3 files changed, 173 insertions, 21 deletions
diff --git a/lib/reline.rb b/lib/reline.rb
index 3d1716c81b..fb19982081 100644
--- a/lib/reline.rb
+++ b/lib/reline.rb
@@ -7,6 +7,7 @@ require 'reline/key_stroke'
 require 'reline/line_editor'
 require 'reline/history'
 require 'reline/terminfo'
+require 'reline/face'
 require 'rbconfig'
 
 module Reline
@@ -36,10 +37,8 @@ module Reline
   DialogRenderInfo = Struct.new(
     :pos,
     :contents,
-    :bg_color,
-    :pointer_bg_color,
-    :fg_color,
-    :pointer_fg_color,
+    :face,
+    :bg_color, # For the time being, this line should stay here for the compatibility with IRB.
     :width,
     :height,
     :scrollbar,
@@ -260,10 +259,7 @@ module Reline
         contents: result,
         scrollbar: true,
         height: [15, preferred_dialog_height].min,
-        bg_color: 46,
-        pointer_bg_color: 45,
-        fg_color: 37,
-        pointer_fg_color: 37
+        face: :completion_dialog
       )
     }
     Reline::DEFAULT_DIALOG_CONTEXT = Array.new
@@ -606,4 +602,6 @@ else
   io
 end
 
+Reline::Face.load_initial_configs
+
 Reline::HISTORY = Reline::History.new(Reline.core.config)
diff --git a/lib/reline/face.rb b/lib/reline/face.rb
new file mode 100644
index 0000000000..b78f3b1ca5
--- /dev/null
+++ b/lib/reline/face.rb
@@ -0,0 +1,157 @@
+# frozen_string_literal: true
+
+class Reline::Face
+  SGR_PARAMETERS = {
+    foreground: {
+      black: 30,
+      red: 31,
+      green: 32,
+      yellow: 33,
+      blue: 34,
+      magenta: 35,
+      cyan: 36,
+      white: 37,
+      bright_black: 90,
+      gray: 90,
+      bright_red: 91,
+      bright_green: 92,
+      bright_yellow: 93,
+      bright_blue: 94,
+      bright_magenta: 95,
+      bright_cyan: 96,
+      bright_white: 97
+    },
+    background: {
+      black: 40,
+      red: 41,
+      green: 42,
+      yellow: 43,
+      blue: 44,
+      magenta: 45,
+      cyan: 46,
+      white: 47,
+      bright_black: 100,
+      gray: 100,
+      bright_red: 101,
+      bright_green: 102,
+      bright_yellow: 103,
+      bright_blue: 104,
+      bright_magenta: 105,
+      bright_cyan: 106,
+      bright_white: 107,
+    },
+    style: {
+      reset: 0,
+      bold: 1,
+      faint: 2,
+      italicized: 3,
+      underlined: 4,
+      slowly_blinking: 5,
+      blinking: 5,
+      rapidly_blinking: 6,
+      negative: 7,
+      concealed: 8,
+      crossed_out: 9
+    }
+  }.freeze
+
+  class Config
+    ESSENTIAL_DEFINE_NAMES = %i(default enhanced scrollbar).freeze
+    RESET_SGR = "\e[0m".freeze
+
+    def initialize(name, &block)
+      @definition = {}
+      block.call(self)
+      ESSENTIAL_DEFINE_NAMES.each do |name|
+        @definition[name] ||= { style: :reset, escape_sequence: RESET_SGR }
+      end
+    end
+
+    attr_reader :definition
+
+    def define(name, **values)
+      values[:escape_sequence] = format_to_sgr(values.to_a).freeze
+      @definition[name] = values
+    end
+
+    def [](name)
+      @definition.dig(name, :escape_sequence) or raise ArgumentError, "unknown face: #{name}"
+    end
+
+    private
+
+    def sgr_rgb(key, value)
+      return nil unless rgb_expression?(value)
+      case key
+      when :foreground
+        "38;2;"
+      when :background
+        "48;2;"
+      end + value[1, 6].scan(/../).map(&:hex).join(";")
+    end
+
+    def format_to_sgr(ordered_values)
+      sgr = "\e[" + ordered_values.map do |key_value|
+        key, value = key_value
+        case key
+        when :foreground, :background
+          case value
+          when Symbol
+            SGR_PARAMETERS[key][value]
+          when String
+            sgr_rgb(key, value)
+          end
+        when :style
+          [ value ].flatten.map do |style_name|
+            SGR_PARAMETERS[:style][style_name]
+          end.then do |sgr_parameters|
+            sgr_parameters.include?(nil) ? nil : sgr_parameters
+          end
+        end.then do |rendition_expression|
+          unless rendition_expression
+            raise ArgumentError, "invalid SGR parameter: #{value.inspect}"
+          end
+          rendition_expression
+        end
+      end.join(';') + "m"
+      sgr == RESET_SGR ? RESET_SGR : RESET_SGR + sgr
+    end
+
+    def rgb_expression?(color)
+      color.respond_to?(:match?) and color.match?(/\A#[0-9a-fA-F]{6}\z/)
+    end
+  end
+
+  private_constant :SGR_PARAMETERS, :Config
+
+  def self.[](name)
+    @configs[name]
+  end
+
+  def self.config(name, &block)
+    @configs ||= {}
+    @configs[name] = Config.new(name, &block)
+  end
+
+  def self.configs
+    @configs.transform_values(&:definition)
+  end
+
+  def self.load_initial_configs
+    config(:default) do |conf|
+      conf.define :default, style: :reset
+      conf.define :enhanced, style: :reset
+      conf.define :scrollbar, style: :reset
+    end
+    config(:completion_dialog) do |conf|
+      conf.define :default, foreground: :white, background: :cyan
+      conf.define :enhanced, foreground: :white, background: :magenta
+      conf.define :scrollbar, foreground: :white, background: :cyan
+    end
+  end
+
+  def self.reset_to_initial_configs
+    @configs = {}
+    load_initial_configs
+  end
+end
diff --git a/lib/reline/line_editor.rb b/lib/reline/line_editor.rb
index 0d990c2c0a..d71b903701 100644
--- a/lib/reline/line_editor.rb
+++ b/lib/reline/line_editor.rb
@@ -831,27 +831,24 @@ class Reline::LineEditor
       dialog.column = 0
       dialog.width = @screen_size.last
     end
+    face = Reline::Face[dialog_render_info.face || :default]
+    scrollbar_sgr = face[:scrollbar]
+    default_sgr = face[:default]
+    enhanced_sgr = face[:enhanced]
     dialog.contents = contents.map.with_index do |item, i|
-      if i == pointer
-        fg_color = dialog_render_info.pointer_fg_color
-        bg_color = dialog_render_info.pointer_bg_color
-      else
-        fg_color = dialog_render_info.fg_color
-        bg_color = dialog_render_info.bg_color
-      end
+      line_sgr = i == pointer ? enhanced_sgr : default_sgr
       str_width = dialog.width - (scrollbar_pos.nil? ? 0 : @block_elem_width)
       str = padding_space_with_escape_sequences(Reline::Unicode.take_range(item, 0, str_width), str_width)
-      colored_content = "\e[#{bg_color}m\e[#{fg_color}m#{str}"
+      colored_content = "#{line_sgr}#{str}"
       if scrollbar_pos
-        color_seq = "\e[37m"
         if scrollbar_pos <= (i * 2) and (i * 2 + 1) < (scrollbar_pos + bar_height)
-          colored_content + color_seq + @full_block
+          colored_content + scrollbar_sgr + @full_block
         elsif scrollbar_pos <= (i * 2) and (i * 2) < (scrollbar_pos + bar_height)
-          colored_content + color_seq + @upper_half_block
+          colored_content + scrollbar_sgr + @upper_half_block
         elsif scrollbar_pos <= (i * 2 + 1) and (i * 2) < (scrollbar_pos + bar_height)
-          colored_content + color_seq + @lower_half_block
+          colored_content + scrollbar_sgr + @lower_half_block
         else
-          colored_content + color_seq + ' ' * @block_elem_width
+          colored_content + scrollbar_sgr + ' ' * @block_elem_width
         end
       else
         colored_content