#!/usr/bin/perl -w
# Copyright © 2007, 2008 Jamie Zawinski <jwz@jwz.org>
#
# Permission to use, copy, modify, distribute, and sell this software and its
# documentation for any purpose is hereby granted without fee, provided that
# the above copyright notice appear in all copies and that both that
# copyright notice and this permission notice appear in supporting
# documentation.  No representations are made about the suitability of this
# software for any purpose.  It is provided "as is" without express or 
# implied warranty.
#
# Given a YouTube URL, downloads the corresponding FLV file.
# The name of the file will be the <TITLE> of the YouTube page.
#
# Created: 25-Apr-2007.

require 5;
use diagnostics;
use strict;

my $progname = $0; $progname =~ s@.*/@@g;
my $version = q{ $Revision: 0.00 $ }; $version =~ s/^[^0-9]+([0-9.]+).*$/$1/;

my $verbose = 1;

sub de_entify($) {
  my ($text) = @_;
  $text =~ s/&uuml;/u/g;
  $text =~ s/&lt;/</g;
  $text =~ s/&gt;/>/g;
  $text =~ s/&amp;/&/g;
  return $text;
}

sub safe_system(@) {
  my (@cmd) = @_;

  print STDOUT "$progname: executing " . join(' ', @cmd) . "\n"
    if ($verbose > 3);

  system @cmd;
  my $exit_value  = $? >> 8;
  my $signal_num  = $? & 127;
  my $dumped_core = $? & 128;
  error ("$cmd[0]: core dumped!") if ($dumped_core);
  error ("$cmd[0]: signal $signal_num!") if ($signal_num);
  error ("$cmd[0]: exited with $exit_value!") if ($exit_value);
}


sub download_url($) {
  my ($url) = @_;

  # Adding fmt=18 means "give us a higher res video if available".
  $url .= "&fmt=18" unless ($url =~ m/&fmt=/);

  my ($id) = ($url =~ m@^http://www\.youtube\.com/watch\?v=([^<>?&,]+)($|&)@);
  error ("no ID in $url") unless ($id);

  my $body = `wget -qO- '$url'`;
  error ("unable to get $url") unless (length($body) > 5000);

  my ($title) = ($body =~ m@<title>\s*(.*?)\s*</title>@si);
  $title =~ s/^Youtube - //si;

  my $file = "$title.flv";
  $file = de_entify($file);

  if ($body =~ m@<div class="errorBox">\s*(.*?)\s*</div>@si) {
    print STDERR "error: $file: \"$1\"\n";
    return;
  }

#  my ($args) = ($body =~ m@/player2.swf(\?[^/"]*?video_id=$id\&[^"]+)"@s);
  my ($args) = ($body =~ m@swfArgs = {(.*?)}@s);

  if (!$args &&
      $body =~ m@may contain content that is (inappropriate)@) {
    print STDERR "error: $file: \"$1\"\n";
    return;
  }

# print STDERR "####\n$body\n####\n\n" unless ($args);

  error ("unable to find args in $url") unless ($args);

  # hl:'en',video_id:'CjGi-1FHq8Y',l:'207',etc
  # becomes:
  # hl=en&video_id=CjGi-1FHq8Y&l=207& etc

  # "hl": "en", "plid": "AAR..."
  # becomes:
  # hl=en&plid=AAR...

  $args =~ s/[\'\"]?, *[\'\"]?/&/gs;
  $args =~ s/[\'\"]?: *[\'\"]?/=/gs;
  $args =~ s/[\'\"] *$//s;
  $args =~ s/^[\'\"] *//s;

  error ("unparsable args: $args") if ($args =~ m/[\s\'\"]/);

  $url = 'http://www.youtube.com/get_video?' . $args;

  print STDERR "$progname: downloading \"$file\"\n" if ($verbose);
  my @cmd = ("wget", "-O", $file, $url);
  push @cmd, "-q" if ($verbose <= 2);
  safe_system (@cmd);
}


sub error($) {
  my ($err) = @_;
  print STDERR "$progname: $err\n";
  exit 1;
}

sub usage() {
  print STDERR "usage: $progname [--verbose] youtube-urls...\n";
  exit 1;
}

sub main() {
  my @urls = ();
  while ($#ARGV >= 0) {
    $_ = shift @ARGV;
    if ($_ eq "--verbose") { $verbose++; }
    elsif (m/^-v+$/) { $verbose += length($_)-1; }
    elsif (m/^-./) { usage; }
    elsif (! m@^http://www\.youtube\.com/@s ) { 
      print STDERR "$progname: not a www.youtube.com url: $_\n";
      usage; }
    else { push @urls, $_; }
  }
  usage unless ($#urls >= 0);
  foreach (@urls) {
    download_url ($_); 
  }
}

main();
exit 0;