import SwiftUI
import MapKit
import CoreLocation

struct GPXImportSheet: View {
    let track: GPXTrack
    let onDismiss: () -> Void

    @Environment(\.dismiss) private var dismiss
    @State private var name: String
    @State private var dogs: [Dog] = []
    @State private var selectedDogIds: Set<Int> = []
    @State private var isPublic: Bool = false
    @State private var isSaving = false
    @State private var errorMessage: String?
    @State private var saved: Bool = false

    init(track: GPXTrack, onDismiss: @escaping () -> Void) {
        self.track = track
        self.onDismiss = onDismiss
        _name = State(initialValue: track.name?.isEmpty == false
                      ? (track.name ?? "Importierte Tour")
                      : "Importierte Tour")
    }

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(alignment: .leading, spacing: 16) {
                    mapView
                    summaryCard
                    importCard
                    viewOnlyCard

                    if let errorMessage {
                        Text(errorMessage)
                            .font(.footnote)
                            .foregroundStyle(.red)
                    }
                }
                .padding()
            }
            .navigationTitle("GPX importieren")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Schließen") {
                        dismiss()
                        onDismiss()
                    }
                }
            }
            .task {
                dogs = (try? await APIClient.shared.get("/api/dogs")) ?? []
            }
        }
    }

    // MARK: - Map

    private var mapView: some View {
        Map {
            MapPolyline(coordinates: track.coordinates)
                .stroke(Color.accentColor, lineWidth: 4)
            if let first = track.coordinates.first {
                Annotation("Start", coordinate: first) {
                    Image(systemName: "flag.circle.fill")
                        .font(.title2)
                        .foregroundStyle(.white, .green)
                        .background(.white, in: Circle())
                }
            }
            if let last = track.coordinates.last, track.coordinates.count > 1 {
                Annotation("Ziel", coordinate: last) {
                    Image(systemName: "flag.checkered.circle.fill")
                        .font(.title2)
                        .foregroundStyle(.white, .red)
                        .background(.white, in: Circle())
                }
            }
        }
        .mapStyle(.standard(elevation: .realistic))
        .frame(height: 220)
        .clipShape(RoundedRectangle(cornerRadius: 16))
        .allowsHitTesting(false)
    }

    // MARK: - Summary

    private var summaryCard: some View {
        HStack(spacing: 16) {
            stat("Distanz", value: distanceLabel, icon: "ruler")
            Divider()
            stat("Punkte", value: "\(track.points.count)", icon: "point.3.connected.trianglepath.dotted")
            if let dur = durationLabel {
                Divider()
                stat("Dauer", value: dur, icon: "clock")
            }
        }
        .padding(14)
        .background(.background.secondary, in: RoundedRectangle(cornerRadius: 12))
    }

    private func stat(_ title: String, value: String, icon: String) -> some View {
        VStack(spacing: 4) {
            Image(systemName: icon).foregroundStyle(Color.accentColor)
            Text(value).font(.headline.monospacedDigit())
            Text(title).font(.caption2).foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity)
    }

    // MARK: - Import (save as route)

    private var importCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            Label("Als Tour übernehmen", systemImage: "square.and.arrow.down.fill")
                .font(.headline)

            TextField("Name", text: $name)
                .textFieldStyle(.roundedBorder)

            if !dogs.isEmpty {
                Text("Hunde").font(.caption).foregroundStyle(.secondary)
                FlowDogs(dogs: dogs, selected: $selectedDogIds)
            }

            Toggle(isOn: $isPublic) {
                Label("Öffentlich teilen", systemImage: "globe")
            }
            .font(.subheadline)

            Button {
                Task { await saveAsRoute() }
            } label: {
                HStack {
                    if isSaving { ProgressView() }
                    Image(systemName: saved ? "checkmark.circle.fill" : "square.and.arrow.down")
                    Text(saved ? "Gespeichert" : "Speichern")
                        .bold()
                }
                .frame(maxWidth: .infinity, minHeight: 44)
            }
            .background((saved ? Color.green : Color.accentColor).opacity(isSaving ? 0.6 : 1), in: Capsule())
            .foregroundStyle(.white)
            .disabled(isSaving || saved || name.trimmingCharacters(in: .whitespaces).isEmpty)
        }
        .padding(14)
        .background(.background.secondary, in: RoundedRectangle(cornerRadius: 12))
    }

    // MARK: - View only

    private var viewOnlyCard: some View {
        VStack(alignment: .leading, spacing: 12) {
            Label("Nur ansehen", systemImage: "eye")
                .font(.headline)
            Text("Den Track in Apple Maps öffnen und dort z. B. eine Route zum Startpunkt planen.")
                .font(.caption)
                .foregroundStyle(.secondary)
            Button {
                openStartInMaps()
            } label: {
                HStack {
                    Image(systemName: "arrow.triangle.turn.up.right.diamond.fill")
                    Text("Startpunkt in Apple Maps").bold()
                }
                .frame(maxWidth: .infinity, minHeight: 44)
            }
            .background(.thinMaterial, in: Capsule())
            .foregroundStyle(.primary)
        }
        .padding(14)
        .background(.background.secondary, in: RoundedRectangle(cornerRadius: 12))
    }

    // MARK: - Actions

    private func saveAsRoute() async {
        isSaving = true
        errorMessage = nil
        defer { isSaving = false }
        let dist = track.distanceMeters / 1000.0
        let durMin: Int = {
            if let s = track.durationSeconds { return Int(s / 60.0) }
            return 0
        }()
        let body = RouteCreateBody(
            name: name.trimmingCharacters(in: .whitespacesAndNewlines),
            gpsTrack: track.points.map { GPSPoint(lat: $0.lat, lon: $0.lon, alt: $0.ele) },
            distanzKm: dist,
            dauerMin: durMin,
            dogIds: Array(selectedDogIds),
            isPublic: isPublic
        )
        do {
            let _: RouteDetail = try await APIClient.shared.post("/api/routes", body: body)
            saved = true
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    private func openStartInMaps() {
        guard let start = track.coordinates.first else { return }
        let item = MKMapItem(placemark: MKPlacemark(coordinate: start))
        item.name = name
        item.openInMaps(launchOptions: nil)
    }

    // MARK: - Labels

    private var distanceLabel: String {
        let km = track.distanceMeters / 1000.0
        return km < 1 ? "\(Int(track.distanceMeters)) m" : String(format: "%.1f km", km)
    }

    private var durationLabel: String? {
        guard let s = track.durationSeconds else { return nil }
        let h = Int(s) / 3600
        let m = (Int(s) % 3600) / 60
        if h > 0 { return "\(h):\(String(format: "%02d", m)) h" }
        return "\(m) min"
    }
}

private struct FlowDogs: View {
    let dogs: [Dog]
    @Binding var selected: Set<Int>

    var body: some View {
        let cols = [GridItem(.adaptive(minimum: 110))]
        LazyVGrid(columns: cols, alignment: .leading, spacing: 8) {
            ForEach(dogs) { d in
                let on = selected.contains(d.id)
                Button {
                    if on { selected.remove(d.id) } else { selected.insert(d.id) }
                } label: {
                    HStack(spacing: 6) {
                        Image(systemName: on ? "checkmark.circle.fill" : "circle")
                        Text(d.name).lineLimit(1)
                    }
                    .font(.caption.bold())
                    .padding(.horizontal, 10)
                    .padding(.vertical, 6)
                    .background(on ? Color.accentColor.opacity(0.2) : Color.secondary.opacity(0.12),
                                in: Capsule())
                    .foregroundStyle(on ? Color.accentColor : .primary)
                }
                .buttonStyle(.plain)
            }
        }
    }
}