RouterOS/RouterOSAssistant/Core/Services/ConnectionService.swift

import Foundation

/// Drives the REST-first, SSH-fallback connection flow and holds the connected device's state.
@MainActor
final class ConnectionService: ObservableObject {
    enum State: Equatable {
        case idle
        case connecting
        case connected(kind: RouterOSTransportKind)
        case needsCertificateConfirmation(fingerprint: String)
        case needsSSHHostKeyConfirmation(fingerprint: String)
        case failed(String)
    }

    @Published private(set) var state: State = .idle
    @Published private(set) var deviceInfo: RouterDeviceInfo?
    @Published private(set) var interfaces: [NetworkInterface] = []
    /// Credentials of the current (or last attempted) connection, shared with features
    /// that need their own dedicated connection, e.g. BackupService's SSH export.
    @Published private(set) var credentials: RouterOSCredentials?

    private let certificateTrust: CertificateTrustStore
    private let sshHostKeyTrust: SSHHostKeyTrustStore
    private var activeTransport: RouterOSTransport?

    init(
        certificateTrust: CertificateTrustStore = CertificateTrustStore(),
        sshHostKeyTrust: SSHHostKeyTrustStore = SSHHostKeyTrustStore()
    ) {
        self.certificateTrust = certificateTrust
        self.sshHostKeyTrust = sshHostKeyTrust
    }

    /// Injection point for tests: bypasses the real REST/SSH transports.
    func connect(with credentials: RouterOSCredentials, makeRestTransport: () -> RouterOSTransport, makeSSHTransport: () -> RouterOSTransport) async {
        state = .connecting
        self.credentials = credentials

        let rest = makeRestTransport()
        do {
            try await rest.connect()
            await finishConnecting(using: rest)
            return
        } catch RouterOSError.untrustedCertificate(let fingerprint) {
            state = .needsCertificateConfirmation(fingerprint: fingerprint)
            return
        } catch {
            // REST fehlgeschlagen (z.B. altes RouterOS ohne REST-API) -> SSH-Fallback versuchen.
        }

        let ssh = makeSSHTransport()
        do {
            try await ssh.connect()
            await finishConnecting(using: ssh)
        } catch RouterOSError.untrustedSSHHostKey(let fingerprint) {
            state = .needsSSHHostKeyConfirmation(fingerprint: fingerprint)
        } catch {
            state = .failed(error.localizedDescription)
        }
    }

    func connect(with credentials: RouterOSCredentials) async {
        await connect(
            with: credentials,
            makeRestTransport: { RestTransport(credentials: credentials, certificateTrust: self.certificateTrust) },
            makeSSHTransport: { SSHTransport(credentials: credentials, hostKeyTrust: self.sshHostKeyTrust) }
        )
    }

    func trustCurrentCertificateAndRetry(fingerprint: String) async {
        guard let credentials else { return }
        certificateTrust.trust(host: credentials.host, fingerprint: fingerprint)
        await connect(with: credentials)
    }

    func trustCurrentSSHHostKeyAndRetry(fingerprint: String) async {
        guard let credentials else { return }
        sshHostKeyTrust.trust(host: credentials.host, fingerprint: fingerprint)
        await connect(with: credentials)
    }

    /// Applies a single configuration change on the active transport (REST or SSH).
    func apply(_ command: RouterOSCommand) async throws {
        guard let activeTransport else { throw RouterOSError.notConnected }
        try await activeTransport.apply(command)
    }

    func fetchFirewallRuleCounts() async throws -> FirewallRuleCounts {
        guard let activeTransport else { throw RouterOSError.notConnected }
        return try await activeTransport.fetchFirewallRuleCounts()
    }

    private func finishConnecting(using transport: RouterOSTransport) async {
        activeTransport = transport
        do {
            deviceInfo = try await transport.fetchDeviceInfo()
            interfaces = try await transport.fetchInterfaces()
            state = .connected(kind: transport.kind)
        } catch {
            state = .failed(error.localizedDescription)
        }
    }

    func disconnect() async {
        await activeTransport?.disconnect()
        activeTransport = nil
        deviceInfo = nil
        interfaces = []
        credentials = nil
        state = .idle
    }
}