package repository

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"github.com/lib/pq"
	"github.com/redis/go-redis/v9"
	"github.com/topfans/backend/services/aiChatService/model"
	"gorm.io/gorm"
)

// ShortTermMemoryRepository 短期记忆仓库接口 (Redis)
type ShortTermMemoryRepository interface {
	SaveContext(ctx context.Context, sessionID string, messages []model.Message, personaID string) error
	GetContext(ctx context.Context, sessionID string) ([]model.Message, error)
	DeleteContext(ctx context.Context, sessionID string) error
}

// LongTermMemoryRepository 长期记忆仓库接口 (PostgreSQL)
type LongTermMemoryRepository interface {
	SaveMemory(ctx context.Context, memory *model.UserMemory) error
	GetMemories(ctx context.Context, userID int64, keywords []string, limit int) ([]model.UserMemory, error)
	GetMemoriesByUserID(ctx context.Context, userID int64) ([]model.UserMemory, error)
}

// MemoryRepository 记忆仓库接口（兼容性别名，用于不需要区分短期/长期的场景）
type MemoryRepository interface {
	ShortTermMemoryRepository
	LongTermMemoryRepository
}

// RedisMemoryRepository Redis 短期记忆实现
type RedisMemoryRepository struct {
	client *redis.Client
	ttl    time.Duration
}

// NewRedisMemoryRepository 创建 Redis 短期记忆仓库
func NewRedisMemoryRepository(client *redis.Client, ttlSeconds int) *RedisMemoryRepository {
	return &RedisMemoryRepository{
		client: client,
		ttl:    time.Duration(ttlSeconds) * time.Second,
	}
}

// contextKey 生成 Redis key
func contextKey(sessionID string) string {
	return fmt.Sprintf("context:%s", sessionID)
}

// SaveContext 保存短期上下文到 Redis
func (r *RedisMemoryRepository) SaveContext(ctx context.Context, sessionID string, messages []model.Message, personaID string) error {
	data := model.ChatContext{
		SessionID: sessionID,
		Messages: messages,
		PersonaID: personaID,
		UpdatedAt: time.Now(),
	}

	jsonData, err := json.Marshal(data)
	if err != nil {
		return fmt.Errorf("failed to marshal context: %w", err)
	}

	return r.client.Set(ctx, contextKey(sessionID), jsonData, r.ttl).Err()
}

// GetContext 从 Redis 获取短期上下文
func (r *RedisMemoryRepository) GetContext(ctx context.Context, sessionID string) ([]model.Message, error) {
	data, err := r.client.Get(ctx, contextKey(sessionID)).Bytes()
	if err != nil {
		if err == redis.Nil {
			return nil, nil
		}
		return nil, fmt.Errorf("failed to get context: %w", err)
	}

	var chatCtx model.ChatContext
	if err := json.Unmarshal(data, &chatCtx); err != nil {
		return nil, fmt.Errorf("failed to unmarshal context: %w", err)
	}

	return chatCtx.Messages, nil
}

// DeleteContext 删除短期上下文
func (r *RedisMemoryRepository) DeleteContext(ctx context.Context, sessionID string) error {
	return r.client.Del(ctx, contextKey(sessionID)).Err()
}

// PostgreSQLMemoryRepository PostgreSQL 长期记忆实现
type PostgreSQLMemoryRepository struct {
	db *gorm.DB
}

// NewPostgreSQLMemoryRepository 创建 PostgreSQL 长期记忆仓库
func NewPostgreSQLMemoryRepository(db *gorm.DB) *PostgreSQLMemoryRepository {
	return &PostgreSQLMemoryRepository{db: db}
}

// SaveMemory 保存长期记忆
func (r *PostgreSQLMemoryRepository) SaveMemory(ctx context.Context, memory *model.UserMemory) error {
	now := time.Now().UnixMilli()
	if memory.CreatedAt == 0 {
		memory.CreatedAt = now
	}
	if memory.UpdatedAt == 0 {
		memory.UpdatedAt = now
	}

	return r.db.WithContext(ctx).Exec(
		`INSERT INTO "ai_user_memories" ("user_id", "content", "keywords", "weight", "is_core", "created_at", "updated_at")
		 VALUES ($1, $2, $3, $4, $5, $6, $7)`,
		memory.UserID,
		memory.Content,
		pq.Array(memory.Keywords),
		memory.Weight,
		memory.IsCore,
		memory.CreatedAt,
		memory.UpdatedAt,
	).Error
}

// GetMemories 根据关键词查询记忆
func (r *PostgreSQLMemoryRepository) GetMemories(ctx context.Context, userID int64, keywords []string, limit int) ([]model.UserMemory, error) {
	var memories []model.UserMemory
	query := r.db.WithContext(ctx).
		Where("user_id = ?", userID).
		Order("weight DESC, created_at DESC").
		Limit(limit)

	if len(keywords) > 0 {
		query = query.Where("keywords && $1", pq.Array(keywords))
	}

	if err := query.Find(&memories).Error; err != nil {
		return nil, fmt.Errorf("failed to get memories: %w", err)
	}

	return memories, nil
}

// GetMemoriesByUserID 获取用户所有记忆
func (r *PostgreSQLMemoryRepository) GetMemoriesByUserID(ctx context.Context, userID int64) ([]model.UserMemory, error) {
	var memories []model.UserMemory
	if err := r.db.WithContext(ctx).
		Where("user_id = ?", userID).
		Order("weight DESC, created_at DESC").
		Find(&memories).Error; err != nil {
		return nil, fmt.Errorf("failed to get memories: %w", err)
	}
	return memories, nil
}