// VPNProvider.swift
// Jarvis — remote-access providers. The app can't start another app's VPN tunnel
// (iOS sandboxing), so the provider only tailors hints, help text, and an
// "open the app" jump. Reachability + endpoint selection is provider-agnostic.

import UIKit

enum VPNProvider: String, CaseIterable, Codable, Identifiable {
    case direct            // LAN only, no VPN
    case tailscale
    case headscale         // self-hosted control plane, Tailscale clients
    case netbird
    case zerotier
    case netmaker
    case wireguard

    var id: String { rawValue }

    var displayName: String {
        switch self {
        case .direct:    return "Direct (LAN)"
        case .tailscale: return "Tailscale"
        case .headscale: return "Headscale"
        case .netbird:   return "NetBird"
        case .zerotier:  return "ZeroTier"
        case .netmaker:  return "Netmaker"
        case .wireguard: return "WireGuard"
        }
    }

    /// Whether a separate remote/VPN address is meaningful for this provider.
    var needsRemote: Bool { self != .direct }

    /// Placeholder shown in the remote-address field.
    var remoteHint: String {
        switch self {
        case .direct:    return "—"
        case .tailscale: return "jarvis.tailnet.ts.net:8080 or 100.x.y.z:8080"
        case .headscale: return "100.x.y.z:8080 (MagicDNS or tailnet IP)"
        case .netbird:   return "100.x.y.z:8080"
        case .zerotier:  return "10.x.x.x:8080 (managed IP)"
        case .netmaker:  return "10.x.x.x:8080"
        case .wireguard: return "10.0.0.x:8080 (peer IP)"
        }
    }

    var blurb: String {
        switch self {
        case .direct:
            return "Use the LAN address only. Best when the phone is always on the home network."
        case .tailscale:
            return "On your home wifi Jarvis uses the LAN address directly; away, it uses your Tailscale address. Make sure Tailscale is connected when remote."
        case .headscale:
            return "Self-hosted Tailscale control plane. Same client behaviour as Tailscale — keep the client connected when away."
        case .netbird:
            return "Open-source WireGuard mesh. Keep the NetBird app connected when off the LAN."
        case .zerotier:
            return "Managed network via ZeroTier. Keep the ZeroTier app joined to the network when remote."
        case .netmaker:
            return "Self-hosted WireGuard mesh. Keep your Netmaker client up when off the LAN."
        case .wireguard:
            return "Plain WireGuard tunnel. Enable the tunnel in the WireGuard app when remote."
        }
    }

    /// Best-effort URL scheme + App Store fallback used by "Open <provider>".
    /// iOS can't start the tunnel for us — this just brings the app forward.
    private var urlScheme: URL? {
        switch self {
        case .tailscale, .headscale: return URL(string: "tailscale://")
        case .zerotier:              return URL(string: "zerotier://")
        case .wireguard:             return URL(string: "wireguard://")
        default:                     return nil
        }
    }

    private var appStoreURL: URL? {
        switch self {
        case .tailscale, .headscale: return URL(string: "https://apps.apple.com/app/id1470499037")
        case .zerotier:              return URL(string: "https://apps.apple.com/app/id1084101492")
        case .wireguard:             return URL(string: "https://apps.apple.com/app/id1441195209")
        case .netbird:               return URL(string: "https://apps.apple.com/app/id6443155627")
        default:                     return nil
        }
    }

    var canOpenApp: Bool { urlScheme != nil || appStoreURL != nil }

    /// Try the app's scheme; fall back to its App Store page.
    @MainActor
    func openApp() {
        let candidates = [urlScheme, appStoreURL].compactMap { $0 }
        func attempt(_ i: Int) {
            guard i < candidates.count else { return }
            UIApplication.shared.open(candidates[i]) { ok in
                if !ok { attempt(i + 1) }
            }
        }
        attempt(0)
    }
}