# frozen_string_literal: true

require "stylegen/data"

module Stylegen
  class Generator
    def initialize(data)
      @data = Data.new(data)
      @file = File.open(@data.output_path, "w")
    end

    def out(line)
      @file << line << "\n"
    end

    def generate
      generate_header
      generate_struct
      generate_colors
      generate_extensions
    end

    def stats
      @stats ||= { output_path: @data.output_path, color_count: @data.colors.count }
    end

    private

    def generate_header
      out "//"
      out "//  #{@data.basename}"
      out "//"
      out "//  Autogenerated by stylegen (v#{@data.version})"
      out "//  DO NOT EDIT"
      out "//"
      out ""
      out "import UIKit"
      out ""
    end

    def generate_struct
      out "#{@data.access_level} struct #{@data.struct_name} {"
      out ""
      out "    let uiColor: UIColor"
      out ""
      out "    fileprivate init(white: CGFloat, alpha: CGFloat) {"
      out "        self.uiColor = UIColor(white: white, alpha: alpha)"
      out "    }"
      out ""
      out "    fileprivate init(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {"
      out "        self.uiColor = UIColor(red: red, green: green, blue: blue, alpha: alpha)"
      out "    }"
      out ""
      out "    fileprivate init(_ color: UIColor) {"
      out "        self.uiColor = color"
      out "    }"
      out ""
      out "    fileprivate init(light: #{@data.struct_name}, dark: #{@data.struct_name}) {"
      out "        if #available(iOS 13.0, *) {"
      out "            self.uiColor = UIColor(dynamicProvider: { (traits: UITraitCollection) -> UIColor in"
      out "                switch traits.userInterfaceStyle {"
      out "                case .dark:"
      out "                    return dark.uiColor"
      out "                default:"
      out "                    return light.uiColor"
      out "                }"
      out "            })"
      out "        } else {"
      out "            self.uiColor = light.uiColor"
      out "        }"
      out "    }"
      out ""
      out "    fileprivate init(base: #{@data.struct_name}, elevated: #{@data.struct_name}) {"
      out "        if #available(iOS 13.0, *) {"
      out "            self.uiColor = UIColor(dynamicProvider: { (traits: UITraitCollection) -> UIColor in"
      out "                switch traits.userInterfaceLevel {"
      out "                case .elevated:"
      out "                    return elevated.uiColor"
      out "                default:"
      out "                    return base.uiColor"
      out "                }"
      out "            })"
      out "        } else {"
      out "            self.uiColor = base.uiColor"
      out "        }"
      out "    }"
      out ""
      out "}"
      out ""
    end

    def generate_colors
      out "#{@data.access_level} extension #{@data.struct_name} {"
      out ""

      @data.colors.each do |member, color|
        out "    static let #{member} = #{color.to_s(@data.struct_name, 4)}"
        out ""
      end

      out "}"
      out ""
    end

    def generate_extensions
      out "#{@data.access_level} extension UIColor {"
      out ""
      out "    @inline(__always)"
      out "    static func #{@data.util_method_name}(_ color: #{@data.struct_name}) -> UIColor {"
      out "       return color.uiColor"
      out "    }"
      out ""
      out "}"
      out ""

      out "#{@data.access_level} extension CGColor {"
      out ""
      out "    @inline(__always)"
      out "    static func #{@data.util_method_name}(_ color: #{@data.struct_name}) -> CGColor {"
      out "       return color.uiColor.cgColor"
      out "    }"
      out ""
      out "}"
    end
  end
end