#!/usr/bin/env python

import theano
import theano.tensor as T
import numpy
import numpy as np
import pickle as pkl
from collections import OrderedDict
import cPickle as pickle

from theano import config
from theano.sandbox.rng_mrg import MRG_RandomStreams as RandomStreams

floatX = config.floatX

def shared_to_cpu(shared_params, params):
    for k, v in shared_params.iteritems():
        params[k] = v.get_value()

def cpu_to_shared(params, shared_params):
    for k, v in params.iteritems():
        shared_params[k].set_value(v)

def save_model(filename, options, params, shared_params=None):
    if not shared_params == None:
        shared_to_cpu(shared_params, params);
    model = OrderedDict()
    model['options'] = options
    model['params'] = params
    pickle.dump(model, open(filename, 'w'))

def load_model(filename):
    model = pickle.load(open(filename, 'rb'))
    options = model['options']
    params = model['params']
    shared_params = init_shared_params(params)
    return options, params, shared_params
   # return options, params, shared_params

def ortho_weight(ndim):
    """
    Random orthogonal weights, we take
    the right matrix in the SVD.

    Remember in SVD, u has the same # rows as W
    and v has the same # of cols as W. So we
    are ensuring that the rows are
    orthogonal.
    """
    W = numpy.random.randn(ndim, ndim)
    u, _, _ = numpy.linalg.svd(W)
    return u.astype('float32')

# activation function for ff layer
def tanh(x):
    return T.tanh(x)

def relu(x):
    return T.maximum(x, np.float32(0.))

def linear(x):
    return x

def init_fflayer(params, nin, nout, options, prefix='ff'):
    ''' initialize ff layer
    '''
    params[prefix + '_w'] = init_weight(nin, nout, options)
    params[prefix + '_b'] = np.zeros(nout, dtype='float32')
    return params

def init_weight(n, d, options):
    ''' initialize weight matrix
    options['init_type'] determines
    gaussian or uniform initlizaiton
    '''
    if options['init_type'] == 'gaussian':
        return (numpy.random.randn(n, d).astype(floatX)) * options['std']
    elif options['init_type'] == 'uniform':
        # [-range, range]
        return ((numpy.random.rand(n, d) * 2 - 1) * \
                options['range']).astype(floatX)
    
    elif options['init_type'] == 'glorot uniform':
        low = -1.0 * np.sqrt(6.0/(n + d))
        high = 1.0 * np.sqrt(6.0/(n + d))
        return numpy.random.uniform(low,high,(n,d)).astype(floatX)

layers = {'ff': ('init_fflayer', 'fflayer'),
          'lstm': ('init_lstm_layer', 'lstm_layer'),
          'lstm_append': (None, 'lstm_append_layer')}

def get_layer(name):
    fns = layers[name]
    return (eval(fns[0]), eval(fns[1]))

# initialize the parmaters
def init_params(options):
    ''' Initialize all the parameters
    '''
    params = OrderedDict()
    n_words = options['n_words']
    n_emb = options['n_emb']
    n_dim = options['n_dim']
    n_image_feat = options['n_image_feat']
    n_common_feat = options['n_common_feat']
    n_output = options['n_output']
    n_attention = options['n_attention']

    # embedding weights
    if 'embedding_file' in options and options['embedding_file'] != '':
        embedding_matrix = pkl.load(open(options['embedding_file'], 'r'))[1:].astype(floatX)
        params['w_emb'] = embedding_matrix
    else:
        ## use the same initialization as BOW
        params['w_emb'] = ((numpy.random.rand(n_words, n_emb) * 2 - 1) * 0.5).astype(floatX)
    
    params = init_fflayer(params, n_image_feat, n_dim, options,
                          prefix='image_mlp')

    # attention model based parameters
    
    params = init_fflayer(params, n_dim, n_output, options,
                          prefix='scale_to_softmax')
    # lstm layer
    params = init_lstm_layer(params, n_emb, n_dim, options, prefix='sent_lstm')
    # mlstm layer
    params = init_mlstm_layer(params,2*n_dim, n_dim, options)
    return params

def init_shared_params(params):
    ''' return a shared version of all parameters
    '''
    shared_params = OrderedDict()
    for k, p in params.iteritems():
        shared_params[k] = theano.shared(params[k], name = k)

    return shared_params


def fflayer(shared_params, x, options, prefix='ff', act_func='tanh'):
    ''' fflayer: multiply weight then add bias
    '''
    return eval(act_func)(T.dot(x, shared_params[prefix + '_w']) +
                          shared_params[prefix + '_b'])

def dropout_layer(x, dropout, trng, drop_ratio=0.5):
    ''' dropout layer
    '''
    x_drop = T.switch(dropout,
                      (x * trng.binomial(x.shape,
                                         p = 1 - drop_ratio,
                                         n = 1,
                                         dtype = x.dtype) \
                       / (numpy.float32(1.0) - drop_ratio)),
                      x)
    return x_drop

def init_lstm_layer(params, nin, ndim, options, prefix='lstm'):
    ''' initializt lstm layer
    '''
    params[prefix + '_w_x'] = init_weight(nin, 4 * ndim, options)
    # use svd trick to initializ
    if options['init_lstm_svd']:
        params[prefix + '_w_h'] = np.concatenate([ortho_weight(ndim),
                                                  ortho_weight(ndim),
                                                  ortho_weight(ndim),
                                                  ortho_weight(ndim)],
                                                 axis=1)
    else:
        params[prefix + '_w_h'] = init_weight(ndim, 4 * ndim, options)
    params[prefix + '_b_h'] = np.zeros(4 * ndim, dtype='float32')
    # set forget bias to be positive
    params[prefix + '_b_h'][ndim : 2*ndim] = np.float32(options.get('forget_bias', 0))
    return params

def init_wbw_att_layer(params, nin, ndim, options, prefix='wbw_attention'):
    '''
    Word by Word layer
    '''
    params[prefix + '_w_y'] = init_weight(ndim,ndim,options)
    params[prefix + '_w_h'] = init_weight(ndim,ndim,options)
    params[prefix + '_w_r'] = init_weight(ndim,ndim,options)
    params[prefix + '_w_alpha'] = init_weight(ndim,1,options)
    params[prefix + '_w_t'] = init_weight(ndim,ndim,options)
    return params

def init_mlstm_layer(params, nin, ndim, options, prefix='mlstm'):
    '''initialize mlstm layer
    '''
    # Additional Parameters
    params[prefix + '_w_s'] = init_weight(ndim, ndim, options)
    params[prefix + '_w_m'] = init_weight(ndim, ndim, options)
    params[prefix + '_w_t'] = init_weight(ndim, ndim, options)
    params[prefix + '_w_alpha'] = init_weight(ndim,1, options)

    # LSTM parameters
    params[prefix + '_w_x'] = init_weight(nin, 4 * ndim, options)
    if options['init_lstm_svd']:
        params[prefix + '_w_h'] = np.concatenate([ortho_weight(ndim),
                                             ortho_weight(ndim),
                                                  ortho_weight(ndim),
                                                  ortho_weight(ndim)],
                                             axis=1)
    else:
        params[prefix + '_w_h'] = init_weight(ndim, 4 * ndim, options)
    params[prefix + '_b_h'] = np.zeros(4 * ndim, dtype='float32')
    # set forget bias to be positive
    params[prefix + '_b_h'][ndim : 2*ndim] = np.float32(options.get('forget_bias', 0))
    return params

def wbw_attention_layer(shared_params, image, question, mask, r_0, options, prefix='wbw_attention',return_final=False):
    ''' wbw attention layer:
    :param shared_params: shared parameters
    :param image: batch_size x num_regions x n_dim
    :param question : T x batch_size x n_dim
    :param r_0 : batch_size x n_dim 
    :param mask: mask for x, T x batch_size
    '''
    
    wbw_w_y = shared_params[prefix + '_w_y'] # n_dim x n_dim
    wbw_w_h = shared_params[prefix + '_w_h'] # n_dim x n_dim
    wbw_w_r = shared_params[prefix + '_w_r'] # n_dim x n_dim
    wbw_w_alpha = shared_params[prefix + '_w_alpha'] # n_dim x 1
    wbw_w_t = shared_params[prefix + '_w_t'] # n_dim x n_dim    
    
    def recurrent(h_t, mask_t, r_tm1, Y):
        # h_t : bt_sz x n_dim
        wht = T.dot(h_t, wbw_w_h) # bt_sz x n_dim
        # r_tm1 : bt_sz x n_dim
        wrtm1 = T.dot(r_tm1, wbw_w_r) # bt_sz x n_dim
        tmp = (wht + wrtm1)[:,None,:] # bt_sz x num_regions x n_dim
        WY = T.dot(Y, wbw_w_y) # bt_sz x num_regions x n_dim
        Mt = tanh(WY + tmp) # bt_sz x num_regions x n_dim         
        
        WMt = T.dot(Mt, wbw_w_alpha).flatten(2) # bt_sz x num_regions
        alpha_t = T.nnet.softmax(WMt) # bt_sz x num_region
        alpha_t = alpha_t.dimshuffle((0,'x',1)) # bt_sz x 1 x num_region
        Y_alpha_t = T.batched_dot(alpha_t, Y)[:,0,:] # bt_sz x n_dim
        r_t = Y_alpha_t + T.dot(r_tm1, wbw_w_t) # bt_sz x n_dim        
        
        r_t = mask_t[:, None] * r_t + (numpy.float32(1.0) - mask_t[:, None]) * r_tm1
        return r_t

    r, updates = theano.scan(fn = recurrent,
                                  sequences = [question, mask],
                                  non_sequences=[image],
                                  outputs_info = r_0[:question.shape[1]],
                                  n_steps = question.shape[0]
                                  )
    if return_final:
        return r[-1]
    return r

def mlstm_layer(shared_params, Y, x, mask, h_0,c_0, options, prefix='mlstm', ):
    '''mlstm layer: 
    :param shared_params: shared parameters
    :param h: input, T x batch_size x n_dim
    :param mask: mask for x, T x batch_size
    :param Y: image layer: batch_size x num_regions x n_dim    
    '''
    n_dim = options['n_dim']
    mlstm_w_x = shared_params[prefix + '_w_x'] # 2 * n_dim x 4 * n_dim
    # weight matrix for h, (2*n_dim) x 4*n_dim (ifoc)
    mlstm_w_h = shared_params[prefix + '_w_h'] # n_dim x 4 * n_dim
    mlstm_b_h = shared_params[prefix + '_b_h'] # 4 * n_dim
    mlstm_w_s = shared_params[prefix + '_w_s'] # n_dim x n_dim
    mlstm_w_m = shared_params[prefix + '_w_m'] # n_dim x n_dim
    mlstm_w_t = shared_params[prefix + '_w_t'] # n_dim x n_dim
    mlstm_w_alpha = shared_params[prefix + '_w_alpha'] # n_dim x 1

    def recurrent(x_t, mask_t, h_tm1, c_tm1, Y):
        '''
        x_t : bt x n_dim
        mask_t : bt x 1
        h_tm1 : bt x n_dim
        c_tm1 : bt x ndim
        Y : bt x num_regions x n_dim
        '''
        WY = T.dot(Y, mlstm_w_s)
        wh_tm1 = T.dot(h_tm1, mlstm_w_m)
        wx_t = T.dot(x_t, mlstm_w_t)
        r = (wh_tm1 + wx_t)[:,None,:]
        e = T.tanh(WY + r)
        we = T.dot(e, mlstm_w_alpha).flatten(2)
        alpha_t = T.nnet.softmax(we)
        alpha_t = alpha_t.dimshuffle((0,'x',1))
        a_t = T.batched_dot(alpha_t, Y)[:,0,:]
        m_t = T.concatenate([a_t, x_t], axis=1)

        ifoc = T.dot(m_t, mlstm_w_x) + T.dot(h_tm1, mlstm_w_h) + mlstm_b_h

        # 0:3*n_dim: input forget and output gate
        i_gate = T.nnet.sigmoid(ifoc[:, 0 : n_dim])
        f_gate = T.nnet.sigmoid(ifoc[:, n_dim : 2*n_dim])
        o_gate = T.nnet.sigmoid(ifoc[:, 2*n_dim : 3*n_dim])
        # 3*n_dim : 4*n_dim c_temp
        c_temp = T.tanh(ifoc[:, 3*n_dim : 4*n_dim])
        # c_t = input_gate * c_temp + forget_gate * c_tm1
        c_t = i_gate * c_temp + f_gate * c_tm1

        if options['use_tanh']:
            h_t = o_gate * T.tanh(c_t)
        else:
            h_t = o_gate * c_t
        # masking
        h_t = mask_t[:, None] * h_t + \
              (numpy.float32(1.0) - mask_t[:, None]) * h_tm1
        c_t = mask_t[:, None] * c_t + \
              (numpy.float32(1.0) - mask_t[:, None]) * c_tm1

        return h_t, c_t

    [h, c], updates = theano.scan(fn = recurrent,
                                  sequences = [x, mask],
                                  outputs_info = [h_0[:x.shape[1]],
                                                  c_0[:x.shape[1]]],
                                  non_sequences = [Y],
                                  n_steps = x.shape[0])

    return h, c




def lstm_layer(shared_params, x, mask, h_0, c_0, options, prefix='lstm'):
    ''' lstm layer:
    :param shared_params: shared parameters
    :param x: input, T x batch_size x n_emb