#!/usr/bin/perl

use warnings;
use strict;

use File::Basename;
use POSIX;

my %cfg = ( SOURCE => "0,0", TARGET => "0,100", TIMETARGET => 2, MARK => '*', TARGETMARK => 'O' );
my @beats;
my $total = 0;

sub fmttime($) {
    my $time = sprintf "%.02f", shift;
    my ($sec,$frac) = $time =~ /^(\d+)(\..*)$/;
    my $min = int($sec/60);
    $sec -= $min*60;
    my $hr = int($min/60);
    $min -= $hr*60;
    return sprintf "%d:%02d:%02d%s", $hr,$min,$sec,$frac;
}

sub interp {
    my ($src,$dst,$frac,$dur) = @_;
    my ($sx,$sy) = split /,/, $src;
    my ($dx,$dy) = split /,/, $dst;
    return sprintf "%d,%d",
        ($sx + ($dx - $sx) * $frac/$dur),
        ($sy + ($dy - $sy) * $frac/$dur);
}

sub durations {
    my @dur = split /,/, shift;
    $_ = m#^(\d+)/(\d+)$# ? $2 / $1 : 1 / $_ for @dur;
    return @dur;
}

sub readbeats {
  @beats = ();
  $total = 0;
  $cfg{$_} = undef for qw (BPM LAST FIRST MID MIDNUM);

  my $f = shift;
  while (<$f>) {
    chomp;
    my $line = $_;
    s/\s*#.*$//;
    if (/^BREAK/) {
        return $total;
    } elsif (m#^(\d+)@([\d.,/]+)\s*(\S*)$#) {
        push @beats, [$1, $2, $3];
        $total += $1 * $_ for durations $2;
    } elsif (/^(\w+)=(.+)$/) {
        $cfg{$1} = $2;
    } elsif (/^\s*$/) {
    } else {
        die "Can't parse line $.: $line\n";
    }
  }
  return $total;
}

my $patname = shift;

my ($basename,$path) = fileparse $patname, qr/\.[^.]+$/;
#$basename = "$path/$basename";

my $hdrname = "beat/$basename.header";
open my $hdr, "<", $hdrname or die "Can't read $hdrname: $!\n";

my $assname = "$basename.ass";
open my $ass, ">", $assname or die "Can't write $assname: $!\n";
print $ass $_ while <$hdr>;

my $lasttarget = 0;
open my $in, "<", "beat/$patname" or die "Can't read $patname: $!\n";
while (readbeats $in) {

die "Need at least one beat!\n" unless $total > 0;

my $finish = $cfg{FINISH} || $cfg{TARGET};
my $timefinish = $cfg{TIMEFINISH} || 0;

my ($base,$bpm);

if ($cfg{BPM}) {
    $bpm = $cfg{BPM};
    $base = 60/$cfg{BPM};
} else {
    $cfg{MID} ||= $cfg{LAST};
    $cfg{MIDNUM} ||= $total;

    my $time = $cfg{MID}-$cfg{FIRST};
    $base = $time / ($cfg{MIDNUM} - 1);
    $bpm = 60 / $base;
}
my $time = $total * $base;
printf "$total full beats over $time sec, %.3f base beat time (%.1f BPM)\n", $base, $bpm;

my $targettime = $cfg{FIRST} - $cfg{TIMETARGET};
$targettime = $lasttarget if $targettime < $lasttarget;
$lasttarget = $targettime;

printf $ass "Dialogue: 0,%s,%s,Target,,0,0,0,,{\\pos($cfg{TARGET})}$cfg{TARGETMARK}\n",
    fmttime $targettime, fmttime $cfg{FIRST}+$total*$base;

my $beat = 0;
for my $entry (@beats) {
    my $start = $beat - 1;
    while ($entry->[0]-- > 0) {
        my @durations = durations $entry->[1];
        my @marks = split /,/, $entry->[2];
        while (@durations) {
        my $time = $cfg{FIRST} + $beat * $base;
        my $durtarget = $cfg{TIMETARGET};
        my $durfinish = $timefinish;
        my $src = $cfg{SOURCE};
        my $mark = shift(@marks) || $cfg{MARK};
        $mark =~ s/\\R/$beat - $start/e;
        $mark =~ s/\\T/$beat/e;
        if ($time < $durtarget){
            $src = interp $src, $cfg{TARGET}, $durtarget-$time, $durtarget;
            $durtarget = $time;
        }

        my $dur = shift @durations;
        printf $ass "Dialogue: 0,%s,%s,Beat%d,,0,0,0,,{\\move(%s,$finish)}%s\n",
            fmttime $time - $durtarget, fmttime $time + $durfinish,
            ceil(1/$dur), $src, $mark;
        $beat += $dur;
        }
    }
}

}