# coding: utf8
from __future__ import unicode_literals

import numpy
from thinc.v2v import Model, Maxout, Softmax, Affine, ReLu
from thinc.i2v import HashEmbed, StaticVectors
from thinc.t2t import ExtractWindow, ParametricAttention
from thinc.t2v import Pooling, sum_pool
from thinc.misc import Residual
from thinc.misc import LayerNorm as LN
from thinc.api import add, layerize, chain, clone, concatenate, with_flatten
from thinc.api import FeatureExtracter, with_getitem, flatten_add_lengths
from thinc.api import uniqued, wrap, noop
from thinc.linear.linear import LinearModel
from thinc.neural.ops import NumpyOps, CupyOps
from thinc.neural.util import get_array_module, copy_array
from thinc.neural._lsuv import svd_orthonormal

from thinc import describe
from thinc.describe import Dimension, Synapses, Biases, Gradient
from thinc.neural._classes.affine import _set_dimensions_if_needed
import thinc.extra.load_nlp
from thinc.neural._lsuv import svd_orthonormal

from .attrs import ID, ORTH, LOWER, NORM, PREFIX, SUFFIX, SHAPE
from . import util


VECTORS_KEY = 'spacy_pretrained_vectors'


@layerize
def _flatten_add_lengths(seqs, pad=0, drop=0.):
    ops = Model.ops
    lengths = ops.asarray([len(seq) for seq in seqs], dtype='i')

    def finish_update(d_X, sgd=None):
        return ops.unflatten(d_X, lengths, pad=pad)

    X = ops.flatten(seqs, pad=pad)
    return (X, lengths), finish_update


@layerize
def _logistic(X, drop=0.):
    xp = get_array_module(X)
    if not isinstance(X, xp.ndarray):
        X = xp.asarray(X)
    # Clip to range (-10, 10)
    X = xp.minimum(X, 10., X)
    X = xp.maximum(X, -10., X)
    Y = 1. / (1. + xp.exp(-X))

    def logistic_bwd(dY, sgd=None):
        dX = dY * (Y * (1-Y))
        return dX

    return Y, logistic_bwd


def _zero_init(model):
    def _zero_init_impl(self, X, y):
        self.W.fill(0)
    model.on_data_hooks.append(_zero_init_impl)
    if model.W is not None:
        model.W.fill(0.)
    return model


@layerize
def _preprocess_doc(docs, drop=0.):
    keys = [doc.to_array([LOWER]) for doc in docs]
    ops = Model.ops
    lengths = ops.asarray([arr.shape[0] for arr in keys])
    keys = ops.xp.concatenate(keys)
    vals = ops.allocate(keys.shape[0]) + 1
    return (keys, vals, lengths), None


@describe.on_data(_set_dimensions_if_needed,
    lambda model, X, y: model.init_weights(model))
@describe.attributes(
    nI=Dimension("Input size"),
    nF=Dimension("Number of features"),
    nO=Dimension("Output size"),
    nP=Dimension("Maxout pieces"),
    W=Synapses("Weights matrix",
        lambda obj: (obj.nF, obj.nO, obj.nP, obj.nI)),
    b=Biases("Bias vector",
        lambda obj: (obj.nO, obj.nP)),
    pad=Synapses("Pad",
        lambda obj: (1, obj.nF, obj.nO, obj.nP),
        lambda M, ops: ops.normal_init(M, 1.)),
    d_W=Gradient("W"),
    d_pad=Gradient("pad"),
    d_b=Gradient("b"))
class PrecomputableAffine(Model):
    def __init__(self, nO=None, nI=None, nF=None, nP=None, **kwargs):
        Model.__init__(self, **kwargs)
        self.nO = nO
        self.nP = nP
        self.nI = nI
        self.nF = nF

    def begin_update(self, X, drop=0.):
        Yf = self.ops.xp.dot(X,
            self.W.reshape((self.nF*self.nO*self.nP, self.nI)).T)
        Yf = Yf.reshape((Yf.shape[0], self.nF, self.nO, self.nP))
        Yf = self._add_padding(Yf)

        def backward(dY_ids, sgd=None):
            dY, ids = dY_ids
            dY, ids = self._backprop_padding(dY, ids)
            Xf = X[ids]
            Xf = Xf.reshape((Xf.shape[0], self.nF * self.nI))

            self.d_b += dY.sum(axis=0)
            dY = dY.reshape((dY.shape[0], self.nO*self.nP))

            Wopfi = self.W.transpose((1, 2, 0, 3))
            Wopfi = self.ops.xp.ascontiguousarray(Wopfi)
            Wopfi = Wopfi.reshape((self.nO*self.nP, self.nF * self.nI))
            dXf = self.ops.dot(dY.reshape((dY.shape[0], self.nO*self.nP)), Wopfi)

            # Reuse the buffer
            dWopfi = Wopfi; dWopfi.fill(0.)
            self.ops.xp.dot(dY.T, Xf, out=dWopfi)
            dWopfi = dWopfi.reshape((self.nO, self.nP, self.nF, self.nI))
            # (o, p, f, i) --> (f, o, p, i)
            self.d_W += dWopfi.transpose((2, 0, 1, 3))

            if sgd is not None:
                sgd(self._mem.weights, self._mem.gradient, key=self.id)
            return dXf.reshape((dXf.shape[0], self.nF, self.nI))
        return Yf, backward
    
    def _add_padding(self, Yf):
        Yf_padded = self.ops.xp.vstack((self.pad, Yf))
        return Yf_padded[1:]

    def _backprop_padding(self, dY, ids):
        for i in range(ids.shape[0]):
            for j in range(ids.shape[1]):
                if ids[i, j] < 0:
                    self.d_pad[0, j] += dY[i, j]
        return dY, ids

    @staticmethod
    def init_weights(model):
        '''This is like the 'layer sequential unit variance', but instead
        of taking the actual inputs, we randomly generate whitened data.

        Why's this all so complicated? We have a huge number of inputs,
        and the maxout unit makes guessing the dynamics tricky. Instead
        we set the maxout weights to values that empirically result in
        whitened outputs given whitened inputs.
        '''
        if (model.W**2).sum() != 0.:
            return
        model.ops.normal_init(model.W, model.nF * model.nI, inplace=True)

        ids = numpy.zeros((5000, model.nF), dtype='i')
        ids += numpy.asarray(numpy.random.uniform(0, 1000, ids.shape), dtype='i')
        tokvecs = numpy.zeros((5000, model.nI), dtype='f')
        tokvecs += numpy.random.normal(loc=0., scale=1.,
                    size=tokvecs.size).reshape(tokvecs.shape)

        def predict(ids, tokvecs):
            # nS ids. nW tokvecs
            hiddens = model(tokvecs) # (nW, f, o, p)
            # need nS vectors
            vectors = model.ops.allocate((ids.shape[0], model.nO, model.nP))
            for i, feats in enumerate(ids):
                for j, id_ in enumerate(feats):
                    vectors[i] += hiddens[id_, j]
            vectors += model.b
            if model.nP >= 2:
                return model.ops.maxout(vectors)[0]
            else:
                return vectors * (vectors >= 0)

        tol_var = 0.01
        tol_mean = 0.01
        t_max = 10
        t_i = 0
        for t_i in range(t_max):
            acts1 = predict(ids, tokvecs)
            var = numpy.var(acts1)
            mean = numpy.mean(acts1)
            if abs(var - 1.0) >= tol_var:
                model.W /= numpy.sqrt(var)
            elif abs(mean) >= tol_mean:
                model.b -= mean
            else:
                break


def link_vectors_to_models(vocab):
    vectors = vocab.vectors
    ops = Model.ops
    for word in vocab:
        if word.orth in vectors.key2row:
            word.rank = vectors.key2row[word.orth]
        else:
            word.rank = 0
    data = ops.asarray(vectors.data)
    # Set an entry here, so that vectors are accessed by StaticVectors
    # (unideal, I know)
    thinc.extra.load_nlp.VECTORS[(ops.device, VECTORS_KEY)] = data


def Tok2Vec(width, embed_size, **kwargs):
    pretrained_dims = kwargs.get('pretrained_dims', 0)
    cnn_maxout_pieces = kwargs.get('cnn_maxout_pieces', 2)
    cols = [ID, NORM, PREFIX, SUFFIX, SHAPE, ORTH]
    with Model.define_operators({'>>': chain, '|': concatenate, '**': clone,
                                 '+': add, '*': reapply}):
        norm = HashEmbed(width, embed_size, column=cols.index(NORM),
                         name='embed_norm')
        prefix = HashEmbed(width, embed_size//2, column=cols.index(PREFIX),
                           name='embed_prefix')
        suffix = HashEmbed(width, embed_size//2, column=cols.index(SUFFIX),
                           name='embed_suffix')
        shape = HashEmbed(width, embed_size//2, column=cols.index(SHAPE),
                          name='embed_shape')
        if pretrained_dims is not None and pretrained_dims >= 1:
            glove = StaticVectors(VECTORS_KEY, width, column=cols.index(ID))

            embed = uniqued(
                (glove | norm | prefix | suffix | shape)
                >> LN(Maxout(width, width*5, pieces=3)), column=5)
        else:
            embed = uniqued(
                (norm | prefix | suffix | shape)
                >> LN(Maxout(width, width*4, pieces=3)), column=5)

        convolution = Residual(
            ExtractWindow(nW=1)
            >> LN(Maxout(width, width*3, pieces=cnn_maxout_pieces))
        )

        tok2vec = (
            FeatureExtracter(cols)
            >> with_flatten(embed >> (convolution ** 4), pad=4)
        )

        # Work around thinc API limitations :(. TODO: Revise in Thinc 7
        tok2vec.nO = width
        tok2vec.embed = embed
    return tok2vec


def reapply(layer, n_times):
    def reapply_fwd(X, drop=0.):
        backprops = []
        for i in range(n_times):
            Y, backprop = layer.begin_update(X, drop=drop)
            X = Y
            backprops.append(backprop)

        def reapply_bwd(dY, sgd=None):
            dX = None
            for backprop in reversed(backprops):
                dY = backprop(dY, sgd=sgd)
                if dX is None:
                    dX = dY
                else:
                    dX += dY
            return dX

        return Y, reapply_bwd
    return wrap(reapply_fwd, layer)


def asarray(ops, dtype):
    def forward(X, drop=0.):
        return ops.asarray(X, dtype=dtype), None
    return layerize(forward)


def _divide_array(X, size):
    parts = []
    index = 0
    while index < len(X):
        parts.append(X[index:index + size])
        index += size
    return parts


def get_col(idx):
    assert idx >= 0, idx

    def forward(X, drop=0.):
        assert idx >= 0, idx
        if isinstance(X, numpy.ndarray):
            ops = NumpyOps()
        else:
            ops = CupyOps()
        output = ops.xp.ascontiguousarray(X[:, idx], dtype=X.dtype)

        def backward(y, sgd=None):
            assert idx >= 0, idx
            dX = ops.allocate(X.shape)
            dX[:, idx] += y
            return dX

        return output, backward

    return layerize(forward)


def doc2feats(cols=None):
    if cols is None:
        cols = [ID, NORM, PREFIX, SUFFIX, SHAPE, ORTH]

    def forward(docs, drop=0.):
        feats = []
        for doc in docs:
            feats.append(doc.to_array(cols))
        return feats, None

    model = layerize(forward)
    model.cols = cols
    return model


def print_shape(prefix):
    def forward(X, drop=0.):
        return X, lambda dX, **kwargs: dX
    return layerize(forward)


@layerize
def get_token_vectors(tokens_attrs_vectors, drop=0.):
    tokens, attrs, vectors = tokens_attrs_vectors

    def backward(d_output, sgd=None):
        return (tokens, d_output)

    return vectors, backward


@layerize
def logistic(X, drop=0.):
    xp = get_array_module(X)
    if not isinstance(X, xp.ndarray):
        X = xp.asarray(X)
    # Clip to range (-10, 10)
    X = xp.minimum(X, 10., X)
    X = xp.maximum(X, -10., X)
    Y = 1. / (1. + xp.exp(-X))

    def logistic_bwd(dY, sgd=None):
        dX = dY * (Y * (1-Y))
        return dX

    return Y, logistic_bwd


def zero_init(model):
    def _zero_init_impl(self, X, y):
        self.W.fill(0)
    model.on_data_hooks.append(_zero_init_impl)
    return model


@layerize
def preprocess_doc(docs, drop=0.):
    keys = [doc.to_array([LOWER]) for doc in docs]
    ops = Model.ops
    lengths = ops.asarray([arr.shape[0] for arr in keys])
    keys = ops.xp.concatenate(keys)
    vals = ops.allocate(keys.shape[0]) + 1
    return (keys, vals, lengths), None


def getitem(i):
    def getitem_fwd(X, drop=0.):
        return X[i], None
    return layerize(getitem_fwd)


def build_tagger_model(nr_class, **cfg):
    embed_size = util.env_opt('embed_size', 7000)
    if 'token_vector_width' in cfg:
        token_vector_width = cfg['token_vector_width']
    else:
        token_vector_width = util.env_opt('token_vector_width', 128)
    pretrained_dims = cfg.get('pretrained_dims', 0)
    with Model.define_operators({'>>': chain, '+': add}):
        if 'tok2vec' in cfg:
            tok2vec = cfg['tok2vec']
        else:
            tok2vec = Tok2Vec(token_vector_width, embed_size,
                              pretrained_dims=pretrained_dims)
        model = (
            tok2vec
            >> with_flatten(Softmax(nr_class, token_vector_width))
        )
    model.nI = None
    model.tok2vec = tok2vec
    return model


@layerize
def SpacyVectors(docs, drop=0.):
    batch = []
    for doc in docs:
        indices = numpy.zeros((len(doc),), dtype='i')
        for i, word in enumerate(doc):
            if word.orth in doc.vocab.vectors.key2row:
                indices[i] = doc.vocab.vectors.key2row[word.orth]
            else:
                indices[i] = 0
        vectors = doc.vocab.vectors.data[indices]
        batch.append(vectors)
    return batch, None


def build_text_classifier(nr_class, width=64, **cfg):
    nr_vector = cfg.get('nr_vector', 5000)
    pretrained_dims = cfg.get('pretrained_dims', 0)
    with Model.define_operators({'>>': chain, '+': add, '|': concatenate,
                                 '**': clone}):
        if cfg.get('low_data'):
            model = (
                SpacyVectors
                >> flatten_add_lengths
                >> with_getitem(0, Affine(width, pretrained_dims))
                >> ParametricAttention(width)
                >> Pooling(sum_pool)
                >> Residual(ReLu(width, width)) ** 2
                >> zero_init(Affine(nr_class, width, drop_factor=0.0))
                >> logistic
            )
            return model

        lower = HashEmbed(width, nr_vector, column=1)
        prefix = HashEmbed(width//2, nr_vector, column=2)
        suffix = HashEmbed(width//2, nr_vector, column=3)
        shape = HashEmbed(width//2, nr_vector, column=4)

        trained_vectors = (
            FeatureExtracter([ORTH, LOWER, PREFIX, SUFFIX, SHAPE, ID])
            >> with_flatten(
                uniqued(
                    (lower | prefix | suffix | shape)
                    >> LN(Maxout(width, width+(width//2)*3)),
                    column=0
                )
            )
        )

        if pretrained_dims:
            static_vectors = (
                SpacyVectors
                >> with_flatten(Affine(width, pretrained_dims))
            )
            # TODO Make concatenate support lists
            vectors = concatenate_lists(trained_vectors, static_vectors)
            vectors_width = width*2
        else:
            vectors = trained_vectors
            vectors_width = width
            static_vectors = None
        cnn_model = (
            vectors
            >> with_flatten(
                LN(Maxout(width, vectors_width))
                >> Residual(
                    (ExtractWindow(nW=1) >> LN(Maxout(width, width*3)))
                ) ** 2, pad=2
            )
            >> flatten_add_lengths
            >> ParametricAttention(width)
            >> Pooling(sum_pool)
            >> Residual(zero_init(Maxout(width, width)))
            >> zero_init(Affine(nr_class, width, drop_factor=0.0))
        )

        linear_model = (
            _preprocess_doc
            >> LinearModel(nr_class, drop_factor=0.)
        )

        model = (
            (linear_model | cnn_model)
            >> zero_init(Affine(nr_class, nr_class*2, drop_factor=0.0))
            >> logistic
        )
    model.nO = nr_class
    model.lsuv = False
    return model


@layerize
def flatten(seqs, drop=0.):
    ops = Model.ops
    lengths = ops.asarray([len(seq) for seq in seqs], dtype='i')

    def finish_update(d_X, sgd=None):
        return ops.unflatten(d_X, lengths, pad=0)

    X = ops.flatten(seqs, pad=0)
    return X, finish_update


def concatenate_lists(*layers, **kwargs):  # pragma: no cover
    """Compose two or more models `f`, `g`, etc, such that their outputs are
    concatenated, i.e. `concatenate(f, g)(x)` computes `hstack(f(x), g(x))`
    """
    if not layers:
        return noop()
    drop_factor = kwargs.get('drop_factor', 1.0)
    ops = layers[0].ops
    layers = [chain(layer, flatten) for layer in layers]
    concat = concatenate(*layers)

    def concatenate_lists_fwd(Xs, drop=0.):
        drop *= drop_factor
        lengths = ops.asarray([len(X) for X in Xs], dtype='i')
        flat_y, bp_flat_y = concat.begin_update(Xs, drop=drop)
        ys = ops.unflatten(flat_y, lengths)

        def concatenate_lists_bwd(d_ys, sgd=None):
            return bp_flat_y(ops.flatten(d_ys), sgd=sgd)

        return ys, concatenate_lists_bwd

    model = wrap(concatenate_lists_fwd, concat)
    return model