swift-composable-architecture-mirror/Sources/ComposableArchitecture/Documentation.docc/Tutorials/BuildingSyncUps/05-PersistingSyncUps/PersistingSyncUps-01-code-0004.swift

import ComposableArchitecture
import SwiftUI

@Reducer
struct SyncUpsList {
  @ObservableState
  struct State: Equatable {
    @Presents var addSyncUp: SyncUpForm.State?
    @Shared(.syncUps) var syncUps
  }
  enum Action {
    case addSyncUpButtonTapped
    case addSyncUp(PresentationAction<SyncUpForm.Action>)
    case confirmAddButtonTapped
    case discardButtonTapped
    case onDelete(IndexSet)
    case syncUpTapped(id: SyncUp.ID)
  }
  var body: some ReducerOf<Self> {
    Reduce { state, action in
      switch action {
      case .addSyncUpButtonTapped:
        state.addSyncUp = SyncUpForm.State(syncUp: SyncUp(id: SyncUp.ID()))
        return .none

      case .addSyncUp:
        return .none

      case .confirmAddButtonTapped:
        guard let newSyncUp = state.addSyncUp?.syncUp
        else { return .none }
        state.addSyncUp = nil
        state.syncUps.append(newSyncUp)
        return .none

      case .discardButtonTapped:
        state.addSyncUp = nil
        return .none

      case let .onDelete(indexSet):
        state.syncUps.remove(atOffsets: indexSet)
        return .none

      case .syncUpTapped:
        return .none
      }
    }
    .ifLet(\.$addSyncUp, action: \.addSyncUp) {
      SyncUpForm()
    }
  }
}

extension PersistenceReaderKey
where Self == PersistenceKeyDefault<FileStorageKey<IdentifiedArrayOf<SyncUp>>> {
  static var syncUps: Self {
    PersistenceKeyDefault(
      .fileStorage(.documentsDirectory.appending(component: "sync-ups.json")),
      []
    )
  }
}