First(&chatItem)
			if res.Error != nil {
				chatItem.ChatId = session.ChatId
				chatItem.UserId = session.UserId
				chatItem.RoleId = role.Id
				chatItem.Model = session.Model
				if utf8.RuneCountInString(prompt) > 30 {
					chatItem.Title = string([]rune(prompt)[:30]) + "..."
				} else {
					chatItem.Title = prompt
				}
				h.db.Create(&chatItem)
			}
		}
	} else {
		body, err := io.ReadAll(response.Body)
		if err != nil {
			return fmt.Errorf("error with reading response: %v", err)
		}
		var res types.ApiError
		err = json.Unmarshal(body, &res)
		if err != nil {
			return fmt.Errorf("error with decode response: %v", err)
		}

		// OpenAI API 调用异常处理
		// TODO: 是否考虑重发消息？
		if strings.Contains(res.Error.Message, "This key is associated with a deactivated account") {
			replyMessage(ws, "请求 OpenAI API 失败：API KEY 所关联的账户被禁用。")
			// 移除当前 API key
			h.db.Where("value = ?", apiKey).Delete(&model.ApiKey{})
		} else if strings.Contains(res.Error.Message, "You exceeded your current quota") {
			replyMessage(ws, "请求 OpenAI API 失败：API KEY 触发并发限制，请稍后再试。")
		} else if strings.Contains(res.Error.Message, "This model's maximum context length") {
			replyMessage(ws, "当前会话上下文长度超出限制，已为您删减会话上下文！")
			// 只保留最近的三条记录
			chatContext := h.app.ChatContexts[session.ChatId]
			chatContext = chatContext[len(chatContext)-3:]
			h.app.ChatContexts[session.ChatId] = chatContext
			return h.sendMessage(ctx, session, role, prompt, ws)
		} else {
			replyMessage(ws, "请求 OpenAI API 失败："+res.Error.Message)
		}
	}

	return nil
}

// 发送请求到 OpenAI 服务器
// useOwnApiKey: 是否使用了用户自己的 API KEY
func (h *ChatHandler) doRequest(ctx context.Context, user vo.User, apiKey *string, req types.ApiRequest) (*http.Response, error) {
	var client *http.Client
	requestBody, err := json.Marshal(req)
	if err != nil {
		return nil, err
	}
	// 创建 HttpClient 请求对象
	request, err := http.NewRequest(http.MethodPost, h.app.ChatConfig.ApiURL, bytes.NewBuffer(requestBody))
	if err != nil {
		return nil, err
	}

	request = request.WithContext(ctx)
	request.Header.Add("Content-Type", "application/json")

	proxyURL := h.config.ProxyURL
	if proxyURL == "" {
		client = &http.Client{}
	} else { // 使用代理
		uri := url.URL{}
		proxy, _ := uri.Parse(proxyURL)
		client = &http.Client{
			Transport: &http.Transport{
				Proxy: http.ProxyURL(proxy),
			},
		}
	}
	// 查询当前用户是否导入了自己的 API KEY
	if user.ChatConfig.ApiKey != "" {
		logger.Info("使用用户自己的 API KEY: ", user.ChatConfig.ApiKey)
		*apiKey = user.ChatConfig.ApiKey
	} else { // 获取系统的 API KEY
		var key model.ApiKey
		res := h.db.Where("user_id = ?", 0).Order("last_used_at ASC").First(&key)
		if res.Error != nil {
			return nil, errors.New("no available key, please import key")
		}
		*apiKey = key.Value
		// 更新 API KEY 的最后使用时间
		h.db.Model(&key).UpdateColumn("last_used_at", time.Now().Unix())
	}

	logger.Infof("Sending OpenAI request, KEY: %s, PROXY: %s, Model: %s", *apiKey, proxyURL, req.Model)
	request.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiKey))
	return client.Do(request)
}

// 回复客户片段端消息
func replyChunkMessage(client core.Client, message types.WsMessage) {
	msg, err := json.Marshal(message)
	if err != nil {
		logger.Errorf("Error for decoding json data: %v", err.Error())
		return
	}
	err = client.(*core.WsClient).Send(msg)
	if err != nil {
		logger.Errorf("Error for reply message: %v", err.Error())
	}
}

// 回复客户端一条完整的消息
func replyMessage(ws core.Client, message string) {
	replyChunkMessage(ws, types.WsMessage{Type: types.WsStart})
	replyChunkMessage(ws, types.WsMessage{Type: types.WsMiddle, Content: message})
	replyChunkMessage(ws, types.WsMessage{Type: types.WsEnd})
}

// Tokens 统计 token 数量
func (h *ChatHandler) Tokens(c *gin.Context) {
	text := c.Query("text")
	md := c.Query("model")
	tokens, err := utils.CalcTokens(text, md)
	if err != nil {
		resp.ERROR(c, err.Error())
		return
	}

	resp.SUCCESS(c, tokens)
}

// StopGenerate 停止生成
func (h *ChatHandler) StopGenerate(c *gin.Context) {
	chatId := c.Query("chat_id")
	if cancel, ok := h.app.ReqCancelFunc[chatId]; ok {
		cancel()
		delete(h.app.ReqCancelFunc, chatId)
	}
	resp.SUCCESS(c, types.OkMsg)
}