# coding: utf8
from __future__ import unicode_literals

from ...symbols import NOUN, PROPN, PRON
from ...errors import Errors


def noun_chunks(doclike):
    """
    Detect base noun phrases from a dependency parse. Works on both Doc and Span.
    """
    # Please see documentation for Turkish NP structure
    labels = [
        "nsubj",
        "iobj",
        "obj",
        "obl",
        "appos",
        "orphan",
        "dislocated",
        "ROOT",
    ]
    doc = doclike.doc  # Ensure works on both Doc and Span.
    if not doc.has_annotation("DEP"):
        raise ValueError(Errors.E029)

    np_deps = [doc.vocab.strings.add(label) for label in labels]
    conj = doc.vocab.strings.add("conj")
    flat = doc.vocab.strings.add("flat")
    np_label = doc.vocab.strings.add("NP")

    def extend_right(w):  # Playing a trick for flat
        rindex = w.i + 1
        for rdep in doc[w.i].rights:  # Extend the span to right if there is a flat
            if rdep.dep == flat and rdep.pos in (NOUN, PROPN):
                rindex = rdep.i + 1
            else:
                break
        return rindex

    prev_end = len(doc) + 1
    for i, word in reversed(list(enumerate(doclike))):
        if word.pos not in (NOUN, PROPN, PRON):
            continue
        # Prevent nested chunks from being produced
        if word.i >= prev_end:
            continue
        if word.dep in np_deps:
            prev_end = word.left_edge.i
            yield word.left_edge.i, extend_right(word), np_label
        elif word.dep == conj:
            cc_token = word.left_edge
            prev_end = cc_token.i
            # Shave off cc tokens from the NP
            yield cc_token.right_edge.i + 1, extend_right(word), np_label


SYNTAX_ITERATORS = {"noun_chunks": noun_chunks}