package engine

import (
	"context"
	"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,
	}
}

// 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
func (ms *MemoryStore) GetCollection(name string) (*Collection, error) {
	ms.mu.RLock()
	defer ms.mu.RUnlock()

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

// Insert 插入文档到内存
func (ms *MemoryStore) Insert(collection string, doc types.Document) error {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return err
	}

	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
func (ms *MemoryStore) Update(collection string, filter types.Filter, update types.Update) (int, int, error) {
	coll, err := ms.GetCollection(collection)
	if err != nil {
		return 0, 0, err
	}

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

	matched := 0
	modified := 0

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

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

	return matched, modified, 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)
	}

	// 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, collection, 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
}