#!/usr/bin/env ruby -w
# encoding: UTF-8
#
# = XMLElement.rb -- The TaskJuggler III Project Management Software
#
# Copyright (c) 2006, 2007, 2008, 2009 by Chris Schlaeger <cs@kde.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#

require 'UTF8String'

class TaskJuggler

  # This class models an XML node that may contain other XML nodes. XML element
  # trees can be constructed with the class constructor and converted into XML.
  class XMLElement

    attr_writer :mayNotBeEmpty

    # Construct a new XML element and include it in an existing XMLElement tree.
    def initialize(name, attributes = {})
      if (name.nil? && attributes.length > 0) ||
         (!name.nil? && !name.is_a?(String))
        raise "Name must be nil or a String "
      end
      @name = name
      attributes.each do |n, v|
        if n.nil? || v.nil?
          raise "Attribute name (#{n}) or value (#{v}) may not be nil"
        end
      end
      @attributes = attributes
      @children = []
      # This can be set to true if <name /> is illegal for this element.
      @mayNotBeEmpty = false
    end

    # Add a new child or a set of new childs to the element.
    def <<(arg)
      # If the argument is an array, we have to insert each element
      # individually.
      if arg.is_a?(XMLElement)
        @children << arg
      elsif arg.is_a?(Array)
        @children += arg
      elsif arg.nil?
        # do nothing
      else
        raise 'Elements must be of type XMLElement'
      end
      self
    end

    # Return the element and all sub elements as properly formatted XML.
    def to_s(indent = 0)
      out = '<' + @name
      @attributes.each do |attrName, attrValue|
        out << ' ' + attrName + '="' + quoteAttr(attrValue) + '"'
      end
      if @children.empty? && !@mayNotBeEmpty
        out << '/>'
      else
        out << '>'
        @children.each do |child|
          # We only insert newlines for multiple childs and after a tag has been
          # closed.
          if @children.size > 1 && !child.is_a?(XMLText) && out[-1] == ?>
            out << "\n" + indentation(indent + 1)
          end
          out << child.to_s(indent + 1)
        end
        out << "\n" + indentation(indent) if @children.size > 1 && out[-1] == ?>
        out << '</' + @name + '>'
      end
    end

  protected

    def indentation(indent)
      ' ' * indent
    end

  private

    # Make sure that any double quote in _str_ is properly quoted.
    def quoteAttr(str)
      out = ''
      str.each_utf8_char do |c|
        if c == '"'
          out << '\"'
        else
          out << c
        end
      end

      out
    end

  end

  # This is a specialized XMLElement to represent a simple text.
  class XMLText < XMLElement

    def initialize(text)
      super(nil, {})
      raise 'Text may not be nil' unless text
      @text = text
    end

    def to_s(indent)
      out = ''
      @text.each_utf8_char do |c|
        case c
        when '<'
          out << '&lt;'
        when '>'
          out << '&gt;'
        when '&'
          out << '&amp;'
        else
          out << c
        end
      end

      out
    end

  end

  # This is a convenience class that allows the creation of an XMLText nested
  # into an XMLElement. The _name_ and _attributes_ belong to the XMLElement,
  # the text to the XMLText.
  class XMLNamedText < XMLElement

    def initialize(text, name, attributes = {})
      super(name, attributes)
      self << XMLText.new(text)
    end

  end

  # This is a specialized XMLElement to represent a comment.
  class XMLComment < XMLElement

    def initialize(text = '')
      super(nil, {})
      @text = text
    end

    def to_s(indent)
      '<!-- ' + @text + '-->'
    end

  end

  # This is a specialized XMLElement to represent XML blobs. The content is not
  # interpreted and must be valid XML in the content it is added.
  class XMLBlob < XMLElement

    def initialize(blob = '')
      super(nil, {})
      @blob = blob
    end

    def to_s(indent)
      @blob
    end

  end

end