package controllers

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"shudao-chat-go/models"
	"shudao-chat-go/utils"

	beego "github.com/beego/beego/v2/server/web"
)

// ReportCompatController keeps the old AI chat frontend contract working
// while routing the request to the service that actually implements it.
type ReportCompatController struct {
	beego.Controller
}

type reportCompleteFlowRequest struct {
	UserQuestion           string `json:"user_question"`
	WindowSize             int    `json:"window_size"`
	NResults               int    `json:"n_results"`
	AIConversationID       uint64 `json:"ai_conversation_id"`
	IsNetworkSearchEnabled bool   `json:"is_network_search_enabled"`
	EnableOnlineModel      bool   `json:"enable_online_model"`
}

type updateAIMessageRequest struct {
	AIMessageID uint64 `json:"ai_message_id"`
	Content     string `json:"content"`
}

type stopSSERequest struct {
	AIConversationID uint64 `json:"ai_conversation_id"`
}

type streamChatAggregateResult struct {
	AIConversationID uint64
	AIMessageID      uint64
	Content          string
}

func (c *ReportCompatController) CompleteFlow() {
	c.setSSEHeaders()

	var requestData reportCompleteFlowRequest
	if err := json.Unmarshal(c.Ctx.Input.RequestBody, &requestData); err != nil {
		c.writeSSEJSON(map[string]interface{}{
			"type":    "online_error",
			"message": fmt.Sprintf("请求参数解析失败: %s", err.Error()),
		})
		c.writeSSEJSON(map[string]interface{}{"type": "completed"})
		return
	}

	userQuestion := strings.TrimSpace(requestData.UserQuestion)
	if userQuestion == "" {
		c.writeSSEJSON(map[string]interface{}{
			"type":    "online_error",
			"message": "问题不能为空",
		})
		c.writeSSEJSON(map[string]interface{}{"type": "completed"})
		return
	}

	if c.shouldProxyToAIChat() {
		if err := c.proxyAIChatSSE("/report/complete-flow", c.Ctx.Input.RequestBody); err == nil {
			return
		} else {
			fmt.Printf("[report-compat] proxy to aichat failed, fallback to local stream: %v\n", err)
		}
	}

	result, err := c.callStreamChatWithDB(requestData)
	if err != nil {
		c.writeSSEJSON(map[string]interface{}{
			"type":               "online_error",
			"ai_conversation_id": result.AIConversationID,
			"ai_message_id":      result.AIMessageID,
			"message":            err.Error(),
		})
		c.writeSSEJSON(map[string]interface{}{
			"type":               "completed",
			"ai_conversation_id": result.AIConversationID,
			"ai_message_id":      result.AIMessageID,
		})
		return
	}

	c.writeSSEJSON(map[string]interface{}{
		"type":               "online_answer",
		"ai_conversation_id": result.AIConversationID,
		"ai_message_id":      result.AIMessageID,
		"content":            result.Content,
	})
	c.writeSSEJSON(map[string]interface{}{
		"type":               "completed",
		"ai_conversation_id": result.AIConversationID,
		"ai_message_id":      result.AIMessageID,
	})
}

func (c *ReportCompatController) UpdateAIMessage() {
	if c.shouldProxyToAIChat() {
		if err := c.proxyAIChatJSON("/report/update-ai-message", c.Ctx.Input.RequestBody); err == nil {
			return
		} else {
			fmt.Printf("[report-compat] proxy update-ai-message failed, fallback to local update: %v\n", err)
		}
	}

	var requestData updateAIMessageRequest
	if err := json.Unmarshal(c.Ctx.Input.RequestBody, &requestData); err != nil {
		c.Data["json"] = map[string]interface{}{
			"success": false,
			"message": fmt.Sprintf("请求参数解析失败: %s", err.Error()),
		}
		c.ServeJSON()
		return
	}

	if requestData.AIMessageID == 0 {
		c.Data["json"] = map[string]interface{}{
			"success": false,
			"message": "ai_message_id 不能为空",
		}
		c.ServeJSON()
		return
	}

	if err := models.DB.Model(&models.AIMessage{}).
		Where("id = ? AND is_deleted = ?", requestData.AIMessageID, 0).
		Update("content", requestData.Content).Error; err != nil {
		c.Data["json"] = map[string]interface{}{
			"success": false,
			"message": fmt.Sprintf("更新 AI 消息失败: %s", err.Error()),
		}
		c.ServeJSON()
		return
	}

	c.Data["json"] = map[string]interface{}{
		"success": true,
		"message": "AI 消息已更新",
	}
	c.ServeJSON()
}

func (c *ReportCompatController) StopSSE() {
	if c.shouldProxyToAIChat() {
		if err := c.proxyAIChatJSON("/sse/stop", c.Ctx.Input.RequestBody); err == nil {
			return
		} else {
			fmt.Printf("[report-compat] proxy sse/stop failed, fallback to local success response: %v\n", err)
		}
	}

	var requestData stopSSERequest
	_ = json.Unmarshal(c.Ctx.Input.RequestBody, &requestData)

	c.Data["json"] = map[string]interface{}{
		"success":            true,
		"message":            "已接收停止请求",
		"ai_conversation_id": requestData.AIConversationID,
	}
	c.ServeJSON()
}

func (c *ReportCompatController) setSSEHeaders() {
	c.Ctx.ResponseWriter.Header().Set("Content-Type", "text/event-stream; charset=utf-8")
	c.Ctx.ResponseWriter.Header().Set("Cache-Control", "no-cache")
	c.Ctx.ResponseWriter.Header().Set("Connection", "keep-alive")
	c.Ctx.ResponseWriter.Header().Set("Access-Control-Allow-Origin", "*")
	c.Ctx.ResponseWriter.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
	c.Ctx.ResponseWriter.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, Token, token")
}

func (c *ReportCompatController) writeSSEJSON(payload map[string]interface{}) {
	responseJSON, _ := json.Marshal(payload)
	fmt.Fprintf(c.Ctx.ResponseWriter, "data: %s\n\n", responseJSON)
	c.Ctx.ResponseWriter.Flush()
}

func (c *ReportCompatController) shouldProxyToAIChat() bool {
	token := c.getRequestToken()
	if token == "" {
		return false
	}

	if _, err := utils.VerifyLocalToken(token); err == nil {
		return false
	}

	return true
}

func (c *ReportCompatController) getRequestToken() string {
	for _, headerName := range []string{"token", "Token", "Authorization"} {
		headerValue := strings.TrimSpace(c.Ctx.Request.Header.Get(headerName))
		if headerValue == "" {
			continue
		}
		if headerName == "Authorization" && strings.HasPrefix(headerValue, "Bearer ") {
			return strings.TrimPrefix(headerValue, "Bearer ")
		}
		return headerValue
	}

	return ""
}

func (c *ReportCompatController) getAIChatBaseURL() string {
	baseURL, err := beego.AppConfig.String("aichat_api_url")
	if err != nil || strings.TrimSpace(baseURL) == "" {
		baseURL = "http://127.0.0.1:28002/api/v1"
	}

	return strings.TrimRight(baseURL, "/")
}

func (c *ReportCompatController) proxyAIChatSSE(path string, requestBody []byte) error {
	upstreamReq, err := http.NewRequest(
		http.MethodPost,
		c.getAIChatBaseURL()+path,
		bytes.NewBuffer(requestBody),
	)
	if err != nil {
		return fmt.Errorf("创建 aichat SSE 请求失败: %w", err)
	}

	upstreamReq.Header.Set("Content-Type", "application/json")
	c.forwardAuthHeaders(upstreamReq)

	client := &http.Client{Timeout: 10 * time.Minute}
	resp, err := client.Do(upstreamReq)
	if err != nil {
		return fmt.Errorf("调用 aichat SSE 失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		responseBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("aichat SSE 返回异常状态: %d %s", resp.StatusCode, strings.TrimSpace(string(responseBody)))
	}

	buffer := make([]byte, 4096)
	for {
		n, readErr := resp.Body.Read(buffer)
		if n > 0 {
			if _, err := c.Ctx.ResponseWriter.Write(buffer[:n]); err != nil {
				return fmt.Errorf("写入前端 SSE 响应失败: %w", err)
			}
			c.Ctx.ResponseWriter.Flush()
		}

		if readErr == io.EOF {
			return nil
		}
		if readErr != nil {
			return fmt.Errorf("读取 aichat SSE 响应失败: %w", readErr)
		}
	}
}

func (c *ReportCompatController) proxyAIChatJSON(path string, requestBody []byte) error {
	upstreamReq, err := http.NewRequest(
		http.MethodPost,
		c.getAIChatBaseURL()+path,
		bytes.NewBuffer(requestBody),
	)
	if err != nil {
		return fmt.Errorf("创建 aichat JSON 请求失败: %w", err)
	}

	upstreamReq.Header.Set("Content-Type", "application/json")
	c.forwardAuthHeaders(upstreamReq)

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(upstreamReq)
	if err != nil {
		return fmt.Errorf("调用 aichat JSON 接口失败: %w", err)
	}
	defer resp.Body.Close()

	responseBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("读取 aichat JSON 响应失败: %w", err)
	}

	c.Ctx.Output.SetStatus(resp.StatusCode)
	c.Ctx.Output.Header("Content-Type", resp.Header.Get("Content-Type"))
	_, _ = c.Ctx.ResponseWriter.Write(responseBody)
	return nil
}

func (c *ReportCompatController) callStreamChatWithDB(requestData reportCompleteFlowRequest) (streamChatAggregateResult, error) {
	upstreamBody := map[string]interface{}{
		"message":            requestData.UserQuestion,
		"ai_conversation_id": requestData.AIConversationID,
		"business_type":      0,
	}

	requestBody, err := json.Marshal(upstreamBody)
	if err != nil {
		return streamChatAggregateResult{}, fmt.Errorf("构建内部请求失败: %w", err)
	}

	httpPort, err := beego.AppConfig.Int("httpport")
	if err != nil || httpPort == 0 {
		httpPort = 22001
	}
	upstreamURL := fmt.Sprintf("http://127.0.0.1:%d/apiv1/stream/chat-with-db", httpPort)

	upstreamReq, err := http.NewRequest(http.MethodPost, upstreamURL, bytes.NewBuffer(requestBody))
	if err != nil {
		return streamChatAggregateResult{}, fmt.Errorf("创建内部请求失败: %w", err)
	}
	upstreamReq.Header.Set("Content-Type", "application/json")
	c.forwardAuthHeaders(upstreamReq)

	client := &http.Client{Timeout: 10 * time.Minute}
	resp, err := client.Do(upstreamReq)
	if err != nil {
		return streamChatAggregateResult{}, fmt.Errorf("调用聊天接口失败: %w", err)
	}
	defer resp.Body.Close()

	result, parseErr := parseStreamChatResponse(resp.Body)
	if resp.StatusCode != http.StatusOK {
		return result, fmt.Errorf("聊天接口返回异常状态: %d", resp.StatusCode)
	}
	if parseErr != nil {
		return result, parseErr
	}
	if strings.TrimSpace(result.Content) == "" {
		return result, fmt.Errorf("聊天接口未返回有效内容")
	}

	return result, nil
}

func (c *ReportCompatController) forwardAuthHeaders(req *http.Request) {
	for _, headerName := range []string{"Authorization", "Token", "token"} {
		if headerValue := strings.TrimSpace(c.Ctx.Request.Header.Get(headerName)); headerValue != "" {
			req.Header.Set(headerName, headerValue)
		}
	}
}

func parseStreamChatResponse(reader io.Reader) (streamChatAggregateResult, error) {
	scanner := bufio.NewScanner(reader)
	scanner.Buffer(make([]byte, 0, 64*1024), 10*1024*1024)

	var result streamChatAggregateResult
	var contentBuilder strings.Builder

	for scanner.Scan() {
		line := strings.TrimRight(scanner.Text(), "\r")
		if strings.TrimSpace(line) == "" {
			continue
		}

		if strings.HasPrefix(line, "data: ") {
			data := strings.TrimPrefix(line, "data: ")
			if data == "[DONE]" {
				break
			}

			var payload map[string]interface{}
			if err := json.Unmarshal([]byte(data), &payload); err == nil {
				if result.AIConversationID == 0 {
					result.AIConversationID = getUint64FromMap(payload, "ai_conversation_id")
				}
				if result.AIMessageID == 0 {
					result.AIMessageID = getUint64FromMap(payload, "ai_message_id")
				}
				if errorMessage, ok := payload["error"].(string); ok && strings.TrimSpace(errorMessage) != "" {
					result.Content = contentBuilder.String()
					return result, fmt.Errorf("%s", errorMessage)
				}
				if content, ok := payload["content"].(string); ok {
					contentBuilder.WriteString(strings.ReplaceAll(content, "\\n", "\n"))
				}
				continue
			}

			if errorMessage, ok := extractRawErrorMessage(data); ok {
				result.Content = contentBuilder.String()
				return result, fmt.Errorf("%s", errorMessage)
			}

			contentBuilder.WriteString(strings.ReplaceAll(data, "\\n", "\n"))
			continue
		}

		contentBuilder.WriteString(strings.ReplaceAll(line, "\\n", "\n"))
	}

	if err := scanner.Err(); err != nil {
		result.Content = contentBuilder.String()
		return result, fmt.Errorf("读取聊天流失败: %w", err)
	}

	result.Content = contentBuilder.String()
	return result, nil
}

func extractRawErrorMessage(data string) (string, bool) {
	if !strings.HasPrefix(data, "{\"error\":") {
		return "", false
	}

	errorMessage := strings.TrimPrefix(data, "{\"error\":")
	errorMessage = strings.TrimSuffix(errorMessage, "}")
	errorMessage = strings.TrimSpace(errorMessage)
	errorMessage = strings.Trim(errorMessage, "\"")
	if errorMessage == "" {
		return "", false
	}

	return errorMessage, true
}

func getUint64FromMap(data map[string]interface{}, key string) uint64 {
	rawValue, ok := data[key]
	if !ok {
		return 0
	}

	switch value := rawValue.(type) {
	case float64:
		return uint64(value)
	case int:
		return uint64(value)
	case int64:
		return uint64(value)
	case uint64:
		return value
	default:
		return 0
	}
}