//
//  TunnelManagerError.swift
//  TunnelManagerError
//
//  Created by pronebird on 07/09/2021.
//  Copyright © 2021 Mullvad VPN AB. All rights reserved.
//

import Foundation

extension TunnelManager {
    /// An error emitted by all public methods of TunnelManager
    enum Error: ChainedError {
        /// Account token is not set
        case missingAccount

        /// A failure to start the VPN tunnel via system call
        case startVPNTunnel(Swift.Error)

        /// A failure to load the system VPN configurations created by the app
        case loadAllVPNConfigurations(Swift.Error)

        /// A failure to save the system VPN configuration
        case saveVPNConfiguration(Swift.Error)

        /// A failure to reload the system VPN configuration
        case reloadVPNConfiguration(Swift.Error)

        /// A failure to remove the system VPN configuration
        case removeVPNConfiguration(Swift.Error)

        /// A failure to perform a recovery (by removing the VPN configuration) when a corrupt
        /// VPN configuration is detected.
        case removeInconsistentVPNConfiguration(Swift.Error)

        /// A failure to read tunnel settings
        case readTunnelSettings(TunnelSettingsManager.Error)

        /// A failure to read relays cache
        case readRelays(RelayCache.Error)

        /// A failure to find a relay satisfying the given constraints
        case cannotSatisfyRelayConstraints

        /// A failure to add the tunnel settings
        case addTunnelSettings(TunnelSettingsManager.Error)

        /// A failure to update the tunnel settings
        case updateTunnelSettings(TunnelSettingsManager.Error)

        /// A failure to remove the tunnel settings from Keychain
        case removeTunnelSettings(TunnelSettingsManager.Error)

        /// A failure to migrate tunnel settings
        case migrateTunnelSettings(TunnelSettingsManager.Error)

        /// Unable to obtain the persistent keychain reference for the tunnel settings
        case obtainPersistentKeychainReference(TunnelSettingsManager.Error)

        /// A failure to push the public WireGuard key
        case pushWireguardKey(REST.Error)

        /// A failure to replace the public WireGuard key
        case replaceWireguardKey(REST.Error)

        /// A failure to remove the public WireGuard key
        case removeWireguardKey(REST.Error)

        /// A failure to schedule background task
        case backgroundTaskScheduler(Swift.Error)

        var errorDescription: String? {
            switch self {
            case .missingAccount:
                return "Missing account token"
            case .startVPNTunnel:
                return "Failed to start the VPN tunnel"
            case .loadAllVPNConfigurations:
                return "Failed to load the system VPN configurations"
            case .saveVPNConfiguration:
                return "Failed to save the system VPN configuration"
            case .reloadVPNConfiguration:
                return "Failed to reload the system VPN configuration"
            case .removeVPNConfiguration:
                return "Failed to remove the system VPN configuration"
            case .removeInconsistentVPNConfiguration:
                return "Failed to remove the inconsistent VPN tunnel"
            case .readTunnelSettings:
                return "Failed to read the tunnel settings"
            case .readRelays:
                return "Failed to read relays"
            case .cannotSatisfyRelayConstraints:
                return "Failed to satisfy the relay constraints"
            case .addTunnelSettings:
                return "Failed to add the tunnel settings"
            case .updateTunnelSettings:
                return "Failed to update the tunnel settings"
            case .removeTunnelSettings:
                return "Failed to remove the tunnel settings"
            case .migrateTunnelSettings:
                return "Failed to migrate the tunnel settings"
            case .obtainPersistentKeychainReference:
                return "Failed to obtain the persistent keychain reference"
            case .pushWireguardKey:
                return "Failed to push the WireGuard key to server"
            case .replaceWireguardKey:
                return "Failed to replace the WireGuard key on server"
            case .removeWireguardKey:
                return "Failed to remove the WireGuard key from server"
            case .backgroundTaskScheduler:
                return "Failed to schedule background task"
            }
        }
    }
}