#!/usr/bin/perl -w

=pod

=head1 NAME

splitvideo - Split video at time stamp


=head1 SYNOPSIS

B<splitvideo> time videofile


=head1 DESCRIPTION

B<splitvideo> splits I<videofile> at I<time>.

I<time> is given in seconds or as HH:MM:SS.s.

I<videofile> will be split into: I<videofile>-00:00:00.0-ZZ:ZZ:ZZ.Z
and I<videofile>-ZZ:ZZ:ZZ.Z-YY:YY:YY.Y where Z is the split time and Y
is the length of the video.

If I<videofile> contains XX:XX:XX.X-YY:YY:YY.Y I<videofile> will be
split into: I<videofile>-XX:XX:XX.X-ZZ:ZZ:ZZ.Z and
I<videofile>-ZZ:ZZ:ZZ.Z-YY:YY:YY.Y.

After splitting is done I<videofile> is moved to ~/.rm/splitvideo.


=head1 USES

B<splitvideo> can be used on the commandline:

   splitvideo 3600 myvideo.mp4

It can also be called from VLC by installing B<splitvideo.lua> from
https://gitlab.com/ole.tange/tangetools/tree/master/splitvideo in
B<~/.local/share/vlc/lua/extensions/>


=head1 AUTHOR

Copyright (C) 2019 Ole Tange,
http://ole.tange.dk and Free Software Foundation, Inc.


=head1 LICENSE

Copyright (C) 2012 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.


=head1 DEPENDENCIES

B<splitvideo> uses B<perl> and B<ffmpeg>.


=head1 SEE ALSO

B<ffmpeg>


=cut

use strict;

my $time = shift;
my $infile = shift;

my $rmdir = find_rm_dir(".") || ".rm";
-d $rmdir or mkdir $rmdir;
$rmdir .= "/splitvideo";
-d $rmdir or mkdir $rmdir;

$time = format_time($time);

if(not -e $infile or $time !~ /\d\d:\d\d:\d\d.\d/) {
    print "$time";
    print "$0 HH:MM:SS.t video.file\n",
	"To split video.file at HH:MM:SS.t\n",
	"The original file will be moved to .../.rm\n\n";
} else {
    my ($start_file,$end_file) = destinationfilenames($infile,$time);
    # fmpeg -t 00:25:29 -i in.mp4 -c copy out-start.mp4
    my @start = ("ffmpeg","-t",$time,"-i","file:$infile","-c","copy","file:$start_file");
    system(@start) == 0 or die(join" ",@start);
    # fmpeg -ss 00:25:29 -i in.mp4 -c copy out-end.mp4
    my @end = ("ffmpeg","-ss",$time,"-i","file:$infile","-c","copy","file:$end_file");
    system(@end) == 0 or die(join" ",@end);
    system("mv",$infile,$rmdir) == 0 or die;
}

sub destinationfilenames {
    # Inputs:
    #   $file = video file name
    #   $time = time to split at
    # Return name with:
    #   basename-(starttime)-(starttime+time).ext
    #   basename-(starttime+time)-(videolength).ext
    my $file = shift;
    my $time = shift;
    my ($startfile,$endfile);
    my $basename = $file;
    $basename =~ s/(\.[^.]+)$//;
    my $extension = $1;
    if($basename =~ s/-(\d\d:\d\d:\d\d.\d)-(\d\d:\d\d:\d\d.\d)//) {
	my $add = format_time(to_secs($1)+to_secs($time));
	$startfile = "$basename-$1-$add$extension";
	$endfile = "$basename-$add-$2$extension";
    } else {
	my $length = videolength($file);
	$startfile = "$basename-00:00:00.0-$time$extension";
	$endfile = "$basename-$time-$length$extension";
    }
    return($startfile,$endfile);
}

sub videolength {
    # Inputs:
    #   $file = video filename
    # Return:
    #   length of $file in 00:00:00.0 format
    my $file = shell_quote_scalar_default(shift);
    # mp4info 'The future of London'"'"'s airports-KXmpdJO9UOc.mp4'
    # The future of London's airports-KXmpdJO9UOc.mp4:
    # Track   Type    Info
    # 1       video   H264 Main@3.1, 561.560 secs, 932 kbps, 1280x720 @ 25.000000 fps
    # 2       audio   MPEG-4 AAC LC, 561.574 secs, 0 kbps, 44100 Hz
    open(my $fh, "-|", "mp4info $file") || die;
    my $length = 0;
    for(<$fh>) {
	/(\d+.\d+) secs/ and $length = max($1,$length);
	warn $_;
    }
    $length ||= "99:99:99.9";
    $length = format_time($length);
    return $length;
}

sub max(@) {
    # Returns:
    #   Maximum value of array
    my $max;
    for (@_) {
        # Skip undefs
        defined $_ or next;
        defined $max or do { $max = $_; next; }; # Set $_ to the first non-undef
        $max = ($max > $_) ? $max : $_;
    }
    return $max;
}

sub shell_quote_scalar_default($) {
    # Quote for other shells (Bourne compatibles)
    # Inputs:
    #   $string = string to be quoted
    # Returns:
    #   $shell_quoted = string quoted as needed by the shell
    my $s = $_[0];
    if($s =~ /[^-_.+a-z0-9\/]/i) {
	$s =~ s/'/'"'"'/g; # "-quote single quotes
	$s = "'$s'";       # '-quote entire string
	$s =~ s/^''//;     # Remove unneeded '' at ends
	$s =~ s/''$//;     # (faster than s/^''|''$//g)
	return $s;
    } elsif ($s eq "") {
	return "''";
    } else {
	# No quoting needed
	return $s;
    }
}

sub to_secs {
    # Inputs:
    #   $time = time in seconds or 00:00:00.0
    # Returns:
    #   time in seconds
    my $time = shift;
    $time =~ /(((\d\d):)?((\d\d):))?(\d\d+)\.(\d+)/;
    my $secs = $3 * 3600 + $5 * 60 + $6 + eval "0.$7";
    return $secs;
}

sub format_time {
    # Inputs:
    #   $time = time in seconds or 00:00:00.0
    # Returns:
    #   time in 00:00:00.0
    my $time = shift;
    if($time =~ /^\d+(\.\d+)?$/) {
	# Time in seconds
	my $h = int($time/3600);
	my $m = int($time/60) - 60*$h;
	my $s = int($time) - 60*$m - 3600*$h;
	my $ys = $time - int($time);
	$time = sprintf("%02d:%02d:%02d.%d",$h,$m,$s,$ys);
    }

    $time =~ s/^(\d):?(\d\d)$/00:0$1:$2/;
    $time =~ s/^(\d\d):?(\d\d)$/00:$1:$2/;
    $time =~ s/^(\d\d:\d\d)$/00:$1/;
    $time =~ s/^(\d\d:\d\d:\d\d)$/$1.0/;
    return $time;
}

sub find_rm_dir {
    my $dir = shift;
    if(-d "$dir/.rm") {
	return "$dir/.rm";
    }
    if(join(" ",stat $dir) eq join(" ",stat "../$dir")) {
	# We have reached root dir (.. = .)
	return undef;
    } else {
	return find_rm_dir("../$dir");
    } 
}