'''
Created on 21.11.2013

@author: Philipp Rauch
'''
from sys import stderr, exit

_config_dir = 'config'
_config_file = 'ems.conf'
_config_path = _config_dir + '/' + _config_file

class config():
    _instance = None

    _confDic = {
               'mySQL_server': '',
               'mySQL_port': '3306',
               'mySQL_user': '',
               'mySQL_pass': '',
               'mySQL_database': '',
               'mySQL_speed' : '0.02',
               'flask_server': '0.0.0.0',
               'flask_port': '5000',
               'config_debug' : False,
               'config_read' : False,
               'config_dictionary' : _config_dir,
               'can_baudrate' : '500k',
               'can_symfile' : ''
               }

    def __new__(cls, *args, **kwargs):
        # http://stackoverflow.com/questions/42558/python-and-the-singleton-pattern
        if not cls._instance:
            cls._instance = super(config, cls).__new__(
                                cls, *args, **kwargs)
        return cls._instance

    def printConf(self):
        '''
        Print the config only if debug is enable.
        '''
        if self._confDic['config_debug']:
            mes = 'config:\t{'
            for x in self._confDic:
                mes = '%s\r     %s \t: %s' % (mes, x, self._confDic[x])
            mes = '%s\r   }\n' % mes
            print mes

    def makeList(self, arg):
        for a in range(len(arg)):
            arg[a] = arg[a].strip()
            arg[a] = True  if arg[a] == 'True'  else arg[a]
            arg[a] = False if arg[a] == 'False' else arg[a]
        return arg

    def getElement(self, line):
        tmp = line.split("=")
        key = tmp[0].strip()
        val = tmp[1].split("#")     #cut off comments, comment is on val[1]
        val = str(val[0].strip())   #overwrite val with string

        if key == '':
            stderr.write('config_error: there is an empty key\r')
            return None, None
        if val == '':
            stderr.write('config_error: %s has no value\r' % key)
            return None, None

        arg = val.split(',')
        while arg.count('') > 0:
            arg.remove('')
        if len(arg) == 0:
            stderr.write('config_error: %s has an empty argument\r' % key)
            return None, None
        return key, arg

    def readConf(self):
        if self._confDic['config_read']:        #prevent re-read
            return self._confDic

        try:
            confFile = open(_config_path, "r")
        except IOError:
            self._confDic.update({'error' : '%s not found' % _config_path})
            stderr.write('config_error %s not found\r' % _config_path)
            return self._confDic

        _linenumber = 0

        for line in confFile:
            _linenumber += 1
            line = line.strip()

            if len(line) == 0 or line[0] == "#":    #remove empty lines and comments
                continue

            if line.find("=") == -1:
                exit('config_error: an error has occurred in line %s\r' % _linenumber)

            key, arg = self.getElement(line)
            if key == None:
                continue     #skip errors
            self.makeList(arg)
            arg = arg if len(arg) > 1 else arg[0]

            self._confDic[key] = arg

        confFile.close()
        self._confDic['config_read'] = True

        for key in self._confDic:
            if self._confDic[key] == '':
                exit('please select a value for {0}'.format(key))

        if self._confDic['config_debug']:
            self.printConf()

        return self._confDic

c = config()
conf = c.readConf()