import codecs


class Alphabet(object):
    def __init__(self, config_file):
        self._config_file = config_file
        self._label_to_str = []
        self._str_to_label = {}
        self._size = 0
        self.blank_token = 1
        with codecs.open(config_file, 'r', 'utf-8') as fin:
            for line in fin:
                if line[0:2] == '\\#':
                    line = '#\n'
                elif line[0] == '#':
                    continue
                self._label_to_str += line[:-1] # remove the line ending
                self._str_to_label[line[:-1]] = self._size
                self._size += 1

    def string_from_label(self, label):
        return self._label_to_str[label]

    def label_from_string(self, string):
        try:
            return self._str_to_label[string]
        except KeyError as e:
            raise KeyError(
                '''ERROR: Your transcripts contain characters which do not occur in data/alphabet.txt! Use util/check_characters.py to see what characters are in your {train,dev,test}.csv transcripts, and then add all these to data/alphabet.txt.'''
            ).with_traceback(e.__traceback__)

    def decode(self, labels):
        res = ''
        for label in labels:
            res += self.string_from_label(label)
        return res

    def size(self):
        return self._size

    def config_file(self):
        return self._config_file