SunMoon.swift

//
//  ContentView.swift
//  Moon
//
//  Created by Tanner W. Stokes on 8/9/20.
//

import SwiftUI

struct ContentView: View {
    @State var day = true
    let sunColor = Color(red: 245 / 255, green: 129 / 255, blue: 66 / 255)

    var body: some View {
        ZStack {
            Orbits()
                .scale(day ? 0.85 : 0.7)
                .rotation(day ? Angle(radians: 0) : Angle(radians: .pi / 3))
                .fill(sunColor)
            Circle()
                .scale(day ? 0.6 : 0.85)
                .fill(day ? sunColor : Color.yellow)
            Circle()
                .scale(0.85)
                .fill(day ? Color.white : Color.black)
                .opacity(day ? 0.0 : 1.0)
                .offset(x: day ? 0 : 60.0, y: day ? 0 : -60.0)

        }
        .background(day ? Color.white : Color.black)
        .ignoresSafeArea()
        .onTapGesture {
            day.toggle()
        }
        .animation(.spring(response: 1, dampingFraction: 1, blendDuration: 0.5))
    }
}

struct Orbits: Shape {
    func path(in rect: CGRect) -> Path {
        let r: CGFloat = 0.25 // relative to unit circle

        var path = Path()
        for rad in stride(from: 0.0, to: .pi*2, by: .pi/4) {
            let origin = CGPoint(x: cos(rad), y: sin(rad))
            let rect = CGRect(origin: origin, size: .init(width: r, height: r))
            path.addEllipse(in: rect)
        }

        let scaleFactor = min(rect.width, rect.height) / 2
        let shiftFactor = scaleFactor * r / 2

        return path
                .applying(.init(scaleX: scaleFactor, y: scaleFactor))
                .applying(.init(translationX: rect.midX - shiftFactor, y: rect.midY - shiftFactor))
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}