ChuckHa

#!/usr/bin/env ruby
require 'optparse'

# create an empty hash to hold the options
options = {}

optparse = OptionParser.new do|opts|
    opts.banner = "Usage: shift_subtitle [options] infile outfile"

    opts.on('-h', '--help', 'Display this screen') do
        puts opts
        exit
    end
    opts.on('-o', '--operation [add|sub]', 'What type of operation to use') do|o|
        if o == 'add' or o == 'sub'
            options[:operation] = o
        else
            puts "operation must be 'add' or 'sub'."
            exit
        end
    end
    opts.on('-t', '--time [HH:[MM:[SS,[mmm]]]]', 'Amount of time to shift') do|t|
        options[:time] = t 
    end
end

optparse.parse!

# make sure the files exist...
ARGV[0] ? options[:file1] = ARGV[0] : exit
ARGV[1] ? options[:file2] = ARGV[1] : exit

class SubtitleTime
    attr_accessor :hours, :minutes, :seconds, :milliseconds

    # reverse char by char block
    # at first comma, set milli
    # at first : set seconds, etc.
    def initialize(time, modifier='add')
        num = ''
        set_sec,set_min,set_hour= false
        time.reverse.each_char do|char|
            if num =~ /\d\d\d/
                @milliseconds = num.to_i
                num = ''
                set_sec = true
            elsif char == ':' and set_sec 
                @seconds = num.to_i
                num = ''
                set_sec = false
                set_min = true
            elsif char == ':' and set_min
                @minutes = num.to_i
                num = ''
                set_min = false
                set_hour = true
            elsif char == ':' and set_hour
                @hours = num.to_i
                num = ''
            else
                num = char + num
            end
        end
        if set_sec
            @seconds = num.to_i
        elsif set_min
            @minutes = num.to_i
        elsif set_hour
            @hours = num.to_i
        end
        @milliseconds = @milliseconds || 0
        @seconds = @seconds || 0
        @minutes = @minutes || 0
        @hours = @hours || 0
        @modifier = modifier 
    end

    def change_hour(hours)
        if @modifier == 'add'
            @hours += hours
        else
            @hours -= hours
            if @hours < 0
                @hours = 0
            end
        end
    end

    def change_min(minutes)
        if @modifier == 'add'
            @minutes += minutes
            if @minutes >= 60
                hours = @minutes/60
                change_hour(hours)
                @minutes %= 60
            end
        else
            @minutes -= minutes
            if @minutes < 0
                change_hour(1)
                @minutes += 60
            end
        end
    end
    
    def change_sec(seconds)
        if @modifier == 'add'
            @seconds += seconds
            if @seconds >= 60
                minutes = @seconds/60
                change_min(minutes)
                @seconds %= 60
            end
        else
            @seconds -= seconds
            if @seconds < 0
                change_min(1)
                @seconds += 60
            end
        end
    end

    def change_milli(milli)
        if @modifier == 'add'
            @milliseconds += milli
            if @milliseconds >= 1000
                seconds = @milliseconds/1000
                change_sec(seconds)
                @milliseconds %= 1000
            end
        else
            @milliseconds -= milli
            if @milliseconds < 0
                change_sec(1)
                @milliseconds += 1000
            end
        end
    end
    
    def to_s
        return sprintf("%02d:%02d:%02d,%03d", @hours, @minutes, @seconds, @milliseconds)
    end
end

# turn the input time into a SubtitleTime object
time_mod = SubtitleTime.new(options[:time])


out_file = File.new(options[:file2], "w")

# every line that has timestamps
# take each time stamp split into h/m/s/ms
# apply the operation
# how to deal with carry overs?
IO.foreach(options[:file1]) do|line|
    if (line =~ /-->/)
        first = SubtitleTime.new(line.split(/ --> /)[0], options[:operation])
        second = SubtitleTime.new(line.split(/ --> /)[1], options[:operation])
        first.change_hour(time_mod.hours)
        first.change_min(time_mod.minutes)
        first.change_sec(time_mod.seconds)
        first.change_milli(time_mod.milliseconds)
        second.change_hour(time_mod.hours)
        second.change_min(time_mod.minutes)
        second.change_sec(time_mod.seconds)
        second.change_milli(time_mod.milliseconds)
        out_file.syswrite("#{first.to_s} --> #{second.to_s}\n")
    else
        out_file.syswrite(line)
    end
end