import Foundation
import CoreData

protocol StorageServiceProtocol {
    
    var context: NSManagedObjectContext { get }
    func store(vehicle: Vehicle) throws -> CDVehicle
}

class StorageService: StorageServiceProtocol {
    
    private let container: NSPersistentCloudKitContainer
    
    static let shared = StorageService()
    
    init(inMemory: Bool = false) {
        
        container = NSPersistentCloudKitContainer(name: "AutoCat2")
        if inMemory {
            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
        }
        
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // TODO: Handle error properly
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
    }
    
    private func save() throws {
        guard context.hasChanges else {
            return
        }
        
        do {
            try context.save()
        } catch {
            context.rollback()
            throw error
        }
    }
    
    // MARK: - StorageServiceProtocol
    
    var context: NSManagedObjectContext {
        container.viewContext
    }
    
    func store(vehicle: Vehicle) throws -> CDVehicle {
        
        let cdVehicle = CDVehicle(vehicle: vehicle, context: context)
        try save()
        return cdVehicle
    }
}