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 red: CGFloat = 0.0
    var green: CGFloat = 0.0
    var blue: CGFloat = 0.0
    var opacity: CGFloat = 1.0

    let length = hexSanitized.count

    Scanner(string: hexSanitized).scanHexInt64(&rgb)

    if length == 6 {
      red = CGFloat((rgb & 0xFF0000) >> 16) / 255.0
      green = CGFloat((rgb & 0x00FF00) >> 8) / 255.0
      blue = CGFloat(rgb & 0x0000FF) / 255.0
    } else if length == 8 {
      red = CGFloat((rgb & 0xFF000000) >> 24) / 255.0
      green = CGFloat((rgb & 0x00FF0000) >> 16) / 255.0
      blue = CGFloat((rgb & 0x0000FF00) >> 8) / 255.0
      opacity = CGFloat(rgb & 0x000000FF) / 255.0
    }

    self.init(.sRGB,
          red: Double(red),
          green: Double(green),
          blue: Double(blue),
          opacity: Double(opacity))
  }

  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 red = Float(components[0])
    let green = Float(components[1])
    let blue = Float(components[2])
    var opacity = Float(1.0)

    if components.count >= 4 {
      opacity = Float(components[3])
    }

    if alpha {
      return String(format: "%02lX%02lX%02lX%02lX",
                    lroundf(red * 255),
                    lroundf(green * 255),
                    lroundf(blue * 255),
                    lroundf(opacity * 255))
    } else {
      return String(format: "%02lX%02lX%02lX",
                    lroundf(red * 255),
                    lroundf(green * 255),
                    lroundf(blue * 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 }
}