import SwiftUI

//
// An example of a loading screen that requires user fingerprint.
//
struct FingerprintView: View {
    @State private var touch: Bool = false

    // Define common animation
    private var ease = Animation.easeInOut(duration: 0.5)
    
    var body: some View {
        VStack {
            ZStack {
                ZStack {
                    // "touch" is an SVG image with rendering specified as "Template Image" allowing us
                    // to specify its color via .foregroundColor modifier.
                    Image("touch")
                        .resizable()
                        .aspectRatio(contentMode: .fit)
                        .foregroundColor(Color(UIColor.systemGray))
                }
                
                GeometryReader { geo in
                    ZStack {
                        Image("touch")
                            .resizable()
                            .aspectRatio(contentMode: .fit)
                            .foregroundColor(Color(UIColor.white))
                            .clipShape(
                                // Use geo.size.width sinze Image is set to be in .fit aspectRatio thus
                                // giving us height of the image area - image is square.
                                Circle().offset(y: touch ? 0 : geo.size.width)
                            )
                            .animation(ease)
                        
                        Circle().fill(LinearGradient(gradient: Gradient(colors: [Color(UIColor.systemGreen), Color(UIColor.systemBlue)]), startPoint: .top, endPoint: .bottom))
                            .blendMode(.darken)
                            .clipShape(
                                Circle().offset(y: touch ? 0 : geo.size.width)
                            ).animation(ease)
                        
                        Circle().fill(LinearGradient(gradient: Gradient(colors: [Color(UIColor.systemGreen), Color(UIColor.systemBlue)]), startPoint: .top, endPoint: .bottom))
                            .opacity(0.2)
                            .clipShape(
                                Circle().offset(y: touch ? 0 : geo.size.width)
                            ).animation(ease)
                    }
                }
            }.padding(150)
            .onTapGesture{
                self.touch.toggle()
            }
        }
    }
}