#!/usr/bin/ruby -Ku
#
# grassurl.rb - URL to Grass language generator
#
# Copyright (C) 2008 aike. All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 
#   1. Redistributions of source code must retain the above copyright
#      notice, this list of conditions and the following disclaimer.
#   2. Redistributions in binary form must reproduce the above copyright
#      notice, this list of conditions and the following disclaimer in
#      the documentation and/or other materials provided with the
#      distribution.
# 
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
# IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

$KCODE='UTF8'

class GrassUrl

	RELEASE_DATE = '2008-10-22'

	def makeCharTable(s)
		@header = "wwWWwWWWwvwwWWwWWWwWWWWwvwwwwWWWwwWwwWWWWWWwwwwWwwvwwwWWwWWWWwvWWwwwwWwwwwWWWwwwwwwWwwwwwwWwwwwwwwWWWWWWwwWwwwwwwwwwwWWWWWWWWWwWwwwwwwwWWWWWWWWWWWwWwwwwwwWWWWWWWWWWWWWwwwwwwwWwwwwwwwwWWWWWWWWWWWWWWWwwwwwwwwwwwwWwwvwWWWWWWWWWWWWWWWWWWWWWWwvWWwWwwwwwwwwwwwwwwwwwwwwwwwwWWWwWWWWwWWWWWwWWWWWWwWWWWWWWwWWWWWWWWwWWWWWWWWWwWWWWWWWWWWwWWWWWWWWWWWwWWWWWWWWWWWWwWWWWWWWWWWWWWwWWWWWWWWWWWWWWwWWWWWWWWWWWWWWWWWWWWwwwwwwwwwwwwwwwvwWWWWWWWWWWWWWWWWWwvWWwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww"

		# scan the max character code from the string
		max = maxChar(s)
		table_size = ('b'..max).to_a.length

		# generate alphabet table (from 'b' to max character code)
		b_z = ""
		table_size.times {|i|
			b_z += "WW"
			i.times { b_z += "W" }
			b_z += "w"
		}

		# generate alias of OUT
		abs_out = "vwWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW"
		table_size.times {
			abs_out += "W"
		}
		abs_out += "wv"

		@header += b_z + abs_out

		# initialize address table
		@table_base = 3 + 10 + (table_size + 1) + 3	# [./:0-9a-z] + (3 OPs)
		@char_pos = {}
		sp = 0
		"./0123456789:".each_byte {|c|
			@char_pos[c.chr] = sp
			sp += 1
		}
		sp += 2
		('a'..max).each {|c|
			@char_pos[c] = sp
			sp += 1
		}
	end

	def generate(s)
		s = "http://" + s
		# raise a exception if character set [^a-z0-9./:] used
		raise "illegal char" if checkString(s).nil?
		makeCharTable(s)

		ret = @header
		out_pos   = 1
		stack_pos = 0
		s.each_byte {|c|
			n = out_pos + stack_pos
			m = @table_base - @char_pos[c.chr] + stack_pos
			n.times {ret += "W"}
			m.times {ret += "w"}
			@char_pos[c.chr] = @table_base + stack_pos
			stack_pos += 1
		}
		ret
	end

	def maxChar(s)
		s.split(//).max
	end

	# check character set
	def checkString(s)
		if s =~ /[^a-z0-9:\.\/]/
                  nil
                else
                  true
                end
	end

end

#print GrassUrl.new.generate("aikelab.net/grass/")