import Foundation

enum NASConnectionState: String, Codable {
    case connected  // manifest loaded, comparison succeeded
    case offline    // NAS unreachable
    case unknown    // not yet checked
}

struct BackupStatusSnapshot: Codable {
    var phoneTotal: Int = 0
    var alreadySafe: Int = 0
    var nasArchiveTotal: Int = 0
    var lastCheckedAt: Date?
    var connectionState: NASConnectionState = .unknown

    // Derived — invariant: alreadySafe + needBackup == phoneTotal (always)
    var needBackup: Int { max(0, phoneTotal - alreadySafe) }

    static let empty = BackupStatusSnapshot()
}