#!/usr/bin/env python
#
# Copyright (c) 2006 Ricardo Garcia Gonzalez
#
# 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.
# 
# Except as contained in this notice, the name(s) of the above copyright
# holders shall not be used in advertising or otherwise to promote the
# sale, use or other dealings in this Software without prior written
# authorization.
#
import sys
import optparse
import httplib
import urllib2
import re

# First off, check Python and refuse to run
if sys.hexversion < 0x020400f0:
	sys.exit('Error: Python 2.4 or later needed to run the program')

# Exit status constants
exit_failure = 1
exit_success = 0

# Global constants
const_video_url_str = 'http://www.youtube.com/watch?v=%s'
const_video_url_re = re.compile(r'http://(?:www\.)?youtube\.com/(?:v/|(?:watch(?:\.php)?)?\?v=)([^&]+).*')
const_login_url_str = 'http://www.youtube.com/signup?next=/'
const_login_post_str = 'current_form=loginForm&next=%%2F&username=%s&password=%s&action_login=Log+In'
const_age_url_str = 'http://www.youtube.com/verify_age?next_url=/watch%%3Fv%%3D%s'
const_age_post_str = 'next_url=%%2Fwatch%%3Fv%%3D%s&action_confirm=Confirm'
const_video_url_params_re = re.compile(r'player2\.swf\?([^"]+)"', re.M)
const_video_url_real_str = 'http://www.youtube.com/get_video?%s'
const_1k = 1024
const_block_size = 10 * const_1k

# Print error message, followed by standard advice information, and then exit
def error_advice_exit(error_text):
	global exit_failure
	sys.stderr.write('Error: %s.\n' % error_text)
	sys.stderr.write('Try again several times. It may be a temporal problem.\n')
	sys.stderr.write('Other typical problems:\n\n')
	sys.stderr.write('\tVideo no longer exists.\n')
	sys.stderr.write('\tVideo requires age confirmation but you did not provide an account.\n')
	sys.stderr.write('\tYou provided the account data, but it is not valid.\n')
	sys.stderr.write('\tThe connection was cut suddenly for some reason.\n')
	sys.stderr.write('\tYouTube changed their system, and the program no longer works.\n')
	sys.stderr.write('\nTry to confirm you are able to view the video using a web browser.\n')
	sys.stderr.write('Use the same video URL and account information, if needed, with this program.\n')
	sys.stderr.write('When using a proxy, make sure http_proxy has http://host:port format.\n')
	sys.stderr.write('Try again several times and contact me if the problem persists.\n')
	sys.exit(exit_failure)

# Wrapper to create custom requests with typical headers
def request_create(url, data=None):
	retval = urllib2.Request(url)
	if not data is None:
		retval.add_data(data)
	# Try to mimic Firefox, at least a little bit
	retval.add_header('User-Agent', 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6')
	retval.add_header('Accept-Charset', 'ISO-8859-1,utf-8;q=0.7,*;q=0.7')
	retval.add_header('Accept', 'text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5')
	retval.add_header('Accept-Language', 'en-us,en;q=0.5')
	return retval

# Perform a request, process headers and return response
def perform_request(url, data=None):
	request = request_create(url, data)
	response = urllib2.urlopen(request)
	return response

# Convert bytes to KiB
def to_k(bytes):
	global const_1k
	return bytes / const_1k

# Conditional print
def cond_print(str):
	global cmdl_opts
	if not cmdl_opts.quiet:
		sys.stdout.write(str)
		sys.stdout.flush()

# Create the command line options parser and parse command line
cmdl_usage = 'usage: %prog [options] video_url'
cmdl_version = '2006.09.25'
cmdl_parser = optparse.OptionParser(usage=cmdl_usage, version=cmdl_version, conflict_handler='resolve')
cmdl_parser.add_option('-h', '--help', action='help', help='print this help text and exit')
cmdl_parser.add_option('-v', '--version', action='version', help='print program version and exit')
cmdl_parser.add_option('-u', '--username', dest='username', metavar='USERNAME', help='account username')
cmdl_parser.add_option('-p', '--password', dest='password', metavar='PASSWORD', help='account password')
cmdl_parser.add_option('-o', '--output', dest='outfile', metavar='FILE', help='output video file name')
cmdl_parser.add_option('-q', '--quiet', action='store_true', dest='quiet', help='activates quiet mode')
cmdl_parser.add_option('-s', '--simulate', action='store_true', dest='simulate', help='do not download video')
(cmdl_opts, cmdl_args) = cmdl_parser.parse_args()

# Get video URL
if len(cmdl_args) != 1:
	cmdl_parser.print_help()
	sys.exit(exit_failure)
video_url_cmdl = cmdl_args[0]

# Verify video URL format and convert to "standard" format
video_url_mo = const_video_url_re.match(video_url_cmdl)
if video_url_mo is None:
	sys.exit('Error: URL does not seem to be a youtube video URL. If it is, report a bug.')
video_url_id = video_url_mo.group(1)
video_url = const_video_url_str % video_url_id

# Check conflicting options
if not cmdl_opts.outfile is None and cmdl_opts.simulate:
	sys.stderr.write('Warning: video file name given but will not be used.\n')

# Get output file name 
if cmdl_opts.outfile is None:
	video_filename = '%s.flv' % video_url_id
else:
	video_filename = cmdl_opts.outfile

# Check name
if not video_filename.lower().endswith('.flv'):
	sys.stderr.write('Warning: video file name does not end in .flv\n')

# Verify both or none present
if ((cmdl_opts.username is None and not cmdl_opts.password is None) or
    (not cmdl_opts.username is None and cmdl_opts.password is None)):
	sys.exit('Error: both username and password must be given, or none.')

# Test writable file
if not cmdl_opts.simulate:
	try:
		disk_test = open(video_filename, 'wb')
		disk_test.close()

	except (OSError, IOError):
		sys.exit('Error: unable to open %s for writing.' % video_filename)

# Install cookie and proxy handlers
urllib2.install_opener(urllib2.build_opener(urllib2.HTTPCookieProcessor()))
urllib2.install_opener(urllib2.build_opener(urllib2.ProxyHandler()))

# Login and confirm age if needed
if not cmdl_opts.username is None:
	try:
		# Log in
		cond_print('Logging in... ')
		perform_request(const_login_url_str, const_login_post_str % (cmdl_opts.username, cmdl_opts.password)).read()
		cond_print('done.\n')

	except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
		cond_print('failed.\n')
		error_advice_exit('unable to login')

	except KeyboardInterrupt:
		sys.exit('\n')

	try:
		# Get age confirmation cookie
		cond_print('Confirming age... ')
		perform_request(const_age_url_str % video_url_id, const_age_post_str % video_url_id).read()
		cond_print('done.\n')

	except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
		cond_print('failed.\n')
		error_advice_exit('unable to confirm age')

	except KeyboardInterrupt:
		sys.exit('\n')

# Retrieve video webpage
try:
	cond_print('Retrieving video webpage... ')
	video_webpage = perform_request(video_url).read()
	cond_print('done.\n')

except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
	cond_print('failed.\n')
	error_advice_exit('unable to download video webpage')

except KeyboardInterrupt:
	sys.exit('\n')

# Extract needed video URL parameters
try:
	cond_print('Extracting video URL parameters... ')
	video_url_params_mo = const_video_url_params_re.search(video_webpage)
	
	if video_url_params_mo is None:
		cond_print('failed.\n')
		error_advice_exit('unable to extract URL parameters')
	
	video_url_params = video_url_params_mo.group(1)
	video_url_real = const_video_url_real_str % video_url_params
	cond_print('done.\n')

except KeyboardInterrupt:
	sys.exit('\n')

# Retrieve video data
try:
	video_data = perform_request(video_url_real)
	cond_print('Video data found at %s\n' % video_data.geturl())

	# Abort here if in simulate mode
	if cmdl_opts.simulate:
		sys.exit()

	cond_print('Retrieving video data... ')
	video_file = open(video_filename, 'wb')
	try:
		video_len_str = '%sk' % to_k(int(video_data.info()['Content-length']))
	except KeyError:
		video_len_str = '(unknown)'

	byte_counter = 0
	video_block = video_data.read(const_block_size)
	while len(video_block) != 0:
		byte_counter += len(video_block)
		video_file.write(video_block)
		cond_print('\rRetrieving video data... %sk of %s ' % (to_k(byte_counter), video_len_str))
		video_block = video_data.read(const_block_size)

	video_file.close()
	cond_print('done.\n')
	cond_print('Video data saved to %s\n' % video_filename)
	sys.exit()

except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
	cond_print('failed.\n')
	error_advice_exit('unable to download video data')

except KeyboardInterrupt:
	sys.exit('\n')