# coding: utf-8

################################################################################
#
# Copyright (C) 2011 James Healy (jimmy@deefa.com)
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
################################################################################

class PDF::Reader
  # A Hash-like object that can convert glyph names into a unicode codepoint.
  # The mapping is read from a data file on disk the first time it's needed.
  #
  class GlyphHash # :nodoc:
    def initialize
      # only parse the glyph list once, and cache the results (for performance)
      adobe = @@cache ||= load_adobe_glyph_mapping
      @by_name      = adobe.first
      @by_codepoint = adobe.last
    end

    # attempt to convert a PDF Name to a unicode codepoint. Returns nil
    # if no conversion is possible.
    #
    #   h = GlyphHash.new
    #
    #   h.name_to_unicode(:A)
    #   => 65
    #
    #   h.name_to_unicode(:Euro)
    #   => 8364
    #
    #   h.name_to_unicode(:G30)
    #   => 48
    #
    #   h.name_to_unicode(:34)
    #   => 34
    #
    def name_to_unicode(name)
      return nil unless name.is_a?(Symbol)

      name = name.to_s.gsub('_', '').intern
      str = name.to_s

      if @by_name.has_key?(name)
        @by_name[name]
      elsif str.match(/\Auni[A-F\d]{4}\Z/)
        "0x#{str[3,4]}".hex
      elsif str.match(/\Au[A-F\d]{4,6}\Z/)
        "0x#{str[1,6]}".hex
      elsif str.match(/\A[A-Za-z]\d{1,5}\Z/)
        str[1,5].to_i
      elsif str.match(/\A[A-Za-z]{2}\d{2,5}\Z/)
        str[2,5].to_i
      else
        nil
      end
    end

    # attempt to convert a Unicode code point to the equivilant PDF Name. Returns nil
    # if no conversion is possible.
    #
    #   h = GlyphHash.new
    #
    #   h.unicode_to_name(65)
    #   => :A
    #
    #   h.unicode_to_name(8364)
    #   => :Euro
    #
    #   h.unicode_to_name(34)
    #   => :34
    #
    def unicode_to_name(codepoint)
      @by_codepoint[codepoint.to_i]
    end

    private

    # returns a hash that maps glyph names to unicode codepoints. The mapping is based on
    # a text file supplied by Adobe at:
    # http://www.adobe.com/devnet/opentype/archives/glyphlist.txt
    def load_adobe_glyph_mapping
      keyed_by_name      = {}
      keyed_by_codepoint = {}

      RUBY_VERSION >= "1.9" ? mode = "r:BINARY" : mode = "r"
      File.open(File.dirname(__FILE__) + "/glyphlist.txt", mode) do |f|
        f.each do |l|
          m, name, code = *l.match(/([0-9A-Za-z]+);([0-9A-F]{4})/)
          if name && code
            cp = "0x#{code}".hex
            keyed_by_name[name.to_sym]   = cp
            keyed_by_codepoint[cp]     ||= []
            keyed_by_codepoint[cp]     << name.to_sym
          end
        end
      end

      [keyed_by_name.freeze, keyed_by_codepoint.freeze]
    end

  end
end