#!/usr/bin/env python3.1

import datetime, http.cookiejar, os, sys, shelve, spacemap, re, urllib.request

class Config:
	__slots__ = frozenset(['_config', '_default', '_section', 'options', 'root'])
	_default = {
		'general': {
			'port': '8008',
		},
		'_other': {
			'verbose': 'no',
			'noetag': 'no',
			'noparts': 'no',
	},}

	# function to read in config file
	def __init__(self):
		import configparser, optparse

		parser = optparse.OptionParser()



		parser.add_option('-c', '--config', dest = 'config', help = 'config file location', metavar = 'FILE', default = 'samesite.conf')



		(self.options, args) = parser.parse_args()

		assert os.access(self.options.config, os.R_OK), "Fatal error: can't read {}".format(self.options.config)

		configDir = re.compile('^(.*)/[^/]+$').match(self.options.config)
		if configDir:
			self.root = configDir.group(1)
		else:
			self.root = os.getcwd()

		self._config = configparser.ConfigParser()
		self._config.readfp(open(self.options.config))

		for section in self._config.sections():
			if section != 'general':
				if self._config.has_option(section, 'dir'):
					if re.compile('^/$').match(self._config.get(section, 'dir')):
						self._config.set(section, 'dir', self.root + os.sep + section)
					thisDir = re.compile('^(.*)/$').match(self._config.get(section, 'dir'))
					if thisDir:
						self._config.set(section, 'dir', thisDir.group(1))
					if not re.compile('^/(.*)$').match(self._config.get(section, 'dir')):
						self._config.set(section, 'dir', self.root + os.sep + self._config.get(section, 'dir'))
				else:
					self._config.set(section, 'dir', self.root + os.sep + section)

				if not self._config.has_option(section, 'root'):
					self._config.set(section, 'root', section)

	# function to select config file section or create one
	def section(self, section):
		if not self._config.has_section(section):
			self._config.add_section(section)
		self._section = section

	# function to get config parameter, if parameter doesn't exists the default
	# value or None is substituted
	def __getitem__(self, name):
		if not self._config.has_option(self._section, name):
			if self._section in self._default:
				if name in self._default[self._section]:
					self._config.set(self._section, name, self._default[self._section][name])
				else:
					self._config.set(self._section, name, None)
			elif name in self._default['_other']:
				self._config.set(self._section, name, self._default['_other'][name])
			else:
				self._config.set(self._section, name, None)
		return(self._config.get(self._section, name))

config = Config()

#assert options.port or os.access(options.log, os.R_OK), 'Log file unreadable'



const_desc_fields = set(['Content-Length', 'Pragma', 'Last-Modified'])
const_ignore_fields = set(['Accept-Ranges', 'Age', 'Cache-Control', 'Connection', 'Content-Type', 'Date', 'Expires', 'Server', 'Via', 'X-Cache', 'X-Cache-Lookup', 'X-Powered-By'])






block_size = 4096



'''
# later, kqueue would be good but later
class Connection:
	__slots__ = frozenset(('__address', '__input', '__socket', '__status', 'error', 'method', 'url', 'http_version'))

	def __init__(self, socket, address):
		self.__address = address

					kq.control([select.kevent(kev.ident, select.KQ_FILTER_READ, select.KQ_EV_DELETE)], 0)
					kq.control([select.kevent(kev.ident, select.KQ_FILTER_WRITE, select.KQ_EV_DELETE)], 0)
					del(connections[kev.ident])
	finally:
		sock.close()
'''

# XXX how about rechecking files?
if True:
	import http.server

	class MyRequestHandler(http.server.BaseHTTPRequestHandler):
		def __process(self):
			# reload means file needs to be reloaded to serve request
			reload = False
			# recheck means file needs to be checked, this also means that if file hav been modified we can serve older copy

			info = 'Checking file: ' + self.path

			myPath = re.compile('^(.*?)(\?.*)$').match(self.path)
			if myPath:
				my_path = myPath.group(1)
			else:
				my_path = self.path

			config.section(self.headers['Host'])

			if not os.access(config['dir'], os.X_OK):
				os.mkdir(config['dir'])
			# this is file index - everything is stored in this file
			# _parts - list of stored parts of file
			# _time - last time the file was checked
			# everything else is just the headers
			index = shelve.open(config['dir'] + os.sep + '.index')

			desc_fields = const_desc_fields.copy()
			ignore_fields = const_ignore_fields.copy()
			if not config['noetag']:
				desc_fields.add('ETag')
			else:
				ignore_fields.add('ETag')

			proxy_ignored = ('Accept', 'Accept-Encoding',
				'Cache-Control', 'Connection',
				'Host',
				'If-Modified-Since', 'If-Unmodified-Since',
				'User-Agent',
				'Via',
				'X-Forwarded-For',
			)

			print('===============[ {} request ]==='.format(self.command))

			for header in self.headers:
				if header in proxy_ignored:
					pass
				elif header in ('Range'):
					isRange = re.compile('bytes=(\d+)-(\d+)').match(self.headers[header])
					if isRange:
						requested_ranges = spacemap.SpaceMap({int(isRange.group(1)): int(isRange.group(2)) + 1})
					else:
						return()
				elif header in ('Pragma'):
					if my_path in index:
						index[my_path][header] = self.headers[header]
				else:
					print('Unknown header - ', header, ': ', self.headers[header], sep='')
					return()
				print(header, self.headers[header])

			# creating empty placeholder in index
			# if there's no space map and there's no file in real directory - we have no file
			# if there's an empty space map - file is full
			# space map generally covers every bit of file we don't posess currently
			if not my_path in index:
				info += '\nThis one is new.'
				reload = True
				record = {}
			else:
				record = index[my_path]

			if not '_parts' in record:
				record['_parts'] = None

			# creating file name from my_path
			file_name = config['dir'] + os.sep + re.compile('%20').sub(' ', my_path)
			# partial file or unfinished download
			temp_name = config['dir'] + os.sep + '.parts' + re.compile('%20').sub(' ', my_path)

			# forcibly checking file if no file present
			if os.access(file_name, os.R_OK):
				file_stat = os.stat(file_name)
			elif '_parts' in record and os.access(temp_name, os.R_OK):
				file_stat = os.stat(temp_name)
			elif not reload:
				print(record)
				info += '\nFile not found or inaccessible.'
				record['_parts'] = None
				reload = True

			# forcibly checking file if file size doesn't match with index data
			if not reload:
				if '_parts' in record and record['_parts'] == spacemap.SpaceMap():
					if 'Content-Length' in record and file_stat and file_stat.st_size != int(record['Content-Length']):
						info += '\nFile size is {} and stored file size is {}.'.format(file_stat.st_size, record['Content-Length'])
						reload = True

			# forcibly checking file if index holds Pragma header
			if not reload and 'Pragma' in record and record['Pragma'] == 'no-cache':
				info +='\nPragma on: recheck imminent.'
				recheck = True

			# skipping file processing if there's no need to recheck it and we have checked it at least 4 hours ago
			if not recheck and not reload and '_time' in record and (datetime.datetime.now() - datetime.timedelta(hours = 4) - record['_time']).days < 0:
				recheck = True

			print(info)
			if reload or recheck:

				try:
					request = 'http://' + config['root'] + my_path
					needed = None
					# XXX and if we specify full file we don't go partial?
					if requested_ranges != None:
						if '_parts' in record and record['_parts'] != None:
							needed = record['_parts'] & requested_ranges
						elif config['noparts']:
							needed = record['_parts']
						else:
							needed = requested_ranges
						ranges = ()
						print('Missing ranges: {}, requested ranges: {}, needed ranges: {}.'.format(record['_parts'], requested_ranges, needed))
						if len(needed) > 0:
							needed.rewind()
							while True:

						if reload:
							print('Reloading.')
							if os.access(temp_name, os.R_OK):
								os.unlink(temp_name)
							if os.access(file_name, os.R_OK):
								os.unlink(file_name)
						if new_record['_parts'] == None or reload:
							new_record['_parts'] = spacemap.SpaceMap({0: int(new_record['Content-Length'])})
						print(new_record)

						# downloading file or segment
						if 'Content-Length' in new_record:
							if needed == None:
								needed = new_record['_parts']
							else:
								if len(needed) > 1:
									print("Multipart requests currently not supported.")
									assert False, 'Skip this one for now.'
						else:
							assert False, 'No Content-Length or Content-Range header.'

						new_record['_time'] = datetime.datetime.now()
						if self.command not in ('HEAD'):
							# file is created at temporary location and moved in place only when download completes
							if not os.access(temp_name, os.R_OK):
								empty_name = config['dir'] + os.sep + '.tmp'
								with open(empty_name, 'w+b') as some_file:
									pass
								os.renames(empty_name, temp_name)
							temp_file = open(temp_name, 'r+b')
							needed.rewind()
							while True:
								(start, end) = needed.pop()

								buffer = source.read(req_block_size)
								length = len(buffer)
								while length > 0 and stream_last < end:
									stream_pos = stream_last + length
									assert not stream_pos > end, 'Received more data then requested: pos:{} start:{} end:{}.'.format(stream_pos, start, end)
									temp_file.seek(stream_last)
									temp_file.write(buffer)
									new_record['_parts'] = new_record['_parts'] - spacemap.SpaceMap({stream_last: stream_pos})
									index[my_path] = old_record
									index.sync()
									old_record = new_record
									stream_last = stream_pos
									if end - stream_last < block_size:
										req_block_size = end - stream_last
									buffer = source.read(req_block_size)
									length = len(buffer)
							# moving downloaded data to real file
							temp_file.close()






						print(new_record)
						index[my_path] = new_record
						index.sync()

				except urllib.error.HTTPError as error:
					# in case of error we don't need to do anything actually,
					# if file download stalls or fails the file would not be moved to it's location
					print(error)

			if '_parts' in index[my_path] and index[my_path]['_parts'] == spacemap.SpaceMap():
				# just moving
				# drop old dirs XXX
				print('Moving temporary file to new destination.')
				os.renames(temp_name, file_name)

			if self.command == 'HEAD':
				self.send_response(200)
				if 'Content-Length' in index[my_path]:
					self.send_header('Content-Length', index[my_path]['Content-Length'])
				self.send_header('Accept-Ranges', 'bytes')
				self.send_header('Content-Type', 'application/octet-stream')
				if 'Last-Modified' in index[my_path]:
					self.send_header('Last-Modified', index[my_path]['Last-Modified'])
				self.end_headers()
			else:
				if ('_parts' in index[my_path] and index[my_path]['_parts'] != spacemap.SpaceMap()) or not os.access(file_name, os.R_OK):
					file_name = temp_name

				with open(file_name, 'rb') as real_file:
					file_stat = os.stat(file_name)
					if 'Range' in self.headers:
						self.send_response(206)
						ranges = ()
						requested_ranges.rewind()
						while True:
							pair = requested_ranges.pop()
							if pair[0] == None:
								break
							ranges += '{}-{}'.format(pair[0], str(pair[1] - 1)),
						self.send_header('Content-Range', 'bytes {}/{}'.format(','.join(ranges), index[my_path]['Content-Length']))
					else:
						self.send_response(200)
						self.send_header('Content-Length', str(file_stat.st_size))
						requested_ranges = spacemap.SpaceMap({0: file_stat.st_size})
					self.send_header('Last-Modified', index[my_path]['Last-Modified'])
					self.send_header('Content-Type', 'application/octet-stream')
					self.end_headers()
					if self.command in ('GET'):
						if len(requested_ranges) > 0:
							requested_ranges.rewind()
							(start, end) = requested_ranges.pop()

							length = len(buffer)
					
		def do_HEAD(self):
			return self.__process()
		def do_GET(self):
			return self.__process()

	config.section('general')
	server = http.server.HTTPServer(('127.0.0.1', int(config['port'])), MyRequestHandler)
	server.serve_forever()

else:
	while True:
		unchecked_files = set()
		checked_files = 0