module CyberarmEngine
  class Element
    class EditLine < Button
      class TextInput < Gosu::TextInput
        def filter=(filter)
          @filter = filter
        end

        def filter(text_in)
          if @filter
            @filter.call(text_in)
          else
            text_in
          end
        end
      end

      def initialize(text, options = {}, block = nil)
        @filter = options.delete(:filter)
        super(text, options, block)

        @type = default(:type)

        @caret_width = default(:caret_width)
        @caret_height = @text.textobject.height
        @caret_color = default(:caret_color)
        @caret_interval = default(:caret_interval)
        @caret_last_interval = Gosu.milliseconds
        @show_caret = true

        @text_input = TextInput.new
        @text_input.filter = @filter
        @text_input.text = text
        @last_text_value = text
        @last_caret_position = @text_input.caret_pos

        @offset_x = 0
        @offset_y = 0

        event(:begin_drag)
        event(:drag_update)
        event(:end_drag)
      end

      def render
        Gosu.clip_to(@text.x, @text.y, @width, @height) do
          Gosu.translate(-@offset_x, -@offset_y) do
            draw_selection
            draw_caret if @focus && @show_caret
            draw_text
          end
        end
      end

      def draw_text
        @text.draw(:draw_text)
      end

      def draw_caret
        Gosu.draw_rect(caret_position, @text.y, @caret_width, @caret_height, @caret_color, @z)
      end

      def draw_selection
        selection_width = caret_position - selection_start_position

        Gosu.draw_rect(selection_start_position, @text.y, selection_width, @text.height, default(:selection_color), @z)
      end

      def update
        @style_event = :active if @focus

        @text.text = if @type == :password
                       default(:password_character) * @text_input.text.length
                     else
                       @text_input.text
                     end

        if @last_text_value != value
          @last_text_value = value
          @show_caret = true
          @caret_last_interval = Gosu.milliseconds

          publish(:changed, value)
        end

        if @last_caret_position != @text_input.caret_pos
          @last_caret_position = @text_input.caret_pos
          @show_caret = true
          @caret_last_interval = Gosu.milliseconds
        end

        if Gosu.milliseconds >= @caret_last_interval + @caret_interval
          @caret_last_interval = Gosu.milliseconds

          @show_caret = !@show_caret
        end

        keep_caret_visible
      end

      def button_down(id)
        handle_keyboard_shortcuts(id)
      end

      def handle_keyboard_shortcuts(id)
        return unless @focus && @enabled

        if Gosu.button_down?(Gosu::KB_LEFT_CONTROL) || Gosu.button_down?(Gosu::KB_RIGHT_CONTROL)
          case id
          when Gosu::KB_A
            @text_input.selection_start = 0
            @text_input.caret_pos = @text_input.text.length

          when Gosu::KB_C
            Gosu.clipboard = if @text_input.selection_start < @text_input.caret_pos
                               @text_input.text[@text_input.selection_start...@text_input.caret_pos]
                             else
                               @text_input.text[@text_input.caret_pos...@text_input.selection_start]
                             end

          when Gosu::KB_X
            chars = @text_input.text.chars

            if @text_input.selection_start < @text_input.caret_pos
              Gosu.clipboard = @text_input.text[@text_input.selection_start...@text_input.caret_pos]
              chars.slice!(@text_input.selection_start, @text_input.caret_pos)
            else
              Gosu.clipboard = @text_input.text[@text_input.caret_pos...@text_input.selection_start]
              chars.slice!(@text_input.caret_pos, @text_input.selection_start)
            end

            @text_input.text = chars.join

          when Gosu::KB_V
            if instance_of?(EditLine) # EditLine assumes a single line of text
              @text_input.insert_text(Gosu.clipboard.gsub("\n", ""))
            else
              @text_input.insert_text(Gosu.clipboard)
            end
          end
        end
      end

      def caret_position_under_mouse(mouse_x)
        1.upto(@text.text.length) do |i|
          return i - 1 if mouse_x < @text.x - @offset_x + @text.width(@text.text[0...i])
        end

        @text_input.text.length
      end

      def move_caret_to_mouse(mouse_x, _mouse_y)
        @text_input.caret_pos = @text_input.selection_start = caret_position_under_mouse(mouse_x)
      end

      def keep_caret_visible
        caret_pos = (caret_position - @text.x) + @caret_width

        @last_text ||= "/\\"
        @last_pos ||= -1

        @last_text = @text.text
        @last_pos = caret_pos

        if caret_pos.between?(@offset_x, @width + @offset_x)
          # Do nothing

        elsif caret_pos < @offset_x
          @offset_x = if caret_pos > @width
                        caret_pos + @width
                      else
                        0
                      end

        elsif caret_pos > @width
          @offset_x = caret_pos - @width

        else
          # Reset to Zero
          @offset_x = 0
        end
      end

      def caret_position
        text_input_position_for(:caret_pos)
      end

      def selection_start_position
        text_input_position_for(:selection_start)
      end

      def text_input_position_for(method)
        if @type == :password
          @text.x + @text.width(default(:password_character) * @text_input.text[0...@text_input.send(method)].length)
        else
          @text.x + @text.width(@text_input.text[0...@text_input.send(method)]) - @style.border_thickness_left
        end
      end

      def left_mouse_button(sender, x, y)
        super
        window.text_input = @text_input

        @caret_last_interval = Gosu.milliseconds
        @show_caret = true

        move_caret_to_mouse(x, y)

        :handled
      end

      def focus(sender)
        @focus = true
        window.text_input = @text_input
        @text_input.caret_pos = @text_input.selection_start = @text_input.text.length

        update_styles(:active)

        :handled
      end

      def enter(sender)
        if @enabled && @focus
          update_styles(:active)
        elsif @enabled && !@focus
          update_styles(:hover)
        else
          update_styles(:disabled)
        end

        :handled
      end

      def leave(sender)
        if @enabled && @focus
          update_styles(:active)
        elsif @enabled && !@focus
          update_styles
        else
          update_styles(:disabled)
        end

        :handled
      end

      def blur(_sender)
        super
        window.text_input = nil

        :handled
      end

      def draggable?(button)
        button == :left
      end

      def begin_drag(_sender, x, _y, _button)
        @drag_start = x
        @offset_drag_start = @offset_x
        @drag_caret_position = @text_input.caret_pos

        :handled
      end

      def drag_update(_sender, x, _y, _button)
        @text_input.caret_pos = caret_position_under_mouse(x)

        :handled
      end

      def end_drag(_sender, _x, _y, _button)
        :handled
      end

      def recalculate
        super

        @width = dimensional_size(@style.width, :width) || default(:width)
        update_background
      end

      def value
        @text_input.text
      end

      def value=(string)
        @text_input.text = string
      end
    end
  end
end