retain order of the exercises during persistence process

WorkoutsPlus/Workout/Workout.swift

@@ -9,40 +9,54 @@ import Foundation
 import SwiftData
 
 @Model
-final class Workout {
-		var isEdited = false
-		
-		var name: String {
-				didSet { isEdited = true }
-		}
+final class Workout: Identifiable {
+		var id = UUID()
+		var name: String
 		static var systemImage = "figure.run.square.stack"
 		
 		// Other properties and methods
 		var timestamp: Date = Date.now
 		
-		var exercises: [Exercise] = []
+		@Relationship(deleteRule: .cascade) var exercises: [Exercise] = []
 		
 		init(name: String) {
 				self.name = name
 		}
 		
-		init(name: String, exercises: [Exercise]) {
-				self.name = name
-				self.exercises = exercises
-		}
-		
 		func addExercise(from exerciseTemplate: ExerciseTemplate) {
 				self.exercises.append(Exercise(from: exerciseTemplate))
+				updateExercisePositions()
 		}
 		
 		func addExercise(_ exercise: Exercise) {
 				self.exercises.append(exercise)
+				updateExercisePositions()
 		}
 		
 		func addExercise(_ exercises: [Exercise]) {
 				for exercise in exercises {
 						self.exercises.append(exercise)
 				}
+				updateExercisePositions()
+		}
+		
+		func moveExercise(from source: IndexSet, to destination: Int) {
+				exercises.move(fromOffsets: source, toOffset: destination)
+				updateExercisePositions()
+		}
+		
+		private func updateExercisePositions() {
+				for (index, exercise) in exercises.enumerated() {
+						exercise.position = index
+				}
+		}
+		
+}
+
+extension Workout {
+		private convenience init(name: String, exercises: [Exercise]) {
+				self.init(name: name)
+				self.exercises = exercises
 		}
 		
 		static let sampleData: [Workout] = [