TodosApp/Todos/Model/Category.swift

//
//  Category.swift
//  Todos
//
//  Created by Sam Jaffe on 3/2/26.
//

import Foundation
import SwiftUI

// https://gist.github.com/peterfriese/bb2fc5df202f6a15cc807bd87ff15193
// Inspired by https://cocoacasts.com/from-hex-to-uicolor-and-back-in-swift
// Make Color codable. This includes support for transparency.
// See https://www.digitalocean.com/community/tutorials/css-hex-code-colors-alpha-values
extension Color: @retroactive Codable {
#if os(macOS)
    fileprivate typealias UnifiedColor = NSColor
#endif
    
#if os(iOS)
    fileprivate typealias UnifiedColor = UIColor
#endif
  
  init(hex: String) {
    var hexSanitized = hex.trimmingCharacters(in: .whitespacesAndNewlines)
    hexSanitized = hexSanitized.replacingOccurrences(of: "#", with: "")
    
    var rgb: UInt64 = 0
    
    var r: CGFloat = 0.0
    var g: CGFloat = 0.0
    var b: CGFloat = 0.0
    var a: CGFloat = 1.0
    
    let length = hexSanitized.count
    
    Scanner(string: hexSanitized).scanHexInt64(&rgb)
    
    if length == 6 {
      r = CGFloat((rgb & 0xFF0000) >> 16) / 255.0
      g = CGFloat((rgb & 0x00FF00) >> 8) / 255.0
      b = CGFloat(rgb & 0x0000FF) / 255.0
    } else if length == 8 {
      r = CGFloat((rgb & 0xFF000000) >> 24) / 255.0
      g = CGFloat((rgb & 0x00FF0000) >> 16) / 255.0
      b = CGFloat((rgb & 0x0000FF00) >> 8) / 255.0
      a = CGFloat(rgb & 0x000000FF) / 255.0
    }

    self.init(.sRGB,
              red: Double(r),
              green: Double(g),
              blue: Double(b),
              opacity: Double(a))
  }
  
  public init(from decoder: Decoder) throws {
    let container = try decoder.singleValueContainer()
    let hex = try container.decode(String.self)
    
    self.init(hex: hex)
  }
  
  public func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()
    try container.encode(hex)
  }
  
  var hex: String? {
    return toHex()
  }
  
  func toHex(alpha: Bool = false) -> String? {
    guard let components = UnifiedColor(self).cgColor.components, components.count >= 3 else {
        return nil
    }
    
    let r = Float(components[0])
    let g = Float(components[1])
    let b = Float(components[2])
    var a = Float(1.0)
    
    if components.count >= 4 {
      a = Float(components[3])
    }
    
    if alpha {
      return String(format: "%02lX%02lX%02lX%02lX",
                    lroundf(r * 255),
                    lroundf(g * 255),
                    lroundf(b * 255),
                    lroundf(a * 255))
    } else {
      return String(format: "%02lX%02lX%02lX",
                    lroundf(r * 255),
                    lroundf(g * 255),
                    lroundf(b * 255))
    }
  }
}

final class Category : Identifiable, Codable {
  var name: String = ""
  var color: Color = Color(.gray)
  
  var id: String { name }
  
  init() {}
  
  init(name: String, color: Color) {
    self.name = name
    self.color = color
  }
  
  var valid: Bool { !name.isEmpty }
}