require 'clevic/swing/delegate'
require 'clevic/swing/tag_editor.rb'

module Clevic

=begin rdoc
Delegate for doing simple multi-value fields. Tags, basically.
=end
class TagDelegate < Delegate
  # Create a GUI widget and fill it with the possible values.
  def init_component( cell_editor = nil )
    line_editor edit_value
    # This should be a collection of entities from the related table
    @items = attribute_value
  end
  
  # Return the GUI component / widget that is displayed when editing.
  # Usually this will be a combo box widget, but it can be a text editor
  # in some cases.
  attr_reader :editor
  
  # the cell must be selected before the edit can be clicked
  def needs_pre_selection?
    true
  end
  
  # Return a string to be shown to the user.
  # model_value is an item stored in the combo box model.
  def display_for( model_value )
    field.transform_attribute( model_value )
  end
  
  def line_editor( value = nil )
    @line_editor ||= javax.swing.JTextField.new( value ).tap do |line|
      line.font = Clevic.tahoma
    end
  end
  
  def editor
    line_editor
  end
  
  # Recreate the model and fill it with anything in population that
  # matches the prefix first, followed by anything in the population that
  # doesn't match the prefix.
  # Then set the editor text value to either text, or to the previous
  # value.
  # Order is important: if the text is set first it's overridden when
  # the model is populated.
  def repopulate( prefix = nil, text = nil )
    autocomplete do
      # save text and popup
      save_item = editor.editor.item
      dropdown_visible = editor.popup_visible?
      
      # repopulate based on the prefix
      prefix ||= editor.editor.item
      editor.model = editor.model.class.new
      # split set into things to display at the top, and things to display further down
      matching, non_matching = population.partition{ |item| display_for( item ) =~ /^#{prefix}/i }
      matching.each {|item| editor << item}
      non_matching.each {|item| editor << item}
      
      # restore text and popup
      editor.editor.item = text || save_item
      editor.popup_visible = dropdown_visible
    end
  end
    
  # make sure we don't react to document change events
  # while we're doing autocompletion. Reentrant
  def autocomplete( &block )
    @autocompleting = true
    yield
  ensure
    @autocompleting = false
  end
  
  # http://www.drdobbs.com/184404457 for autocompletion steps
  def filter_prefix( prefix )
    # search for matching item in the UI display_for for the items in the combo model
    candidate = population.map{|item| display_for( item ) }.select {|x| x =~ /^#{prefix}/i }.first
    unless candidate.nil?
      first_not_of = candidate.match( /^#{prefix}/i ).offset(0).last
      invoke_later do
        autocomplete do
          # set the shortlist, and the text editor value
          repopulate prefix, candidate
          
          # set the suggestion selection
          editor.editor.editor_component.with do |text_edit|
            # highlight the suggested match, and leave caret
            # at the beginning of the suggested text
            text_edit.caret_position = candidate.length
            text_edit.move_caret_position( first_not_of )
          end
        end
      end
    end
  end
  
  # open the combo box, just like if F4 was pressed
  # big trouble here with JComboBox firing an comboEdited action
  # (probably) on focusGained
  # which causes the popup to be hidden again
  def full_edit
    # Must request focus and then once focus is received, show popup.
    # Otherwise focus received hides popup.
    invoke_later do
      #~ editor.add_focus_listener( LittleFocusPopper.new )
      #~ editor.request_focus_in_window
      editor.show_popup
    end
  end
  
  # open the text editor component
  #~ def minimal_edit
  #~ end
  
  # return an array of related entity objects, to be
  # passed into the attribute setter
  def value
    "the value"
  end
end

end