#!/usr/bin/env ruby
#http://pastebin.com/KSS0zU2F

unless ARGV.count == 1
	abort 'Merges sequentially-named files.'
end

outfile = ARGV.first.sub(/.?\d+\z/, '')

if File.size? outfile
	abort 'The outfile already exists.'
end

pattern = ARGV.first.sub(/\d+\z/, '')
pattern.gsub!(/[\[\]\*\{\}]/, "\\\\\\0")
if digits = ARGV.first[ /\d+\z/ ]
	pattern << '[0-9]' * digits.length
else
	pattern << '.[0-9]*'
end

files = Dir.glob(pattern).sort

if files.count < 2
	abort 'There needs to be at least 2 files.'
end

if files.first[ /\d+\z/ ].to_i != 1
	abort 'The first file in the series is missing.'
end

file_count = files.last[ /\d+\z/ ].to_i

unless files.count == file_count
	abort '%s of %s files are missing.' % [
		file_count-files.count, file_count
	]
end

unless size = File.size?(files.first)
	abort '"%s" is empty.' % files.first
end

if File.size?(files.first) == File.size?(files.last)
	abort 'One or more files seem to be missing.'
end

files[0..-2].each do |path|
	size == File.size?(path) and next
	abort '"%s" has an incorrect size.' % file
end

File.open outfile, 'w' do |outstream|
	files.each do |path|
		puts 'Merging "%s"' % path
		File.open(path) do |instream|
			IO.copy_stream(instream, outstream)
		end
	end
	outstream.fsync
end

files.each(&File.method(:unlink))