package service

import (
	"context"
	"strings"

	"github.com/topfans/backend/pkg/logger"
	"github.com/topfans/backend/services/aiChatService/model"
	"github.com/topfans/backend/services/aiChatService/repository"
	"go.uber.org/zap"
)

// MemoryService 记忆服务
type MemoryService struct {
	shortTermRepo repository.ShortTermMemoryRepository
	longTermRepo  repository.LongTermMemoryRepository
}

// NewMemoryService 创建记忆服务
func NewMemoryService(shortTermRepo repository.ShortTermMemoryRepository, longTermRepo repository.LongTermMemoryRepository) *MemoryService {
	return &MemoryService{
		shortTermRepo: shortTermRepo,
		longTermRepo:  longTermRepo,
	}
}

// SaveContext 保存短期上下文
func (s *MemoryService) SaveContext(ctx context.Context, sessionID string, messages []model.Message, personaID string) error {
	return s.shortTermRepo.SaveContext(ctx, sessionID, messages, personaID)
}

// GetContext 获取短期上下文
func (s *MemoryService) GetContext(ctx context.Context, sessionID string) ([]model.Message, error) {
	return s.shortTermRepo.GetContext(ctx, sessionID)
}

// RecallMemories 召回相关记忆
func (s *MemoryService) RecallMemories(ctx context.Context, userID int64, userInput string, limit int) (string, error) {
	// 从用户输入提取关键词
	keywords := extractKeywords(userInput)

	// 查询长期记忆
	memories, err := s.longTermRepo.GetMemories(ctx, userID, keywords, limit)
	if err != nil {
		return "", err
	}

	if len(memories) == 0 {
		return "", nil
	}

	// 组装记忆文本
	var builder strings.Builder
	builder.WriteString("# 用户核心记忆\n")
	for _, m := range memories {
		builder.WriteString("- ")
		builder.WriteString(m.Content)
		builder.WriteString("\n")
	}

	return builder.String(), nil
}

// ExtractMemory 提取记忆（每5轮对话触发一次）
func (s *MemoryService) ExtractMemory(ctx context.Context, userID int64, recentMessages []model.Message) error {
	// 从最近的用户消息中提取关键词
	var userMessages []string
	for i := len(recentMessages) - 1; i >= 0 && len(userMessages) < 5; i-- {
		if recentMessages[i].Role == "user" {
			userMessages = append(userMessages, recentMessages[i].Content)
		}
	}

	if len(userMessages) == 0 {
		return nil
	}

	// 简单关键词提取
	keywords := extractKeywordsFromMessages(userMessages)

	// 生成记忆摘要
	content := summarizeMessages(userMessages)
	if content == "" {
		return nil
	}

	// 保存到长期记忆
	memory := &model.UserMemory{
		UserID:   userID,
		Content:  content,
		Keywords: keywords,
		Weight:   50,
	}

	return s.longTermRepo.SaveMemory(ctx, memory)
}

// GetUserMemories 获取用户所有长期记忆
func (s *MemoryService) GetUserMemories(ctx context.Context, userID int64) ([]model.UserMemory, error) {
	return s.longTermRepo.GetMemoriesByUserID(ctx, userID)
}

// extractKeywords 从用户输入提取关键词
func extractKeywords(text string) []string {
	// 简单实现：按标点符号分割，检查长度大于2的词
	var keywords []string
	words := strings.FieldsFunc(text, func(r rune) bool {
		return r == ',' || r == '.' || r == '!' || r == '?' || r == '，' || r == '。' || r == '！' || r == '？' || r == ' ' || r == '\n'
	})

	for _, word := range words {
		word = strings.TrimSpace(word)
		if len(word) >= 2 {
			keywords = append(keywords, word)
		}
	}

	return keywords
}

// extractKeywordsFromMessages 从多条消息提取关键词
func extractKeywordsFromMessages(messages []string) []string {
	var allKeywords []string
	seen := make(map[string]bool)

	for _, msg := range messages {
		keywords := extractKeywords(msg)
		for _, k := range keywords {
			if !seen[k] {
				seen[k] = true
				allKeywords = append(allKeywords, k)
			}
		}
	}

	// 只保留前5个关键词
	if len(allKeywords) > 5 {
		allKeywords = allKeywords[:5]
	}

	return allKeywords
}

// summarizeMessages 生成记忆摘要
func summarizeMessages(messages []string) string {
	if len(messages) == 0 {
		return ""
	}

	// 简单实现：拼接前3条消息的核心内容
	var summary strings.Builder
	count := 0
	for _, msg := range messages {
		if count >= 3 {
			break
		}
		// 截断过长的消息
		if len(msg) > 100 {
			msg = msg[:100] + "..."
		}
		summary.WriteString(msg)
		summary.WriteString("; ")
		count++
	}

	result := strings.TrimSpace(summary.String())
	if len(result) > 200 {
		result = result[:200] + "..."
	}

	return result
}

// FormatMemoriesForPrompt 将记忆格式化为 prompt 片段
func FormatMemoriesForPrompt(memories []model.UserMemory) string {
	if len(memories) == 0 {
		return ""
	}

	var builder strings.Builder
	builder.WriteString("# 用户核心记忆\n")
	for _, m := range memories {
		builder.WriteString("- ")
		builder.WriteString(m.Content)
		builder.WriteString("\n")
	}

	return builder.String()
}

// GetTurnCount 计算对话轮数
func GetTurnCount(messages []model.Message) int {
	turns := 0
	for i := 0; i < len(messages)-1; i += 2 {
		if i+1 < len(messages) && messages[i].Role == "user" && messages[i+1].Role == "assistant" {
			turns++
		}
	}
	return turns
}

// ShouldExtractMemory 判断是否应该触发记忆提取
func ShouldExtractMemory(messages []model.Message, triggerTurns int) bool {
	turns := GetTurnCount(messages)
	logger.Logger.Info("ShouldExtractMemory check",
		zap.Int("turns", turns),
		zap.Int("trigger_turns", triggerTurns),
		zap.Bool("should_extract", turns >= triggerTurns),
	)
	return turns >= triggerTurns
}