##
## Name:     kore.py
## Purpose:  Encodes and decodes "Koremutake" syllables
## Author:   M. J. Fromberger, Copyright 2004.
## Info:     $Id: kore.py 523 2007-11-14 19:38:30Z sting $
##
## Notes:    http://shorl.com/koremutake.php
##
## Permission is hereby granted, free of charge, to any person
## obtaining a copy of this software and associated documentation
## files (the "Software"), to deal in the Software without
## restriction, including without limitation the rights to use, copy,
## modify, merge, publish, distribute, sublicense, and/or sell copies
## of the Software, and to permit persons to whom the Software is
## furnished to do so, subject to the following conditions:
## 
## The above copyright notice and this permission notice shall be
## included in all copies or substantial portions of the Software.
## 
## THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
## EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
## MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
## NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
## HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
## WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
## OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
## DEALINGS IN THE SOFTWARE.
##

import re

# This table taken from http://shorl.com/koremutake.php
syllables = [
    'BA', 'BE', 'BI', 'BO', 'BU', 'BY',
    'DA', 'DE', 'DI', 'DO', 'DU', 'DY',          
    'FA', 'FE', 'FI', 'FO', 'FU', 'FY', 
    'GA', 'GE', 'GI', 'GO', 'GU', 'GY', 
    'HA', 'HE', 'HI', 'HO', 'HU', 'HY', 
    'JA', 'JE', 'JI', 'JO', 'JU', 'JY', 
    'KA', 'KE', 'KI', 'KO', 'KU', 'KY', 
    'LA', 'LE', 'LI', 'LO', 'LU', 'LY', 
    'MA', 'ME', 'MI', 'MO', 'MU', 'MY', 
    'NA', 'NE', 'NI', 'NO', 'NU', 'NY', 
    'PA', 'PE', 'PI', 'PO', 'PU', 'PY', 
    'RA', 'RE', 'RI', 'RO', 'RU', 'RY', 
    'SA', 'SE', 'SI', 'SO', 'SU', 'SY', 
    'TA', 'TE', 'TI', 'TO', 'TU', 'TY', 
    'VA', 'VE', 'VI', 'VO', 'VU', 'VY', 
    'BRA', 'BRE', 'BRI', 'BRO', 'BRU', 'BRY', 
    'DRA', 'DRE', 'DRI', 'DRO', 'DRU', 'DRY', 
    'FRA', 'FRE', 'FRI', 'FRO', 'FRU', 'FRY', 
    'GRA', 'GRE', 'GRI', 'GRO', 'GRU', 'GRY', 
    'PRA', 'PRE', 'PRI', 'PRO', 'PRU', 'PRY', 
    'STA', 'STE', 'STI', 'STO', 'STU', 'STY', 
    'TRA', 'TRE' ]

# Construct a regular expression matching any syllable
# This could be more efficiently done by hand
decoder = re.compile('(%s)' % str.join('|', syllables), re.IGNORECASE)

def encode(val):
    """Encode a positive integer numeric value in Koremutake syllables."""
    if not isinstance(val, (int, long)) or val < 0:
        raise TypeError("Input value must be a non-negative integer")
    
    if val == 0:
        return syllables[0].lower()
    
    out = []
    while val <> 0:
        out.append(syllables[val % 128])
        val //= 128
    
    out.reverse()
    return str.join('', out).lower()

def split(kor):
    """Split a sequence of Koremutake syllables into a list of
    strings.
    """
    kor = kor.strip().replace(' ', '')

    out = [] ; sw = True
    for elt in decoder.split(kor):
        if sw:
            if elt:
                raise ValueError("substring '%s' does not "
                                 "begin a valid syllable" % elt)
        else:
            out.append(elt)
        
        sw = not sw
    
    return out

def decode(kor):
    """Decode a sequence of Koremutake syllables to an integer."""

    output = 0
    for elt in split(kor):
        output *= 128
        output += syllables.index(elt.upper())

    return output

# Here there be dragons