#!/usr/bin/env python

import sys, os
import urllib2
import json, hashlib

def rsa_verify(message, signature, key):
    from struct import pack
    from hashlib import sha256
    from sys import version_info
    def b(x):
        if version_info[0] == 2: return x
        else: return x.encode('latin1')
    assert(type(message) == type(b('')))
    block_size = 0
    n = key[0]
    while n:
        block_size += 1
        n >>= 8
    signature = pow(int(signature, 16), key[1], key[0])
    raw_bytes = []
    while signature:
        raw_bytes.insert(0, pack("B", signature & 0xFF))
        signature >>= 8
    signature = (block_size - len(raw_bytes)) * b('\x00') + b('').join(raw_bytes)
    if signature[0:2] != b('\x00\x01'): return False
    signature = signature[2:]
    if not b('\x00') in signature: return False
    signature = signature[signature.index(b('\x00'))+1:]
    if not signature.startswith(b('\x30\x31\x30\x0D\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01\x05\x00\x04\x20')): return False
    signature = signature[19:]
    if signature != sha256(message).digest(): return False
    return True

sys.stderr.write(u'Hi! We changed distribution method and now youtube-dl needs to update itself one more time.\n')
sys.stderr.write(u'This will only happen once. Simply press enter to go on. Sorry for the trouble!\n')
sys.stderr.write(u'From now on, get the binaries from http://rg3.github.com/youtube-dl/download.html, not from the git repository.\n\n')

raw_input()

filename = sys.argv[0]

UPDATE_URL = "http://rg3.github.com/youtube-dl/update/"
VERSION_URL = UPDATE_URL + 'LATEST_VERSION'
JSON_URL = UPDATE_URL + 'versions.json'
UPDATES_RSA_KEY = (0x9d60ee4d8f805312fdb15a62f87b95bd66177b91df176765d13514a0f1754bcd2057295c5b6f1d35daa6742c3ffc9a82d3e118861c207995a8031e151d863c9927e304576bc80692bc8e094896fcf11b66f3e29e04e3a71e9a11558558acea1840aec37fc396fb6b65dc81a1c4144e03bd1c011de62e3f1357b327d08426fe93, 65537)

if not os.access(filename, os.W_OK):
    sys.exit('ERROR: no write permissions on %s' % filename)

exe = os.path.abspath(filename)
directory = os.path.dirname(exe)
if not os.access(directory, os.W_OK):
    sys.exit('ERROR: no write permissions on %s' % directory)

try:
    versions_info = urllib2.urlopen(JSON_URL).read().decode('utf-8')
    versions_info = json.loads(versions_info)
except:
    sys.exit(u'ERROR: can\'t obtain versions info. Please try again later.')
if not 'signature' in versions_info:
    sys.exit(u'ERROR: the versions file is not signed or corrupted. Aborting.')
signature = versions_info['signature']
del versions_info['signature']
if not rsa_verify(json.dumps(versions_info, sort_keys=True), signature, UPDATES_RSA_KEY):
    sys.exit(u'ERROR: the versions file signature is invalid. Aborting.')

version = versions_info['versions'][versions_info['latest']]

try:
    urlh = urllib2.urlopen(version['exe'][0])
    newcontent = urlh.read()
    urlh.close()
except (IOError, OSError) as err:
    sys.exit('ERROR: unable to download latest version')

newcontent_hash = hashlib.sha256(newcontent).hexdigest()
if newcontent_hash != version['exe'][1]:
    sys.exit(u'ERROR: the downloaded file hash does not match. Aborting.')

try:
    with open(exe + '.new', 'wb') as outf:
        outf.write(newcontent)
except (IOError, OSError) as err:
    sys.exit(u'ERROR: unable to write the new version')

try:
    bat = os.path.join(directory, 'youtube-dl-updater.bat')
    b = open(bat, 'w')
    b.write("""
echo Updating youtube-dl...
ping 127.0.0.1 -n 5 -w 1000 > NUL
move /Y "%s.new" "%s"
del "%s"
    \n""" %(exe, exe, bat))
    b.close()

    os.startfile(bat)
except (IOError, OSError) as err:
    sys.exit('ERROR: unable to overwrite current version')

sys.stderr.write(u'Done! Now you can run youtube-dl.\n')
