package model

import (
	"encoding/json"
	"time"
)

// MemoryPriority 记忆优先级
type MemoryPriority int

const (
	MemoryTemp      MemoryPriority = 0 // 临时记忆 (会话内)
	MemoryNormal    MemoryPriority = 1 // 普通记忆
	MemoryImportant MemoryPriority = 2 // 重要记忆
	MemoryCore      MemoryPriority = 3 // 核心记忆 (永远保留)
)

// String 返回优先级的中文描述
func (p MemoryPriority) String() string {
	switch p {
	case MemoryCore:
		return "核心"
	case MemoryImportant:
		return "重要"
	case MemoryNormal:
		return "普通"
	case MemoryTemp:
		return "临时"
	default:
		return "未知"
	}
}

// MemoryCategory 记忆分类
type MemoryCategory string

const (
	CategoryUserPreference MemoryCategory = "user_preference" // 用户偏好 (食物、颜色、习惯)
	CategoryPersonalInfo   MemoryCategory = "personal_info"   // 个人信息 (姓名、年龄、职业)
	CategoryConversation   MemoryCategory = "conversation"    // 对话摘要
	CategoryKnowledge      MemoryCategory = "knowledge"       // 知识性信息
	CategoryEvent          MemoryCategory = "event"           // 事件记录
	CategoryTask           MemoryCategory = "task"            // 任务/计划
	CategoryRelationship   MemoryCategory = "relationship"    // 关系信息

	// 向后兼容的旧分类别名
	CategoryPreference = CategoryUserPreference
	CategoryFact       = CategoryPersonalInfo
	CategoryHabit      = CategoryUserPreference
	CategoryOther      = CategoryKnowledge
)

// CategoryDisplayName 返回分类的中文显示名
func (c MemoryCategory) DisplayName() string {
	switch c {
	case CategoryUserPreference:
		return "用户偏好"
	case CategoryPersonalInfo:
		return "个人信息"
	case CategoryConversation:
		return "对话摘要"
	case CategoryKnowledge:
		return "知识信息"
	case CategoryEvent:
		return "事件记录"
	case CategoryTask:
		return "任务计划"
	case CategoryRelationship:
		return "关系情感"
	default:
		return "其他"
	}
}

// MemoryEntry 记忆条目
type MemoryEntry struct {
	ID          string         `json:"id" db:"id"`
	UserID      string         `json:"user_id" db:"user_id"`
	Content     string         `json:"content" db:"content"`
	Summary     string         `json:"summary" db:"summary"`       // 简短摘要
	Category    MemoryCategory `json:"category" db:"category"`
	Priority    MemoryPriority `json:"priority" db:"priority"`
	Importance  int            `json:"importance" db:"importance"`   // 重要程度 1-10
	Keywords    []string       `json:"keywords" db:"keywords"`       // 关键词标签
	SessionID   string         `json:"session_id" db:"session_id"`   // 来源会话
	Source      string         `json:"source" db:"source"`           // 来源 (conversation/thinking)
	Embedding   []float32      `json:"-" db:"embedding"`             // 向量 (pgvector)
	AccessCount int            `json:"access_count" db:"access_count"`
	LastAccess  time.Time      `json:"last_access" db:"last_access"`
	CreatedAt   time.Time      `json:"created_at" db:"created_at"`
	UpdatedAt   time.Time      `json:"updated_at" db:"updated_at"`   // 最后更新时间
	ExpiresAt   *time.Time     `json:"expires_at,omitempty" db:"expires_at"` // 临时记忆过期时间
}

// KeywordsJSON 将关键词序列化为 JSON 字符串（用于数据库存储）
func (e *MemoryEntry) KeywordsJSON() string {
	if len(e.Keywords) == 0 {
		return "[]"
	}
	data, _ := json.Marshal(e.Keywords)
	return string(data)
}

// ParseKeywords 从 JSON 字符串解析关键词
func ParseKeywords(raw string) []string {
	if raw == "" || raw == "[]" {
		return nil
	}
	var keywords []string
	if err := json.Unmarshal([]byte(raw), &keywords); err != nil {
		return nil
	}
	return keywords
}

// SimilarityScore 计算两个记忆条目的简单文本相似度（基于词汇重叠）
// 返回值 0.0 - 1.0
func (e *MemoryEntry) SimilarityScore(other *MemoryEntry) float64 {
	if e.Content == other.Content {
		return 1.0
	}

	// 基于关键词的重叠度
	if len(e.Keywords) > 0 && len(other.Keywords) > 0 {
		keywordSet := make(map[string]bool, len(e.Keywords))
		for _, k := range e.Keywords {
			keywordSet[k] = true
		}
		overlap := 0
		for _, k := range other.Keywords {
			if keywordSet[k] {
				overlap++
			}
		}
		keywordScore := float64(overlap) / float64(max(len(e.Keywords), len(other.Keywords)))
		if keywordScore > 0.6 {
			return keywordScore
		}
	}

	// 基于内容的字符级 Jaccard 相似度
	return jaccardSimilarity(e.Content, other.Content)
}

// jaccardSimilarity 计算两个字符串的 Jaccard 相似度
func jaccardSimilarity(a, b string) float64 {
	if a == b {
		return 1.0
	}
	if len(a) == 0 || len(b) == 0 {
		return 0.0
	}

	// 使用 bigram 分词
	bigramsA := make(map[string]int)
	runesA := []rune(a)
	for i := 0; i < len(runesA)-1; i++ {
		bigramsA[string(runesA[i:i+2])]++
	}

	bigramsB := make(map[string]int)
	runesB := []rune(b)
	for i := 0; i < len(runesB)-1; i++ {
		bigramsB[string(runesB[i:i+2])]++
	}

	intersection := 0
	for bg, countA := range bigramsA {
		if countB, ok := bigramsB[bg]; ok {
			intersection += min(countA, countB)
		}
	}

	union := 0
	allBigrams := make(map[string]bool)
	for bg := range bigramsA {
		allBigrams[bg] = true
	}
	for bg := range bigramsB {
		allBigrams[bg] = true
	}
	for bg := range allBigrams {
		union += max(bigramsA[bg], bigramsB[bg])
	}

	if union == 0 {
		return 0.0
	}
	return float64(intersection) / float64(union)
}

// MemoryQuery 记忆查询参数
type MemoryQuery struct {
	UserID     string
	Query      string         // 查询文本
	Category   MemoryCategory
	Priority   MemoryPriority
	MinImportance int         // 最低重要程度筛选
	Limit      int
	Offset     int
}