keevault/KeeVault/ViewModels/GroupFilterViewModel.swift

import Foundation
import Combine
import KeeVaultCore

@MainActor
final class GroupFilterViewModel: ObservableObject {
    @Published var selectedGroupIds: Set<UUID> = []
    /// The group id passed to the most recent `toggle(_:)` call that resulted in a non-empty
    /// selection, used as a "best effort" default group for new entries. Cleared to `nil`
    /// whenever a toggle empties the selection, or by `clear()`.
    @Published private(set) var lastToggledGroupId: UUID?

    private let session: VaultSession

    init(session: VaultSession) {
        self.session = session
    }

    func isSelected(_ group: KeeVaultCore.Group) -> Bool {
        selectedGroupIds.contains(group.id)
    }

    func toggle(_ group: KeeVaultCore.Group) {
        guard let root = session.database?.root else { return }
        selectedGroupIds = GroupSelection.toggling(group.id, in: root, current: selectedGroupIds)
        lastToggledGroupId = selectedGroupIds.isEmpty ? nil : group.id
    }

    func clear() {
        selectedGroupIds = []
        lastToggledGroupId = nil
    }
}