import SwiftUI

/// Rendert die Karten-Inhalte je nach `CardType`. Front-/Back-Seite
/// werden über `isFlipped` gesteuert.
///
/// β-2 deckt `basic`, `basic-reverse`, `cloze` ab. Restliche Typen
/// zeigen einen Placeholder mit Hinweis auf die kommende Phase.
struct CardRenderer: View {
    let card: ReviewCard
    let subIndex: Int
    let isFlipped: Bool

    var body: some View {
        Group {
            switch card.type {
            case .basic:
                basicView(front: "front", back: "back")
            case .basicReverse:
                // sub_index 0 = front→back, sub_index 1 = back→front
                if subIndex == 0 {
                    basicView(front: "front", back: "back")
                } else {
                    basicView(front: "back", back: "front")
                }
            case .cloze:
                clozeView
            case .imageOcclusion, .audioFront, .typing, .multipleChoice:
                placeholderView
            }
        }
        .padding(24)
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    @ViewBuilder
    private func basicView(front frontKey: String, back backKey: String) -> some View {
        VStack(spacing: 16) {
            text(card.fields[frontKey] ?? "")
                .font(.title2)
                .foregroundStyle(CardsTheme.foreground)
            if isFlipped {
                Divider().background(CardsTheme.border)
                text(card.fields[backKey] ?? "")
                    .font(.title3)
                    .foregroundStyle(CardsTheme.mutedForeground)
            }
        }
    }

    @ViewBuilder
    private var clozeView: some View {
        let raw = card.fields["text"] ?? ""
        let clusterId = Cloze.clusterId(for: raw, subIndex: subIndex) ?? 1
        let rendered = isFlipped
            ? Cloze.renderAnswer(raw, activeClusterId: clusterId)
            : Cloze.renderPrompt(raw, activeClusterId: clusterId)
        VStack(spacing: 12) {
            text(rendered)
                .font(.title3)
                .foregroundStyle(CardsTheme.foreground)
        }
    }

    @ViewBuilder
    private var placeholderView: some View {
        VStack(spacing: 8) {
            Image(systemName: "questionmark.square.dashed")
                .font(.largeTitle)
                .foregroundStyle(CardsTheme.mutedForeground)
            Text("Card-Type »\(card.type.rawValue)« kommt in einer späteren Phase")
                .font(.caption)
                .multilineTextAlignment(.center)
                .foregroundStyle(CardsTheme.mutedForeground)
        }
    }

    /// Markdown-Bold (`**...**`) wird auf SwiftUI's AttributedString gemappt.
    private func text(_ markdown: String) -> some View {
        let attributed = (try? AttributedString(
            markdown: markdown,
            options: AttributedString.MarkdownParsingOptions(
                interpretedSyntax: .inlineOnlyPreservingWhitespace
            )
        )) ?? AttributedString(markdown)
        return Text(attributed)
            .multilineTextAlignment(.center)
    }
}