import ManaCore
import SwiftUI

/// Card-Create-View. Type-Picker oben, type-spezifische Felder unten.
/// Deckt basic, basic-reverse, cloze, typing, multiple-choice ab —
/// image-occlusion und audio-front kommen in β-4 (brauchen Media).
struct CardEditorView: View {
    let deckId: String
    let onCreated: (Card) -> Void

    @Environment(AuthClient.self) private var auth
    @Environment(\.dismiss) private var dismiss

    @State private var type: CardType = .basic
    @State private var front: String = ""
    @State private var back: String = ""
    @State private var clozeText: String = ""
    @State private var typingAnswer: String = ""
    @State private var multipleChoiceAnswer: String = ""
    @State private var isSubmitting = false
    @State private var errorMessage: String?

    /// β-3-Card-Types (β-4 ergänzt image-occlusion + audio-front).
    private static let supportedTypes: [CardType] = [
        .basic, .basicReverse, .cloze, .typing, .multipleChoice,
    ]

    var body: some View {
        Form {
            Section("Card-Type") {
                Picker("Typ", selection: $type) {
                    ForEach(Self.supportedTypes, id: \.self) { t in
                        Text(label(for: t)).tag(t)
                    }
                }
                .pickerStyle(.menu)
            }

            typeFields

            if let errorMessage {
                Section {
                    Text(errorMessage)
                        .font(.footnote)
                        .foregroundStyle(CardsTheme.error)
                }
            }
        }
        .navigationTitle("Neue Karte")
        #if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
        #endif
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Abbrechen") { dismiss() }
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("Erstellen") { Task { await submit() } }
                        .disabled(!canSubmit || isSubmitting)
                }
            }
    }

    @ViewBuilder
    private var typeFields: some View {
        switch type {
        case .basic, .basicReverse:
            Section("Vorderseite") {
                TextField("Front", text: $front, axis: .vertical)
                    .lineLimit(2 ... 6)
            }
            Section("Rückseite") {
                TextField("Back", text: $back, axis: .vertical)
                    .lineLimit(2 ... 6)
            }
            if type == .basicReverse {
                Section {
                    Text("Beide Richtungen werden gelernt — front→back und back→front.")
                        .font(.caption)
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            }

        case .cloze:
            Section("Cloze-Text") {
                TextField("Beispiel: Die Hauptstadt von {{c1::Frankreich}} ist {{c2::Paris}}.",
                          text: $clozeText, axis: .vertical)
                    .lineLimit(3 ... 8)
                    .autocorrectionDisabled()
                    .textInputAutocapitalization(.sentences)
                    .monospaced()
            }
            Section {
                let count = Cloze.subIndexCount(clozeText)
                if count > 0 {
                    Label("\(count) Lücken erkannt → \(count) Reviews", systemImage: "checkmark.circle.fill")
                        .font(.caption)
                        .foregroundStyle(CardsTheme.success)
                } else {
                    Label("Mindestens ein Cluster `{{c1::...}}` erforderlich", systemImage: "exclamationmark.circle")
                        .font(.caption)
                        .foregroundStyle(CardsTheme.warning)
                }
                Text("Mit Hint: `{{c1::Berlin::Hauptstadt von DE}}`")
                    .font(.caption2)
                    .foregroundStyle(CardsTheme.mutedForeground)
            }

        case .typing:
            Section("Frage") {
                TextField("Front", text: $front, axis: .vertical)
                    .lineLimit(2 ... 4)
            }
            Section("Erwartete Antwort") {
                TextField("Answer", text: $typingAnswer)
            }

        case .multipleChoice:
            Section("Frage") {
                TextField("Front", text: $front, axis: .vertical)
                    .lineLimit(2 ... 4)
            }
            Section("Richtige Antwort") {
                TextField("Answer", text: $multipleChoiceAnswer)
            }
            Section {
                Text("Distractor-Optionen werden zur Lernzeit automatisch aus anderen Karten desselben Decks gezogen.")
                    .font(.caption)
                    .foregroundStyle(CardsTheme.mutedForeground)
            }

        case .imageOcclusion, .audioFront:
            Section {
                Label("Dieser Typ kommt in Phase β-4 (Media)", systemImage: "clock")
                    .foregroundStyle(CardsTheme.mutedForeground)
            }
        }
    }

    private var canSubmit: Bool {
        switch type {
        case .basic, .basicReverse:
            !front.trimmed.isEmpty && !back.trimmed.isEmpty
        case .cloze:
            Cloze.subIndexCount(clozeText) > 0
        case .typing:
            !front.trimmed.isEmpty && !typingAnswer.trimmed.isEmpty
        case .multipleChoice:
            !front.trimmed.isEmpty && !multipleChoiceAnswer.trimmed.isEmpty
        case .imageOcclusion, .audioFront:
            false
        }
    }

    private func submit() async {
        isSubmitting = true
        errorMessage = nil
        defer { isSubmitting = false }
        let api = CardsAPI(auth: auth)

        let fields: [String: String]
        switch type {
        case .basic, .basicReverse:
            fields = CardFieldsBuilder.basic(front: front.trimmed, back: back.trimmed)
        case .cloze:
            fields = CardFieldsBuilder.cloze(text: clozeText.trimmed)
        case .typing:
            fields = CardFieldsBuilder.typing(front: front.trimmed, answer: typingAnswer.trimmed)
        case .multipleChoice:
            fields = CardFieldsBuilder.multipleChoice(front: front.trimmed, answer: multipleChoiceAnswer.trimmed)
        case .imageOcclusion, .audioFront:
            return // disabled
        }

        let body = CardCreateBody(deckId: deckId, type: type, fields: fields, mediaRefs: nil)
        do {
            let card = try await api.createCard(body)
            onCreated(card)
            dismiss()
        } catch {
            errorMessage = (error as? LocalizedError)?.errorDescription ?? String(describing: error)
        }
    }

    private func label(for type: CardType) -> String {
        switch type {
        case .basic: "Einfach (Vorder/Rück)"
        case .basicReverse: "Beidseitig"
        case .cloze: "Lückentext"
        case .typing: "Eintippen"
        case .multipleChoice: "Multiple Choice"
        case .imageOcclusion: "Bild-Verdeckung"
        case .audioFront: "Audio"
        }
    }
}

private extension String {
    var trimmed: String {
        trimmingCharacters(in: .whitespacesAndNewlines)
    }
}