// 1. Define a migration
struct MigrateUserDataToAppGroup: Migration {
    @MigrationDependency private var userDefaultsAppState
    @MigrationDependency private var sharedAppState

    static let id: MigrationID = "MigrateUserDataToAppGroup"

    func run() async throws {
        // Migrate the user data from UserDefaults to an app group, so you can share data across targets
        sharedAppState.userData = userDefaultsAppState.userData

        userDefaultsAppState.userData = nil
    }
}

// 2. Group your migrations and add dependencies
let migrations = MigrationGroup {
    MigrateUserDataToAppGroup()
    // Add more migrations here
}
.migrationDependency(self.userDefaultsAppState)
.migrationDependency(self.sharedAppState)

// 3. Run migrations in your SwiftUI app
struct ContentView: View {
    var body: some View {
        Text("Hello, Monarch! 🦋")
            .runMigrations {
                migrations
            }
    }
}

struct ButterflyTrackerApp: App {
    @State var appState = AppState()
    @State var preferences = Preferences()
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .task { 
                    try await self.runMigrations()
                }
        }
    }
    
    func runMigrations() async throws {
        MigrationRunner.removeAllMigrations()

        MigrationRunner.markMigrationAsCompleted(withID: ResetButterflyListMigration.id)
        
        let migrationGroup = MigrationGroup {
            ProvideButterlyFansPremiumAccountAccessMigration()
            RemoveAccidentallyAddedMothMigration()
        }
        .migrationDependency(self.appState)
        .migrationDependency(self.preferences)

        try await MigrationRunner.runMigrations({ migrationGroup })
    }
}

// Run the migrations in a MigrationGroup.
public static func runMigrations(_ migrationGroup: MigrationGroup) async throws

// Mark a migration as completed, without actually running it. This is useful when transitioning to Monarch from another migration system.
public static func markMigrationAsCompleted(withID id: MigrationID)

// Remove a specific migration that has previously run, allowing it to be re-run.
public static func removeMigration(withID id: MigrationID)

// Remove all previously run migrations.
public static func removeAllMigrations()

dependencies: [
    .package(url: "https://github.com/yourusername/Monarch.git", .upToNextMajor(from: "1.0.0"))
]

targets: [
    .target(
        name: "YourTarget",
        dependencies: ["Monarch"]
    )
]