#!/usr/bin/ruby -w

if ARGV.size < 2
    $stderr.puts "I need two or three parameters"
    $stderr.puts "#{$0} file.srt add_seconds [from_subtitle_number]"
    exit(1)
end

filename = ARGV.shift
add      = Float(ARGV.shift)
mark     = ARGV.shift || '1'

inside = false
File.readlines(filename).each_with_index do |line,count|
    if inside
        if line =~ /^(\d\d):(\d\d):(\d\d),(\d+) --> (\d\d):(\d\d):(\d\d),(\d+)/
            h1, m1, s1, us1, h2, m2, s2, us2 = $1, $2, $3, $4, $5, $6, $7, $8
            h1, m1, s1, us1 = h1.to_i, m1.to_i, s1.to_i, us1.to_i * 1_000
            h2, m2, s2, us2 = h2.to_i, m2.to_i, s2.to_i, us2.to_i * 1_000
            t1 = Time.local(2006, 1, 1, h1, m1, s1, us1) + add
            t2 = Time.local(2006, 1, 1, h2, m2, s2, us2) + add
            line = "#{t1.hour.to_s.rjust(2, '0')}:#{t1.min.to_s.rjust(2, '0')}:#{t1.sec.to_s.rjust(2, '0')},#{t1.usec / 1000} --> #{t2.hour.to_s.rjust(2, '0')}:#{t2.min.to_s.rjust(2, '0')}:#{t2.sec.to_s.rjust(2, '0')},#{t2.usec / 1000}\r\n"
        end
    else
        if line =~ /^#{mark}/
            inside = true
        end
    end

    $stderr.puts "#{count} lines..." if count % 100 == 0 and count != 0
    print line
end