FEATURE: Theme settings (2) (#5611)

Allows theme authors to specify custom theme settings for the theme. 

Centralizes the theme/site settings into a single construct

lib/theme_settings_manager.rb

@@ -0,0 +1,157 @@
+class ThemeSettingsManager
+  attr_reader :name, :theme, :default
+
+  def self.types
+    ThemeSetting.types
+  end
+
+  def self.create(name, default, type, theme, opts = {})
+    type_name = self.types.invert[type].downcase.capitalize
+    klass = "ThemeSettingsManager::#{type_name}".constantize
+    klass.new(name, default, theme, opts)
+  end
+
+  def initialize(name, default, theme, opts = {})
+    @name = name.to_sym
+    @default = default
+    @theme = theme
+    @opts = opts
+    @types = self.class.types
+  end
+
+  def value
+    has_record? ? db_record.value : @default
+  end
+
+  def type_name
+    self.class.name.demodulize.downcase.to_sym
+  end
+
+  def type
+    @types[type_name]
+  end
+
+  def description
+    @opts[:description]
+  end
+
+  def value=(new_value)
+    ensure_is_valid_value!(new_value)
+
+    record = has_record? ? db_record : create_record!
+    record.value = new_value.to_s
+    record.save!
+    record.value
+  end
+
+  def db_record
+    ThemeSetting.where(name: @name, data_type: type, theme: @theme).first
+  end
+
+  def has_record?
+    db_record.present?
+  end
+
+  def create_record!
+    record = ThemeSetting.new(name: @name, data_type: type, theme: @theme)
+    record.save!
+    record
+  end
+
+  def is_valid_value?(new_value)
+    true
+  end
+
+  def invalid_value_error_message
+    name = type == @types[:integer] || type == @types[:float] ? "number" : type_name
+    primary_key = "themes.settings_errors.#{name}_value_not_valid"
+
+    secondary_key = primary_key
+    secondary_key += "_min" if has_min?
+    secondary_key += "_max" if has_max?
+
+    translation = I18n.t(primary_key)
+    return translation if secondary_key == primary_key
+
+    translation += " #{I18n.t(secondary_key, min: @opts[:min], max: @opts[:max])}"
+    translation
+  end
+
+  def ensure_is_valid_value!(new_value)
+    unless is_valid_value?(new_value)
+      raise Discourse::InvalidParameters.new invalid_value_error_message
+    end
+  end
+
+  def has_min?
+    min = @opts[:min]
+    (min.is_a?(::Integer) || min.is_a?(::Float)) && min != -::Float::INFINITY
+  end
+
+  def has_max?
+    max = @opts[:max]
+    (max.is_a?(::Integer) || max.is_a?(::Float)) && max != ::Float::INFINITY
+  end
+
+  class List    < self; end
+  class String  < self
+    def is_valid_value?(new_value)
+      (@opts[:min]..@opts[:max]).include? new_value.to_s.length
+    end
+  end
+
+  class Bool < self
+    def value
+      [true, "true"].include?(super)
+    end
+
+    def value=(new_value)
+      new_value = ([true, "true"].include?(new_value)).to_s
+      super(new_value)
+    end
+  end
+
+  class Integer < self
+    def value
+      super.to_i
+    end
+
+    def value=(new_value)
+      super(new_value.to_i)
+    end
+
+    def is_valid_value?(new_value)
+      (@opts[:min]..@opts[:max]).include? new_value.to_i
+    end
+  end
+
+  class Float < self
+    def value
+      super.to_f
+    end
+
+    def value=(new_value)
+      super(new_value.to_f)
+    end
+
+    def is_valid_value?(new_value)
+      (@opts[:min]..@opts[:max]).include? new_value.to_f
+    end
+  end
+
+  class Enum < self
+    def value
+      val = super
+      match = choices.find { |choice| choice == val || choice.to_s == val }
+      match || val
+    end
+
+    def is_valid_value?(new_value)
+      choices.include?(new_value) || choices.map(&:to_s).include?(new_value)
+    end
+
+    def choices
+      @opts[:choices]
+    end
+  end
+end