from gtnlplib import constants

# Deliverable 1.1
def word_feats(words,y,y_prev,m):
    """This function should return at most two features:
    - (y,constants.CURR_WORD_FEAT,words[m])
    - (y,constants.OFFSET)

    Note! You need to handle the case where $m >= len(words)$. In this case, you should only output the offset feature. 

    :param words: list of word tokens
    :param m: index of current word
    :returns: dict of features, containing a single feature and a count of 1
    :rtype: dict

    """
    fv = dict()    
    return fv

# Deliverable 2.1
def word_suff_feats(words,y,y_prev,m):
    """This function should return all the features returned by word_feats,
    plus an additional feature for each token, indicating the final two characters.

    You may call word_feats in this function.

    :param words: list of word tokens
    :param y: proposed tag for word m
    :param y_prev: proposed tag for word m-1 (ignored)
    :param m: index m
    :returns: dict of features
    :rtype: dict

    """
    raise NotImplementedError
    
def word_neighbor_feats(words,y,y_prev,m):
    """compute features for the current word being tagged, its predecessor, and its successor.

    :param words: list of word tokens
    :param y: proposed tag for word m
    :param y_prev: proposed tag for word m-1 (ignored)
    :param m: index m
    :returns: dict of features
    :rtype: dict

    """

    # hint: use constants.PREV_WORD_FEAT and constants.NEXT_WORD_FEAT
    raise NotImplementedError

    
def word_feats_competitive_en(words,y,y_prev,m):
    raise NotImplementedError
    
def word_feats_competitive_ja(words,y,y_prev,m):
    raise NotImplementedError

def hmm_feats(words,y,y_prev,m):
    fv = dict()
    return fv

def hmm_feats_competitive_en(words,y,y_prev,m):
    raise NotImplementedError

def hmm_feats_competitive_ja(words,y,y_prev,m):
    raise NotImplementedError