/// Copyright (c) 2020 Razeware LLC
/// 
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
/// 
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
/// 
/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
/// distribute, sublicense, create a derivative work, and/or sell copies of the
/// Software in any work that is designed, intended, or marketed for pedagogical or
/// instructional purposes related to programming, coding, application development,
/// or information technology.  Permission for such use, copying, modification,
/// merger, publication, distribution, sublicensing, creation of derivative works,
/// or sale is expressly withheld.
/// 
/// This project and source code may use libraries or frameworks that are
/// released under various Open-Source licenses. Use of those libraries and
/// frameworks are governed by their own individual licenses.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
/// THE SOFTWARE.

import Foundation
import CoreData

open class CoreDataStack {
  public static let modelName = "PandemicReport"

  public static let model: NSManagedObjectModel = {
    // swiftlint:disable force_unwrapping
    let modelURL = Bundle.main.url(forResource: modelName, withExtension: "momd")!
    return NSManagedObjectModel(contentsOf: modelURL)!
  }()
  // swiftlint:enable force_unwrapping

  public init() {
  }

  public lazy var mainContext: NSManagedObjectContext = {
    return self.storeContainer.viewContext
  }()

  public lazy var storeContainer: NSPersistentContainer = {
    let container = NSPersistentContainer(name: CoreDataStack.modelName, managedObjectModel: CoreDataStack.model)
    container.loadPersistentStores { _, error in
      if let error = error as NSError? {
        fatalError("Unresolved error \(error), \(error.userInfo)")
      }
    }
    return container
  }()

  public func newDerivedContext() -> NSManagedObjectContext {
    let context = storeContainer.newBackgroundContext()
    return context
  }

  public func saveContext() {
    saveContext(mainContext)
  }

  public func saveContext(_ context: NSManagedObjectContext) {
    if context != mainContext {
      saveDerivedContext(context)
      return
    }

    context.perform {
      do {
        try context.save()
      } catch let error as NSError {
        fatalError("Unresolved error \(error), \(error.userInfo)")
      }
    }
  }

  public func saveDerivedContext(_ context: NSManagedObjectContext) {
    context.perform {
      do {
        try context.save()
      } catch let error as NSError {
        fatalError("Unresolved error \(error), \(error.userInfo)")
      }

      self.saveContext(self.mainContext)
    }
  }
}
