=begin rdoc

= interface.rb Provides an interface to the TMail object

=end
#--
# Copyright (c) 1998-2003 Minero Aoki <aamine@loveruby.net>
#
# 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.
#
# Note: Originally licensed under LGPL v2+. Using MIT license for Rails
# with permission of Minero Aoki.
#++

# TMail::Mail objects get accessed primarily through the methods in this file.
# 
# 

require 'tmail/utils'

module TMail

  class Mail

    # Allows you to query the mail object with a string to get the contents
    # of the field you want.
    # 
    # Returns a string of the exact contnts of the field
    # 
    #  mail.from = "mikel <mikel@lindsaar.net>"
    #  mail.header_string("From") #=> "mikel <mikel@lindsaar.net>"
    def header_string( name, default = nil )
      h = @header[name.downcase] or return default
      h.to_s
    end

    #:stopdoc:
    #--
    #== Attributes

    include TextUtils

    def set_string_array_attr( key, strs )
      strs.flatten!
      if strs.empty?
        @header.delete key.downcase
      else
        store key, strs.join(', ')
      end
      strs
    end
    private :set_string_array_attr

    def set_string_attr( key, str )
      if str
        store key, str
      else
        @header.delete key.downcase
      end
      str
    end
    private :set_string_attr

    def set_addrfield( name, arg )
      if arg
        h = HeaderField.internal_new(name, @config)
        h.addrs.replace [arg].flatten
        @header[name] = h
      else
        @header.delete name
      end
      arg
    end
    private :set_addrfield

    def addrs2specs( addrs )
      return nil unless addrs
      list = addrs.map {|addr|
          if addr.address_group?
          then addr.map {|a| a.spec }
          else addr.spec
          end
      }.flatten
      return nil if list.empty?
      list
    end
    private :addrs2specs

    #:startdoc:

    #== Date and Time methods

    # Returns the date of the email message as per the "date" header value or returns
    # nil by default (if no date field exists).  
    # 
    # You can also pass whatever default you want into this method and it will return 
    # that instead of nil if there is no date already set. 
    def date( default = nil )
      if h = @header['date']
        h.date
      else
        default
      end
    end

    # Destructively sets the date of the mail object with the passed Time instance,
    # returns a Time instance set to the date/time of the mail
    # 
    # Example:
    # 
    #  now = Time.now
    #  mail.date = now
    #  mail.date #=> Sat Nov 03 18:47:50 +1100 2007
    #  mail.date.class #=> Time
    def date=( time )
      if time
        store 'Date', time2str(time)
      else
        @header.delete 'date'
      end
      time
    end

    # Returns the time of the mail message formatted to your taste using a 
    # strftime format string.  If no date set returns nil by default or whatever value
    # you pass as the second optional parameter.
    # 
    #  time = Time.now # (on Nov 16 2007)
    #  mail.date = time
    #  mail.strftime("%D") #=> "11/16/07"
    def strftime( fmt, default = nil )
      if t = date
        t.strftime(fmt)
      else
        default
      end
    end

    #== Destination methods

    # Return a TMail::Addresses instance for each entry in the "To:" field of the mail object header.
    # 
    # If the "To:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.to_addrs #=> nil
    #  mail.to_addrs([]) #=> []
    #  mail.to = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.to_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def to_addrs( default = nil )
      if h = @header['to']
        h.addrs
      else
        default
      end
    end

    # Return a TMail::Addresses instance for each entry in the "Cc:" field of the mail object header.
    # 
    # If the "Cc:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.cc_addrs #=> nil
    #  mail.cc_addrs([]) #=> []
    #  mail.cc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.cc_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
     def cc_addrs( default = nil )
      if h = @header['cc']
        h.addrs
      else
        default
      end
    end

    # Return a TMail::Addresses instance for each entry in the "Bcc:" field of the mail object header.
    # 
    # If the "Bcc:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.bcc_addrs #=> nil
    #  mail.bcc_addrs([]) #=> []
    #  mail.bcc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.bcc_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def bcc_addrs( default = nil )
      if h = @header['bcc']
        h.addrs
      else
        default
      end
    end

    # Destructively set the to field of the "To:" header to equal the passed in string.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.to = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.to_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def to_addrs=( arg )
      set_addrfield 'to', arg
    end

    # Destructively set the to field of the "Cc:" header to equal the passed in string.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.cc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.cc_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def cc_addrs=( arg )
      set_addrfield 'cc', arg
    end

    # Destructively set the to field of the "Bcc:" header to equal the passed in string.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.bcc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.bcc_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def bcc_addrs=( arg )
      set_addrfield 'bcc', arg
    end

    # Returns who the email is to as an Array of email addresses as opposed to an Array of 
    # TMail::Address objects which is what Mail#to_addrs returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.to = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.to #=>  ["mikel@me.org", "mikel@you.org"]
    def to( default = nil )
      addrs2specs(to_addrs(nil)) || default
    end

    # Returns who the email cc'd as an Array of email addresses as opposed to an Array of 
    # TMail::Address objects which is what Mail#to_addrs returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.cc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.cc #=>  ["mikel@me.org", "mikel@you.org"]
    def cc( default = nil )
      addrs2specs(cc_addrs(nil)) || default
    end

    # Returns who the email bcc'd as an Array of email addresses as opposed to an Array of 
    # TMail::Address objects which is what Mail#to_addrs returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.bcc = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.bcc #=>  ["mikel@me.org", "mikel@you.org"]
    def bcc( default = nil )
      addrs2specs(bcc_addrs(nil)) || default
    end

    # Destructively sets the "To:" field to the passed array of strings (which should be valid 
    # email addresses)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.to = ["mikel@abc.com", "Mikel <mikel@xyz.com>"]
    #  mail.to #=>  ["mikel@abc.org", "mikel@xyz.org"]
    #  mail['to'].to_s #=> "mikel@abc.com, Mikel <mikel@xyz.com>"
    def to=( *strs )
      set_string_array_attr 'To', strs
    end

    # Destructively sets the "Cc:" field to the passed array of strings (which should be valid 
    # email addresses)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.cc = ["mikel@abc.com", "Mikel <mikel@xyz.com>"]
    #  mail.cc #=>  ["mikel@abc.org", "mikel@xyz.org"]
    #  mail['cc'].to_s #=> "mikel@abc.com, Mikel <mikel@xyz.com>"
    def cc=( *strs )
      set_string_array_attr 'Cc', strs
    end

    # Destructively sets the "Bcc:" field to the passed array of strings (which should be valid 
    # email addresses)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.bcc = ["mikel@abc.com", "Mikel <mikel@xyz.com>"]
    #  mail.bcc #=>  ["mikel@abc.org", "mikel@xyz.org"]
    #  mail['bcc'].to_s #=> "mikel@abc.com, Mikel <mikel@xyz.com>"
    def bcc=( *strs )
      set_string_array_attr 'Bcc', strs
    end

    #== Originator methods

    # Return a TMail::Addresses instance for each entry in the "From:" field of the mail object header.
    # 
    # If the "From:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.from_addrs #=> nil
    #  mail.from_addrs([]) #=> []
    #  mail.from = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.from_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def from_addrs( default = nil )
      if h = @header['from']
        h.addrs
      else
        default
      end
    end

    # Destructively set the to value of the "From:" header to equal the passed in string.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.from_addrs = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.from_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def from_addrs=( arg )
      set_addrfield 'from', arg
    end

    # Returns who the email is from as an Array of email address strings instead to an Array of 
    # TMail::Address objects which is what Mail#from_addrs returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.from = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.from #=>  ["mikel@me.org", "mikel@you.org"]
    def from( default = nil )
      addrs2specs(from_addrs(nil)) || default
    end

    # Destructively sets the "From:" field to the passed array of strings (which should be valid 
    # email addresses)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.from = ["mikel@abc.com", "Mikel <mikel@xyz.com>"]
    #  mail.from #=>  ["mikel@abc.org", "mikel@xyz.org"]
    #  mail['from'].to_s #=> "mikel@abc.com, Mikel <mikel@xyz.com>"
    def from=( *strs )
      set_string_array_attr 'From', strs
    end

    # Returns the "friendly" human readable part of the address
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.from = "Mikel Lindsaar <mikel@abc.com>"
    #  mail.friendly_from #=> "Mikel Lindsaar"
    def friendly_from( default = nil )
      h = @header['from']
      a, = h.addrs
      return default unless a
      return a.phrase if a.phrase
      return h.comments.join(' ') unless h.comments.empty?
      a.spec
    end

    # Return a TMail::Addresses instance for each entry in the "Reply-To:" field of the mail object header.
    # 
    # If the "Reply-To:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.reply_to_addrs #=> nil
    #  mail.reply_to_addrs([]) #=> []
    #  mail.reply_to = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.reply_to_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def reply_to_addrs( default = nil )
      if h = @header['reply-to']
        h.addrs.blank? ? default : h.addrs
      else
        default
      end
    end

    # Destructively set the to value of the "Reply-To:" header to equal the passed in argument.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.reply_to_addrs = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.reply_to_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def reply_to_addrs=( arg )
      set_addrfield 'reply-to', arg
    end

    # Returns who the email is from as an Array of email address strings instead to an Array of 
    # TMail::Address objects which is what Mail#reply_to_addrs returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.reply_to = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.reply_to #=>  ["mikel@me.org", "mikel@you.org"]
    def reply_to( default = nil )
      addrs2specs(reply_to_addrs(nil)) || default
    end

    # Destructively sets the "Reply-To:" field to the passed array of strings (which should be valid 
    # email addresses)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.reply_to = ["mikel@abc.com", "Mikel <mikel@xyz.com>"]
    #  mail.reply_to #=>  ["mikel@abc.org", "mikel@xyz.org"]
    #  mail['reply_to'].to_s #=> "mikel@abc.com, Mikel <mikel@xyz.com>"
    def reply_to=( *strs )
      set_string_array_attr 'Reply-To', strs
    end

    # Return a TMail::Addresses instance of the "Sender:" field of the mail object header.
    # 
    # If the "Sender:" field does not exist, will return nil by default or the value you
    # pass as the optional parameter.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.sender #=> nil
    #  mail.sender([]) #=> []
    #  mail.sender = "Mikel <mikel@me.org>"
    #  mail.reply_to_addrs #=>  [#<TMail::Address mikel@me.org>]
    def sender_addr( default = nil )
      f = @header['sender'] or return default
      f.addr                or return default
    end

    # Destructively set the to value of the "Sender:" header to equal the passed in argument.
    # 
    # TMail will parse your contents and turn each valid email address into a TMail::Address 
    # object before assigning it to the mail message.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.sender_addrs = "Mikel <mikel@me.org>, another Mikel <mikel@you.org>"
    #  mail.sender_addrs #=>  [#<TMail::Address mikel@me.org>, #<TMail::Address mikel@you.org>]
    def sender_addr=( addr )
      if addr
        h = HeaderField.internal_new('sender', @config)
        h.addr = addr
        @header['sender'] = h
      else
        @header.delete 'sender'
      end
      addr
    end

    # Returns who the sender of this mail is as string instead to an Array of 
    # TMail::Address objects which is what Mail#sender_addr returns
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.sender = "Mikel <mikel@me.org>"
    #  mail.sender #=>  "mikel@me.org"
    def sender( default = nil )
      f = @header['sender'] or return default
      a = f.addr            or return default
      a.spec
    end

    # Destructively sets the "Sender:" field to the passed string (which should be a valid 
    # email address)
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.sender = "mikel@abc.com"
    #  mail.sender #=>  "mikel@abc.org"
    #  mail['sender'].to_s #=> "mikel@abc.com"
    def sender=( str )
      set_string_attr 'Sender', str
    end

    #== Subject methods

    # Returns the subject of the mail instance.
    # 
    # If the subject field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.subject #=> nil
    #  mail.subject("") #=> ""
    #  mail.subject = "Hello"
    #  mail.subject #=> "Hello"
    def subject( default = nil )
      if h = @header['subject']
        h.body
      else
        default
      end
    end
    alias quoted_subject subject

    # Destructively sets the passed string as the subject of the mail message.
    # 
    # Example
    # 
    #  mail = TMail::Mail.new
    #  mail.subject #=> "This subject"
    #  mail.subject = "Another subject"
    #  mail.subject #=> "Another subject"
    def subject=( str )
      set_string_attr 'Subject', str
    end

    #== Message Identity & Threading Methods
    
    # Returns the message ID for this mail object instance.
    # 
    # If the message_id field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.message_id #=> nil
    #  mail.message_id(TMail.new_message_id) #=> "<47404c5326d9c_2ad4fbb80161@baci.local.tmail>"
    #  mail.message_id = TMail.new_message_id
    #  mail.message_id #=> "<47404c5326d9c_2ad4fbb80161@baci.local.tmail>"
    def message_id( default = nil )
      if h = @header['message-id']
        h.id || default
      else
        default
      end
    end

    # Destructively sets the message ID of the mail object instance to the passed in string
    # 
    # Invalid message IDs are ignored (silently, unless configured otherwise) and result in 
    # a nil message ID.  Left and right angle brackets are required.
    #
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.message_id = "<348F04F142D69C21-291E56D292BC@xxxx.net>"
    #  mail.message_id #=> "<348F04F142D69C21-291E56D292BC@xxxx.net>"
    #  mail.message_id = "this_is_my_badly_formatted_message_id"
    #  mail.message_id #=> nil
    def message_id=( str )
      set_string_attr 'Message-Id', str
    end

    # Returns the "In-Reply-To:" field contents as an array of this mail instance if it exists
    # 
    # If the in_reply_to field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.in_reply_to #=> nil
    #  mail.in_reply_to([]) #=> []
    #  TMail::Mail.load("../test/fixtures/raw_email_reply")
    #  mail.in_reply_to #=> ["<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    def in_reply_to( default = nil )
      if h = @header['in-reply-to']
        h.ids
      else
        default
      end
    end

    # Destructively sets the value of the "In-Reply-To:" field of an email.
    # 
    # Accepts an array of a single string of a message id
    #
    # Example: 
    # 
    #  mail = TMail::Mail.new
    #  mail.in_reply_to = ["<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    #  mail.in_reply_to #=> ["<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    def in_reply_to=( *idstrs )
      set_string_array_attr 'In-Reply-To', idstrs
    end

    # Returns the references of this email (prior messages relating to this message)
    # as an array of message ID strings.  Useful when you are trying to thread an
    # email.
    # 
    # If the references field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    #
    #  mail = TMail::Mail.new
    #  mail.references #=> nil
    #  mail.references([]) #=> []
    #  mail = TMail::Mail.load("../test/fixtures/raw_email_reply")
    #  mail.references #=> ["<473FF3B8.9020707@xxx.org>", "<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    def references( default = nil )
      if h = @header['references']
        h.refs
      else
        default
      end
    end

    # Destructively sets the value of the "References:" field of an email.
    # 
    # Accepts an array of strings of message IDs
    #
    # Example: 
    # 
    #  mail = TMail::Mail.new
    #  mail.references = ["<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    #  mail.references #=> ["<348F04F142D69C21-291E56D292BC@xxxx.net>"]
    def references=( *strs )
      set_string_array_attr 'References', strs
    end

    #== MIME header methods

    # Returns the listed MIME version of this email from the "Mime-Version:" header field
    # 
    # If the mime_version field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    #
    #  mail = TMail::Mail.new
    #  mail.mime_version #=> nil
    #  mail.mime_version([]) #=> []
    #  mail = TMail::Mail.load("../test/fixtures/raw_email")
    #  mail.mime_version #=> "1.0"
    def mime_version( default = nil )
      if h = @header['mime-version']
        h.version || default
      else
        default
      end
    end

    def mime_version=( m, opt = nil )
      if opt
        if h = @header['mime-version']
          h.major = m
          h.minor = opt
        else
          store 'Mime-Version', "#{m}.#{opt}"
        end
      else
        store 'Mime-Version', m
      end
      m
    end

    # Returns the current "Content-Type" of the mail instance.
    #
    # If the content_type field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    #
    #  mail = TMail::Mail.new
    #  mail.content_type #=> nil
    #  mail.content_type([]) #=> []
    #  mail = TMail::Mail.load("../test/fixtures/raw_email")
    #  mail.content_type #=> "text/plain"
    def content_type( default = nil )
      if h = @header['content-type']
        h.content_type || default
      else
        default
      end
    end

    # Returns the current main type of the "Content-Type" of the mail instance.
    #
    # If the content_type field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    #
    #  mail = TMail::Mail.new
    #  mail.main_type #=> nil
    #  mail.main_type([]) #=> []
    #  mail = TMail::Mail.load("../test/fixtures/raw_email")
    #  mail.main_type #=> "text"
    def main_type( default = nil )
      if h = @header['content-type']
        h.main_type || default
      else
        default
      end
    end

    # Returns the current sub type of the "Content-Type" of the mail instance.
    #
    # If the content_type field does not exist, returns nil by default or you can pass in as
    # the parameter for what you want the default value to be.
    # 
    # Example:
    #
    #  mail = TMail::Mail.new
    #  mail.sub_type #=> nil
    #  mail.sub_type([]) #=> []
    #  mail = TMail::Mail.load("../test/fixtures/raw_email")
    #  mail.sub_type #=> "plain"
    def sub_type( default = nil )
      if h = @header['content-type']
        h.sub_type || default
      else
        default
      end
    end

    # Destructively sets the "Content-Type:" header field of this mail object
    # 
    # Allows you to set the main type, sub type as well as parameters to the field.
    # The main type and sub type need to be a string.
    # 
    # The optional params hash can be passed with keys as symbols and values as a string,
    # or strings as keys and values.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.set_content_type("text", "plain")
    #  mail.to_s #=> "Content-Type: text/plain\n\n"
    # 
    #  mail.set_content_type("text", "plain", {:charset => "EUC-KR", :format => "flowed"})
    #  mail.to_s #=> "Content-Type: text/plain; charset=EUC-KR; format=flowed\n\n"
    #
    #  mail.set_content_type("text", "plain", {"charset" => "EUC-KR", "format" => "flowed"})
    #  mail.to_s #=> "Content-Type: text/plain; charset=EUC-KR; format=flowed\n\n"
    def set_content_type( str, sub = nil, param = nil )
      if sub
        main, sub = str, sub
      else
        main, sub = str.split(%r</>, 2)
        raise ArgumentError, "sub type missing: #{str.inspect}" unless sub
      end
      if h = @header['content-type']
        h.main_type = main
        h.sub_type  = sub
        h.params.clear
      else
        store 'Content-Type', "#{main}/#{sub}"
      end
      @header['content-type'].params.replace param if param
      str
    end

    alias content_type= set_content_type
    
    # Returns the named type parameter as a string, from the "Content-Type:" header.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.type_param("charset") #=> nil
    #  mail.type_param("charset", []) #=> []
    #  mail.set_content_type("text", "plain", {:charset => "EUC-KR", :format => "flowed"})
    #  mail.type_param("charset") #=> "EUC-KR"
    #  mail.type_param("format") #=> "flowed"
    def type_param( name, default = nil )
      if h = @header['content-type']
        h[name] || default
      else
        default
      end
    end

    # Returns the character set of the email.  Returns nil if no encoding set or returns
    # whatever default you pass as a parameter - note passing the parameter does NOT change
    # the mail object in any way.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.load("path_to/utf8_email")
    #  mail.charset #=> "UTF-8"
    # 
    #  mail = TMail::Mail.new
    #  mail.charset #=> nil
    #  mail.charset("US-ASCII") #=> "US-ASCII"
    def charset( default = nil )
      if h = @header['content-type']
        h['charset'] or default
      else
        default
      end
    end

    # Destructively sets the character set used by this mail object to the passed string, you
    # should note though that this does nothing to the mail body, just changes the header
    # value, you will need to transliterate the body as well to match whatever you put 
    # in this header value if you are changing character sets.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.charset #=> nil
    #  mail.charset = "UTF-8"
    #  mail.charset #=> "UTF-8"
    def charset=( str )
      if str
        if h = @header[ 'content-type' ]
          h['charset'] = str
        else
          store 'Content-Type', "text/plain; charset=#{str}"
        end
      end
      str
    end

    # Returns the transfer encoding of the email.  Returns nil if no encoding set or returns
    # whatever default you pass as a parameter - note passing the parameter does NOT change
    # the mail object in any way.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.load("path_to/base64_encoded_email")
    #  mail.transfer_encoding #=> "base64"
    # 
    #  mail = TMail::Mail.new
    #  mail.transfer_encoding #=> nil
    #  mail.transfer_encoding("base64") #=> "base64"
    def transfer_encoding( default = nil )
      if h = @header['content-transfer-encoding']
        h.encoding || default
      else
        default
      end
    end

    # Destructively sets the transfer encoding of the mail object to the passed string, you
    # should note though that this does nothing to the mail body, just changes the header
    # value, you will need to encode or decode the body as well to match whatever you put 
    # in this header value.
    # 
    # Example:
    # 
    #  mail = TMail::Mail.new
    #  mail.transfer_encoding #=> nil
    #  mail.transfer_encoding = "base64"
    #  mail.transfer_encoding #=> "base64"
    def transfer_encoding=( str )
      set_string_attr 'Content-Transfer-Encoding', str
    end

    alias encoding                   transfer_encoding
    alias encoding=                  transfer_encoding=
    alias content_transfer_encoding  transfer_encoding
    alias content_transfer_encoding= transfer_encoding=

    # Returns the content-disposition of the mail object, returns nil or the passed 
    # default value if given
    # 
    # Example:
    # 
    #  mail = TMail::Mail.load("path_to/raw_mail_with_attachment") 
    #  mail.disposition #=> "attachment"
    #
    #  mail = TMail::Mail.load("path_to/plain_simple_email")
    #  mail.disposition #=> nil
    #  mail.disposition(false) #=> false
    def disposition( default = nil )
      if h = @header['content-disposition']
        h.disposition || default
      else
        default
      end
    end

    alias content_disposition     disposition

    # Allows you to set the content-disposition of the mail object.  Accepts a type
    # and a hash of parameters.
    # 
    # Example:
    # 
    #  mail.set_disposition("attachment", {:filename => "test.rb"})
    #  mail.disposition #=> "attachment"
    #  mail['content-disposition'].to_s #=> "attachment; filename=test.rb"
    def set_disposition( str, params = nil )
      if h = @header['content-disposition']
        h.disposition = str
        h.params.clear
      else
        store('Content-Disposition', str)
        h = @header['content-disposition']
      end
      h.params.replace params if params
    end

    alias disposition=            set_disposition
    alias set_content_disposition set_disposition
    alias content_disposition=    set_disposition

    # Returns the value of a parameter in an existing content-disposition header
    # 
    # Example:
    # 
    #  mail.set_disposition("attachment", {:filename => "test.rb"})
    #  mail['content-disposition'].to_s #=> "attachment; filename=test.rb"
    #  mail.disposition_param("filename") #=> "test.rb"
    #  mail.disposition_param("missing_param_key") #=> nil
    #  mail.disposition_param("missing_param_key", false) #=> false
    #  mail.disposition_param("missing_param_key", "Nothing to see here") #=> "Nothing to see here"
    def disposition_param( name, default = nil )
      if h = @header['content-disposition']
        h[name] || default
      else
        default
      end
    end

    # Convert the Mail object's body into a Base64 encoded email
    # returning the modified Mail object
    def base64_encode!
      store 'Content-Transfer-Encoding', 'Base64'
      self.body = base64_encode
    end

    # Return the result of encoding the TMail::Mail object body
    # without altering the current body
    def base64_encode
      Base64.folding_encode(self.body)
    end

    # Convert the Mail object's body into a Base64 decoded email
    # returning the modified Mail object
    def base64_decode!
      if /base64/i === self.transfer_encoding('')
        store 'Content-Transfer-Encoding', '8bit'
        self.body = base64_decode
      end
    end

    # Returns the result of decoding the TMail::Mail object body
    # without altering the current body
    def base64_decode
      Base64.decode(self.body, @config.strict_base64decode?)
    end

    # Returns an array of each destination in the email message including to: cc: or bcc:
    # 
    # Example:
    # 
    #  mail.to = "Mikel <mikel@lindsaar.net>"
    #  mail.cc = "Trans <t@t.com>"
    #  mail.bcc = "bob <bob@me.com>"
    #  mail.destinations #=> ["mikel@lindsaar.net", "t@t.com", "bob@me.com"]
    def destinations( default = nil )
      ret = []
      %w( to cc bcc ).each do |nm|
        if h = @header[nm]
          h.addrs.each {|i| ret.push i.address }
        end
      end
      ret.empty? ? default : ret
    end

    # Yields a block of destination, yielding each as a string.
    #  (from the destinations example)
    #  mail.each_destination { |d| puts "#{d.class}: #{d}" }
    #  String: mikel@lindsaar.net
    #  String: t@t.com
    #  String: bob@me.com
    def each_destination( &block )
      destinations([]).each do |i|
        if Address === i
          yield i
        else
          i.each(&block)
        end
      end
    end

    alias each_dest each_destination

    # Returns an array of reply to addresses that the Mail object has, 
    # or if the Mail message has no reply-to, returns an array of the
    # Mail objects from addresses.  Else returns the default which can
    # either be passed as a parameter or defaults to nil
    # 
    # Example:
    #  mail.from = "Mikel <mikel@lindsaar.net>"
    #  mail.reply_to = nil
    #  mail.reply_addresses #=> [""]  
    # 
    def reply_addresses( default = nil )
      reply_to_addrs(nil) or from_addrs(nil) or default
    end

    # Returns the "sender" field as an array -> useful to find out who to 
    # send an error email to.
    def error_reply_addresses( default = nil )
      if s = sender(nil)
        [s]
      else
        from_addrs(default)
      end
    end

    # Returns true if the Mail object is a multipart message
    def multipart?
      main_type('').downcase == 'multipart'
    end

    # Creates a new email in reply to self.  Sets the In-Reply-To and
    # References headers for you automagically.
    #
    # Example:
    #  mail = TMail::Mail.load("my_email")
    #  reply_email = mail.create_reply
    #  reply_email.class         #=> TMail::Mail
    #  reply_email.references  #=> ["<d3b8cf8e49f04480850c28713a1f473e@lindsaar.net>"]
    #  reply_email.in_reply_to #=> ["<d3b8cf8e49f04480850c28713a1f473e@lindsaar.net>"]
    def create_reply
      setup_reply create_empty_mail()
    end

    # Creates a new email in reply to self.  Sets the In-Reply-To and
    # References headers for you automagically.
    #
    # Example:
    #  mail = TMail::Mail.load("my_email")
    #  forward_email = mail.create_forward
    #  forward_email.class         #=> TMail::Mail
    #  forward_email.content_type  #=> "multipart/mixed"
    #  forward_email.body          #=> "Attachment: (unnamed)"
    #  forward_email.encoded       #=> Returns the original email as a MIME attachment
    def create_forward
      setup_forward create_empty_mail()
    end

    #:stopdoc:
    private

    def create_empty_mail
      self.class.new(StringPort.new(''), @config)
    end

    def setup_reply( mail )
      if tmp = reply_addresses(nil)
        mail.to_addrs = tmp
      end

      mid = message_id(nil)
      tmp = references(nil) || []
      tmp.push mid if mid
      mail.in_reply_to = [mid] if mid
      mail.references = tmp unless tmp.empty?
      mail.subject = 'Re: ' + subject('').sub(/\A(?:\[[^\]]+\])?(?:\s*Re:)*\s*/i, '')
      mail.mime_version = '1.0'
      mail
    end

    def setup_forward( mail )
      m = Mail.new(StringPort.new(''))
      m.body = decoded
      m.set_content_type 'message', 'rfc822'
      m.encoding = encoding('7bit')
      mail.parts.push m
      # call encoded to reparse the message
      mail.encoded
      mail
    end

  #:startdoc:
  end   # class Mail

end   # module TMail
