import Foundation

/// Local (device-only) state for the pre-login public store locator —
/// see docs/plans/app-migrate-atomenta-calls-to-pedifoods-bff.md.
final class GuestLocationStore: @unchecked Sendable {
    static let shared = GuestLocationStore()

    private let serviceName = "com.br.pedifoods.app.guest"
    private let deviceIdKey = "device_id"
    private let attestationKey = "attestation"
    private let attestKeyIdKey = "attest_key_id"
    private let stateKey = "selected_state"
    private let cityKey = "selected_city"

    /// Stable per-install identifier sent as `deviceId` in the guest handshake.
    var deviceId: String {
        if let existing = KeychainStore.load(service: serviceName, key: deviceIdKey) {
            return existing
        }
        let generated = UUID().uuidString
        KeychainStore.save(generated, service: serviceName, key: deviceIdKey)
        return generated
    }

    /// Fallback-only placeholder (backend just checks non-empty) for
    /// environments that can't run real App Attest — Simulator, or non-iOS.
    /// Real devices use DCAppAttestService via GuestSessionService instead.
    var attestationPlaceholder: String {
        if let existing = KeychainStore.load(service: serviceName, key: attestationKey) {
            return existing
        }
        let generated = UUID().uuidString
        KeychainStore.save(generated, service: serviceName, key: attestationKey)
        return generated
    }

    /// App Attest key ID already registered with the backend for this
    /// device, if any. Present -> use it to sign assertions; absent -> this
    /// device needs to attest a freshly generated key first.
    var appAttestKeyId: String? {
        get { KeychainStore.load(service: serviceName, key: attestKeyIdKey) }
        set {
            if let newValue {
                KeychainStore.save(newValue, service: serviceName, key: attestKeyIdKey)
            } else {
                KeychainStore.delete(service: serviceName, key: attestKeyIdKey)
            }
        }
    }

    var selectedState: String? {
        get { KeychainStore.load(service: serviceName, key: stateKey) }
        set {
            if let newValue {
                KeychainStore.save(newValue, service: serviceName, key: stateKey)
            } else {
                KeychainStore.delete(service: serviceName, key: stateKey)
            }
        }
    }

    var selectedCity: String? {
        get { KeychainStore.load(service: serviceName, key: cityKey) }
        set {
            if let newValue {
                KeychainStore.save(newValue, service: serviceName, key: cityKey)
            } else {
                KeychainStore.delete(service: serviceName, key: cityKey)
            }
        }
    }

    func clearSelectedLocation() {
        KeychainStore.delete(service: serviceName, key: stateKey)
        KeychainStore.delete(service: serviceName, key: cityKey)
    }
}