#!/usr/local/bin/ruby

require 'getopts'
require 'digest/sha1'
require 'digest/sha2'

def print_usage (command)
    $stderr.printf("usage: %s [-hr235][files...]\n", command)
end

unless getopts("hr235")
    print_usage($0)
    exit 1
end

if $OPT_h
    print_usage($0)
    exit 1
end

if ARGV.empty?
    if $OPT_2
	print Digest::SHA256.hexdigest($stdin.read), "\n"
    elsif $OPT_3
	print Digest::SHA384.hexdigest($stdin.read), "\n"
    elsif $OPT_5
	print Digest::SHA512.hexdigest($stdin.read), "\n"
    else
	print Digest::SHA1.hexdigest($stdin.read), "\n"
    end
else
    if $OPT_r
	ARGV.each do |i|
	    if $OPT_2
		print Digest::SHA256.hexdigest(File.read(i)), " ", i, "\n"
	    elsif $OPT_3
		print Digest::SHA384.hexdigest(File.read(i)), " ", i, "\n"
	    elsif $OPT_5
		print Digest::SHA512.hexdigest(File.read(i)), " ", i, "\n"
	    else
		print Digest::SHA1.hexdigest(File.read(i)), " ", i, "\n"
	    end
	end 
    else
	ARGV.each do |i|
	    if $OPT_2
		print "SHA256 (", i, ") = ", Digest::SHA256.hexdigest(File.read(i)), "\n"
	    elsif $OPT_3
		print "SHA384 (", i, ") = ", Digest::SHA384.hexdigest(File.read(i)), "\n"
	    elsif $OPT_5
		print "SHA512 (", i, ") = ", Digest::SHA512.hexdigest(File.read(i)), "\n"
	    else
		print "SHA1 (", i, ") = ", Digest::SHA1.hexdigest(File.read(i)), "\n"
	    end
	end
    end
end