# --
# Copyright 2007 Nominet UK
# 
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# 
#     http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ++
module Dnsruby
  # == Dnsruby::Name class
  # 
  # A representation of a DNS name
  # (RFC1035, section 3.1)
  # 
  # == methods
  # 
  # * Name::create(namestring)
  # * Name#absolute?
  # * Name#wild?
  # * Name#subdomain_of?(other)
  # * Name#labels
  # 
  class Name
    include Comparable
    MaxNameLength=255
    # --
    #  A Name is a collection of Labels. Each label is presentation-formatted
    #  When a Name is wire-encoded, the label array is walked, and each label is wire-encoded.
    #  When a Name is unencoded, each label is unencoded, and added to the Name collection of labels.
    #  When a Name is made from a string, the Name is split into Labels.
    # ++
    # Creates a new Dnsruby::Name from +arg+. +arg+ can be :
    # 
    # * Name:: returns +arg+
    # * String:: returns a new Name
    def self.create(arg)
      case arg
      when Name
        return Name.new(arg.labels, arg.absolute?)
      when String
        #         arg.gsub!(/\.$/o, "")
        if (arg==".")
          return Name.new([],true)
        end
        if (arg=="")
          return Name.new([],false)
        end
        return Name.new(split_escaped(arg), /\.\z/ =~ arg ? true : false)
        #         return Name.new(Label.split(arg), /\.\z/ =~ arg ? true : false)
      when Array
        return Name.new(arg, /\.\z/ =~ (arg.last ? ((arg.last.kind_of?String)?arg.last : arg.last.string) : arg.last) ? true : false)
      else
        raise ArgumentError.new("cannot interpret as DNS name: #{arg.inspect}")
      end
    end

    def self.split_escaped(arg) #:nodoc: all
      encodedlabels = name2encodedlabels(arg)
      return encodedlabels
    end

    def self.split(name)
      encodedlabels = name2encodedlabels(name)
      labels = encodedlabels.each  {|el| Name.decode(el.to_s)}
      return labels
    end

    attr_accessor :labels

    # This method should only be called internally.
    # Use Name::create to create a new Name
    def initialize(labels, absolute=true) #:nodoc: all
      total_length=labels.length-1
      labels.each do |l|
        if (!l.kind_of?Label)
          raise ArgumentError.new("Name::new called with non-labels. Use Name::create instead?")
        end
        total_length+=l.length
      end
      if (total_length > MaxNameLength)
        raise ResolvError.new("Name length is #{total_length}, greater than max of #{MaxNameLength} octets!")
      end
      @labels = labels
      @absolute = absolute
    end

    def downcase
      labels = []
      @labels.each do |label| labels << Label.new(label.downcase) end
      return Name.new(labels)
    end

    def inspect # :nodoc:
      "#<#{self.class}: #{self.to_s}#{@absolute ? '.' : ''}>"
    end

    # Returns true if this Name is absolute
    def absolute?
      return @absolute
    end

    def absolute=(on) # :nodoc:
      @absolute = on
    end

    def strip_label # :nodoc:
      n = Name.new(self.labels()[1, self.labels.length-1], self.absolute?)
      return n
    end

    # Is this name a wildcard?
    def wild?
      if (labels.length == 0)
        return false
      end
      return (labels[0].string == '*')
    end

    #  Return the canonical form of this name (RFC 4034 section 6.2)
    def canonical
      # 
      return MessageEncoder.new {|msg|
        msg.put_name(self, true)
      }.to_s

    end

    def <=>(other)
      #  return -1 if other less than us, +1 if greater than us
      return 0 if (canonical == other.canonical)
      if (canonically_before(other))
        return +1
      end
      return -1
    end

    def canonically_before(n)
      if (!(Name === n))
        n = Name.create(n)
      end
      #  Work out whether this name is canonically before the passed Name
      #  RFC 4034 section 6.1
      #  For the purposes of DNS security, owner names are ordered by treating
      # individual labels as unsigned left-justified octet strings.  The
      # absence of a octet sorts before a zero value octet, and uppercase
      # US-ASCII letters are treated as if they were lowercase US-ASCII
      # letters.
      # To compute the canonical ordering of a set of DNS names, start by
      # sorting the names according to their most significant (rightmost)
      # labels.  For names in which the most significant label is identical,
      # continue sorting according to their next most significant label, and
      # so forth.

      #  Get the list of labels for both names, and then swap them
      my_labels = @labels.reverse
      other_labels = n.labels.reverse
      my_labels.each_index {|i|
        if (!other_labels[i])
          return false
        end
        next if (other_labels[i].downcase == my_labels[i].downcase)
        return (my_labels[i].downcase < other_labels[i].downcase)
      }
      return true
    end

    def ==(other) # :nodoc:
      return false if other.class != Name
      return @labels == other.labels && @absolute == other.absolute?
    end
    alias eql? == # :nodoc:

    #  Tests subdomain-of relation : returns true if this name
    #  is a subdomain of +other+.
    # 
    #    domain = Resolv::Name.create("y.z")
    #    p Resolv::Name.create("w.x.y.z").subdomain_of?(domain) #=> true
    #    p Resolv::Name.create("x.y.z").subdomain_of?(domain) #=> true
    #    p Resolv::Name.create("y.z").subdomain_of?(domain) #=> false
    #    p Resolv::Name.create("z").subdomain_of?(domain) #=> false
    #    p Resolv::Name.create("x.y.z.").subdomain_of?(domain) #=> false
    #    p Resolv::Name.create("w.z").subdomain_of?(domain) #=> false
    def subdomain_of?(other)
      raise ArgumentError, "not a domain name: #{other.inspect}" unless Name === other
      return false if @absolute != other.absolute?
      other_len = other.length
      return false if @labels.length <= other_len
      return @labels[-other_len, other_len] == other.to_a
    end

    def hash # :nodoc:
      return @labels.hash ^ @absolute.hash
    end

    def to_a #:nodoc: all
      return @labels
    end

    def length #:nodoc: all
      return @labels.length
    end

    def [](i) #:nodoc: all
      return @labels[i]
    end

    #  returns the domain name as a string.
    # 
    #  The domain name doesn't have a trailing dot even if the name object is
    #  absolute.
    # 
    #  Example :
    # 
    #    p Resolv::Name.create("x.y.z.").to_s #=> "x.y.z"
    #    p Resolv::Name.create("x.y.z").to_s #=> "x.y.z"
    # 
    def to_s(include_absolute=false)
      ret = to_str(@labels)
      if (@absolute && include_absolute)
        ret += "."
      end
      return ret
    end

    def to_str(labels) # :nodoc: all
      ls =[]
      labels.each {|el| ls.push(Name.decode(el.to_s))}
      return ls.join('.')
      #       return @labels.collect{|l| (l.kind_of?String) ? l : l.string}.join('.')
    end

    #  Utility function
    # 
    #  name2labels to translate names from presentation format into an
    #  array of "wire-format" labels.
    #  in: dName a string with a domain name in presentation format (1035
    #  sect 5.1)
    #  out: an array of labels in wire format.
    def self.name2encodedlabels (dName) #:nodoc: all
      #  Check for "\" in the name  : If there, then decode properly - otherwise, cheat and split on "."
      if (dName.index("\\"))
        names=[]
        j=0;
        while (dName && dName.length > 0)
          names[j],dName = encode(dName)
          j+=1
        end

        return names
      else
        labels = []
        dName.split(".").each {|l|
          labels.push(Label.new(l))
        }
        return labels
      end
    end

    def self.decode(wire) #:nodoc: all
      presentation=""
      length=wire.length
      #  There must be a nice regexp to do this.. but since I failed to
      #  find one I scan the name string until I find a '\', at that time
      #  I start looking forward and do the magic.

      i=0;

      unpacked = wire.unpack("C*")
      while (i < length )
        c = unpacked[i]
        if ( c < 33 || c > 126 )
          presentation=presentation + sprintf("\\%03u" ,c)
        elsif ( c.chr ==  "\"" )
          presentation=presentation +  "\\\""
        elsif ( c.chr ==  "\$")
          presentation=presentation +  "\\\$"
        elsif ( c.chr == "(" )
          presentation=presentation + "\\("
        elsif ( c.chr == ")" )
          presentation=presentation +  "\\)"
        elsif ( c.chr == ";" )
          presentation=presentation +  "\\;"
        elsif ( c.chr == "@" )
          presentation=presentation +  "\\@"
        elsif ( c.chr == "\\" )
          presentation=presentation + "\\\\"
        elsif ( c.chr == ".")
          presentation=presentation +  "\\."
        else
          presentation=presentation + c.chr()
        end
        i=i+1
      end

      return presentation
      #       return Label.new(presentation)
    end



    #  wire,leftover=presentation2wire(leftover)
    #  Will parse the input presentation format and return everything before
    #  the first non-escaped "." in the first element of the return array and
    #  all that has not been parsed yet in the 2nd argument.
    def self.encode(presentation) #:nodoc: all
      presentation=presentation.to_s
      wire="";
      length=presentation.length;

      i=0;

      while (i < length )
        c=presentation.unpack("x#{i}C1") [0]
        if (c == 46) # ord('.')
          endstring = presentation[i+1, presentation.length-(i+1)]
          return Label.new(wire),endstring
        end
        if (c == 92) # ord'\\'
          # backslash found
          pos = i+1
          #  pos sets where next pattern matching should start
          if (presentation.index(/\G(\d\d\d)/o, pos))
            wire=wire+[$1.to_i].pack("C")
            i=i+3
          elsif(presentation.index(/\Gx(\h\h)/o, pos))
            wire=wire+[$1].pack("H*")
            i=i+3
          elsif(presentation.index(/\G\./o, pos))
            wire=wire+"\."
            i=i+1
          elsif(presentation.index(/\G@/o,pos))
            wire=wire+"@"
            i=i+1
          elsif(presentation.index(/\G\(/o, pos))
            wire=wire+"("
            i=i+1
          elsif(presentation.index(/\G\)/o, pos))
            wire=wire+")"
            i=i+1
          elsif(presentation.index(/\G\\/o, pos))
            wire=wire+"\\"
            i+=1
          end
        else
          wire = wire + [c].pack("C")
        end
        i=i+1
      end

      return Label.new(wire)
    end

    #   end


    # == Dnsruby::Label class
    # 
    # (RFC1035, section 3.1)
    # 
    class Label
      include Comparable
      MaxLabelLength = 63
      @@max_length=MaxLabelLength
      #  Split a Name into its component Labels
      def self.split(arg)
        return Name.split(arg)
      end

      def self.set_max_length(l)
        @@max_length=l
      end

      def initialize(string)
        if (string.length > @@max_length)
          raise ResolvError.new("Label too long (#{string.length}, max length=#{MaxLabelLength}). Label = #{string}")
        end
        @downcase = string.downcase
        @string = string
        @string_length = string.length
      end
      attr_reader :string, :downcase

      def to_s
        return @string.to_s # + "."
      end

      def length
        return @string_length
      end

      def inspect
        return "#<#{self.class} #{self.to_s}>"
      end

      def <=>(other)
        return (@downcase <=> other.downcase)
      end


      def ==(other)
        return @downcase == other.downcase
      end

      def eql?(other)
        return self == other
      end

      def hash
        return @downcase.hash
      end

    end
  end
end
