import SwiftUI

struct SettingsView: View {
    @ObservedObject var monitor: ServerMonitor
    @State private var draft = ServerProfile()
    @State private var editingID: UUID?
    @State private var validation = ""
    @State private var interval = 5
    @State private var notifications = true
    @State private var newRequiredService = ""
    @State private var showUninstalled = false

    var body: some View {
        HStack(spacing: 0) {
            VStack(spacing: 8) {
                Text("Servers").font(.headline).frame(maxWidth: .infinity, alignment: .leading)
                List(selection: $editingID) {
                    ForEach(monitor.servers) { server in
                        HStack {
                            Image(systemName: "server.rack")
                            Text(server.name)
                            if !server.enabled { Image(systemName: "pause.circle") }
                        }.tag(server.id)
                    }
                    .onMove { monitor.move(from: $0, to: $1) }
                }
                HStack {
                    Button { newProfile() } label: { Image(systemName: "plus") }
                    Button { if let id = editingID { monitor.remove(id); editingID = monitor.servers.first?.id } } label: { Image(systemName: "minus") }
                        .disabled(editingID == nil)
                    Spacer()
                }
                .buttonStyle(.borderless)
            }
            .frame(width: 205)
            .padding()
            Divider()
            VStack(alignment: .leading, spacing: 14) {
                Text(editingID == nil ? "Add a server" : "Connection details")
                    .font(.title3.bold())
                Form {
                    TextField("Display name", text: $draft.name)
                    TextField("Host / SSH alias", text: $draft.host)
                    TextField("SSH username", text: $draft.user)
                    TextField("SSH port", text: $draft.port)
                    TextField("SSH key path (optional)", text: $draft.keyFile)
                    TextField("Remote health command", text: $draft.remoteCommand)
                    Toggle("Monitoring enabled", isOn: $draft.enabled)
                    Toggle("Automatically discover services", isOn: $draft.discoverServices)
                }
                serviceConfiguration
                Text("Use the Pegasus adapter for Pegasus, or install server/remote-health-json on other Linux servers. SSH must work without interactive prompts. SSH known_hosts is enforced.")
                    .font(.caption).foregroundStyle(.secondary)
                if !validation.isEmpty { Text(validation).foregroundStyle(.red).font(.caption) }
                HStack {
                    Button("New Server") { newProfile() }
                    Spacer()
                    Button("Save and Refresh") { save() }
                        .buttonStyle(.borderedProminent)
                }
                Divider()
                HStack {
                    Picker("Refresh every", selection: $interval) {
                        ForEach([1, 5, 10, 15, 30], id: \.self) { value in
                            Text("\(value) min").tag(value)
                        }
                    }
                    Toggle("Notifications", isOn: $notifications)
                }
            }
            .padding(20)
            .frame(minWidth: 460)
        }
        .onAppear {
            interval = monitor.intervalMinutes
            notifications = monitor.notifications
            editingID = monitor.selectedID
            if let selected = monitor.selected { draft = selected }
        }
        .onChange(of: editingID) { _, newValue in
            if let id = newValue, let server = monitor.servers.first(where: { $0.id == id }) { draft = server }
            validation = ""
            newRequiredService = ""
        }
        .onChange(of: interval) { _, value in monitor.intervalMinutes = value }
        .onChange(of: notifications) { _, value in monitor.notifications = value }
    }

    private var serviceConfiguration: some View {
        VStack(alignment: .leading, spacing: 10) {
            HStack {
                Text("Service monitoring").font(.headline)
                Spacer()
                Button("Refresh services") {
                    if let id = editingID { Task { await monitor.refresh(id: id) } }
                }.disabled(editingID == nil)
            }
            Text("Mark critical services as Required. Missing or non-running required services count as failures. Optional services not installed do not affect health.")
                .font(.caption).foregroundStyle(.secondary)
            Toggle("Show not installed services", isOn: $showUninstalled)
                .font(.caption)
            let discovered = editingID.map { monitor.discoveredServices(for: $0) } ?? []
            let display = discovered.filter { showUninstalled || $0.isInstalled || draft.requiredServices.contains($0.name) }
            if display.isEmpty {
                Text("No service discovery data yet. Refresh the server or add a required service below.")
                    .font(.caption).foregroundStyle(.secondary)
            } else {
                ScrollView {
                    LazyVStack(spacing: 6) {
                        ForEach(display) { service in
                            HStack(spacing: 8) {
                                Image(systemName: service.symbol).foregroundStyle(service.color).frame(width: 20)
                                Text(service.name).frame(maxWidth: .infinity, alignment: .leading)
                                Text(service.title).font(.caption).foregroundStyle(.secondary)
                                Toggle("Required", isOn: Binding(
                                    get: { draft.requiredServices.contains(service.name) },
                                    set: { required in setRequired(service.name, required: required) }
                                )).labelsHidden().help("Require \(service.name) to be running")
                            }
                            .font(.system(size: 12))
                        }
                    }
                }.frame(maxHeight: 190)
            }
            HStack {
                TextField("Add required service (e.g. mysql)", text: $newRequiredService)
                    .onSubmit { addRequiredService() }
                Button("Add Required") { addRequiredService() }
                    .disabled(newRequiredService.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty)
            }
            if !draft.requiredServices.isEmpty {
                Text("Required: \(draft.requiredServices.sorted().joined(separator: ", "))")
                    .font(.caption).foregroundStyle(.secondary)
            }
        }
    }

    private func setRequired(_ name: String, required: Bool) {
        if required && !draft.requiredServices.contains(name) { draft.requiredServices.append(name) }
        if !required { draft.requiredServices.removeAll { $0 == name } }
    }
    private func addRequiredService() {
        let name = newRequiredService.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !name.isEmpty, name.range(of: #"^[a-zA-Z0-9@_.-]+$"#, options: .regularExpression) != nil else {
            validation = "Use a valid systemd service name (letters, digits, @, _, -, or .)."
            return
        }
        setRequired(name, required: true)
        newRequiredService = ""
        validation = ""
    }
    private func newProfile() {
        editingID = nil
        draft = ServerProfile()
        validation = ""
        newRequiredService = ""
    }
    private func save() {
        guard !draft.name.trimmingCharacters(in: .whitespaces).isEmpty,
              !draft.host.trimmingCharacters(in: .whitespaces).isEmpty,
              !draft.user.trimmingCharacters(in: .whitespaces).isEmpty,
              let port = Int(draft.port), (1...65535).contains(port),
              !draft.remoteCommand.trimmingCharacters(in: .whitespaces).isEmpty else {
            validation = "Enter a name, host, SSH username, valid port and remote command."
            return
        }
        monitor.save(draft)
        editingID = draft.id
        validation = ""
    }
}