IceCubesApp/Packages/DesignSystem/Sources/DesignSystem/Theme.swift

import Combine
import SwiftUI

public class Theme: ObservableObject {
  enum ThemeKey: String {
    case colorScheme, tint, label, primaryBackground, secondaryBackground
    case avatarPosition
    case selectedSet, selectedScheme
  }
  
  public enum AvatarPosition: String, CaseIterable {
    case leading, top
    
    public var description: LocalizedStringKey {
      switch self {
      case .leading:
        return "Leading"
      case .top:
        return "Top"
      }
    }
  }
  
  @AppStorage("is_previously_set") private var isSet: Bool = false
  @AppStorage(ThemeKey.selectedScheme.rawValue) public var selectedScheme: ColorScheme = .dark
  @AppStorage(ThemeKey.tint.rawValue) public var tintColor: Color = .black
  @AppStorage(ThemeKey.primaryBackground.rawValue) public var primaryBackgroundColor: Color = .white
  @AppStorage(ThemeKey.secondaryBackground.rawValue) public var secondaryBackgroundColor: Color = .gray
  @AppStorage(ThemeKey.label.rawValue) public var labelColor: Color = .black
  @AppStorage(ThemeKey.avatarPosition.rawValue) var rawAvatarPosition: String = AvatarPosition.top.rawValue
  @AppStorage(ThemeKey.selectedSet.rawValue) var storedSet: ColorSetName = .iceCubeDark
  @Published public var avatarPosition: AvatarPosition = .top
  @Published public var selectedSet: ColorSetName = .iceCubeDark
  
  private var cancellables = Set<AnyCancellable>()
  
  public init() {
    selectedSet = storedSet
    
    // If theme is never set before set the default store. This should only execute once after install.
    
    if !isSet {
      setColor(withName: .iceCubeDark)
      isSet = true
    }
    
    avatarPosition = AvatarPosition(rawValue: rawAvatarPosition) ?? .top
    
    $avatarPosition
      .dropFirst()
      .map(\.rawValue)
      .sink { [weak self] position in
        self?.rawAvatarPosition = position
      }
      .store(in: &cancellables)
    
    // Workaround, since @AppStorage can't be directly observed
    $selectedSet
      .dropFirst()
      .sink { [weak self] colorSetName in
        self?.setColor(withName: colorSetName)
      }
      .store(in: &cancellables)
  }
  
  public static var allColorSet: [ColorSet] {
    [
      IceCubeDark(),
      IceCubeLight(),
      DesertDark(),
      DesertLight(),
      NemesisDark(),
      NemesisLight()
    ]
  }
  
  public func setColor(withName name: ColorSetName) {
    let colorSet = Theme.allColorSet.filter { $0.name == name }.first ?? IceCubeDark()
    self.selectedScheme = colorSet.scheme
    self.tintColor = colorSet.tintColor
    self.primaryBackgroundColor = colorSet.primaryBackgroundColor
    self.secondaryBackgroundColor = colorSet.secondaryBackgroundColor
    self.labelColor = colorSet.labelColor
    self.storedSet = name
  }
}