#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Author: Ricardo Garcia Gonzalez
# License: Public domain code
import htmlentitydefs
import httplib
import locale
import math
import netrc
import os
import os.path
import re
import socket
import string
import sys
import time
import urllib
import urllib2

std_headers = {
        'User-Agent': 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1',
        'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
        'Accept': 'text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5',
        'Accept-Language': 'en-us,en;q=0.5',
}

simple_title_chars = string.ascii_letters.decode('ascii') + string.digits.decode('ascii')

class DownloadError(Exception):
    """Download Error exception.

    This exception may be thrown by FileDownloader objects if they are not
    configured to continue on errors. They will contain the appropriate
    error message.
    """
    pass

class SameFileError(Exception):
    """Same File exception.

    This exception will be thrown by FileDownloader objects if they detect
    multiple files would have to be downloaded to the same file on disk.
    """
    pass

class PostProcessingError(Exception):
    """Post Processing exception.

    This exception may be raised by PostProcessor's .run() method to
    indicate an error in the postprocessing task.
    """
    pass

class FileDownloader(object):
    """File Downloader class.

    File downloader objects are the ones responsible of downloading the
    actual video file and writing it to disk if the user has requested
    it, among some other tasks. In most cases there should be one per
    program. As, given a video URL, the downloader doesn't know how to
    extract all the needed information, task that InfoExtractors do, it
    has to pass the URL to one of them.

    For this, file downloader objects have a method that allows
    InfoExtractors to be registered in a given order. When it is passed
    a URL, the file downloader handles it to the first InfoExtractor it
    finds that reports being able to handle it. The InfoExtractor returns
    all the information to the FileDownloader and the latter downloads the
    file or does whatever it's instructed to do.

    File downloaders accept a lot of parameters. In order not to saturate
    the object constructor with arguments, it receives a dictionary of
    options instead. These options are available through the get_params()
    method for the InfoExtractors to use. The FileDownloader also registers
    itself as the downloader in charge for the InfoExtractors that are
    added to it, so this is a "mutual registration".

    Available options:

    username:       Username for authentication purposes.
    password:       Password for authentication purposes.
    usenetrc:       Use netrc for authentication instead.
    quiet:          Do not print messages to stdout.
    forceurl:       Force printing final URL.
    forcetitle:     Force printing title.
    simulate:       Do not download the video files.
    format:         Video format code.
    outtmpl:        Template for output names.
    ignoreerrors:   Do not stop on download errors.
    ratelimit:      Download speed limit, in bytes/sec.
    """

    _params = None
    _ies = []
    _pps = []

    def __init__(self, params):
        """Create a FileDownloader object with the given options."""
        self._ies = []
        self._pps = []
        self.set_params(params)

    @staticmethod
    def pmkdir(filename):
        """Create directory components in filename. Similar to Unix "mkdir -p"."""
        components = filename.split(os.sep)
        aggregate = [os.sep.join(components[0:x]) for x in xrange(1, len(components))]
        aggregate = ['%s%s' % (x, os.sep) for x in aggregate] # Finish names with separator
        for dir in aggregate:
            if not os.path.exists(dir):
                os.mkdir(dir)

    @staticmethod
    def format_bytes(bytes):
        if bytes is None:
            return 'N/A'
        if bytes == 0:
            exponent = 0
        else:
            exponent = long(math.log(float(bytes), 1024.0))
        suffix = 'bkMGTPEZY'[exponent]
        converted = float(bytes) / float(1024**exponent)
        return '%.2f%s' % (converted, suffix)

    @staticmethod
    def calc_percent(byte_counter, data_len):
        if data_len is None:
            return '---.-%'
        return '%6s' % ('%3.1f%%' % (float(byte_counter) / float(data_len) * 100.0))

    @staticmethod
    def calc_eta(start, now, total, current):
        if total is None:
            return '--:--'
        dif = now - start
        if current == 0 or dif < 0.001: # One millisecond
            return '--:--'
        rate = float(current) / dif
        eta = long((float(total) - float(current)) / rate)
        (eta_mins, eta_secs) = divmod(eta, 60)
        if eta_mins > 99:
            return '--:--'
        return '%02d:%02d' % (eta_mins, eta_secs)

    @staticmethod
    def calc_speed(start, now, bytes):
        dif = now - start
        if bytes == 0 or dif < 0.001: # One millisecond
            return '%10s' % '---b/s'
        return '%10s' % ('%s/s' % FileDownloader.format_bytes(float(bytes) / dif))

    @staticmethod
    def best_block_size(elapsed_time, bytes):
        new_min = max(bytes / 2.0, 1.0)
        new_max = min(max(bytes * 2.0, 1.0), 4194304) # Do not surpass 4 MB
        if elapsed_time < 0.001:
            return int(new_max)
        rate = bytes / elapsed_time
        if rate > new_max:
            return int(new_max)
        if rate < new_min:
            return int(new_min)
        return int(rate)

    @staticmethod
    def parse_bytes(bytestr):
        """Parse a string indicating a byte quantity into a long integer."""
        matchobj = re.match(r'(?i)^(\d+(?:\.\d+)?)([kMGTPEZY]?)$', bytestr)
        if matchobj is None:
            return None
        number = float(matchobj.group(1))
        multiplier = 1024.0 ** 'bkmgtpezy'.index(matchobj.group(2).lower())
        return long(round(number * multiplier))

    def set_params(self, params):
        """Sets parameters."""
        if type(params) != dict:
            raise ValueError('params: dictionary expected')
        self._params = params

    def get_params(self):
        """Get parameters."""
        return self._params

    def add_info_extractor(self, ie):
        """Add an InfoExtractor object to the end of the list."""
        self._ies.append(ie)
        ie.set_downloader(self)

    def add_post_processor(self, pp):
        """Add a PostProcessor object to the end of the chain."""
        self._pps.append(pp)
        pp.set_downloader(self)

    def to_stdout(self, message, skip_eol=False):
        """Print message to stdout if not in quiet mode."""
        if not self._params.get('quiet', False):
            print u'%s%s' % (message, [u'\n', u''][skip_eol]),
            sys.stdout.flush()

    def to_stderr(self, message):
        """Print message to stderr."""
        print >>sys.stderr, message

    def fixed_template(self):
        """Checks if the output template is fixed."""
        return (re.search(ur'(?u)%\(.+?\)s', self._params['outtmpl']) is None)

    def trouble(self, message=None):
        """Determine action to take when a download problem appears.

        Depending on if the downloader has been configured to ignore
        download errors or not, this method may throw an exception or
        not when errors are found, after printing the message. If it
        doesn't raise, it returns an error code suitable to be returned
        later as a program exit code to indicate error.
        """
        if message is not None:
            self.to_stderr(message)
        if not self._params.get('ignoreerrors', False):
            raise DownloadError(message)
        return 1

    def slow_down(self, start_time, byte_counter):
        """Sleep if the download speed is over the rate limit."""
        rate_limit = self._params.get('ratelimit', None)
        if rate_limit is None or byte_counter == 0:
            return
        now = time.time()
        elapsed = now - start_time
        if elapsed <= 0.0:
            return
        speed = float(byte_counter) / elapsed
        if speed > rate_limit:
            time.sleep((byte_counter - rate_limit * (now - start_time)) / rate_limit)

    def report_destination(self, filename):
        """Report destination filename."""
        self.to_stdout(u'[download] Destination: %s' % filename)

    def report_progress(self, percent_str, data_len_str, speed_str, eta_str):
        """Report download progress."""
        self.to_stdout(u'\r[download] %s of %s at %s ETA %s' %
                        (percent_str, data_len_str, speed_str, eta_str), skip_eol=True)

    def report_finish(self):
        """Report download finished."""
        self.to_stdout(u'')

    def download(self, url_list):
        """Download a given list of URLs."""
        retcode = 0
        if len(url_list) > 1 and self.fixed_template():
            raise SameFileError(self._params['outtmpl'])

        for url in url_list:
            suitable_found = False
            for ie in self._ies:
                if not ie.suitable(url):
                    continue
                # Suitable InfoExtractor found
                suitable_found = True
                all_results = ie.extract(url)
                results = [x for x in all_results if x is not None]
                if len(results) != len(all_results):
                    retcode = self.trouble()

                if len(results) > 1 and self.fixed_template():
                    raise SameFileError(self._params['outtmpl'])

                for result in results:
                    # Forced printings
                    if self._params.get('forcetitle', False):
                        print result['title']
                    if self._params.get('forceurl', False):
                        print result['url']

                    # Do nothing else if in simulate mode
                    if self._params.get('simulate', False):
                        continue

                    try:
                        filename = self._params['outtmpl'] % result
                        self.report_destination(filename)
                    except (ValueError, KeyError), err:
                        retcode = self.trouble('ERROR: invalid output template or system charset: %s' % str(err))
                        continue
                    try:
                        self.pmkdir(filename)
                    except (OSError, IOError), err:
                        retcode = self.trouble('ERROR: unable to create directories: %s' % str(err))
                        continue
                    try:
                        outstream = open(filename, 'wb')
                    except (OSError, IOError), err:
                        retcode = self.trouble('ERROR: unable to open for writing: %s' % str(err))
                        continue
                    try:
                        self._do_download(outstream, result['url'])
                        outstream.close()
                    except (OSError, IOError), err:
                        retcode = self.trouble('ERROR: unable to write video data: %s' % str(err))
                        continue
                    except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        retcode = self.trouble('ERROR: unable to download video data: %s' % str(err))
                        continue
                    try:
                        self.post_process(filename, result)
                    except (PostProcessingError), err:
                        retcode = self.trouble('ERROR: postprocessing: %s' % str(err))
                        continue

                break
            if not suitable_found:
                retcode = self.trouble('ERROR: no suitable InfoExtractor: %s' % url)

        return retcode

    def post_process(self, filename, ie_info):
        """Run the postprocessing chain on the given file."""
        info = dict(ie_info)
        info['filepath'] = filename
        for pp in self._pps:
            info = pp.run(info)
            if info is None:
                break

    def _do_download(self, stream, url):
        request = urllib2.Request(url, None, std_headers)
        data = urllib2.urlopen(request)
        data_len = data.info().get('Content-length', None)
        data_len_str = self.format_bytes(data_len)
        byte_counter = 0
        block_size = 1024
        start = time.time()
        while True:
            # Progress message
            percent_str = self.calc_percent(byte_counter, data_len)
            eta_str = self.calc_eta(start, time.time(), data_len, byte_counter)
            speed_str = self.calc_speed(start, time.time(), byte_counter)
            self.report_progress(percent_str, data_len_str, speed_str, eta_str)

            # Download and write
            before = time.time()
            data_block = data.read(block_size)
            after = time.time()
            data_block_len = len(data_block)
            if data_block_len == 0:
                break
            byte_counter += data_block_len
            stream.write(data_block)
            block_size = self.best_block_size(after - before, data_block_len)

            # Apply rate limit
            self.slow_down(start, byte_counter)

        self.report_finish()
        if data_len is not None and str(byte_counter) != data_len:
            raise ValueError('Content too short: %s/%s bytes' % (byte_counter, data_len))

class InfoExtractor(object):
    """Information Extractor class.

    Information extractors are the classes that, given a URL, extract
    information from the video (or videos) the URL refers to. This
    information includes the real video URL, the video title and simplified
    title, author and others. It is returned in a list of dictionaries when
    calling its extract() method. It is a list because a URL can refer to
    more than one video (think of playlists). The dictionaries must include
    the following fields:

    id:             Video identifier.
    url:            Final video URL.
    uploader:       Nickname of the video uploader.
    title:          Literal title.
    stitle:         Simplified title.
    ext:            Video filename extension.

    Subclasses of this one should re-define the _real_initialize() and
    _real_extract() methods, as well as the suitable() static method.
    Probably, they should also be instantiated and added to the main
    downloader.
    """

    _ready = False
    _downloader = None

    def __init__(self, downloader=None):
        """Constructor. Receives an optional downloader."""
        self._ready = False
        self.set_downloader(downloader)

    @staticmethod
    def suitable(url):
        """Receives a URL and returns True if suitable for this IE."""
        return False

    def initialize(self):
        """Initializes an instance (authentication, etc)."""
        if not self._ready:
            self._real_initialize()
            self._ready = True

    def extract(self, url):
        """Extracts URL information and returns it in list of dicts."""
        self.initialize()
        return self._real_extract(url)

    def set_downloader(self, downloader):
        """Sets the downloader for this IE."""
        self._downloader = downloader

    def to_stdout(self, message):
        """Print message to stdout if downloader is not in quiet mode."""
        if self._downloader is None or not self._downloader.get_params().get('quiet', False):
            print message

    def to_stderr(self, message):
        """Print message to stderr."""
        print >>sys.stderr, message

    def _real_initialize(self):
        """Real initialization process. Redefine in subclasses."""
        pass

    def _real_extract(self, url):
        """Real extraction process. Redefine in subclasses."""
        pass

class YoutubeIE(InfoExtractor):
    """Information extractor for youtube.com."""

    _VALID_URL = r'^((?:http://)?(?:\w+\.)?youtube\.com/(?:(?:v/)|(?:(?:watch(?:\.php)?)?\?(?:.+&)?v=)))?([0-9A-Za-z_-]+)(?(1).+)?$'
    _LOGIN_URL = 'http://www.youtube.com/login?next=/'
    _AGE_URL = 'http://www.youtube.com/verify_age?next_url=/'
    _NETRC_MACHINE = 'youtube'

    @staticmethod
    def suitable(url):
        return (re.match(YoutubeIE._VALID_URL, url) is not None)

    def report_login(self):
        """Report attempt to log in."""
        self.to_stdout(u'[youtube] Logging in')

    def report_age_confirmation(self):
        """Report attempt to confirm age."""
        self.to_stdout(u'[youtube] Confirming age')

    def report_webpage_download(self, video_id):
        """Report attempt to download webpage."""
        self.to_stdout(u'[youtube] %s: Downloading video webpage' % video_id)

    def report_information_extraction(self, video_id):
        """Report attempt to extract video information."""
        self.to_stdout(u'[youtube] %s: Extracting video information' % video_id)

    def report_video_url(self, video_id, video_real_url):
        """Report extracted video URL."""
        self.to_stdout(u'[youtube] %s: URL: %s' % (video_id, video_real_url))

    def _real_initialize(self):
        if self._downloader is None:
            return

        username = None
        password = None
        downloader_params = self._downloader.get_params()

        # Attempt to use provided username and password or .netrc data
        if downloader_params.get('username', None) is not None:
            username = downloader_params['username']
            password = downloader_params['password']
        elif downloader_params.get('usenetrc', False):
            try:
                info = netrc.netrc().authenticators(self._NETRC_MACHINE)
                if info is not None:
                    username = info[0]
                    password = info[2]
                else:
                    raise netrc.NetrcParseError('No authenticators for %s' % self._NETRC_MACHINE)
            except (IOError, netrc.NetrcParseError), err:
                self.to_stderr(u'WARNING: parsing .netrc: %s' % str(err))
                return

        # No authentication to be performed
        if username is None:
            return

        # Log in
        login_form = {
                        'current_form': 'loginForm',
                        'next':         '/',
                        'action_login': 'Log In',
                        'username':     username,
                        'password':     password,
                        }
        request = urllib2.Request(self._LOGIN_URL, urllib.urlencode(login_form), std_headers)
        try:
            self.report_login()
            login_results = urllib2.urlopen(request).read()
            if re.search(r'(?i)<form[^>]* name="loginForm"', login_results) is not None:
                self.to_stderr(u'WARNING: unable to log in: bad username or password')
                return
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'WARNING: unable to log in: %s' % str(err))
            return

        # Confirm age
        age_form = {
                        'next_url':             '/',
                        'action_confirm':       'Confirm',
                        }
        request = urllib2.Request(self._AGE_URL, urllib.urlencode(age_form), std_headers)
        try:
            self.report_age_confirmation()
            age_results = urllib2.urlopen(request).read()
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'ERROR: unable to confirm age: %s' % str(err))
            return

    def _real_extract(self, url):
        # Extract video id from URL
        mobj = re.match(self._VALID_URL, url)
        if mobj is None:
            self.to_stderr(u'ERROR: invalid URL: %s' % url)
            return [None]
        video_id = mobj.group(2)

        # Downloader parameters
        format_param = None
        if self._downloader is not None:
            params = self._downloader.get_params()
            format_param = params.get('format', None)

        # Extension
        video_extension = {'18': 'mp4', '17': '3gp'}.get(format_param, 'flv')

        # Normalize URL, including format
        normalized_url = 'http://www.youtube.com/watch?v=%s' % video_id
        if format_param is not None:
            normalized_url = '%s&fmt=%s' % (normalized_url, format_param)
        request = urllib2.Request(normalized_url, None, std_headers)
        try:
            self.report_webpage_download(video_id)
            video_webpage = urllib2.urlopen(request).read()
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'ERROR: unable to download video webpage: %s' % str(err))
            return [None]
        self.report_information_extraction(video_id)

        # "t" param
        mobj = re.search(r', "t": "([^"]+)"', video_webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract "t" parameter')
            return [None]
        video_real_url = 'http://www.youtube.com/get_video?video_id=%s&t=%s' % (video_id, mobj.group(1))
        if format_param is not None:
            video_real_url = '%s&fmt=%s' % (video_real_url, format_param)
        self.report_video_url(video_id, video_real_url)

        # uploader
        mobj = re.search(r"var watchUsername = '([^']+)';", video_webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract uploader nickname')
            return [None]
        video_uploader = mobj.group(1)

        # title
        mobj = re.search(r'(?im)<title>YouTube - ([^<]*)</title>', video_webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract video title')
            return [None]
        video_title = mobj.group(1).decode('utf-8')
        video_title = re.sub(ur'(?u)&(.+?);', lambda x: unichr(htmlentitydefs.name2codepoint[x.group(1)]), video_title)
        video_title = video_title.replace(os.sep, u'%')

        # simplified title
        simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)
        simple_title = simple_title.strip(ur'_')

        # Return information
        return [{
                'id':           video_id.decode('utf-8'),
                'url':          video_real_url.decode('utf-8'),
                'uploader':     video_uploader.decode('utf-8'),
                'title':        video_title,
                'stitle':       simple_title,
                'ext':          video_extension.decode('utf-8'),
                }]

class MetacafeIE(InfoExtractor):
    """Information Extractor for metacafe.com."""

    _VALID_URL = r'(?:http://)?(?:www\.)?metacafe\.com/watch/([^/]+)/([^/]+)/.*'
    _DISCLAIMER = 'http://www.metacafe.com/family_filter/'
    _youtube_ie = None

    def __init__(self, youtube_ie, downloader=None):
        InfoExtractor.__init__(self, downloader)
        self._youtube_ie = youtube_ie

    @staticmethod
    def suitable(url):
        return (re.match(MetacafeIE._VALID_URL, url) is not None)

    def report_disclaimer(self):
        """Report disclaimer retrieval."""
        self.to_stdout(u'[metacafe] Retrieving disclaimer')

    def report_age_confirmation(self):
        """Report attempt to confirm age."""
        self.to_stdout(u'[metacafe] Confirming age')

    def report_download_webpage(self, video_id):
        """Report webpage download."""
        self.to_stdout(u'[metacafe] %s: Downloading webpage' % video_id)

    def report_extraction(self, video_id):
        """Report information extraction."""
        self.to_stdout(u'[metacafe] %s: Extracting information' % video_id)

    def _real_initialize(self):
        # Retrieve disclaimer
        request = urllib2.Request(self._DISCLAIMER, None, std_headers)
        try:
            self.report_disclaimer()
            disclaimer = urllib2.urlopen(request).read()
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'ERROR: unable to retrieve disclaimer: %s' % str(err))
            return

        # Confirm age
        disclaimer_form = {
                'filters': '0',
                'submit': "Continue - I'm over 18",
                }
        request = urllib2.Request('http://www.metacafe.com/', urllib.urlencode(disclaimer_form), std_headers)
        try:
            self.report_age_confirmation()
            disclaimer = urllib2.urlopen(request).read()
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'ERROR: unable to confirm age: %s' % str(err))
            return

    def _real_extract(self, url):
        # Extract id and simplified title from URL
        mobj = re.match(self._VALID_URL, url)
        if mobj is None:
            self.to_stderr(u'ERROR: invalid URL: %s' % url)
            return [None]

        video_id = mobj.group(1)

        # Check if video comes from YouTube
        mobj2 = re.match(r'^yt-(.*)$', video_id)
        if mobj2 is not None:
            return self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % mobj2.group(1))

        simple_title = mobj.group(2).decode('utf-8')
        video_extension = 'flv'

        # Retrieve video webpage to extract further information
        request = urllib2.Request('http://www.metacafe.com/watch/%s/' % video_id)
        try:
            self.report_download_webpage(video_id)
            webpage = urllib2.urlopen(request).read()
        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
            self.to_stderr(u'ERROR: unable retrieve video webpage: %s' % str(err))
            return [None]

        # Extract URL, uploader and title from webpage
        self.report_extraction(video_id)
        mobj = re.search(r'(?m)"mediaURL":"(http.*?\.flv)"', webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract media URL')
            return [None]
        mediaURL = mobj.group(1).replace('\\', '')

        mobj = re.search(r'(?m)"gdaKey":"(.*?)"', webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract gdaKey')
            return [None]
        gdaKey = mobj.group(1)

        video_url = '%s?__gda__=%s' % (mediaURL, gdaKey)

        mobj = re.search(r'(?im)<title>(.*) - Video</title>', webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract title')
            return [None]
        video_title = mobj.group(1).decode('utf-8')

        mobj = re.search(r'(?m)<li id="ChnlUsr">.*?Submitter:<br />(.*?)</li>', webpage)
        if mobj is None:
            self.to_stderr(u'ERROR: unable to extract uploader nickname')
            return [None]
        video_uploader = re.sub(r'<.*?>', '', mobj.group(1))

        # Return information
        return [{
                'id':           video_id.decode('utf-8'),
                'url':          video_url.decode('utf-8'),
                'uploader':     video_uploader.decode('utf-8'),
                'title':        video_title,
                'stitle':       simple_title,
                'ext':          video_extension.decode('utf-8'),
                }]

class YoutubePlaylistIE(InfoExtractor):
    """Information Extractor for YouTube playlists."""

    _VALID_URL = r'(?:http://)?(?:\w+\.)?youtube.com/view_play_list\?p=(.+)'
    _TEMPLATE_URL = 'http://www.youtube.com/view_play_list?p=%s&page=%s'
    _VIDEO_INDICATOR = r'/watch\?v=(.+?)&'
    _MORE_PAGES_INDICATOR = r'/view_play_list?p=%s&amp;page=%s'
    _youtube_ie = None

    def __init__(self, youtube_ie, downloader=None):
        InfoExtractor.__init__(self, downloader)
        self._youtube_ie = youtube_ie

    @staticmethod
    def suitable(url):
        return (re.match(YoutubePlaylistIE._VALID_URL, url) is not None)

    def report_download_page(self, playlist_id, pagenum):
        """Report attempt to download playlist page with given number."""
        self.to_stdout(u'[youtube] PL %s: Downloading page #%s' % (playlist_id, pagenum))

    def _real_initialize(self):
        self._youtube_ie.initialize()

    def _real_extract(self, url):
        # Extract playlist id
        mobj = re.match(self._VALID_URL, url)
        if mobj is None:
            self.to_stderr(u'ERROR: invalid url: %s' % url)
            return [None]

        # Download playlist pages
        playlist_id = mobj.group(1)
        video_ids = []
        pagenum = 1

        while True:
            self.report_download_page(playlist_id, pagenum)
            request = urllib2.Request(self._TEMPLATE_URL % (playlist_id, pagenum), None, std_headers)
            try:
                page = urllib2.urlopen(request).read()
            except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                self.to_stderr(u'ERROR: unable to download webpage: %s' % str(err))
                return [None]

            # Extract video identifiers
            ids_in_page = set()
            for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                ids_in_page.add(mobj.group(1))
            video_ids.extend(list(ids_in_page))

            if (self._MORE_PAGES_INDICATOR % (playlist_id, pagenum + 1)) not in page:
                break
            pagenum = pagenum + 1

        information = []
        for id in video_ids:
            information.extend(self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % id))
        return information

class PostProcessor(object):
    """Post Processor class.

    PostProcessor objects can be added to downloaders with their
    add_post_processor() method. When the downloader has finished a
    successful download, it will take its internal chain of PostProcessors
    and start calling the run() method on each one of them, first with
    an initial argument and then with the returned value of the previous
    PostProcessor.

    The chain will be stopped if one of them ever returns None or the end
    of the chain is reached.

    PostProcessor objects follow a "mutual registration" process similar
    to InfoExtractor objects.
    """

    _downloader = None

    def __init__(self, downloader=None):
        self._downloader = downloader

    def to_stdout(self, message):
        """Print message to stdout if downloader is not in quiet mode."""
        if self._downloader is None or not self._downloader.get_params().get('quiet', False):
            print message

    def to_stderr(self, message):
        """Print message to stderr."""
        print >>sys.stderr, message

    def set_downloader(self, downloader):
        """Sets the downloader for this PP."""
        self._downloader = downloader

    def run(self, information):
        """Run the PostProcessor.

        The "information" argument is a dictionary like the ones
        returned by InfoExtractors. The only difference is that this
        one has an extra field called "filepath" that points to the
        downloaded file.

        When this method returns None, the postprocessing chain is
        stopped. However, this method may return an information
        dictionary that will be passed to the next postprocessing
        object in the chain. It can be the one it received after
        changing some fields.

        In addition, this method may raise a PostProcessingError
        exception that will be taken into account by the downloader
        it was called from.
        """
        return information # by default, do nothing

### MAIN PROGRAM ###
if __name__ == '__main__':
    try:
        # Modules needed only when running the main program
        import getpass
        import optparse

        # General configuration
        urllib2.install_opener(urllib2.build_opener(urllib2.ProxyHandler()))
        urllib2.install_opener(urllib2.build_opener(urllib2.HTTPCookieProcessor()))
        socket.setdefaulttimeout(300) # 5 minutes should be enough (famous last words)

        # Parse command line
        parser = optparse.OptionParser(
                        usage='Usage: %prog [options] url...',
                        version='2008.08.09',
                        conflict_handler='resolve',
                        )
        parser.add_option('-h', '--help',
                        action='help', help='print this help text and exit')
        parser.add_option('-v', '--version',
                        action='version', help='print program version and exit')
        parser.add_option('-u', '--username',
                        dest='username', metavar='UN', help='account username')
        parser.add_option('-p', '--password',
                        dest='password', metavar='PW', help='account password')
        parser.add_option('-o', '--output',
                        dest='outtmpl', metavar='TPL', help='output filename template')
        parser.add_option('-q', '--quiet',
                        action='store_true', dest='quiet', help='activates quiet mode', default=False)
        parser.add_option('-s', '--simulate',
                        action='store_true', dest='simulate', help='do not download video', default=False)
        parser.add_option('-t', '--title',
                        action='store_true', dest='usetitle', help='use title in file name', default=False)
        parser.add_option('-l', '--literal',
                        action='store_true', dest='useliteral', help='use literal title in file name', default=False)
        parser.add_option('-n', '--netrc',
                        action='store_true', dest='usenetrc', help='use .netrc authentication data', default=False)
        parser.add_option('-g', '--get-url',
                        action='store_true', dest='geturl', help='simulate, quiet but print URL', default=False)
        parser.add_option('-e', '--get-title',
                        action='store_true', dest='gettitle', help='simulate, quiet but print title', default=False)
        parser.add_option('-f', '--format',
                        dest='format', metavar='FMT', help='video format code')
        parser.add_option('-b', '--best-quality',
                        action='store_const', dest='format', help='alias for -f 18', const='18')
        parser.add_option('-m', '--mobile-version',
                        action='store_const', dest='format', help='alias for -f 17', const='17')
        parser.add_option('-i', '--ignore-errors',
                        action='store_true', dest='ignoreerrors', help='continue on download errors', default=False)
        parser.add_option('-r', '--rate-limit',
                        dest='ratelimit', metavar='L', help='download rate limit (e.g. 50k or 44.6m)')
        (opts, args) = parser.parse_args()

        # Conflicting, missing and erroneous options
        if len(args) < 1:
            sys.exit(u'ERROR: you must provide at least one URL')
        if opts.usenetrc and (opts.username is not None or opts.password is not None):
            sys.exit(u'ERROR: using .netrc conflicts with giving username/password')
        if opts.password is not None and opts.username is None:
            sys.exit(u'ERROR: account username missing')
        if opts.outtmpl is not None and (opts.useliteral or opts.usetitle):
            sys.exit(u'ERROR: using output template conflicts with using title or literal title')
        if opts.usetitle and opts.useliteral:
            sys.exit(u'ERROR: using title conflicts with using literal title')
        if opts.username is not None and opts.password is None:
            opts.password = getpass.getpass(u'Type account password and press return:')
        if opts.ratelimit is not None:
            numeric_limit = FileDownloader.parse_bytes(opts.ratelimit)
            if numeric_limit is None:
                sys.exit(u'ERROR: invalid rate limit specified')
            opts.ratelimit = numeric_limit

        # Information extractors
        youtube_ie = YoutubeIE()
        metacafe_ie = MetacafeIE(youtube_ie)
        youtube_pl_ie = YoutubePlaylistIE(youtube_ie)

        # File downloader
        fd = FileDownloader({
                'usenetrc': opts.usenetrc,
                'username': opts.username,
                'password': opts.password,
                'quiet': (opts.quiet or opts.geturl or opts.gettitle),
                'forceurl': opts.geturl,
                'forcetitle': opts.gettitle,
                'simulate': (opts.simulate or opts.geturl or opts.gettitle),
                'format': opts.format,
                'outtmpl': ((opts.outtmpl is not None and opts.outtmpl.decode(locale.getdefaultlocale()[1]))
                        or (opts.usetitle and u'%(stitle)s-%(id)s.%(ext)s')
                        or (opts.useliteral and u'%(title)s-%(id)s.%(ext)s')
                        or u'%(id)s.%(ext)s'),
                'ignoreerrors': opts.ignoreerrors,
                'ratelimit': opts.ratelimit,
                })
        fd.add_info_extractor(youtube_pl_ie)
        fd.add_info_extractor(metacafe_ie)
        fd.add_info_extractor(youtube_ie)
        retcode = fd.download(args)
        sys.exit(retcode)

    except DownloadError:
        sys.exit(1)
    except SameFileError:
        sys.exit(u'ERROR: fixed output name but more than one file to download')
    except KeyboardInterrupt:
        sys.exit(u'\nERROR: Interrupted by user')
