import Foundation
import CoreData
import SwiftUI
import Combine

class CoreDataManager: ObservableObject {
    static let shared = CoreDataManager()
    
    let container: NSPersistentContainer
    
    init() {
        container = NSPersistentContainer(name: "MyQrCode")
        
        container.loadPersistentStores { description, error in
            if let error = error {
                print("Core Data 加载失败: \(error.localizedDescription)")
            }
        }
        
        // 启用自动合并更改
        container.viewContext.automaticallyMergesChangesFromParent = true
        container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
    }
    
    // 保存上下文
    func save() {
        let context = container.viewContext
        
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                print("保存失败: \(error.localizedDescription)")
            }
        }
    }
    
    // 获取历史记录
    func fetchHistoryItems() -> [HistoryItem] {
        let request: NSFetchRequest<HistoryItem> = HistoryItem.fetchRequest()
        request.sortDescriptors = [NSSortDescriptor(keyPath: \HistoryItem.createdAt, ascending: false)]
        
        do {
            return try container.viewContext.fetch(request)
        } catch {
            print("获取历史记录失败: \(error.localizedDescription)")
            return []
        }
    }
    
    // 添加历史记录
    func addHistoryItem(_ item: HistoryItem) {
        container.viewContext.insert(item)
        save()
    }
    
    // 删除历史记录
    func deleteHistoryItem(_ item: HistoryItem) {
        container.viewContext.delete(item)
        save()
    }
    
    // 清空所有历史记录
    func clearAllHistory() {
        let request: NSFetchRequest<NSFetchRequestResult> = HistoryItem.fetchRequest()
        let deleteRequest = NSBatchDeleteRequest(fetchRequest: request)
        
        do {
            try container.viewContext.execute(deleteRequest)
            save()
        } catch {
            print("清空历史记录失败: \(error.localizedDescription)")
        }
    }
    
    // 搜索历史记录
    func searchHistoryItems(query: String) -> [HistoryItem] {
        let request: NSFetchRequest<HistoryItem> = HistoryItem.fetchRequest()
        
        if !query.isEmpty {
            let contentPredicate = NSPredicate(format: "content CONTAINS[cd] %@", query)
            let barcodeTypePredicate = NSPredicate(format: "barcodeType CONTAINS[cd] %@", query)
            let qrCodeTypePredicate = NSPredicate(format: "qrCodeType CONTAINS[cd] %@", query)
            
            let compoundPredicate = NSCompoundPredicate(
                orPredicateWithSubpredicates: [
                    contentPredicate,
                    barcodeTypePredicate,
                    qrCodeTypePredicate
                ]
            )
            
            request.predicate = compoundPredicate
        }
        
        request.sortDescriptors = [NSSortDescriptor(keyPath: \HistoryItem.createdAt, ascending: false)]
        
        do {
            return try container.viewContext.fetch(request)
        } catch {
            print("搜索历史记录失败: \(error.localizedDescription)")
            return []
        }
    }
    
    // 按类型过滤
    func filterByType(_ type: DataType) -> [HistoryItem] {
        let request: NSFetchRequest<HistoryItem> = HistoryItem.fetchRequest()
        request.predicate = NSPredicate(format: "dataType == %@", type.rawValue)
        request.sortDescriptors = [NSSortDescriptor(keyPath: \HistoryItem.createdAt, ascending: false)]
        
        do {
            return try container.viewContext.fetch(request)
        } catch {
            print("按类型过滤失败: \(error.localizedDescription)")
            return []
        }
    }
    
    // 按来源过滤
    func filterBySource(_ source: DataSource) -> [HistoryItem] {
        let request: NSFetchRequest<HistoryItem> = HistoryItem.fetchRequest()
        request.predicate = NSPredicate(format: "dataSource == %@", source.rawValue)
        request.sortDescriptors = [NSSortDescriptor(keyPath: \HistoryItem.createdAt, ascending: false)]
        
        do {
            return try container.viewContext.fetch(request)
        } catch {
            print("按来源过滤失败: \(error.localizedDescription)")
            return []
        }
    }
    
    // 获取收藏项目
    func getFavoriteItems() -> [HistoryItem] {
        let request: NSFetchRequest<HistoryItem> = HistoryItem.fetchRequest()
        request.predicate = NSPredicate(format: "isFavorite == YES")
        request.sortDescriptors = [NSSortDescriptor(keyPath: \HistoryItem.createdAt, ascending: false)]
        
        do {
            return try container.viewContext.fetch(request)
        } catch {
            print("获取收藏项目失败: \(error.localizedDescription)")
            return []
        }
    }
}