#!/usr/bin/env python3
# -*- coding: utf-8 -*-

'''
ponysay - Ponysay, cowsay reimplementation for ponies
Copyright (C) 2012, 2013  Erkin Batu Altunbaş et al.

This program is free software. It comes without any warranty, to
the extent permitted by applicable law. You can redistribute it
and/or modify it under the terms of the Do What The Fuck You Want
To Public License, Version 2, as published by Sam Hocevar. See
http://sam.zoy.org/wtfpl/COPYING for more details.
'''
from common import *



'''
Metadata functions
'''
class Metadata():
    '''
    Make restriction test logic function
    
    @param   restriction:list<string>  Metadata based restrictions
    @return  :dict<str, str>→bool      Test function
    '''
    @staticmethod
    def makeRestrictionLogic(restriction):
        table = [(get_test(cell[:cell.index('=')],
                           cell[cell.index('=') + 1:]
                          )
                  for cell in clause.lower().replace('_', '').replace(' ', '').split('+'))
                  for clause in restriction
                ]
        
        def get_test(cell):
            strict = cell[0][-1] != '?'
            key = cell[0][:-2 if strict else -1]
            invert = cell[1][0] == '!'
            value = cell[1][1 if invert else 0:]
            
            class SITest():
                def __init__(self, cellkey, cellvalue):
                    (self.cellkey, self.callvalue) = (key, value)
                def __call__(self, has):
                    return False if key not in has else (value not in has[key])
            class STest():
                def __init__(self, cellkey, cellvalue):
                    (self.cellkey, self.callvalue) = (key, value)
                def __call__(self, has):
                    return False if key not in has else (value in has[key])
            class ITest():
                def __init__(self, cellkey, cellvalue):
                    (self.cellkey, self.callvalue) = (key, value)
                def __call__(self, has):
                    return True if key not in has else (value not in has[key])
            class NTest():
                def __init__(self, cellkey, cellvalue):
                    (self.cellkey, self.callvalue) = (key, value)
                def __call__(self, has):
                    return True if key not in has else (value in has[key])
            
            if strict and invert:  return SITest(key, value)
            if strict:             return STest(key, value)
            if invert:             return ITest(key, value)
            return NTest(key, value)
        
        def logic(cells):
            for alternative in table:
                ok = True
                for cell in alternative:
                    if not cell(cells):
                        ok = False
                        break
                if ok:
                    return True
            return False
        
        return logic
    
    
    '''
    Get ponies that pass restriction
    
    @param   ponydir:str                Pony directory, must end with `os.sep`
    @param   logic:dict<str, str>→bool  Restriction test functor
    @return  :list<str>                 Passed ponies
    '''
    @staticmethod
    def restrictedPonies(ponydir, logic):
        import cPickle
        passed = []
        if os.path.exists(ponydir + 'metadata'):
            data = None
            with open(ponydir + 'metadata', 'rb') as file:
                data = cPickle.load(file)
            for ponydata in data:
                (pony, meta) = ponydata
                if logic(meta):
                    passed.append(pony)
        return passed