from __future__ import unicode_literals
from os import path
import re

from .. import orth
from ..vocab import Vocab
from ..tokenizer import Tokenizer
from ..syntax.parser import GreedyParser
from ..syntax.arc_eager import ArcEager
from ..syntax.ner import BiluoPushDown
from ..tokens import Tokens
from .pos import EnPosTagger
from .pos import POS_TAGS
from .attrs import get_flags


from ..util import read_lang_data


def get_lex_props(string):
    return {
        'flags': get_flags(string),
        'length': len(string),
        'orth': string,
        'lower': string.lower(),
        'norm': string,
        'shape': orth.word_shape(string),
        'prefix': string[0],
        'suffix': string[-3:],
        'cluster': 0,
        'prob': 0,
        'sentiment': 0
    }


LOCAL_DATA_DIR = path.join(path.dirname(__file__), 'data')

parse_if_model_present = -1


class English(object):
    """The English NLP pipeline.

    Provides a tokenizer, lexicon, part-of-speech tagger and parser.

    Keyword args:
        data_dir (unicode):
            A path to a directory, from which to load the pipeline.

            By default, data is installed within the spaCy package directory. So
            if no data_dir is specified, spaCy attempts to load from a
            directory named "data" that is a sibling of the spacy/en/__init__.py
            file.  You can find the location of this file by running:

                $ python -c "import spacy.en; print spacy.en.__file__"

            To prevent any data files from being loaded, pass data_dir=None. This
            is useful if you want to construct a lexicon, which you'll then save
            for later loading.
    """
    ParserTransitionSystem = ArcEager
    EntityTransitionSystem = BiluoPushDown

    def __init__(self, data_dir=''):
        if data_dir == '':
            data_dir = LOCAL_DATA_DIR
        self._data_dir = data_dir
        self.vocab = Vocab(data_dir=path.join(data_dir, 'vocab') if data_dir else None,
                           get_lex_props=get_lex_props)
        tag_names = list(POS_TAGS.keys())
        tag_names.sort()
        if data_dir is None:
            tok_rules = {}
            prefix_re = None
            suffix_re = None
            infix_re = None
            self.has_parser_model = False
            self.has_tagger_model = False
            self.has_entity_model = False
        else:
            tok_data_dir = path.join(data_dir, 'tokenizer')
            tok_rules, prefix_re, suffix_re, infix_re = read_lang_data(tok_data_dir)
            prefix_re = re.compile(prefix_re)
            suffix_re = re.compile(suffix_re)
            infix_re = re.compile(infix_re)
            self.has_parser_model = path.exists(path.join(self._data_dir, 'deps'))
            self.has_tagger_model = path.exists(path.join(self._data_dir, 'pos'))
            self.has_entity_model = path.exists(path.join(self._data_dir, 'ner'))

        self.tokenizer = Tokenizer(self.vocab, tok_rules, prefix_re,
                                   suffix_re, infix_re,
                                   POS_TAGS, tag_names)
        # These are lazy-loaded
        self._tagger = None
        self._parser = None
        self._entity = None

    @property
    def tagger(self):
        if self._tagger is None:
            self._tagger = EnPosTagger(self.vocab.strings, self._data_dir)
        return self._tagger

    @property
    def parser(self):
        if self._parser is None:
            self._parser = GreedyParser(path.join(self._data_dir, 'deps'),
                                        self.ParserTransitionSystem)
        return self._parser

    @property
    def entity(self):
        if self._entity is None:
            self._entity = GreedyParser(path.join(self._data_dir, 'ner'),
                                        self.EntityTransitionSystem)
        return self._entity

    def __call__(self, text, tag=True, parse=parse_if_model_present,
                 entity=parse_if_model_present):
        """Apply the pipeline to some text.  The text can span multiple sentences,
        and can contain arbtrary whitespace.  Alignment into the original string
        
        The tagger and parser are lazy-loaded the first time they are required.
        Loading the parser model usually takes 5-10 seconds.
        
        Args:
            text (unicode): The text to be processed.

        Keyword args:
            tag (bool): Whether to add part-of-speech tags to the text.  Also
                sets morphological analysis and lemmas.
        
            parse (True, False, -1): Whether to add labelled syntactic dependencies.
            
              -1 (default) is "guess": It will guess True if tag=True and the
                model has been installed.

        Returns:
            tokens (spacy.tokens.Tokens):

        >>> from spacy.en import English
        >>> nlp = English()
        >>> tokens = nlp('An example sentence. Another example sentence.')
        >>> tokens[0].orth_, tokens[0].head.tag_
        ('An', 'NN')
        """
        if parse == True and tag == False:
            msg = ("Incompatible arguments: tag=False, parse=True"
                   "Part-of-speech tags are required for parsing.")
            raise ValueError(msg)
        if entity == True and tag == False:
            msg = ("Incompatible arguments: tag=False, entity=True"
                   "Part-of-speech tags are required for entity recognition.")
            raise ValueError(msg)

        tokens = self.tokenizer(text)
        if parse == -1 and tag == False:
            parse = False
        elif parse == -1 and not self.has_parser_model:
            parse = False
        if entity == -1 and tag == False:
            entity = False
        elif entity == -1 and not self.has_entity_model:
            entity = False
        if tag and self.has_tagger_model:
            self.tagger(tokens)
        if parse == True and not self.has_parser_model:
            msg = ("Received parse=True, but parser model not found.\n\n"
                  "Run:\n"
                  "$ python -m spacy.en.download\n"
                  "To install the model.")
            raise IOError(msg)
        if entity == True and not self.has_entity_model:
            msg = ("Received entity=True, but entity model not found.\n\n"
                  "Run:\n"
                  "$ python -m spacy.en.download\n"
                  "To install the model.")
            raise IOError(msg)

        if parse and self.has_parser_model:
            self.parser(tokens)
        if entity and self.has_entity_model:
            self.entity(tokens)
        return tokens

    @property
    def tags(self):
        """List of part-of-speech tag names."""
        return self.tagger.tag_names