#!/usr/bin/env ruby

require 'stringio'

module RTF
   # This class represents a font for use with some RTF content.
   class Font
      # A declaration for a font family. This family is used for monospaced
      # fonts (e.g. Courier New).
      MODERN                        = :modern

      # A declaration for a font family. This family is used for proportionally
      # spaced serif fonts (e.g. Arial, Times New Roman).
      ROMAN                         = :roman

      # A declaration for a font family. This family is used for proportionally
      # spaced sans serif fonts (e.g. Tahoma, Lucida Sans).
      SWISS                         = :swiss

      # A declaration for a font family. This family is used where none of the
      # other families apply.
      NIL                           = 'nil'.intern


      # Attribute accessor.
      attr_reader :family, :name


      # This is the constructor for the Font class.
      #
      # ==== Parameters
      # family::  The font family for the new font. This should be one of
      #           Font::MODERN, Font::ROMAN, Font::SWISS or
      #           Font::NIL.
      # name::    A string containing the font name.
      #
      # ==== Exceptions
      # RTFError::  Generated whenever an invalid font family is specified.
      def initialize(family, name)
         # Check that a valid family has been provided.
         if ![MODERN, ROMAN, SWISS, NIL].include?(family)
            RTFError::fire("Unknown font family specified for Font object.")
         end
         @family = family
         @name   = name
      end

      # This method overloads the equivalence test operator for the Font class
      # to allow for Font comparisons.
      #
      # ==== Parameters
      # object::  A reference to the object to be compared with.
      def ==(object)
         object.instance_of?(Font) &&
         object.family == @family &&
         object.name   == @name
      end

      # This method fetches a textual description for a Font object.
      #
      # ==== Parameters
      # indent::  The number of spaces to prefix to the lines generated by the
      #           method. Defaults to zero.
      def to_s(indent=0)
         prefix = indent > 0 ? ' ' * indent : ''
         "#{prefix}Family: #{@family.id2name}, Name: #{@name}"
      end

      # This method generates the RTF representation for a Font object as it
      # would appear within a document font table.
      #
      # ==== Parameters
      # indent::  The number of spaces to prefix to the lines generated by the
      #           method. Defaults to zero.
      def to_rtf(indent=0)
         prefix = indent > 0 ? ' ' * indent : ''
         "#{prefix}\\f#{@family.id2name} #{@name};"
      end
   end # End of the Font class.


   # This class represents the font table for an RTF document. An instance of
   # the class is used internally by the Document class and should not need to
   # be explicitly instantiated (although it can be obtained from a Document
   # object if needed).
   class FontTable
      # This is the constructor for the RTFTable class.
      #
      # ==== Parameters
      # *fonts::  Zero or more font objects that are to be added to the font
      #           table. Objects that are not Fonts will be ignored.
      def initialize(*fonts)
         @fonts = []
         fonts.each {|font| add(font)}
      end

      # This method is used to retrieve a count of the number of fonts held
      # within an instance of the FontTable class.
      def size
         @fonts.size
      end

      # This method adds a font to a FontTable instance. This method returns
      # a reference to the FontTable object updated.
      #
      # ==== Parameters
      # font::  A reference to the font to be added. If this is not a Font
      #         object or already exists in the table it will be ignored.
      def add(font)
         if font.instance_of?(Font)
            @fonts.push(font) if @fonts.index(font).nil?
         end
         self
      end

      # This method iterates over the contents of a FontTable object. This
      # method expects a block that takes a single parameter (the next font
      # from the table).
      def each
         @fonts.each {|font| yield font} if block_given?
      end

      # This method overloads the array dereference operator for the FontTable
      # class.
      #
      # ==== Parameters
      # index::  The index into the font table of the font to be retrieved. If
      #          the index is invalid then nil is returned.
      def [](index)
         @fonts[index]
      end

      # This method fetches the index of a font within a FontTable object. If
      # the font does not exist in the table then nil is returned.
      #
      # ==== Parameters
      # font::  A reference to the font to check for.
      def index(font)
         @fonts.index(font)
      end

      # This method generates a textual description for a FontTable object.
      #
      # ==== Parameters
      # indent::  The number of spaces to prefix to the lines generated by the
      #           method. Defaults to zero.
      def to_s(indent=0)
         prefix = indent > 0 ? ' ' * indent : ''
         text   = StringIO.new
         text << "#{prefix}Font Table (#{@fonts.size} fonts)"
         @fonts.each {|font| text << "\n#{prefix}   #{font}"}
         text.string
      end

      # This method generates the RTF text for a FontTable object.
      #
      # ==== Parameters
      # indent::  The number of spaces to prefix to the lines generated by the
      #           method. Defaults to zero.
      def to_rtf(indent=0)
         prefix = indent > 0 ? ' ' * indent : ''
         text   = StringIO.new
         text << "#{prefix}{\\fonttbl"
         @fonts.each_index do |index|
            text << "\n#{prefix}{\\f#{index}#{@fonts[index].to_rtf}}"
         end
         text << "\n#{prefix}}"
         text.string
      end

      alias << add
   end # End of the FontTable class.
end # End of the RTF module.