package engine

import (
	"context"
	"fmt"
	"log"
	"strings"
	"sync"
	"time"

	"git.kingecg.top/kingecg/gomog/internal/database"
	"git.kingecg.top/kingecg/gomog/pkg/errors"
	"git.kingecg.top/kingecg/gomog/pkg/types"
)

// MemoryStore 内存数据存储
type MemoryStore struct {
	mu          sync.RWMutex
	collections map[string]*Collection
	adapter     database.DatabaseAdapter
}

// Collection 内存集合
type Collection struct {
	name      string
	documents map[string]types.Document // id -> Document
	mu        sync.RWMutex
}

// NewMemoryStore 创建内存存储
func NewMemoryStore(adapter database.DatabaseAdapter) *MemoryStore {
	return &MemoryStore{
		collections: make(map[string]*Collection),
		adapter:     adapter,
	}
}

// Initialize 从数据库加载所有现有集合到内存
func (ms *MemoryStore) Initialize(ctx context.Context) error {
	if ms.adapter == nil {
		log.Println("[INFO] No database adapter, skipping initialization")
		return nil
	}

	// 获取所有现有集合
	tables, err := ms.adapter.ListCollections(ctx)
	if err != nil {
		// 如果 ListCollections 未实现，返回 nil（不加载）
		if err.Error() == "not implemented" {
			log.Println("[WARN] ListCollections not implemented, skipping initialization")
			return nil
		}
		return fmt.Errorf("failed to list collections: %w", err)
	}

	log.Printf("[INFO] Found %d collections in database", len(tables))

	// 逐个加载集合
	loadedCount := 0
	for _, tableName := range tables {
		// 从数据库加载所有文档
		docs, err := ms.adapter.FindAll(ctx, tableName)
		if err != nil {
			log.Printf("[WARN] Failed to load collection %s: %v", tableName, err)
			continue
		}

		// 创建集合并加载文档
		// 注意：为了兼容 HTTP API 的 dbName.collection 格式，我们同时创建两个名称的引用
		ms.mu.Lock()
		coll := &Collection{
			name:      tableName,
			documents: make(map[string]types.Document),
		}
		for _, doc := range docs {
			coll.documents[doc.ID] = doc
		}

		// 以表名作为集合名存储（例如：users）
		ms.collections[tableName] = coll

		// TODO: 如果需要支持 dbName.collection 格式，需要在这里建立映射
		// 但目前无法确定 dbName，所以暂时只使用纯表名

		ms.mu.Unlock()

		loadedCount++
		log.Printf("[DEBUG] Loaded collection %s with %d documents", tableName, len(docs))
	}

	log.Printf("[INFO] Successfully loaded %d collections from database", loadedCount)
	return nil
}

// CreateTestCollectionForTesting 为测试创建集合（仅用于测试）
func CreateTestCollectionForTesting(store *MemoryStore, name string, documents map[string]types.Document) {
	store.collections[name] = &Collection{
		name:      name,
		documents: documents,
	}
}

// LoadCollection 从数据库加载集合到内存
func (ms *MemoryStore) LoadCollection(ctx context.Context, name string) error {
	// 检查集合是否存在
	exists, err := ms.adapter.CollectionExists(ctx, name)
	if err != nil {
		return err
	}
	if !exists {
		// 创建集合
		if err := ms.adapter.CreateCollection(ctx, name); err != nil {
			return err
		}
	}

	// 从数据库加载所有文档
	docs, err := ms.adapter.FindAll(ctx, name)
	if err != nil {
		return err
	}

	ms.mu.Lock()
	defer ms.mu.Unlock()

	coll := &Collection{
		name:      name,
		documents: make(map[string]types.Document),
	}
	for _, doc := range docs {
		coll.documents[doc.ID] = doc
	}
	ms.collections[name] = coll

	return nil
}

// GetCollection 获取集合（支持 dbName.collection 和纯表名两种格式）
func (ms *MemoryStore) GetCollection(name string) (*Collection, error) {
	ms.mu.RLock()
	defer ms.mu.RUnlock()

	// 首先尝试完整名称（例如：testdb.users）
	coll, exists := ms.collections[name]
	if exists {
		return coll, nil
	}

	// 如果找不到，尝试去掉数据库前缀（例如：users）
	if idx := strings.Index(name, "."); idx > 0 {
		tableName := name[idx+1:]
		coll, exists = ms.collections[tableName]
		if exists {
			return coll, nil
		}
	}

	return nil, errors.ErrCollectionNotFnd
}

// Insert 插入文档到内存（集合不存在时自动创建）
func (ms *MemoryStore) Insert(collection string, doc types.Document) error {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		// 集合不存在则创建
		ms.mu.Lock()
		ms.collections[collection] = &Collection{
			name:      collection,
			documents: make(map[string]types.Document),
		}
		coll = ms.collections[collection]
		ms.mu.Unlock()
	}

	coll.mu.Lock()
	defer coll.mu.Unlock()

	coll.documents[doc.ID] = doc
	return nil
}

// Find 查询文档
func (ms *MemoryStore) Find(collection string, filter types.Filter) ([]types.Document, error) {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return nil, err
	}

	coll.mu.RLock()
	defer coll.mu.RUnlock()

	var results []types.Document
	for _, doc := range coll.documents {
		if MatchFilter(doc.Data, filter) {
			results = append(results, doc)
		}
	}

	return results, nil
}

// Update 更新文档（支持 upsert 和 arrayFilters）
func (ms *MemoryStore) Update(collection string, filter types.Filter, update types.Update, upsert bool, arrayFilters []types.Filter) (int, int, []string, error) {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return 0, 0, nil, err
	}

	coll.mu.Lock()
	defer coll.mu.Unlock()

	matched := 0
	modified := 0
	var upsertedIDs []string

	for id, doc := range coll.documents {
		if MatchFilter(doc.Data, filter) {
			matched++

			// 应用更新
			newData := applyUpdateWithFilters(doc.Data, update, false, arrayFilters)
			coll.documents[id] = types.Document{
				ID:        doc.ID,
				Data:      newData,
				CreatedAt: doc.CreatedAt,
				UpdatedAt: time.Now(),
			}
			modified++
		}
	}

	// 处理 upsert：如果没有匹配的文档且设置了 upsert
	if matched == 0 && upsert {
		// 创建新文档
		newID := generateID()
		newDoc := make(map[string]interface{})

		// 应用更新（$setOnInsert 会生效）
		newData := applyUpdateWithFilters(newDoc, update, true, arrayFilters)

		coll.documents[newID] = types.Document{
			ID:        newID,
			Data:      newData,
			CreatedAt: time.Now(),
			UpdatedAt: time.Now(),
		}
		matched = 1
		modified = 1
		upsertedIDs = append(upsertedIDs, newID)
	}

	return matched, modified, upsertedIDs, nil
}

// Delete 删除文档
func (ms *MemoryStore) Delete(collection string, filter types.Filter) (int, error) {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return 0, err
	}

	coll.mu.Lock()
	defer coll.mu.Unlock()

	deleted := 0
	for id, doc := range coll.documents {
		if MatchFilter(doc.Data, filter) {
			delete(coll.documents, id)
			deleted++
		}
	}

	return deleted, nil
}

// SyncToDB 同步集合到数据库
func (ms *MemoryStore) SyncToDB(ctx context.Context, collection string) error {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return err
	}

	coll.mu.RLock()
	defer coll.mu.RUnlock()

	// 转换为文档数组
	docs := make([]types.Document, 0, len(coll.documents))
	for _, doc := range coll.documents {
		docs = append(docs, doc)
	}

	// 对于 SQLite，去掉数据库前缀（例如：testdb.users -> users）
	tableName := collection
	if idx := strings.Index(collection, "."); idx > 0 {
		tableName = collection[idx+1:]
	}

	// 检查集合是否存在，不存在则创建
	exists, err := ms.adapter.CollectionExists(ctx, tableName)
	if err != nil {
		// 如果 CollectionExists 未实现（返回 ErrNotImplemented），尝试直接创建表
		if err.Error() == "not implemented" {
			// 尝试创建表，忽略已存在的错误
			_ = ms.adapter.CreateCollection(ctx, tableName)
		} else {
			return err
		}
	} else if !exists {
		// 集合不存在，创建它
		if err := ms.adapter.CreateCollection(ctx, tableName); err != nil {
			return err
		}
	}

	// 批量插入/更新到数据库
	// 注意：这里简化处理，实际应该区分新增和更新
	return ms.adapter.InsertMany(ctx, tableName, docs)
}

// GetAllDocuments 获取集合的所有文档（用于聚合）
func (ms *MemoryStore) GetAllDocuments(collection string) ([]types.Document, error) {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return nil, err
	}

	coll.mu.RLock()
	defer coll.mu.RUnlock()

	docs := make([]types.Document, 0, len(coll.documents))
	for _, doc := range coll.documents {
		docs = append(docs, doc)
	}

	return docs, nil
}

// DropCollection 删除整个集合
func (ms *MemoryStore) DropCollection(name string) error {
	ms.mu.Lock()
	defer ms.mu.Unlock()

	if _, exists := ms.collections[name]; !exists {
		return errors.ErrCollectionNotFnd
	}

	delete(ms.collections, name)

	// 如果使用了数据库适配器，同步到数据库
	if ms.adapter != nil {
		ctx := context.Background()
		_ = ms.adapter.DropCollection(ctx, name) // 忽略错误，继续执行
	}

	return nil
}

// InsertDocument 插入单个文档（已存在则更新）
func (ms *MemoryStore) InsertDocument(collection string, doc types.Document) error {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		// 集合不存在则创建
		ms.mu.Lock()
		ms.collections[collection] = &Collection{
			name:      collection,
			documents: make(map[string]types.Document),
		}
		coll = ms.collections[collection]
		ms.mu.Unlock()
	}

	coll.mu.Lock()
	defer coll.mu.Unlock()

	coll.documents[doc.ID] = doc
	return nil
}

// UpdateDocument 更新单个文档
func (ms *MemoryStore) UpdateDocument(collection string, doc types.Document) error {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return err
	}

	coll.mu.Lock()
	defer coll.mu.Unlock()

	if _, exists := coll.documents[doc.ID]; !exists {
		return errors.ErrDocumentNotFnd
	}

	coll.documents[doc.ID] = doc
	return nil
}