import SwiftUI

/// Zuordnen per Scan: erst ein Einzelstück (…/i/<UID>) scannen, dann einen
/// Lagerort (…/l/<ID>) – das Stück wird dem Ort zugewiesen. Danach gleich das
/// nächste Stück, ohne Tippen.
struct AssignScanView: View {
    @Environment(\.dismiss) private var dismiss

    @State private var paused = false
    @State private var torchOn = false
    @State private var torchLocked = false
    @State private var pending: Item?          // gescanntes/gewähltes Stück, wartet auf Ort
    @State private var status: String?
    @State private var error: String?
    @State private var showPicker = false

    var body: some View {
        ScrollView {
            VStack(spacing: 14) {
                ScannerView(onCode: { code in Task { await handle(code) } },
                            isPaused: $paused, torchOn: $torchOn, torchLocked: $torchLocked)
                    .aspectRatio(4.0 / 3.0, contentMode: .fit)
                    .clipShape(RoundedRectangle(cornerRadius: 16))
                    .padding(.horizontal)

                if let pending {
                    VStack(spacing: 4) {
                        Text("Einzelstück \(pending.uid)").font(.headline)
                        Text("Jetzt den Lagerort-QR scannen")
                            .font(.caption).foregroundStyle(.secondary)
                        Button("Abbrechen") { self.pending = nil }
                            .font(.caption).padding(.top, 2)
                    }
                    .padding().frame(maxWidth: .infinity)
                    .background(Color.marke.opacity(0.15))
                    .clipShape(RoundedRectangle(cornerRadius: 12)).padding(.horizontal)
                } else {
                    VStack(spacing: 8) {
                        Text("Schritt 1: Einzelstück-QR scannen – oder ohne Code:")
                            .font(.caption).foregroundStyle(.secondary)
                        // Für Stücke ohne eigenen QR (z.B. Kleidung): aus der Liste wählen.
                        Button { showPicker = true } label: {
                            Label("Einzelstück aus Liste wählen", systemImage: "list.bullet")
                        }
                    }
                }

                if let status {
                    Text(status).font(.callout).foregroundStyle(.green)
                        .frame(maxWidth: .infinity, alignment: .leading).padding(.horizontal)
                }
                if let error {
                    Text(error).font(.callout).foregroundStyle(.red)
                        .frame(maxWidth: .infinity, alignment: .leading).padding(.horizontal)
                }
            }
            .padding(.vertical)
        }
        .navigationTitle("Ort zuordnen")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .topBarLeading) { Button("Fertig") { dismiss() } }
            ToolbarItem(placement: .topBarTrailing) { TorchButton(isOn: $torchOn, locked: $torchLocked) }
        }
        .sheet(isPresented: $showPicker) {
            ItemPickerSheet { it in pending = it; status = nil; error = nil }
        }
    }

    private func handle(_ code: String) async {
        // Lagerort-QR (…/l/<Code>)? Der Code ist eine 10-stellige Zeichenkette.
        if let r = code.range(of: "/l/") {
            let locCode = String(code[r.upperBound...])
                .trimmingCharacters(in: CharacterSet(charactersIn: "/ "))
                .uppercased()
            if !locCode.isEmpty {
                guard let it = pending else {
                    error = "Erst ein Einzelstück scannen."; status = nil; return
                }
                do {
                    _ = try await APIClient.shared.updateItem(id: it.id, ItemUpdateRequest(
                        locationId: locCode, shopId: it.shopId,
                        acquiredOn: it.acquiredOn, warrantyUntil: it.warrantyUntil, note: it.note))
                    status = "\(it.uid) zugeordnet. Nächstes Stück scannen."
                    error = nil
                    pending = nil
                } catch { self.error = error.localizedDescription }
                return
            }
        }
        // Einzelstück-QR (…/i/<UID>)?
        if let r = code.range(of: "/i/") {
            let uid = String(code[r.upperBound...])
                .trimmingCharacters(in: CharacterSet(charactersIn: "/ ")).uppercased()
            if !uid.isEmpty, let it = try? await APIClient.shared.itemByUid(uid: uid) {
                pending = it; status = nil; error = nil
                return
            }
        }
        error = "Unbekannter Code – bitte einen Einzelstück- oder Lagerort-QR scannen."
    }
}

/// Einzelstück aus einer durchsuchbaren Liste wählen – für Stücke ohne eigenen QR.
struct ItemPickerSheet: View {
    var onPick: (Item) -> Void

    @Environment(\.dismiss) private var dismiss
    @State private var items: [Item] = []
    @State private var locations: [StorageLocation] = []
    @State private var query = ""
    @State private var busy = true

    private var gefiltert: [Item] {
        let q = query.trimmingCharacters(in: .whitespaces).lowercased()
        guard !q.isEmpty else { return items }
        return items.filter {
            [$0.productName, $0.uid, $0.productBrand, $0.note]
                .compactMap { $0 }.joined(separator: " ").lowercased().contains(q)
        }
    }

    var body: some View {
        NavigationStack {
            List {
                if busy && items.isEmpty { ProgressView() }
                ForEach(gefiltert) { it in
                    Button { onPick(it); dismiss() } label: {
                        ItemRow(item: it, locations: locations)
                    }
                    .buttonStyle(.plain)
                }
                if !busy && gefiltert.isEmpty {
                    Text("Nichts gefunden.").foregroundStyle(.secondary)
                }
            }
            .searchable(text: $query, prompt: "Produkt, UID oder Notiz")
            .navigationTitle("Einzelstück wählen")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar { ToolbarItem(placement: .topBarLeading) { Button("Abbrechen") { dismiss() } } }
            .task {
                items = (try? await APIClient.shared.allItems()) ?? []
                locations = (try? await APIClient.shared.locations()) ?? []
                busy = false
            }
        }
    }
}