import SwiftUI

struct ACProgressView: View {
    @State var isDeterminate: Bool = false
    @State var progress: CGFloat = 0
    @State var text: String? = nil
    @State var isAnimating: Bool = false
    
    var body: some View {
        ZStack(alignment: .center) {
            Color.black.opacity(0.4)
            VStack {
                VStack(spacing: 24) {
                    if self.isDeterminate {
                        ZStack {
                            Circle()
                                .stroke(Color.secondary.opacity(0.2), style: StrokeStyle(lineWidth: 4))
                                .frame(width: 100, height: 100)
                            Circle()
                                .trim(from: 0, to: self.progress)
                                .stroke(Color.blue, style: StrokeStyle(lineWidth: 4))
                                .rotationEffect(.degrees(-90))
                                .frame(width: 100, height: 100)
                            Text("\(Int(self.progress*100)) %")
                        }
                    } else {
                        let gradient = AngularGradient(
                            gradient: Gradient(colors: [Color.blue, Color.blue.opacity(0.01)]),
                            center: .center,
                            startAngle: .degrees(360),
                            endAngle: .degrees(0))
                        Circle()
                            .stroke(gradient, style: StrokeStyle(lineWidth: 4))
                            .rotationEffect(Angle(degrees: self.isAnimating ? 360 : 0))
                            .onAppear {
                                withAnimation(.linear(duration: 1).repeatForever(autoreverses: false)) {
                                    self.isAnimating = true
                                }
                            }
                            .onDisappear(perform: {
                                self.isAnimating = false
                            })
                            .frame(width: 100, height: 100)
                    }
                    
                    if let msg = self.text {
                        Text(msg)
                    }
                }
                .padding(28)
            }
            //.frame(width: 160, height: 160)
            .background(.regularMaterial)
            .cornerRadius(20)
        }
        .edgesIgnoringSafeArea(.all)
    }
}

struct ACProgressView_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            ACProgressView()
            ACProgressView(isDeterminate: true, progress: 0.3, text: "Loading...")
                .preferredColorScheme(.dark)
        }
    }
}