class String
  def message_quote
    quote = self.split("\n")
    body_quote = ''
    quote.each do |line|
      body_quote = body_quote + '> ' + line + "\n"
    end
    body_quote
  end
  def word_wrap(*args)
    options = args.extract_options!
    unless args.blank?
      options[:line_width] = args[0] || 82
    end
    options.reverse_merge!(line_width: 82)

    lines = self
    lines.split("\n").collect do |line|
      line.length > options[:line_width] ? line.gsub(/(.{1,#{options[:line_width]}})(\s+|$)/, "\\1\n").strip : line
    end * "\n"
  end

=begin

  filename = 'Some::Module'.to_filename

  returns
    'some/module'

=end

  def to_filename
    camel_cased_word = "#{self}"
    camel_cased_word.gsub(/::/, '/').downcase
  end

  # because of mysql inno_db limitations, strip 4 bytes utf8 chars (e. g. emojis)
  # unfortunaly UTF8mb4 will raise other limitaions of max varchar and lower index sizes
  # More details: http://pjambet.github.io/blog/emojis-and-mysql/
  def utf8_to_3bytesutf8
    return if ActiveRecord::Base.connection_config[:adapter] != 'mysql2'
    self.each_char.select {|c|
      if c.bytes.count > 3
        Rails.logger.warn "strip out 4 bytes utf8 chars '#{c}' of '#{ self }'"
        next
      end
      c
    }
    .join('')
  end

=begin

  text = html_string.html2text

  returns

    'string with text'

=end

  def html2text
    string = "#{self}"

    # in case of invalid encodeing, strip invalid chars
    # see also test/fixtures/mail21.box
    # note: string.encode!('UTF-8', 'UTF-8', :invalid => :replace, :replace => '?') was not detecting invalid chars
    if !string.valid_encoding?
      string = string.chars.select { |c| c.valid_encoding? }.join
    end

    # find <a href=....> and replace it with [x]
    link_list = ''
    counter   = 0
    string.gsub!( /<a\s.*?href=("|')(.+?)("|').*?>/ix ) { |item|
      link = $2
      counter   = counter + 1
      link_list += "[#{counter}] #{link}\n"
      "[#{counter}] "
    }

    # remove empty lines
    string.gsub!( /^\s*/m, '' )

    # pre/code handling 1/2
    string.gsub!( %r{<pre>(.+?)</pre>}m ) { |placeholder|
      placeholder = placeholder.gsub(/\n/, '###BR###')
    }
    string.gsub!( %r{<code>(.+?)</code>}m ) { |placeholder|
      placeholder = placeholder.gsub(/\n/, '###BR###')
    }

    # remove all new lines
    string.gsub!( /(\n\r|\r\r\n|\r\n|\n)/, '' )

    # pre/code handling 2/2
    string.gsub!( /###BR###/, "\n" )

    # add counting
    string.gsub!(/<li(| [^>]*)>/i, "\n* ")

    # add quoting
    string.gsub!(/<blockquote(| [^>]*)>/i, '> ')

    # add hr
    string.gsub!(%r{<hr(|/| [^>]*)>}i, "___\n")

    # add new lines
    string.gsub!( %r{<(br|table)(|/| [^>]*)>}i, "\n" )
    string.gsub!( %r{</(div|p|pre|blockquote|table|tr)(|\s.+?)>}i, "\n" )
    string.gsub!( %r{</td>}i, ' '  )

    # strip all other tags
    string.gsub!( /\<.+?\>/, '' )

    # strip all &amp; &lt; &gt; &quot;
    string.gsub!( '&amp;', '&' )
    string.gsub!( '&lt;', '<' )
    string.gsub!( '&gt;', '>' )
    string.gsub!( '&quot;', '"' )
    string.gsub!( '&nbsp;', ' ' )

    # encode html entities like "&#8211;"
    string.gsub!( /(&\#(\d+);?)/x ) { |item|
      $2.chr
    }

    # encode html entities like "&#3d;"
    string.gsub!( /(&\#[xX]([0-9a-fA-F]+);?)/x ) { |item|
      chr_orig = $1
      hex      = $2.hex
      if hex
        chr = hex.chr
        if chr
          chr_orig = chr
        else
          chr_orig
        end
      else
        chr_orig
      end

      # check valid encoding
      begin
        if !chr_orig.encode('UTF-8').valid_encoding?
          chr_orig = '?'
        end
      rescue
        chr_orig = '?'
      end
      chr_orig
    }

    # remove tailing empty spaces
    string.gsub!(/\s+\n$/, "\n")

    # remove multible empty lines
    string.gsub!(/\n\n\n/, "\n\n")

    # add extracted links
    if link_list != ''
      string += "\n\n" + link_list
    end

    string.strip
  end

=begin

  html = text_string.text2html

=end

  def text2html
    text = CGI.escapeHTML( self )
    text.gsub!(/\n/, '<br>')
    text.chomp
  end

end