import SwiftUI

/// Artikel per Namenssuche auswählen (Alternative zum Scannen).
struct ProductSearchView: View {
    var onPick: (Product) -> Void

    @Environment(\.dismiss) private var dismiss
    @State private var query = ""
    @State private var results: [Product] = []
    @State private var busy = false

    var body: some View {
        List {
            ForEach(results) { product in
                Button {
                    onPick(product)
                    dismiss()
                } label: {
                    VStack(alignment: .leading, spacing: 2) {
                        Text(product.name)
                        Text("\(formatted(product.stockInArticleUnits)) \(product.articleUnitLabel)")
                            .font(.caption).foregroundStyle(.secondary)
                    }
                }
            }
            if results.isEmpty && !busy {
                Text("Keine Treffer").foregroundStyle(.secondary)
            }
        }
        .searchable(text: $query, prompt: "Artikel suchen")
        .onSubmit(of: .search) { Task { await search() } }
        .task { await search() }
        .onChange(of: query) { _ in Task { await search() } }
        .navigationTitle("Artikel suchen")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .topBarLeading) { Button("Abbrechen") { dismiss() } }
        }
    }

    private func formatted(_ value: Double) -> String {
        value == value.rounded() ? String(Int(value)) : String(format: "%.2f", value)
    }

    private func search() async {
        busy = true
        defer { busy = false }
        results = (try? await APIClient.shared.searchProducts(query)) ?? []
    }
}

/// Neues Produkt anlegen – bei Bedarf mit den Daten von Open Food Facts vorbefüllt.
struct ProductFormView: View {
    let prefillBarcode: String?
    let groupId: Int?
    var suggestion: LookupResult.Suggestion?
    var onCreated: (Product) -> Void

    @Environment(\.dismiss) private var dismiss
    @EnvironmentObject private var session: Session

    @State private var barcode = ""
    @State private var name = ""
    @State private var brand = ""
    @State private var baseUnit = "piece"
    @State private var packageSize = ""
    @State private var packageLabel = ""
    @State private var datePrecision = "day"
    @State private var selectedGroupId: Int?
    @State private var selectedCategoryId: Int?
    @State private var groups: [GroupItem] = []
    @State private var categories: [CategoryItem] = []
    @State private var units: [Unit] = []
    @State private var newGroupShown = false
    @State private var busy = false
    @State private var error: String?

    private let baseUnits = [("piece", "Stück"), ("gram", "Gramm"), ("milliliter", "Milliliter")]
    // Beschriftungen kommen sonst aus DisplaySettings.baseUnitLabel.
    private let labels = ["", "Glas", "Tüte", "Flasche", "Dose", "Tube", "Becher", "Beutel", "Karton"]

    var body: some View {
        Form {
            Section("Artikel") {
                LabeledField(label: "Barcode", text: $barcode, keyboard: .numberPad)
                LabeledField(label: "Name", text: $name)
                LabeledField(label: "Marke", text: $brand)
            }
            Section {
                CategoryPicker(categories: categories, selection: $selectedCategoryId)
            } footer: {
                Text("Kategorie: nur für den Überblick in der Artikelliste.")
            }
            Section {
                Picker("Gruppe", selection: $selectedGroupId) {
                    Text("– keine –").tag(Int?.none)
                    ForEach(groups) { gruppe in
                        Text(gruppe.name).tag(Int?.some(gruppe.id))
                    }
                }
                if session.isAdmin {
                    Button {
                        newGroupShown = true
                    } label: {
                        Label("Neue Gruppe anlegen", systemImage: "plus")
                    }
                }
            } footer: {
                Text("Gruppe: zählt Bestände mehrerer Marken zusammen. Der EAN-Code "
                     + "dieses Artikels erscheint danach automatisch bei der Gruppe.")
            }
            Section("Einheit") {
                Picker("Basiseinheit", selection: $baseUnit) {
                    ForEach(baseUnits, id: \.0) { Text($0.1).tag($0.0) }
                }
                QuantityField(label: "Packungsgröße", text: $packageSize,
                              suffix: DisplaySettings.baseUnitLabel(baseUnit))
                Picker("Bezeichnung", selection: $packageLabel) {
                    ForEach(labels, id: \.self) { Text($0.isEmpty ? "Packung (Standard)" : $0).tag($0) }
                }
            }
            Section("MHD") {
                Picker("Angabe", selection: $datePrecision) {
                    Text("Tagesdatum").tag("day")
                    Text("nur Monat/Jahr").tag("month")
                }
            }
            if let error {
                Section { Text(error).foregroundStyle(.red).font(.callout) }
            }
            Section {
                Button(busy ? "Anlegen…" : "Anlegen & weiter") { Task { await create() } }
                    .disabled(busy || name.isEmpty)
            }
        }
        .navigationTitle("Neuer Artikel")
        .navigationBarTitleDisplayMode(.inline)
        .onAppear(perform: prefill)
        .task {
            groups = (try? await APIClient.shared.groups()) ?? []
            categories = (try? await APIClient.shared.categories()) ?? []
            units = (try? await APIClient.shared.units()) ?? []
        }
        .sheet(isPresented: $newGroupShown) {
            NavigationStack {
                NewGroupSheet(units: units) { created in
                    groups.append(created)
                    selectedGroupId = created.id
                }
            }
        }
    }

    private func prefill() {
        barcode = suggestion?.barcode ?? prefillBarcode ?? ""
        // Aus dem gescannten Code vorgeschlagene Gruppe uebernehmen.
        selectedGroupId = groupId
        if let suggestion {
            name = suggestion.name
            brand = suggestion.brand ?? ""
            baseUnit = suggestion.baseUnit ?? "piece"
            if let size = suggestion.packageSize { packageSize = String(size) }
        }
    }

    private func create() async {
        error = nil
        busy = true
        defer { busy = false }
        do {
            let product = try await APIClient.shared.createProduct(
                NewProductRequest(
                    barcode: barcode.isEmpty ? nil : barcode,
                    name: name,
                    brand: brand.isEmpty ? nil : brand,
                    imageUrl: suggestion?.imageUrl,
                    baseUnit: baseUnit,
                    packageSize: Double(packageSize.replacingOccurrences(of: ",", with: ".")),
                    packageLabel: packageLabel.isEmpty ? nil : packageLabel,
                    datePrecision: datePrecision,
                    groupId: selectedGroupId,
                    categoryId: selectedCategoryId
                )
            )
            onCreated(product)
            dismiss()
        } catch {
            self.error = error.localizedDescription
        }
    }
}