//
//  View+AppListStyle.swift
//  Tusker
//
//  Created by Shadowfacts on 2/6/23.
//  Copyright © 2023 Shadowfacts. All rights reserved.
//

import SwiftUI
import Combine
import TuskerPreferences

extension View {
    func appGroupedListBackground(container: UIAppearanceContainer.Type) -> some View {
        self.modifier(AppGroupedListBackground(container: container))
    }
    
    func appGroupedListRowBackground() -> some View {
        self.modifier(AppGroupedListRowBackground())
    }
}

private struct AppGroupedListBackground: ViewModifier {
    let container: any UIAppearanceContainer.Type
    @Environment(\.colorScheme) private var colorScheme
    @Environment(\.pureBlackDarkMode) private var environmentPureBlackDarkMode
    
    private var pureBlackDarkMode: Bool {
        // using @PreferenceObserving just does not work for this, so try the environment key when available
        // if it's not available, the color won't update automatically, but it will be correct when the view is created
        if #available(iOS 17.0, *) {
            environmentPureBlackDarkMode
        } else {
            false
        }
    }
    
    func body(content: Content) -> some View {
        if #available(iOS 16.0, *) {
            if colorScheme == .dark, !pureBlackDarkMode {
                content
                    .scrollContentBackground(.hidden)
                    .background(Color.appGroupedBackground.edgesIgnoringSafeArea(.all))
            } else {
                content
            }
        } else {
            content
                .onAppear {
                    UITableView.appearance(whenContainedInInstancesOf: [container]).backgroundColor = .appGroupedBackground
                }
        }
    }
}

private struct AppGroupedListRowBackground: ViewModifier {
    @Environment(\.colorScheme) private var colorScheme
    @PreferenceObserving(\.$pureBlackDarkMode) private var pureBlackDarkMode
    
    func body(content: Content) -> some View {
        if colorScheme == .dark, !pureBlackDarkMode {
            content
                .listRowBackground(Color.appGroupedCellBackground)
        } else {
            content
        }
    }
}

@propertyWrapper
private struct PreferenceObserving<Key: TuskerPreferences.PreferenceKey>: DynamicProperty {
    typealias PrefKeyPath = KeyPath<PreferenceStore, PreferencePublisher<Key>>
    
    let keyPath: PrefKeyPath
    @StateObject private var observer: Observer
    
    init(_ keyPath: PrefKeyPath) {
        self.keyPath = keyPath
        self._observer = StateObject(wrappedValue: Observer(keyPath: keyPath))
    }
    
    var wrappedValue: Key.Value {
        Preferences.shared.getValue(preferenceKeyPath: keyPath)
    }
    
    @MainActor
    private class Observer: ObservableObject {
        private var cancellable: AnyCancellable?
        
        init(keyPath: PrefKeyPath) {
            cancellable = Preferences.shared[keyPath: keyPath].sink { [unowned self] _ in
                self.objectWillChange.send()
            }
        }
    }
}