import SwiftUI

/// Fahrzeuge anlegen, umbenennen und entfernen.
struct ProfilesView: View {
    @Environment(DeviceStore.self) private var store
    @Environment(BluetoothManager.self) private var bluetooth
    @Environment(\.dismiss) private var dismiss

    @State private var editing: Profile?
    @State private var pendingDeletion: Profile?

    var body: some View {
        NavigationStack {
            List {
                Section {
                    ForEach(store.profiles) { profile in
                        row(for: profile)
                    }
                } footer: {
                    Text("Antippen wählt das Fahrzeug aus, das ⓘ öffnet Name, Symbol "
                         + "und Maße. Jedes Fahrzeug hat seine eigenen Geräte, und die "
                         + "App liest immer nur die des gewählten aus.")
                }

                Section {
                    Button("Fahrzeug hinzufügen", systemImage: "plus") {
                        let profile = store.addProfile(named: "Camper \(store.profiles.count + 1)")
                        editing = profile
                    }
                }
            }
            .navigationTitle("Fahrzeuge")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .confirmationAction) {
                    Button("Fertig") { dismiss() }
                }
            }
            .sheet(item: $editing) { profile in
                ProfileEditView(profile: profile)
            }
            .confirmationDialog("Fahrzeug entfernen?",
                                isPresented: .init(get: { pendingDeletion != nil },
                                                   set: { if !$0 { pendingDeletion = nil } }),
                                titleVisibility: .visible) {
                Button("Entfernen", role: .destructive) {
                    if let pendingDeletion {
                        store.removeProfile(pendingDeletion)
                        bluetooth.refreshConfiguration()
                    }
                    pendingDeletion = nil
                }
            } message: {
                if let pendingDeletion {
                    Text("„\(pendingDeletion.name)“ und die \(store.deviceCount(in: pendingDeletion)) "
                         + "darin eingerichteten Geräte werden gelöscht.")
                }
            }
        }
    }

    private func row(for profile: Profile) -> some View {
        HStack(spacing: 12) {
            Label {
                VStack(alignment: .leading, spacing: 2) {
                    Text(profile.name)
                    Text(summary(for: profile))
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
            } icon: {
                Image(systemName: profile.symbol)
            }
            // Nur dieser Bereich wählt aus; der Knopf rechts bleibt frei.
            .contentShape(.rect)
            .onTapGesture {
                store.selectProfile(profile)
                bluetooth.refreshConfiguration()
            }

            Spacer(minLength: 0)

            if profile.id == store.activeProfileID {
                Image(systemName: "checkmark")
                    .foregroundStyle(.tint)
                    .fontWeight(.semibold)
            }

            // Zum Bearbeiten reichte bisher nur das Wischen - das findet
            // niemand, erst recht nicht für die Fahrzeugmaße.
            Button {
                editing = profile
            } label: {
                Image(systemName: "info.circle")
                    .font(.title3)
            }
            .buttonStyle(.borderless)
            .accessibilityLabel("\(profile.name) bearbeiten")
        }
        .swipeActions(edge: .trailing) {
            // Das letzte Fahrzeug muss bleiben, sonst hätten Geräte keinen Ort.
            if store.hasMultipleProfiles {
                Button("Entfernen", systemImage: "trash", role: .destructive) {
                    pendingDeletion = profile
                }
            }
            Button("Bearbeiten", systemImage: "pencil") {
                editing = profile
            }
            .tint(.gray)
        }
    }

    private func summary(for profile: Profile) -> String {
        let count = store.deviceCount(in: profile)
        var parts = [count == 1 ? "1 Gerät" : "\(count) Geräte"]
        if profile.trackWidth != nil || profile.wheelbase != nil {
            parts.append("Maße hinterlegt")
        }
        return parts.joined(separator: " · ")
    }
}

/// Name, Symbol und Maße eines Fahrzeugs ändern.
private struct ProfileEditView: View {

    /// Nimmt Komma wie Punkt an – auf einer deutschen Tastatur liegt das Komma
    /// näher. Unplausible Werte werden verworfen, damit die Keilhöhe nicht
    /// stillschweigend Unsinn ergibt.
    static func metres(from text: String) -> Double? {
        let cleaned = text.replacingOccurrences(of: ",", with: ".")
            .trimmingCharacters(in: .whitespaces)
        guard let value = Double(cleaned), value > 0.5, value < 12 else { return nil }
        return value
    }

    static func text(from value: Double?) -> String {
        guard let value else { return "" }
        return String(format: "%.2f", value).replacingOccurrences(of: ".", with: ",")
    }

    let profile: Profile

    @Environment(DeviceStore.self) private var store
    @Environment(\.dismiss) private var dismiss

    @State private var name = ""
    @State private var symbol = "suv.side"
    @State private var trackWidth = ""
    @State private var wheelbase = ""

    private let columns = [GridItem(.adaptive(minimum: 60), spacing: 12)]

    var body: some View {
        NavigationStack {
            Form {
                Section("Name") {
                    TextField("Name", text: $name)
                }
                Section {
                    LabeledContent("Spurweite") {
                        HStack {
                            TextField("z. B. 2,00", text: $trackWidth)
                                .keyboardType(.decimalPad)
                                .multilineTextAlignment(.trailing)
                            Text("m").foregroundStyle(.secondary)
                        }
                    }
                    LabeledContent("Radstand") {
                        HStack {
                            TextField("z. B. 3,50", text: $wheelbase)
                                .keyboardType(.decimalPad)
                                .multilineTextAlignment(.trailing)
                            Text("m").foregroundStyle(.secondary)
                        }
                    }
                } header: {
                    Text("Fahrzeugmaße")
                } footer: {
                    Text("Nur für den Ausrichtungs-Assistenten: Aus Neigung und "
                         + "Abstand errechnet er, wie hoch der Auffahrkeil sein muss. "
                         + "Ohne Angabe entfällt diese Anzeige.")
                }

                Section("Symbol") {
                    LazyVGrid(columns: columns, spacing: 12) {
                        ForEach(Profile.symbols, id: \.self) { candidate in
                            Button {
                                symbol = candidate
                            } label: {
                                Image(systemName: candidate)
                                    .font(.title2)
                                    .frame(width: 52, height: 52)
                                    .background(symbol == candidate ? Color.accentColor.opacity(0.18)
                                                                    : Color.secondary.opacity(0.08),
                                                in: .rect(cornerRadius: 12))
                                    .foregroundStyle(symbol == candidate ? Color.accentColor : Color.primary)
                            }
                            .buttonStyle(.plain)
                        }
                    }
                    .padding(.vertical, 4)
                }
            }
            .navigationTitle("Fahrzeug")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Abbrechen") { dismiss() }
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("Sichern") {
                        var updated = profile
                        updated.name = name.trimmingCharacters(in: .whitespaces)
                        updated.symbol = symbol
                        updated.trackWidth = Self.metres(from: trackWidth)
                        updated.wheelbase = Self.metres(from: wheelbase)
                        store.update(updated)
                        dismiss()
                    }
                    .disabled(name.trimmingCharacters(in: .whitespaces).isEmpty)
                }
            }
            .onAppear {
                name = profile.name
                symbol = profile.symbol
                trackWidth = Self.text(from: profile.trackWidth)
                wheelbase = Self.text(from: profile.wheelbase)
            }
        }
    }
}