#!/usr/bin/ruby

require "ftools"
require "rfc822"
require "smtpclient"
require "popclient"

MAILCLIENT_VERSION = "0.1"

POP3 = :POP3
APOP = :APOP
POP = []

STDOUT.sync = true

class RFC822
  attr_reader :header_string
end

load(File.expand_path("~/.mailclient.rb"))
if defined?(SPOOL_DIR)
  SPOOL = File.expand_path(SPOOL_DIR)
else
  SPOOL = File.expand_path("~/spool/mqueue")
end
unless File.exist?(SPOOL)
  File.makedirs(SPOOL)
end
if defined?(DONT_DELETE) && DONT_DELETE
  DELETE = false
elsif defined?(DONT_DELETE_IMMEDIATELY) && DONT_DELETE_IMMEDIATELY
  DELETE = :delete
else
  DELETE = :delete!
end

class Mail
  MDA_FORMAT = "|" + MDA
  
  attr_reader :contents, :sender, :recipients
  
  def initialize(contents, sender, recipients)
    @contents = contents
    @sender = sender
    @recipients = recipients
  end
  
  def save(file)
    file.chmod(0600)
    file.print("<", @sender, "\n")
    for recipient in @recipients
      file.print(">", recipient, "\n")
    end
    file.print("\n")
    file.print(@contents)
  end
  
  def send(smtp)
    unless @recipients.empty?
      smtp.sendmail(@contents, @sender, @recipients)
    end
  end
  
  def deliver(user)
    Mail.deliver(@contents, user)
  end
  
  def Mail.load(file)
    sender = file.gets[1..-2]
    recipients = []
    while /^$/ !~ line = file.gets
      recipients.push(line[1..-2])
    end
    contents = file.read
    return new(contents, sender, recipients)
  end
  
  def Mail.parse(file, recipients = nil)
    mail = RFC822.new(STDIN)
    if mail.from
      sender = mail.from.get_address[0]
    elsif POP[0]
      sender = POP[0][:USER] + "@" + POP[0][:SERVER]
    else
      raise "can't get sender address"
    end
    if recipients.nil?
      recipients = []
      for addr in [mail.to, mail.cc, mail.get_address("Bcc")]
	recipients += addr.get_address if addr
      end
    end
    contents = mail.header_string.gsub(/(\r\n|\r|\n){2}\Z/) {
      $1 + format("X-Dispatcher: mailclient version %s (ruby %s)",
		  MAILCLIENT_VERSION, VERSION) + $1 + $1
    }
    contents.concat(mail.body)
    return Mail.new(contents, sender, recipients)
  end
  
  def Mail.deliver(mail, user)
    open(format(MDA_FORMAT, user), "w") do |dma|
      dma.write(mail)
    end
  end
end

def parseopts
  extract = false
  recipients = []
  if File.basename($0) =~ /^imput/
    extract = true
  else
    while arg = ARGV.shift
      if /^-/ =~ arg
	case arg[1..-1]
	when "t"
	  extract = true
	when /^(C|oC|F|f|h|oA|oD|oE|oG|oL|oQ|oR|oT|oX|oM?)$/
	  # ignore option
	  ARGV.shift
	else
	  # ignore option
	end
      else
	recipients.push(arg)
      end
    end
  end
  return extract, recipients
end

def smtpsend(mail)
  smtp = SMTPclient.new(SMTP_SERVER, 25, nil, SMTP_TIMEOUT, SMTP_TIMEOUT)
  smtp.login
  begin
    mail.send(smtp)
  ensure
    smtp.logout
  end
end

def generate_filename
  filename = File.expand_path(Time.new.strftime("%Y%m%d%H%M-000"),
			      SPOOL)
  while File.exist?(filename)
    filename = filename.succ
  end
  return filename
end

def savemail(mail)
  filename = generate_filename
  file = open(filename, "w")
  begin
    begin
      mail.save(file)
    ensure
      file.close
    end
  rescue Exception
    File.delete(filename) if File.exist?(filename)
    raise
  end
end

def sendmail
  extract, recipients = parseopts
  
  if extract
    mail = Mail.parse(STDIN)
  else
    mail = Mail.parse(STDIN, $recipients)
  end
  
#  mail.recipients.delete_if do |recipient|
#    if /@/ !~ recipient
#      mail.deliver(recipient)
#      true
#    else
#      false
#    end
#  end
#  return if mail.recipients.empty?
  
#  begin
#    smtpsend(mail)
#  rescue
    savemail(mail)
#  end
end

def sendqueue
  files = Dir[File.expand_path("*", SPOOL)].find_all { |i|
    /\/\d{12}-\d{3,}$/ =~ i
  }
  unless files.empty?
    puts "sending mails to #{SMTP_SERVER}..."
    smtp = SMTPclient.new(SMTP_SERVER)
    smtp.login
    begin
      for file in files
	if File.file?(file)
	  open(file) do |f|
	    mail = Mail.load(f)
	    mail.send(smtp)
	  end
	  File.delete(file)
	end
      end
    ensure
      smtp.logout
    end
  end
end

def fetchmail
  for popconf in POP
    if popconf[:TYPE] == APOP
      client_class = APOPclient
    else
      client_class = POP3client
    end
    pop = client_class.new(popconf[:SERVER],110, nil, nil, nil, POP3_TIMEOUT, POP3_TIMEOUT)
    pop.login(popconf[:USER], popconf[:PASSWORD])
    begin
      count = pop.mails.size
      puts "#{count} message for #{popconf[:USER]} at #{popconf[:SERVER]}."
      i = 1
      for mail in pop.mails
	print "reading message #{i} of #{count} (#{mail.size} bytes): "
	Mail.deliver(mail.mail.gsub!(/\r\n/, "\n"), ENV["USER"])
	mail.send(DELETE) if DELETE
	puts "flushed"
	i += 1
      end
    ensure
      pop.logout
    end
  end
end

if /^(sendmail|imput)/ =~ File.basename($0) || ARGV.delete("--sendmail")
  sendmail
  sendqueue
else
  sendqueue
  fetchmail
end