import SwiftUI

struct MarqueeText: View {
    let text: String
    let font: Font
    let foregroundColor: Color
    private let speed: CGFloat = 10 // пикселей в секунду

    @State private var textWidth: CGFloat = 0
    @State private var containerWidth: CGFloat = 0
    @State private var offset: CGFloat = 0
    @State private var animationStarted = false

    var body: some View {
        GeometryReader { geo in
            Text(text)
                .font(font)
                .foregroundColor(foregroundColor)
                .lineLimit(1)
                .fixedSize() // важно, чтобы не обрезался
                .background(WidthGetter())
                .offset(x: offset)
                .onAppear {
                    containerWidth = geo.size.width
                    if textWidth > containerWidth, !animationStarted {
                        animationStarted = true
                        let distance = textWidth - containerWidth
                        let duration = Double(distance / speed)
                        withAnimation(.linear(duration: duration).repeatForever(autoreverses: true)) {
                            offset = -distance
                        }
                    }
                }
                .clipped()
        }
        .frame(height: lineHeight(for: font))
        .onPreferenceChange(WidthKey.self) { width in
            textWidth = width
        }
    }

    private func lineHeight(for font: Font) -> CGFloat {
        switch font {
        case .largeTitle: return 34
        case .title: return 28
        case .title2: return 22
        case .title3: return 20
        case .headline: return 17
        case .body: return 17
        case .callout: return 16
        case .subheadline: return 15
        case .caption: return 13
        case .caption2: return 12
        default: return 17
        }
    }
}

// MARK: — Helpers для измерения ширины текста
private struct WidthKey: PreferenceKey {
    static var defaultValue: CGFloat = 0
    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) { value = nextValue() }
}

private struct WidthGetter: View {
    var body: some View {
        GeometryReader { geo in
            Color.clear.preference(key: WidthKey.self, value: geo.size.width)
        }
    }
}