#!/usr/bin/env cython
# cython: boundscheck=False
# cython: wraparound=False
# cython: cdivision=True
# coding: utf-8
#
# Copyright (C) 2013 Radim Rehurek <me@radimrehurek.com>
# Licensed under the GNU LGPL v2.1 - http://www.gnu.org/licenses/lgpl.html

import cython
import numpy as np
from numpy import zeros, float32 as REAL
cimport numpy as np

from libc.math cimport exp
from libc.string cimport memset, memcpy

# scipy <= 0.15
try:
     from scipy.linalg.blas import fblas
except ImportError:
     # in scipy > 0.15, fblas function has been removed
     import scipy.linalg.blas as fblas

from word2vec_inner cimport bisect_left, random_int32, \
     scopy, saxpy, sdot, dsdot, snrm2, sscal, \
     REAL_t, EXP_TABLE, \
     our_dot, our_saxpy, \
     our_dot_double, our_dot_float, our_dot_noblas, our_saxpy_noblas

from word2vec import FAST_VERSION

DEF MAX_DOCUMENT_LEN = 10000

cdef int ONE = 1
cdef REAL_t ONEF = <REAL_t>1.0

DEF EXP_TABLE_SIZE = 1000
DEF MAX_EXP = 6

cdef void fast_document_dbow_hs(
    const np.uint32_t *word_point, const np.uint8_t *word_code, const int codelen,
    REAL_t *context_vectors, REAL_t *syn1, const int size,
    const np.uint32_t context_index, const REAL_t alpha, REAL_t *work, int learn_context, int learn_hidden, 
    REAL_t *context_locks) nogil:

    cdef long long a, b
    cdef long long row1 = context_index * size, row2
    cdef REAL_t f, g

    memset(work, 0, size * cython.sizeof(REAL_t))
    for b in range(codelen):
        row2 = word_point[b] * size
        f = our_dot(&size, &context_vectors[row1], &ONE, &syn1[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (1 - word_code[b] - f) * alpha
        our_saxpy(&size, &g, &syn1[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&size, &g, &context_vectors[row1], &ONE, &syn1[row2], &ONE)
    if learn_context:
        our_saxpy(&size, &context_locks[context_index], work, &ONE, &context_vectors[row1], &ONE)


cdef unsigned long long fast_document_dbow_neg(
    const int negative, np.uint32_t *cum_table, unsigned long long cum_table_len,
    REAL_t *context_vectors, REAL_t *syn1neg, const int size, const np.uint32_t word_index,
    const np.uint32_t context_index, const REAL_t alpha, REAL_t *work,
    unsigned long long next_random, int learn_context, int learn_hidden, REAL_t *context_locks) nogil:

    cdef long long a
    cdef long long row1 = context_index * size, row2
    cdef unsigned long long modulo = 281474976710655ULL
    cdef REAL_t f, g, label
    cdef np.uint32_t target_index
    cdef int d

    memset(work, 0, size * cython.sizeof(REAL_t))

    for d in range(negative+1):
        if d == 0:
            target_index = word_index
            label = ONEF
        else:
            target_index = bisect_left(cum_table, (next_random >> 16) % cum_table[cum_table_len-1], 0, cum_table_len)
            next_random = (next_random * <unsigned long long>25214903917ULL + 11) & modulo
            if target_index == word_index:
                continue
            label = <REAL_t>0.0
        row2 = target_index * size
        f = our_dot(&size, &context_vectors[row1], &ONE, &syn1neg[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (label - f) * alpha
        our_saxpy(&size, &g, &syn1neg[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&size, &g, &context_vectors[row1], &ONE, &syn1neg[row2], &ONE)
    if learn_context:
        our_saxpy(&size, &context_locks[context_index], work, &ONE, &context_vectors[row1], &ONE)

    return next_random


cdef void fast_document_dm_hs(
    const np.uint32_t *word_point, const np.uint8_t *word_code, int word_code_len,
    REAL_t *neu1, REAL_t *syn1, const REAL_t alpha, REAL_t *work,
    const int size, int learn_hidden) nogil:

    cdef long long b
    cdef long long row2
    cdef REAL_t f, g

    # l1 already composed by caller, passed in as neu1
    # work (also passed in)  will accumulate l1 error
    for b in range(word_code_len):
        row2 = word_point[b] * size
        f = our_dot(&size, neu1, &ONE, &syn1[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (1 - word_code[b] - f) * alpha
        our_saxpy(&size, &g, &syn1[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&size, &g, neu1, &ONE, &syn1[row2], &ONE)


cdef unsigned long long fast_document_dm_neg(
    const int negative, np.uint32_t *cum_table, unsigned long long cum_table_len, unsigned long long next_random,
    REAL_t *neu1, REAL_t *syn1neg, const int predict_word_index, const REAL_t alpha, REAL_t *work,
    const int size, int learn_hidden) nogil:

    cdef long long row2
    cdef unsigned long long modulo = 281474976710655ULL
    cdef REAL_t f, g, label
    cdef np.uint32_t target_index
    cdef int d

    # l1 already composed by caller, passed in as neu1
    # work (also passsed in) will accumulate l1 error for outside application
    for d in range(negative+1):
        if d == 0:
            target_index = predict_word_index
            label = ONEF
        else:
            target_index = bisect_left(cum_table, (next_random >> 16) % cum_table[cum_table_len-1], 0, cum_table_len)
            next_random = (next_random * <unsigned long long>25214903917ULL + 11) & modulo
            if target_index == predict_word_index:
                continue
            label = <REAL_t>0.0

        row2 = target_index * size
        f = our_dot(&size, neu1, &ONE, &syn1neg[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (label - f) * alpha
        our_saxpy(&size, &g, &syn1neg[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&size, &g, neu1, &ONE, &syn1neg[row2], &ONE)

    return next_random

cdef void fast_document_dmc_hs(
    const np.uint32_t *word_point, const np.uint8_t *word_code, int word_code_len,
    REAL_t *neu1, REAL_t *syn1, const REAL_t alpha, REAL_t *work, 
    const int layer1_size, const int vector_size, int learn_hidden) nogil:

    cdef long long a, b
    cdef long long row2
    cdef REAL_t f, g
    cdef int m

    # l1 already composed by caller, passed in as neu1
    # work accumulates net l1 error; eventually applied by caller
    for b in range(word_code_len):
        row2 = word_point[b] * layer1_size
        f = our_dot(&layer1_size, neu1, &ONE, &syn1[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (1 - word_code[b] - f) * alpha
        our_saxpy(&layer1_size, &g, &syn1[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&layer1_size, &g, neu1, &ONE, &syn1[row2], &ONE)


cdef unsigned long long fast_document_dmc_neg(
    const int negative, np.uint32_t *cum_table, unsigned long long cum_table_len, unsigned long long next_random,
    REAL_t *neu1, REAL_t *syn1neg, const int predict_word_index, const REAL_t alpha, REAL_t *work, 
    const int layer1_size, const int vector_size, int learn_hidden) nogil:

    cdef long long a
    cdef long long row2
    cdef unsigned long long modulo = 281474976710655ULL
    cdef REAL_t f, g, label
    cdef np.uint32_t target_index
    cdef int d, m

    # l1 already composed by caller, passed in as neu1
    # work accumulates net l1 error; eventually applied by caller    
    for d in range(negative+1):
        if d == 0:
            target_index = predict_word_index
            label = ONEF
        else:
            target_index = bisect_left(cum_table, (next_random >> 16) % cum_table[cum_table_len-1], 0, cum_table_len)
            next_random = (next_random * <unsigned long long>25214903917ULL + 11) & modulo
            if target_index == predict_word_index:
                continue
            label = <REAL_t>0.0

        row2 = target_index * layer1_size
        f = our_dot(&layer1_size, neu1, &ONE, &syn1neg[row2], &ONE)
        if f <= -MAX_EXP or f >= MAX_EXP:
            continue
        f = EXP_TABLE[<int>((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]
        g = (label - f) * alpha
        our_saxpy(&layer1_size, &g, &syn1neg[row2], &ONE, work, &ONE)
        if learn_hidden:
            our_saxpy(&layer1_size, &g, neu1, &ONE, &syn1neg[row2], &ONE)

    return next_random


def train_document_dbow(model, doc_words, doctag_indexes, alpha, work=None,
                        train_words=False, learn_doctags=True, learn_words=True, learn_hidden=True,
                        word_vectors=None, word_locks=None, doctag_vectors=None, doctag_locks=None):
    cdef int hs = model.hs
    cdef int negative = model.negative
    cdef int sample = (model.sample != 0)
    cdef int _train_words = train_words
    cdef int _learn_words = learn_words
    cdef int _learn_hidden = learn_hidden
    cdef int _learn_doctags = learn_doctags

    cdef REAL_t *_word_vectors
    cdef REAL_t *_doctag_vectors
    cdef REAL_t *_word_locks
    cdef REAL_t *_doctag_locks
    cdef REAL_t *_work
    cdef REAL_t _alpha = alpha
    cdef int size = model.layer1_size

    cdef int codelens[MAX_DOCUMENT_LEN]
    cdef np.uint32_t indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t _doctag_indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t reduced_windows[MAX_DOCUMENT_LEN]
    cdef int document_len
    cdef int doctag_len
    cdef int window = model.window

    cdef int i, j
    cdef unsigned long long r
    cdef long result = 0

    # For hierarchical softmax
    cdef REAL_t *syn1
    cdef np.uint32_t *points[MAX_DOCUMENT_LEN]
    cdef np.uint8_t *codes[MAX_DOCUMENT_LEN]

    # For negative sampling
    cdef REAL_t *syn1neg
    cdef np.uint32_t *cum_table
    cdef unsigned long long cum_table_len
    cdef unsigned long long next_random

    # default vectors, locks from syn0/doctag_syn0
    if word_vectors is None:
       word_vectors = model.syn0
    _word_vectors = <REAL_t *>(np.PyArray_DATA(word_vectors))
    if doctag_vectors is None:
       doctag_vectors = model.docvecs.doctag_syn0
    _doctag_vectors = <REAL_t *>(np.PyArray_DATA(doctag_vectors))
    if word_locks is None:
       word_locks = model.syn0_lockf
    _word_locks = <REAL_t *>(np.PyArray_DATA(word_locks))
    if doctag_locks is None:
       doctag_locks = model.docvecs.doctag_syn0_lockf
    _doctag_locks = <REAL_t *>(np.PyArray_DATA(doctag_locks))

    if hs:
        syn1 = <REAL_t *>(np.PyArray_DATA(model.syn1))

    if negative:
        syn1neg = <REAL_t *>(np.PyArray_DATA(model.syn1neg))
        cum_table = <np.uint32_t *>(np.PyArray_DATA(model.cum_table))
        cum_table_len = len(model.cum_table)
    if negative or sample:
        next_random = (2**24) * model.random.randint(0, 2**24) + model.random.randint(0, 2**24)

    # convert Python structures to primitive types, so we can release the GIL
    if work is None:
       work = zeros(model.layer1_size, dtype=REAL)
    _work = <REAL_t *>np.PyArray_DATA(work)

    vlookup = model.vocab
    i = 0
    for token in doc_words:
        predict_word = vlookup[token] if token in vlookup else None
        if predict_word is None:  # shrink document to leave out word
            continue  # leaving i unchanged
        if sample and predict_word.sample_int < random_int32(&next_random):
            continue
        indexes[i] = predict_word.index
        if hs:
            codelens[i] = <int>len(predict_word.code)
            codes[i] = <np.uint8_t *>np.PyArray_DATA(predict_word.code)
            points[i] = <np.uint32_t *>np.PyArray_DATA(predict_word.point)
        result += 1
        i += 1
        if i == MAX_DOCUMENT_LEN:
            break  # TODO: log warning, tally overflow?
    document_len = i

    if _train_words:
        # single randint() call avoids a big thread-synchronization slowdown
        for i, item in enumerate(model.random.randint(0, window, document_len)):
            reduced_windows[i] = item

    doctag_len = <int>min(MAX_DOCUMENT_LEN, len(doctag_indexes))
    for i in range(doctag_len):
        _doctag_indexes[i] = doctag_indexes[i]
        result += 1

    # release GIL & train on the document
    with nogil:
        for i in range(document_len):
            if _train_words:  # simultaneous skip-gram wordvec-training
                j = i - window + reduced_windows[i]
                if j < 0:
                    j = 0
                k = i + window + 1 - reduced_windows[i]
                if k > document_len:
                    k = document_len
                for j in range(j, k):
                    if j == i:
                        continue
                    if hs:
                        # we reuse the DBOW function, as it is equivalent to skip-gram for this purpose
                        fast_document_dbow_hs(points[i], codes[i], codelens[i], _word_vectors, syn1, size, indexes[j],
                                              _alpha, _work, _learn_words, _learn_hidden, _word_locks)
                    if negative:
                        # we reuse the DBOW function, as it is equivalent to skip-gram for this purpose
                        next_random = fast_document_dbow_neg(negative, cum_table, cum_table_len, _word_vectors, syn1neg, size,
                                                             indexes[i], indexes[j], _alpha, _work, next_random,
                                                             _learn_words, _learn_hidden, _word_locks)

            # docvec-training
            for j in range(doctag_len):
                if hs:
                    fast_document_dbow_hs(points[i], codes[i], codelens[i], _doctag_vectors, syn1, size, _doctag_indexes[j],
                                          _alpha, _work, _learn_doctags, _learn_hidden, _doctag_locks)
                if negative:
                    next_random = fast_document_dbow_neg(negative, cum_table, cum_table_len, _doctag_vectors, syn1neg, size,
                                                             indexes[i], _doctag_indexes[j], _alpha, _work, next_random,
                                                             _learn_doctags, _learn_hidden, _doctag_locks)

    return result


def train_document_dm(model, doc_words, doctag_indexes, alpha, work=None, neu1=None,
                      learn_doctags=True, learn_words=True, learn_hidden=True,
                      word_vectors=None, word_locks=None, doctag_vectors=None, doctag_locks=None):
    cdef int hs = model.hs
    cdef int negative = model.negative
    cdef int sample = (model.sample != 0)
    cdef int _learn_doctags = learn_doctags
    cdef int _learn_words = learn_words
    cdef int _learn_hidden = learn_hidden
    cdef int cbow_mean = model.cbow_mean
    cdef REAL_t count, inv_count = 1.0

    cdef REAL_t *_word_vectors
    cdef REAL_t *_doctag_vectors
    cdef REAL_t *_word_locks
    cdef REAL_t *_doctag_locks
    cdef REAL_t *_work
    cdef REAL_t *_neu1
    cdef REAL_t _alpha = alpha
    cdef int size = model.layer1_size

    cdef int codelens[MAX_DOCUMENT_LEN]
    cdef np.uint32_t indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t _doctag_indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t reduced_windows[MAX_DOCUMENT_LEN]
    cdef int document_len
    cdef int doctag_len
    cdef int window = model.window

    cdef int i, j, k, m
    cdef long result = 0

    # For hierarchical softmax
    cdef REAL_t *syn1
    cdef np.uint32_t *points[MAX_DOCUMENT_LEN]
    cdef np.uint8_t *codes[MAX_DOCUMENT_LEN]

    # For negative sampling
    cdef REAL_t *syn1neg
    cdef np.uint32_t *cum_table
    cdef unsigned long long cum_table_len
    cdef unsigned long long next_random

    # default vectors, locks from syn0/doctag_syn0
    if word_vectors is None:
       word_vectors = model.syn0
    _word_vectors = <REAL_t *>(np.PyArray_DATA(word_vectors))
    if doctag_vectors is None:
       doctag_vectors = model.docvecs.doctag_syn0
    _doctag_vectors = <REAL_t *>(np.PyArray_DATA(doctag_vectors))
    if word_locks is None:
       word_locks = model.syn0_lockf
    _word_locks = <REAL_t *>(np.PyArray_DATA(word_locks))
    if doctag_locks is None:
       doctag_locks = model.docvecs.doctag_syn0_lockf
    _doctag_locks = <REAL_t *>(np.PyArray_DATA(doctag_locks))

    if hs:
        syn1 = <REAL_t *>(np.PyArray_DATA(model.syn1))

    if negative:
        syn1neg = <REAL_t *>(np.PyArray_DATA(model.syn1neg))
        cum_table = <np.uint32_t *>(np.PyArray_DATA(model.cum_table))
        cum_table_len = len(model.cum_table)
    if negative or sample:
        next_random = (2**24) * model.random.randint(0, 2**24) + model.random.randint(0, 2**24)

    # convert Python structures to primitive types, so we can release the GIL
    if work is None:
       work = zeros(model.layer1_size, dtype=REAL)
    _work = <REAL_t *>np.PyArray_DATA(work)
    if neu1 is None:
       neu1 = zeros(model.layer1_size, dtype=REAL)
    _neu1 = <REAL_t *>np.PyArray_DATA(neu1)

    vlookup = model.vocab
    i = 0
    for token in doc_words:
        predict_word = vlookup[token] if token in vlookup else None
        if predict_word is None:  # shrink document to leave out word
            continue  # leaving i unchanged
        if sample and predict_word.sample_int < random_int32(&next_random):
            continue
        indexes[i] = predict_word.index
        if hs:
            codelens[i] = <int>len(predict_word.code)
            codes[i] = <np.uint8_t *>np.PyArray_DATA(predict_word.code)
            points[i] = <np.uint32_t *>np.PyArray_DATA(predict_word.point)
        result += 1
        i += 1
        if i == MAX_DOCUMENT_LEN:
            break  # TODO: log warning, tally overflow?
    document_len = i

    # single randint() call avoids a big thread-sync slowdown
    for i, item in enumerate(model.random.randint(0, window, document_len)):
        reduced_windows[i] = item

    doctag_len = <int>min(MAX_DOCUMENT_LEN, len(doctag_indexes))
    for i in range(doctag_len):
        _doctag_indexes[i] = doctag_indexes[i]
        result += 1

    # release GIL & train on the document
    with nogil:
        for i in range(document_len):
            j = i - window + reduced_windows[i]
            if j < 0:
                j = 0
            k = i + window + 1 - reduced_windows[i]
            if k > document_len:
                k = document_len

            # compose l1 (in _neu1) & clear _work
            memset(_neu1, 0, size * cython.sizeof(REAL_t))
            count = <REAL_t>0.0
            for m in range(j, k):
                if m == i:
                    continue
                else:
                    count += ONEF
                    our_saxpy(&size, &ONEF, &_word_vectors[indexes[m] * size], &ONE, _neu1, &ONE)
            for m in range(doctag_len):
                count += ONEF
                our_saxpy(&size, &ONEF, &_doctag_vectors[_doctag_indexes[m] * size], &ONE, _neu1, &ONE)
            if count > (<REAL_t>0.5):
                inv_count = ONEF/count
            if cbow_mean:
                sscal(&size, &inv_count, _neu1, &ONE)  # (does this need BLAS-variants like saxpy?)
            memset(_work, 0, size * cython.sizeof(REAL_t))  # work to accumulate l1 error
            if hs:
                fast_document_dm_hs(points[i], codes[i], codelens[i],
                                    _neu1, syn1, _alpha, _work,
                                    size, _learn_hidden)
            if negative:
                next_random = fast_document_dm_neg(negative, cum_table, cum_table_len, next_random,
                                                   _neu1, syn1neg, indexes[i], _alpha, _work,
                                                   size, _learn_hidden)

            if not cbow_mean:
                sscal(&size, &inv_count, _work, &ONE)  # (does this need BLAS-variants like saxpy?)
            # apply accumulated error in work
            if _learn_doctags:
                for m in range(doctag_len):
                    our_saxpy(&size, &_doctag_locks[_doctag_indexes[m]], _work,
                              &ONE, &_doctag_vectors[_doctag_indexes[m] * size], &ONE)
            if _learn_words:
                for m in range(j, k):
                    if m == i:
                        continue
                    else:
                         our_saxpy(&size, &_word_locks[indexes[m]], _work, &ONE,
                                   &_word_vectors[indexes[m] * size], &ONE)

    return result


def train_document_dm_concat(model, doc_words, doctag_indexes, alpha, work=None, neu1=None,
                             learn_doctags=True, learn_words=True, learn_hidden=True,
                             word_vectors=None, word_locks=None, doctag_vectors=None, doctag_locks=None):
    cdef int hs = model.hs
    cdef int negative = model.negative
    cdef int sample = (model.sample != 0)
    cdef int _learn_doctags = learn_doctags
    cdef int _learn_words = learn_words
    cdef int _learn_hidden = learn_hidden

    cdef REAL_t *_word_vectors
    cdef REAL_t *_doctag_vectors
    cdef REAL_t *_word_locks
    cdef REAL_t *_doctag_locks
    cdef REAL_t *_work
    cdef REAL_t *_neu1
    cdef REAL_t _alpha = alpha
    cdef int layer1_size = model.layer1_size
    cdef int vector_size = model.vector_size

    cdef int codelens[MAX_DOCUMENT_LEN]
    cdef np.uint32_t indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t _doctag_indexes[MAX_DOCUMENT_LEN]
    cdef np.uint32_t window_indexes[MAX_DOCUMENT_LEN] 
    cdef int document_len
    cdef int doctag_len
    cdef int window = model.window
    cdef int expected_doctag_len = model.dm_tag_count

    cdef int i, j, k, m, n
    cdef long result = 0
    cdef int null_word_index = model.vocab['\0'].index

    # For hierarchical softmax
    cdef REAL_t *syn1
    cdef np.uint32_t *points[MAX_DOCUMENT_LEN]
    cdef np.uint8_t *codes[MAX_DOCUMENT_LEN]

    # For negative sampling
    cdef REAL_t *syn1neg
    cdef np.uint32_t *cum_table
    cdef unsigned long long cum_table_len
    cdef unsigned long long next_random

    doctag_len = <int>min(MAX_DOCUMENT_LEN, len(doctag_indexes))
    if doctag_len != expected_doctag_len:
        return 0  # skip doc without expected number of tags

    # default vectors, locks from syn0/doctag_syn0
    if word_vectors is None:
       word_vectors = model.syn0
    _word_vectors = <REAL_t *>(np.PyArray_DATA(word_vectors))
    if doctag_vectors is None:
       doctag_vectors = model.docvecs.doctag_syn0
    _doctag_vectors = <REAL_t *>(np.PyArray_DATA(doctag_vectors))
    if word_locks is None:
       word_locks = model.syn0_lockf
    _word_locks = <REAL_t *>(np.PyArray_DATA(word_locks))
    if doctag_locks is None:
       doctag_locks = model.docvecs.doctag_syn0_lockf
    _doctag_locks = <REAL_t *>(np.PyArray_DATA(doctag_locks))

    if hs:
        syn1 = <REAL_t *>(np.PyArray_DATA(model.syn1))

    if negative:
        syn1neg = <REAL_t *>(np.PyArray_DATA(model.syn1neg))
        cum_table = <np.uint32_t *>(np.PyArray_DATA(model.cum_table))
        cum_table_len = len(model.cum_table)
    if negative or sample:
        next_random = (2**24) * model.random.randint(0, 2**24) + model.random.randint(0, 2**24)

    # convert Python structures to primitive types, so we can release the GIL
    if work is None:
       work = zeros(model.layer1_size, dtype=REAL)
    _work = <REAL_t *>np.PyArray_DATA(work)
    if neu1 is None:
       neu1 = zeros(model.layer1_size, dtype=REAL)
    _neu1 = <REAL_t *>np.PyArray_DATA(neu1)

    vlookup = model.vocab
    i = 0
    for token in doc_words:
        predict_word = vlookup[token] if token in vlookup else None
        if predict_word is None:  # shrink document to leave out word
            continue  # leaving i unchanged
        if sample and predict_word.sample_int < random_int32(&next_random):
            continue
        indexes[i] = predict_word.index
        if hs:
            codelens[i] = <int>len(predict_word.code)
            codes[i] = <np.uint8_t *>np.PyArray_DATA(predict_word.code)
            points[i] = <np.uint32_t *>np.PyArray_DATA(predict_word.point)
        result += 1
        i += 1
        if i == MAX_DOCUMENT_LEN:
            break  # TODO: log warning, tally overflow?
    document_len = i

    for i in range(doctag_len):
        _doctag_indexes[i] = doctag_indexes[i]
        result += 1

    # release GIL & train on the document
    with nogil:
        for i in range(document_len):
            j = i - window      # negative OK: will pad with null word
            k = i + window + 1  # past document end OK: will pad with null word

            # compose l1 & clear work
            for m in range(doctag_len):
                # doc vector(s)
                memcpy(&_neu1[m * vector_size], &_doctag_vectors[_doctag_indexes[m] * vector_size],
                       vector_size * cython.sizeof(REAL_t))
            n = 0
            for m in range(j, k):
                # word vectors in window
                if m == i:
                    continue
                if m < 0 or m >= document_len:
                    window_indexes[n] =  null_word_index
                else:
                    window_indexes[n] = indexes[m]
                n = n + 1
            for m in range(2 * window):
                memcpy(&_neu1[(doctag_len + m) * vector_size], &_word_vectors[window_indexes[m] * vector_size],
                       vector_size * cython.sizeof(REAL_t))
            memset(_work, 0, layer1_size * cython.sizeof(REAL_t))  # work to accumulate l1 error

            if hs:
                fast_document_dmc_hs(points[i], codes[i], codelens[i],
                                     _neu1, syn1, _alpha, _work,
                                     layer1_size, vector_size, _learn_hidden)
            if negative:
                next_random = fast_document_dmc_neg(negative, cum_table, cum_table_len, next_random,
                                                    _neu1, syn1neg, indexes[i], _alpha, _work, 
                                                   layer1_size, vector_size, _learn_hidden)

            if _learn_doctags:
                for m in range(doctag_len):
                    our_saxpy(&vector_size, &_doctag_locks[_doctag_indexes[m]], &_work[m * vector_size],
                              &ONE, &_doctag_vectors[_doctag_indexes[m] * vector_size], &ONE)
            if _learn_words:
                for m in range(2 * window):
                    our_saxpy(&vector_size, &_word_locks[window_indexes[m]], &_work[(doctag_len + m) * vector_size],
                              &ONE, &_word_vectors[window_indexes[m] * vector_size], &ONE)

    return result
