VolumePopupView.swift

//
//  VolumePopupView.swift
//
//  Created by Alex Rosenberg on 1/24/24.
//

import SwiftUI
import AVFoundation
import MediaPlayer

extension MPVolumeView {
    static func setVolume(_ volume: Float) -> Void {
        let volumeView = MPVolumeView()
        let slider = volumeView.subviews.first(where: { $0 is UISlider }) as? UISlider

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.01) {
            slider?.value = volume
        }
    }
}

func ImageForVolumeLevel(level: Float) -> some View {
    let allowedRange = 0.0...1.0
    precondition(allowedRange.contains(Double(level)))

    var systemName = "speaker.slash.fill"
    
//    switch (level) {
//    case 0.0 :              systemName = "speaker.slash.fill"
//    case 0.0..<0.333 :      systemName = "speaker.wave.1.fill"
//    case 0.333..<0.666 :    systemName = "speaker.wave.2.fill"
//    case 0.666...1 :        systemName = "speaker.wave.3.fill"
//    default:                unreachable()
//    }
    
    switch (level) {
    case 0.0: systemName = "speaker.slash.fill"
    default: systemName = "speaker.wave.3.fill"
    }
    
    return Image(systemName: systemName, variableValue: Double(level))
        .imageScale(.large)
}

struct VolumeImageView: View {
    @State private var volume: Float = 0
    private let action: (() -> Void)?
    
    public init(action: (() -> Void)? = nil) {
        self.action = action
    }
    
    var body: some View {
        Button(action: { action?() }) {
            ImageForVolumeLevel(level: volume)
        }
        .onReceive(AVAudioSession.sharedInstance().publisher(for: \.outputVolume), perform: { value in
            self.volume = value
        })
        .buttonStyle(.plain)
        .frameForLargestSymbol(symbols: ["speaker.slash.fill",
                                         "speaker.wave.1.fill",
                                         "speaker.wave.2.fill",
                                         "speaker.wave.3.fill"],
                               alignment: .leading)
    }
}

struct VolumePopupView: View {
    @Binding var volumeIsShowing : Bool

    @State var volume: Float = 0
    @State var timer = Timer.publish(every: 5, on: .main, in: .common).autoconnect()
    
    var body: some View {
        HStack {
            Slider(value: $volume, onEditingChanged: { data in
                MPVolumeView.setVolume(self.volume)
            })
            .controlSize(.small)
            .onReceive(AVAudioSession.sharedInstance().publisher(for: \.outputVolume), perform: { value in
                self.volume = value
            })
            .padding(.leading)
            
            ImageForVolumeLevel(level: volume)
            .frameForLargestSymbol(symbols: ["speaker.slash.fill",
                                             "speaker.wave.1.fill",
                                             "speaker.wave.2.fill",
                                             "speaker.wave.3.fill"],
                                   alignment: .leading,
                                   scale: .large)
            .simultaneousGesture(volumeIsShowing ? TapGesture().onEnded {
                volumeIsShowing = false
            } : nil)
            .padding(10)
        }
        // TODO should have a 5s inactivity timer self-dismiss
        // see https://stackoverflow.com/questions/63927489/how-to-track-all-touches-across-swiftui-app
        
        //MPVolumeViewRepresenter()   // TODO this doesn't work in the simulator
            //.frame(height: 24)
            //.offset(y: 2) // centering
    }
}

struct MPVolumeViewRepresenter: UIViewRepresentable {

    func makeUIView(context: Context) -> MPVolumeView {
        MPVolumeView(frame: .zero)
    }

    func updateUIView(_ uiView: MPVolumeView, context: UIViewRepresentableContext<MPVolumeViewRepresenter>) {}

}

#Preview {
    @State var volumeIsShowing : Bool = true
    return VolumePopupView(volumeIsShowing: $volumeIsShowing).previewLayout(.sizeThatFits)
}