#!/usr/bin/env ruby
# coding: utf-8
#	ファイルに値を保存するカウンタ(Ruby)
#	~yas/syspro/file/file-counter-ruby.rb

DATA_FILENAME = "file-counter-value.data"
$comname = $0

def usage()
    printf("Usage$ %s {get,inc,set newvalue}\n", $comname)
    printf("Data file: %s\n", DATA_FILENAME)
    exit( 1 )
end

def main(argv)
    usage() if( argv.length() < 1 )
    cmd = argv[0]
    counter = 0
    case( cmd )
    when "get"
        counter = counter_load()
    when "inc"
        counter = counter_load()
        counter += 1
    when "set"
        usage() if( argv.length() != 2 )
        newvalue = argv[1].to_i()
        counter = newvalue
    else
        usage()
    end
    printf("%d\n", counter)
    counter_save(counter) if( cmd != "get" )
end

def counter_save(counter)
    data = [counter].pack("i") # signed int
    IO.binwrite(DATA_FILENAME, data)
end

def counter_load()
    counter = 0
    begin
        data = IO.read(DATA_FILENAME, 4)
        counter = data.unpack("i")[0]
    rescue Errno::ENOENT
        # nop
    end
    return counter
end

main(ARGV)