#!/usr/bin/perl -w

=pod

=head1 NAME

tv_grab_combiner - Grab listings by combining data from several grabbers.

=head1 SYNOPSIS

tv_grab_combiner --help

tv_grab_combiner --configure [--config-file FILE]

tv_grab_combiner [--config-file FILE]
                 [--days N] [--offset N]
                 [--output FILE] [--quiet]

=head1 DESCRIPTION

Output TV and listings in XMLTV format by combining data from several
other grabbers.

First you must run B<tv_grab_combiner --configure> to choose which grabbers
you want to grab data with and how these grabbers should be configured.

Then you can run B<tv_grab_combiner> with the --days and --offset options
to grab data. Omitting these options will use the default values for these
parameters for each grabber. Since these defaults differs between grabbers,
you might end up with data for different periods of time for different
channels.

=head1 OPTIONS

B<--configure> Prompt for which grabbers to use, how these grabbers shall
be configured and write the configuration file.

B<--config-file FILE> Set the name of the configuration file, the
default is B<~/.xmltv/tv_grab_combiner.conf>.  This is the file written by
B<--configure> and read when grabbing.

B<--output FILE> When grabbing, write output to FILE rather than
standard output.

B<--days N> When grabbing, grab N days rather than 5.

B<--offset N> Start grabbing at today + N days.  N may be negative.

B<--quiet> Suppress the progress-bar normally shown on standard error.

B<--version> Show the version of the grabber.

B<--help> Print a help message and exit.

=head1 ERROR HANDLING

If any of the called grabbers exit with an error, tv_grab_combiner will
exit with a status code of 1 to indicate that the data is incomplete. If any
grabber produces output that is not well-formed xml, the output from that
grabber will be ignored and tv_grab_combiner will exit with a status code of 1.

=head1 ENVIRONMENT VARIABLES

The environment variable HOME can be set to change where configuration
files are stored. All configuration is stored in $HOME/.xmltv/.

=head1 AUTHOR

Mattias Holmlund, mattias -at- holmlund -dot- se.

=head1 BUGS

=cut

use strict;

use XMLTV;
use XMLTV::Version "$XMLTV::VERSION";
use XMLTV::Capabilities qw/baseline manualconfig/;
use XMLTV::Description "Combine data from several other grabbers";
use XMLTV::Usage << "END";
To configure: $0 --configure [--config-file FILE]
To grab listings: $0 [--config-file FILE] [--output FILE] [--quiet]

END

use XMLTV::Ask;
use XMLTV::Config_file;

use XML::LibXML;
use Getopt::Long;
use File::Temp qw/tempfile/;

my $opt = {
           help => 0,
           configure => 0,
           'config-file' =>
             XMLTV::Config_file::filename(undef, 'tv_grab_combiner', 1 ),
           days => undef,
           offset => undef,
           quiet => 0,
           output => undef,
           };

GetOptions( $opt, qw/help configure config-file=s days=s offset=s quiet
                     output=s/ )
  or usage();

if( $opt->{configure} ) {
  configure();
  exit;
}

if( grab_data() > 0 ) {
  exit 1;
}
else {
  exit 0;
}

sub grab_data {
  my @lines = XMLTV::Config_file::read_lines( $opt->{'config-file'} );

  my $parser = XML::LibXML->new();
  my $result;
  my $errors=0;

  my $grabber;
  foreach my $line (@lines) {
    next if not defined $line;
    my( $key, $value ) = split( '=', $line, 2 );
    die "Unknown key $key in $opt->{'config-file'}" unless $key eq 'grabber';

    my( $grabber, $config ) = split( /;/, $value, 2 );
    my( $exitcode, $data ) = run_grabber( $grabber, $config );
    if( $exitcode ) {
      print STDERR "$grabber exited with an error-code.\n";
      $errors++;
    }

    my $t;
    eval {
      $t = $parser->parse_string( $data );
    };

    if( not defined $t ) {
      print STDERR "$grabber returned invalid data. Ignoring.\n";
      $errors++;
      next;
    }

    if( defined $result ) {
      concatenate( $result, $t );
    }
    else {
      $result = $t;
    }
  }

  if( defined $result ) {
    if( defined( $opt->{output} ) ) {
      $result->toFile( $opt->{output}, 1 );
    }
    else {
      $result->toFH( *STDOUT, 1 );
    }
  }

  return $errors;
}

sub run_grabber {
  my( $grabber, $config ) = @_;

  my( $fh, $filename ) = tempfile(UNLINK => 1);
  write_config( $config, $fh );
  close($fh);

  my $options = "";
  $options .= " --quiet" if $opt->{quiet};
  $options .= " --days $opt->{days}" if defined $opt->{days};
  $options .= " --offset $opt->{offset}" if defined $opt->{offset};

  print STDERR "Running $grabber\n" unless $opt->{quiet};

  my $result = qx/$grabber $options --config-file $filename/;

  return ($? >> 8, $result );
}

sub configure_grabber {
  my( $grabber ) = @_;

  print "Configuring $grabber\n";

  my( $fh, $filename ) = tempfile(UNLINK => 1);
  system( $grabber, '--configure', '--config-file', $filename );

  return read_config( $filename );
}

# Read a config-file from disk and encode it into a one-line string.
sub read_config {
  my( $filename ) = @_;

  my $result = slurp( $filename )
    or die "Failed to read from $filename";

  $result =~ s/&/&a/g;
  $result =~ s/\n/&n/g;
  $result =~ s/#/&c/g;

  return $result;
}

sub write_config {
  my( $config, $fh ) = @_;

  $config =~ s/&c/#/g;
  $config =~ s/&n/\n/g;
  $config =~ s/&a/&/g;

  print $fh $config;
}

sub configure {
  XMLTV::Config_file::check_no_overwrite( $opt->{'config-file'} );

  print "Looking for grabbers...\n";
  my @result = qx/tv_find_grabbers baseline manualconfig/;
  my %grabbers;

  foreach (reverse @result) {
    chomp;
    chomp;
    my($g, $t) = split( /\|/, $_ );
    $grabbers{$t}=$g
      unless $g=~/tv_grab_combiner/;
  }

  open( CONF, "> " . $opt->{'config-file'});
  while( 1 ) {
    my $t = ask_choice( "Select a grabber:", "Done",
                        "Done", sort( keys %grabbers) );
    last if $t eq "Done";
    my $g = $grabbers{$t};

    my $config = configure_grabber( $g );
    print CONF "grabber=$g;$config\n";
  }
  close( CONF );
}

# Takes two XML::LibXML representations of XMLTV files as parameters
# and merges the second tree into the first.
sub concatenate {
  my( $t1, $t2 ) = @_;

  $t1->setEncoding('UTF-8');

  my $root = $t1->findnodes( '/tv' )->[0];
  my $last_chan = $root->findnodes( 'channel[last()]' )->[0]
    or die "Failed to find any channel entries";

  foreach my $chan (  $t2->findnodes( '//channel' ) ) {
    $root->insertAfter( $chan, $last_chan );
    $last_chan = $chan;
  }

  my $last_prog;
  $last_prog = $root->findnodes( 'programme[last()]' )->[0]
    or $last_prog = $last_chan;

  foreach my $prog ( $t2->findnodes( '//programme' ) ) {
    $root->insertAfter( $prog, $last_prog );
    $last_prog = $prog;
  }

}

sub slurp {
  local( $/, @ARGV ) = ( wantarray ? $/ : undef, @_ );
  return <ARGV>;
}