Retrospring/app/helpers/theme_helper.rb

# frozen_string_literal: true

module ThemeHelper
  ATTRIBUTE_MAP = {
    "primary_color"      => %w[primary primary-rgb],
    "primary_text"       => "primary-text",
    "danger_color"       => "danger",
    "danger_text"        => "danger-text",
    "warning_color"      => "warning",
    "warning_text"       => "warning-text",
    "info_color"         => "info",
    "info_text"          => "info-text",
    "success_color"      => "success",
    "success_text"       => "success-text",
    "dark_color"         => "dark",
    "dark_text"          => "dark-text",
    "light_color"        => "light",
    "light_text"         => "light-text",
    "raised_background"  => %w[raised-bg raised-bg-rgb],
    "raised_text"        => "raised-text",
    "raised_accent"      => %w[raised-accent raised-accent-rgb],
    "raised_accent_text" => "raised-accent-text",
    "background_color"   => "background",
    "body_text"          => "body-text",
    "input_color"        => "input-bg",
    "input_text"         => "input-text",
    "input_placeholder"  => "input-placeholder",
    "muted_text"         => "muted-text"
  }.freeze

  def render_theme
    theme = get_active_theme

    return unless theme

    body = ":root {\n"

    theme.attributes.each do |k, v|
      next unless ATTRIBUTE_MAP.key?(k)

      Array(ATTRIBUTE_MAP[k]).each do |var|
        body += "\t--#{var}: #{get_color_for_key(var, v)};\n"
      end
    end
    body += "\t--turbolinks-progress-color: ##{lighten(theme.primary_color)}\n}"

    content_tag(:style, body)
  end

  def get_color_for_key(key, color)
    hex = get_hex_color_from_theme_value(color)

    if key.include?("text") || key.include?("placeholder") || key.include?("rgb")
      get_decimal_triplet_from_hex(hex)
    else
      "##{hex}"
    end
  end

  def theme_color
    theme = get_active_theme
    if theme
      theme.theme_color
    else
      "#5e35b1"
    end
  end

  def mobile_theme_color
    theme = get_active_theme
    if theme
      theme.mobile_theme_color
    else
      "#f0edf4"
    end
  end

  def get_active_theme
    if @user&.theme
      if user_signed_in?
        if current_user&.show_foreign_themes?
          @user.theme
        else
          current_user&.theme
        end
      else
        @user.theme
      end
    elsif @answer&.user&.theme
      if user_signed_in?
        if current_user&.show_foreign_themes?
          @answer.user.theme
        else
          current_user&.theme
        end
      else
        @answer.user.theme
      end
    elsif current_user&.theme
      current_user.theme
    end
  end

  def get_hex_color_from_theme_value(value)
    "0000000#{value.to_s(16)}"[-6, 6]
  end

  def get_decimal_triplet_from_hex(value)
    hexes = value.split(/(.{2})/).reject(&:empty?)
    hexes.map(&:hex).join(", ")
  end

  def rgb_values_from_hex(value)
    [
      (value & 0xFF0000) >> 16, # R
      (value & 0x00FF00) >> 8, # G
      value & 0x0000FF # B
    ]
  end

  def rgb_to_hex(rgb_values)
    rgb_values.map.with_index { |v, i| v << ((2 - i) * 8) }.reduce(&:+).to_s(16)
  end

  def lighten(value, amount = 0.25)
    rgb_to_hex(rgb_values_from_hex(value).map { |v| [(v + (255 * amount)).round, 255].min })
  end
end