from __future__ import division

import collections
import gzip
import itertools

from cdec.sa._sa import gzip_or_text

# Same as Cython implementation.  Collisions with NULL in bitext?
NULL_WORD = 'NULL'

def learn_vocab(text_f):
    vocab = set()
    for line in gzip_or_text(text_f):
        for word in line.strip().split():
            vocab.add(word)
    return vocab

def write_vocab(vocab, out_f):
    with gzip.open(out_f, 'wb') as out:
        for word in sorted(vocab):
            out.write('{}\n'.format(word))

def read_vocab(in_f):
    return set(line.strip() for line in gzip_or_text(in_f))

class Bilex:

    def __init__(self, in_f=None):
        self.f = collections.defaultdict(int)
        self.e = collections.defaultdict(int)
        self.fe = collections.defaultdict(int)
        if in_f:
            self.read(in_f)

    # Compatibility with Cython implementation
    def get_score(self, f, e, dir):
        if dir == 0:
            p = self.p_fe(f, e)
        elif dir == 1:
            p = self.p_ef(e, f)
        return p

    def p_fe(self, f, e):
        denom = self.f.get(f, None)
        if not denom:
            return None
        num = self.fe.get((f, e), None)
        if not num:
            return None
        return num / denom

    def p_ef(self, e, f):
        denom = self.e.get(e, None)
        if not denom:
            return None
        num = self.fe.get((f, e), None)
        if not num:
            return None
        return num / denom

    # Update counts from aligned sentence
    def update(self, f_words, e_words, links):
        covered_f = set()
        covered_e = set()
        for (i, j) in links:
            covered_f.add(i)
            covered_e.add(j)
            self.f[f_words[i]] += 1
            self.e[e_words[j]] += 1
            self.fe[(f_words[i], e_words[j])] += 1
        # e being covered corresponds to f->e
        for j in range(len(e_words)):
            if j not in covered_e:
                self.f[NULL_WORD] += 1
                self.e[e_words[j]] += 1
                self.fe[(NULL_WORD, e_words[j])] += 1
        # e->f
        for i in range(len(f_words)):
            if i not in covered_f:
                self.f[f_words[i]] += 1
                self.e[NULL_WORD] += 1
                self.fe[(f_words[i], NULL_WORD)] += 1

    # Update counts from alignd bitext
    def add_bitext(self, alignment_f, text_f, target_text_f=None):
        # Allow one or two args for bitext
        if target_text_f:
            t = itertools.izip((line.strip() for line in gzip_or_text(text_f)), (line.strip() for line in gzip_or_text(target_text_f)))
        else:
            t = (line.strip().split(' ||| ') for line in gzip_or_text(text_f))
        a = (line.strip() for line in gzip_or_text(alignment_f))
        for (source, target) in t:
            links = sorted(tuple(int(link) for link in link_str.split('-')) for link_str in a.next().split())
            self.update(source.split(), target.split(), links)

    def write(self, out_f):
        with gzip.open(out_f, 'wb') as out:
            for f in sorted(self.f):
                out.write('{} {}\n'.format(f, self.f[f]))
            out.write('\n')
            for e in sorted(self.e):
                out.write('{} {}\n'.format(e, self.e[e]))
            out.write('\n')
            for (f, e) in sorted(self.fe):
                out.write('{} {} {}\n'.format(f, e, self.fe[(f, e)]))
            out.write('\n')

    def read(self, in_f):
        with gzip_or_text(in_f) as inp:
            while True:
                line = inp.readline().strip()
                if not line:
                    break
                (w, c) = line.split()
                self.f[w] = int(c)
            while True:
                line = inp.readline().strip()
                if not line:
                    break
                (w, c) = line.split()
                self.e[w] = int(c)
            while True:
                line = inp.readline().strip()
                if not line:
                    break
                (f, e, c) = line.split()
                self.fe[(f, e)] = float(c)

# Bilex get_score for multiple instances
def get_score_multilex(f, e, dir, bilex_list):
    num = 0
    denom = 0
    for bilex in bilex_list:
        if dir == 0:
            denom += bilex.f.get(f, 0)
        else:
            denom += bilex.e.get(e, 0)
        num += bilex.fe.get((f, e), 0)
    if (not num) or (not denom):
        return None
    return num / denom