import SwiftUI

struct SnackbarOverlay: View {
#if os(Android)
    let center: SnackbarCenter
    @State var current: SnackbarMessage?
    @State var observer: Any?
#else
    @ObservedObject var center: SnackbarCenter
#endif

    var body: some View {
#if os(Android)
        VStack {
            if let message = current {
                HStack(spacing: 10) {
                    if let icon = message.iconSystemName, !icon.isEmpty {
                        Image(systemName: icon)
                            .font(.system(size: 16, weight: .semibold))
                    }
                    Text(message.title)
                        .font(AppTypography.heading3)
                        .multilineTextAlignment(.leading)
                        .lineLimit(3)
                    Spacer(minLength: 0)
                }
                .foregroundStyle(Color.white)
                .padding(.top, 14)
                .padding(.horizontal, 16)
                .padding(.bottom, 16)
                .frame(maxWidth: .infinity, alignment: .leading)
                .background(message.style.backgroundColor)
                .appContentShape(Rectangle())
                .onTapGesture {
                    center.handleTap()
                }
                .transition(.move(edge: .top).combined(with: .opacity))
                .zIndex(999)
            }
            Spacer()
        }
        .animation(.spring(response: 0.3, dampingFraction: 0.9), value: current?.id)
        .allowsHitTesting(current != nil)
        .onAppear {
            current = center.current
            attachObserverIfNeeded()
        }
        .onDisappear {
            detachObserver()
        }
#else
        VStack {
            if let message = center.current {
                HStack(spacing: 10) {
                    if let icon = message.iconSystemName, !icon.isEmpty {
                        Image(systemName: icon)
                            .font(.system(size: 16, weight: .semibold))
                    }
                    Text(message.title)
                        .font(AppTypography.heading3)
                        .multilineTextAlignment(.leading)
                        .lineLimit(3)
                    Spacer(minLength: 0)
                }
                .foregroundStyle(Color.white)
                .padding(.top, 14)
                .padding(.horizontal, 16)
                .padding(.bottom, 16)
                .frame(maxWidth: .infinity, alignment: .leading)
                .background(message.style.backgroundColor)
                .appContentShape(Rectangle())
                .onTapGesture {
                    center.handleTap()
                }
                .transition(.move(edge: .top).combined(with: .opacity))
                .zIndex(999)
            }
            Spacer()
        }
        .animation(.spring(response: 0.3, dampingFraction: 0.9), value: center.current?.id)
        .allowsHitTesting(center.current != nil)
#endif
    }

#if os(Android)
    private func attachObserverIfNeeded() {
        guard observer == nil else { return }
        observer = NotificationCenter.default.addObserver(
            forName: .snackbarDidChange,
            object: nil,
            queue: nil
        ) { _ in
            Task { @MainActor in
                current = center.current
            }
        }
    }

    private func detachObserver() {
        guard let observer else { return }
        NotificationCenter.default.removeObserver(observer)
        self.observer = nil
    }
#endif
}