"""An NNTP client class based on RFC 977: Network News Transfer Protocol.

Example:

>>> from nntplib import NNTP
>>> s = NNTP('news')
>>> resp, count, first, last, name = s.group('comp.lang.python')
>>> print 'Group', name, 'has', count, 'articles, range', first, 'to', last
Group comp.lang.python has 51 articles, range 5770 to 5821
>>> resp, subs = s.xhdr('subject', first + '-' + last)
>>> resp = s.quit()
>>>

Here 'resp' is the server response line.
Error responses are turned into exceptions.

To post an article from a file:
>>> f = open(filename, 'r') # file containing article, including header
>>> resp = s.post(f)
>>>

For descriptions of all methods, read the comments in the code below.
Note that all arguments and return values representing article numbers
are strings, not numbers, since they are rarely used for calculations.
"""

# RFC 977 by Brian Kantor and Phil Lapsley.
# xover, xgtitle, xpath, date methods by Kevan Heydon


# Imports
import re
import socket
import string


# Exception raised when an error or invalid response is received
error_reply = 'nntplib.error_reply'	# unexpected [123]xx reply
error_temp = 'nntplib.error_temp'	# 4xx errors
error_perm = 'nntplib.error_perm'	# 5xx errors
error_proto = 'nntplib.error_proto'	# response does not begin with [1-5]
error_data = 'nntplib.error_data'	# error in response data


# Standard port used by NNTP servers
NNTP_PORT = 119


# Response numbers that are followed by additional text (e.g. article)
LONGRESP = ['100', '215', '220', '221', '222', '224', '230', '231', '282']


# Line terminators (we always output CRLF, but accept any of CRLF, CR, LF)
CRLF = '\r\n'


# The class itself

class NNTP:

	def __init__(self, host, port = NNTP_PORT, user=None, password=None):
		"""Initialize an instance.  Arguments:
		- host: hostname to connect to
		- port: port to connect to (default the standard NNTP port)"""

		self.host = host
		self.port = port
		self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		self.sock.connect(self.host, self.port)
		self.file = self.sock.makefile('rb')
		self.debugging = 0
		self.welcome = self.getresp()
		if user:
			resp = self.shortcmd('authinfo user '+user)
			if resp[:3] == '381':
				if not password:
					raise error_reply, resp
				else:
					resp = self.shortcmd(
						'authinfo pass '+password)
					if resp[:3] != '281':
						raise error_perm, resp

	def getwelcome(self):
		"""Get the welcome message from the server
		(this is read and squirreled away by __init__()).
		If the response code is 200, posting is allowed;
		if it 201, posting is not allowed."""

		if self.debugging: print '*welcome*', `self.welcome`
		return self.welcome

	def set_debuglevel(self, level):
		"""Set the debugging level.  Argument 'level' means:
		0: no debugging output (default)
		1: print commands and responses but not body text etc.
		2: also print raw lines read and sent before stripping CR/LF"""

		self.debugging = level
	debug = set_debuglevel

	def putline(self, line):
		"""Internal: send one line to the server, appending CRLF."""
		line = line + CRLF
		if self.debugging > 1: print '*put*', `line`
		self.sock.send(line)

	def putcmd(self, line):
		"""Internal: send one command to the server (through putline())."""
		if self.debugging: print '*cmd*', `line`
		self.putline(line)

	def getline(self):
		"""Internal: return one line from the server, stripping CRLF.
		Raise EOFError if the connection is closed."""
		line = self.file.readline()
		if self.debugging > 1:
			print '*get*', `line`
		if not line: raise EOFError
		if line[-2:] == CRLF: line = line[:-2]
		elif line[-1:] in CRLF: line = line[:-1]
		return line

	def getresp(self):
		"""Internal: get a response from the server.
		Raise various errors if the response indicates an error."""
		resp = self.getline()
		if self.debugging: print '*resp*', `resp`
		c = resp[:1]
		if c == '4':
			raise error_temp, resp
		if c == '5':
			raise error_perm, resp
		if c not in '123':
			raise error_proto, resp
		return resp

	def getlongresp(self):
		"""Internal: get a response plus following text from the server.
		Raise various errors if the response indicates an error."""
		resp = self.getresp()
		if resp[:3] not in LONGRESP:
			raise error_reply, resp
		list = []
		while 1:
			line = self.getline()
			if line == '.':
				break
			if line[:2] == '..':
				line = line[1:]
			list.append(line)
		return resp, list

	def shortcmd(self, line):
		"""Internal: send a command and get the response."""
		self.putcmd(line)
		return self.getresp()

	def longcmd(self, line):
		"""Internal: send a command and get the response plus following text."""
		self.putcmd(line)
		return self.getlongresp()

	def newgroups(self, date, time):
		"""Process a NEWGROUPS command.  Arguments:
		- date: string 'yymmdd' indicating the date
		- time: string 'hhmmss' indicating the time
		Return:
		- resp: server response if succesful
		- list: list of newsgroup names"""

		return self.longcmd('NEWGROUPS ' + date + ' ' + time)

	def newnews(self, group, date, time):
		"""Process a NEWNEWS command.  Arguments:
		- group: group name or '*'
		- date: string 'yymmdd' indicating the date
		- time: string 'hhmmss' indicating the time
		Return:
		- resp: server response if succesful
		- list: list of article ids"""

		cmd = 'NEWNEWS ' + group + ' ' + date + ' ' + time
		return self.longcmd(cmd)

	def list(self):
		"""Process a LIST command.  Return:
		- resp: server response if succesful
		- list: list of (group, last, first, flag) (strings)"""

		resp, list = self.longcmd('LIST')
		for i in range(len(list)):
			# Parse lines into "group last first flag"
			list[i] = tuple(string.split(list[i]))
		return resp, list

	def group(self, name):
		"""Process a GROUP command.  Argument:
		- group: the group name
		Returns:
		- resp: server response if succesful
		- count: number of articles (string)
		- first: first article number (string)
		- last: last article number (string)
		- name: the group name"""

		resp = self.shortcmd('GROUP ' + name)
		if resp[:3] <> '211':
			raise error_reply, resp
		words = string.split(resp)
		count = first = last = 0
		n = len(words)
		if n > 1:
			count = words[1]
			if n > 2:
				first = words[2]
				if n > 3:
					last = words[3]
					if n > 4:
						name = string.lower(words[4])
		return resp, count, first, last, name

	def help(self):
		"""Process a HELP command.  Returns:
		- resp: server response if succesful
		- list: list of strings"""

		return self.longcmd('HELP')

	def statparse(self, resp):
		"""Internal: parse the response of a STAT, NEXT or LAST command."""
		if resp[:2] <> '22':
			raise error_reply, resp
		words = string.split(resp)
		nr = 0
		id = ''
		n = len(words)
		if n > 1:
			nr = words[1]
			if n > 2:
				id = words[2]
		return resp, nr, id

	def statcmd(self, line):
		"""Internal: process a STAT, NEXT or LAST command."""
		resp = self.shortcmd(line)
		return self.statparse(resp)

	def stat(self, id):
		"""Process a STAT command.  Argument:
		- id: article number or message id
		Returns:
		- resp: server response if succesful
		- nr:   the article number
		- id:   the article id"""

		return self.statcmd('STAT ' + id)

	def next(self):
		"""Process a NEXT command.  No arguments.  Return as for STAT."""
		return self.statcmd('NEXT')

	def last(self):
		"""Process a LAST command.  No arguments.  Return as for STAT."""
		return self.statcmd('LAST')

	def artcmd(self, line):
		"""Internal: process a HEAD, BODY or ARTICLE command."""
		resp, list = self.longcmd(line)
		resp, nr, id = self.statparse(resp)
		return resp, nr, id, list

	def head(self, id):
		"""Process a HEAD command.  Argument:
		- id: article number or message id
		Returns:
		- resp: server response if succesful
		- nr: article number
		- id: message id
		- list: the lines of the article's header"""

		return self.artcmd('HEAD ' + id)

	def body(self, id):
		"""Process a BODY command.  Argument:
		- id: article number or message id
		Returns:
		- resp: server response if succesful
		- nr: article number
		- id: message id
		- list: the lines of the article's body"""

		return self.artcmd('BODY ' + id)

	def article(self, id):
		"""Process an ARTICLE command.  Argument:
		- id: article number or message id
		Returns:
		- resp: server response if succesful
		- nr: article number
		- id: message id
		- list: the lines of the article"""

		return self.artcmd('ARTICLE ' + id)

	def slave(self):
		"""Process a SLAVE command.  Returns:
		- resp: server response if succesful"""

		return self.shortcmd('SLAVE')

	def xhdr(self, hdr, str):
		"""Process an XHDR command (optional server extension).  Arguments:
		- hdr: the header type (e.g. 'subject')
		- str: an article nr, a message id, or a range nr1-nr2
		Returns:
		- resp: server response if succesful
		- list: list of (nr, value) strings"""

		pat = re.compile('^([0-9]+) ?(.*)\n?')
		resp, lines = self.longcmd('XHDR ' + hdr + ' ' + str)
		for i in range(len(lines)):
			line = lines[i]
			m = pat.match(line)
			if m:
				lines[i] = m.group(1, 2)
		return resp, lines

	def xover(self,start,end):
		"""Process an XOVER command (optional server extension) Arguments:
		- start: start of range
		- end: end of range
		Returns:
		- resp: server response if succesful
		- list: list of (art-nr, subject, poster, date,
		                 id, references, size, lines)"""

		resp, lines = self.longcmd('XOVER ' + start + '-' + end)
		xover_lines = []
		for line in lines:
			elem = string.splitfields(line,"\t")
			try:
				xover_lines.append((elem[0],
						    elem[1],
						    elem[2],
						    elem[3],
						    elem[4],
						    string.split(elem[5]),
						    elem[6],
						    elem[7]))
			except IndexError:
				raise error_data,line
		return resp,xover_lines

	def xgtitle(self, group):
		"""Process an XGTITLE command (optional server extension) Arguments:
		- group: group name wildcard (i.e. news.*)
		Returns:
		- resp: server response if succesful
		- list: list of (name,title) strings"""

		line_pat = re.compile("^([^ \t]+)[ \t]+(.*)$")
		resp, raw_lines = self.longcmd('XGTITLE ' + group)
		lines = []
		for raw_line in raw_lines:
			match = line_pat.search(string.strip(raw_line))
			if match:
				lines.append(match.group(1, 2))
		return resp, lines

	def xpath(self,id):
		"""Process an XPATH command (optional server extension) Arguments:
		- id: Message id of article
		Returns:
		resp: server response if succesful
		path: directory path to article"""

		resp = self.shortcmd("XPATH " + id)
		if resp[:3] <> '223':
			raise error_reply, resp
		try:
			[resp_num, path] = string.split(resp)
		except ValueError:
			raise error_reply, resp
		else:
			return resp, path

	def date (self):
		"""Process the DATE command. Arguments:
		None
		Returns:
		resp: server response if succesful
		date: Date suitable for newnews/newgroups commands etc.
		time: Time suitable for newnews/newgroups commands etc."""

		resp = self.shortcmd("DATE")
		if resp[:3] <> '111':
			raise error_reply, resp
		elem = string.split(resp)
		if len(elem) != 2:
			raise error_data, resp
		date = elem[1][2:8]
		time = elem[1][-6:]
		if len(date) != 6 or len(time) != 6:
			raise error_data, resp
		return resp, date, time


	def post(self, f):
		"""Process a POST command.  Arguments:
		- f: file containing the article
		Returns:
		- resp: server response if succesful"""

		resp = self.shortcmd('POST')
		# Raises error_??? if posting is not allowed
		if resp[0] <> '3':
			raise error_reply, resp
		while 1:
			line = f.readline()
			if not line:
				break
			if line[-1] == '\n':
				line = line[:-1]
			if line[:1] == '.':
				line = '.' + line
			self.putline(line)
		self.putline('.')
		return self.getresp()

	def ihave(self, id, f):
		"""Process an IHAVE command.  Arguments:
		- id: message-id of the article
		- f:  file containing the article
		Returns:
		- resp: server response if succesful
		Note that if the server refuses the article an exception is raised."""

		resp = self.shortcmd('IHAVE ' + id)
		# Raises error_??? if the server already has it
		if resp[0] <> '3':
			raise error_reply, resp
		while 1:
			line = f.readline()
			if not line:
				break
			if line[-1] == '\n':
				line = line[:-1]
			if line[:1] == '.':
				line = '.' + line
			self.putline(line)
		self.putline('.')
		return self.getresp()

	def quit(self):
		"""Process a QUIT command and close the socket.  Returns:
		- resp: server response if succesful"""

		resp = self.shortcmd('QUIT')
		self.file.close()
		self.sock.close()
		del self.file, self.sock
		return resp


def _test():
	"""Minimal test function."""
	s = NNTP('news')
	resp, count, first, last, name = s.group('comp.lang.python')
	print resp
	print 'Group', name, 'has', count, 'articles, range', first, 'to', last
	resp, subs = s.xhdr('subject', first + '-' + last)
	print resp
	for item in subs:
		print "%7s %s" % item
	resp = s.quit()
	print resp


# Run the test when run as a script
if __name__ == '__main__':
	_test()