# Copyright 2017 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# ==============================================================================
from __future__ import print_function

import h5py
import numpy as np
import os

from utils import write_datasets
import matplotlib
import matplotlib.pyplot as plt
import scipy.signal


def generate_rnn(rng, N, g, tau, dt, max_firing_rate):
  """Create a (vanilla) RNN with a bunch of hyper parameters for generating
chaotic data.
  Args:
    rng: numpy random number generator
    N: number of hidden units
    g: scaling of recurrent weight matrix in g W, with W ~ N(0,1/N)
    tau: time scale of individual unit dynamics
    dt: time step for equation updates
    max_firing_rate: how to resecale the -1,1 firing rates
  Returns:
    the dictionary of these parameters, plus some others.
"""
  rnn = {}
  rnn['N'] = N
  rnn['W'] = rng.randn(N,N)/np.sqrt(N)
  rnn['Bin'] = rng.randn(N)/np.sqrt(1.0)
  rnn['Bin2'] = rng.randn(N)/np.sqrt(1.0)
  rnn['b'] = np.zeros(N)
  rnn['g'] = g
  rnn['tau'] = tau
  rnn['dt'] = dt
  rnn['max_firing_rate'] = max_firing_rate
  mfr = rnn['max_firing_rate']                   # spikes / sec
  nbins_per_sec = 1.0/rnn['dt']                  # bins / sec
  # Used for plotting in LFADS
  rnn['conversion_factor'] = mfr / nbins_per_sec # spikes / bin
  return rnn


def generate_data(rnn, T, E, x0s=None, P_sxn=None, input_magnitude=0.0,
                  input_times=None):
  """ Generates data from an randomly initialized RNN.
  Args:
    rnn: the rnn
    T: Time in seconds to run (divided by rnn['dt'] to get steps, rounded down.
    E: total number of examples
    S: number of samples (subsampling N)
  Returns:
    A list of length E of NxT tensors of the network being run.
  """
  N = rnn['N']
  def run_rnn(rnn, x0, ntime_steps, input_time=None):
    rs = np.zeros([N,ntime_steps])
    x_tm1 = x0
    r_tm1 = np.tanh(x0)
    tau = rnn['tau']
    dt = rnn['dt']
    alpha = (1.0-dt/tau)
    W = dt/tau*rnn['W']*rnn['g']
    Bin = dt/tau*rnn['Bin']
    Bin2 = dt/tau*rnn['Bin2']
    b = dt/tau*rnn['b']

    us = np.zeros([1, ntime_steps])
    for t in range(ntime_steps):
      x_t = alpha*x_tm1 + np.dot(W,r_tm1) + b
      if input_time is not None and t == input_time:
        us[0,t] = input_magnitude
        x_t += Bin * us[0,t] # DCS is this what was used?
      r_t = np.tanh(x_t)
      x_tm1 = x_t
      r_tm1 = r_t
      rs[:,t] = r_t
    return rs, us

  if P_sxn is None:
    P_sxn = np.eye(N)
  ntime_steps = int(T / rnn['dt'])
  data_e = []
  inputs_e = []
  for e in range(E):
    input_time = input_times[e] if input_times is not None else None
    r_nxt, u_uxt = run_rnn(rnn, x0s[:,e], ntime_steps, input_time)
    r_sxt = np.dot(P_sxn, r_nxt)
    inputs_e.append(u_uxt)
    data_e.append(r_sxt)

  S = P_sxn.shape[0]
  data_e = normalize_rates(data_e, E, S)

  return data_e, x0s, inputs_e


def normalize_rates(data_e, E, S):
  # Normalization, made more complex because of the P matrices.
  # Normalize by min and max in each channel.  This normalization will
  # cause offset differences between identical rnn runs, but different
  # t hits.
  for e in range(E):
    r_sxt = data_e[e]
    for i in range(S):
      rmin = np.min(r_sxt[i,:])
      rmax = np.max(r_sxt[i,:])
      assert rmax - rmin != 0, 'Something wrong'
      r_sxt[i,:] = (r_sxt[i,:] - rmin)/(rmax-rmin)
    data_e[e] = r_sxt
  return data_e


def spikify_data(data_e, rng, dt=1.0, max_firing_rate=100):
  """ Apply spikes to a continuous dataset whose values are between 0.0 and 1.0
  Args:
    data_e: nexamples length list of NxT trials
    dt: how often the data are sampled
    max_firing_rate: the firing rate that is associated with a value of 1.0
  Returns:
    spikified_data_e: a list of length b of the data represented as spikes,
    sampled from the underlying poisson process.
    """

  spikifies_data_e = []
  E = len(data_e)
  spikes_e = []
  for e in range(E):
    data = data_e[e]
    N,T = data.shape
    data_s = np.zeros([N,T]).astype(np.int)
    for n in range(N):
      f = data[n,:]
      s = rng.poisson(f*max_firing_rate*dt, size=T)
      data_s[n,:] = s
    spikes_e.append(data_s)

  return spikes_e


def get_train_n_valid_inds(num_trials, train_fraction, nspikifications):
  """Split the numbers between 0 and num_trials-1 into two portions for
  training and validation, based on the train fraction.
  Args:
    num_trials: the number of trials
    train_fraction: (e.g. .80)
    nspikifications: the number of spiking trials per initial condition
  Returns:
    a 2-tuple of two lists: the training indices and validation indices
    """
  train_inds = []
  valid_inds = []
  for i in range(num_trials):
    # This line divides up the trials so that within one initial condition,
    # the randomness of spikifying the condition is shared among both
    # training and validation data splits.
    if (i % nspikifications)+1 > train_fraction * nspikifications:
      valid_inds.append(i)
    else:
      train_inds.append(i)

  return train_inds, valid_inds


def split_list_by_inds(data, inds1, inds2):
  """Take the data, a list, and split it up based on the indices in inds1 and
  inds2.
  Args:
    data: the list of data to split
    inds1, the first list of indices
    inds2, the second list of indices
  Returns: a 2-tuple of two lists.
  """
  if data is None or len(data) == 0:
    return [], []
  else:
    dout1 = [data[i] for i in inds1]
    dout2 = [data[i] for i in inds2]
    return dout1, dout2


def nparray_and_transpose(data_a_b_c):
  """Convert the list of items in data to a numpy array, and transpose it
  Args:
    data: data_asbsc: a nested, nested list of length a, with sublist length
      b, with sublist length c.
  Returns:
    a numpy 3-tensor with dimensions a x c x b
"""
  data_axbxc = np.array([datum_b_c for datum_b_c in data_a_b_c])
  data_axcxb = np.transpose(data_axbxc, axes=[0,2,1])
  return data_axcxb


def add_alignment_projections(datasets, npcs, ntime=None, nsamples=None):
  """Create a matrix that aligns the datasets a bit, under
  the assumption that each dataset is observing the same underlying dynamical
  system.

  Args:
    datasets: The dictionary of dataset structures.
    npcs:  The number of pcs for each, basically like lfads factors.
    nsamples (optional): Number of samples to take for each dataset.
    ntime (optional): Number of time steps to take in each sample.

  Returns:
    The dataset structures, with the field alignment_matrix_cxf added.
    This is # channels x npcs dimension
"""
  nchannels_all = 0
  channel_idxs = {}
  conditions_all = {}
  nconditions_all = 0
  for name, dataset in datasets.items():
    cidxs = np.where(dataset['P_sxn'])[1] # non-zero entries in columns
    channel_idxs[name] = [cidxs[0], cidxs[-1]+1]
    nchannels_all += cidxs[-1]+1 - cidxs[0]
    conditions_all[name] = np.unique(dataset['condition_labels_train'])

  all_conditions_list = \
      np.unique(np.ndarray.flatten(np.array(conditions_all.values())))
  nconditions_all = all_conditions_list.shape[0]

  if ntime is None:
    ntime = dataset['train_data'].shape[1]
  if nsamples is None:
    nsamples = dataset['train_data'].shape[0]

  # In the data workup in the paper, Chethan did intra condition
  # averaging, so let's do that here.
  avg_data_all = {}
  for name, conditions in conditions_all.items():
    dataset = datasets[name]
    avg_data_all[name] = {}
    for cname in conditions:
      td_idxs = np.argwhere(np.array(dataset['condition_labels_train'])==cname)
      data = np.squeeze(dataset['train_data'][td_idxs,:,:], axis=1)
      avg_data = np.mean(data, axis=0)
      avg_data_all[name][cname] = avg_data

  # Visualize this in the morning.
  all_data_nxtc = np.zeros([nchannels_all, ntime * nconditions_all])
  for name, dataset in datasets.items():
    cidx_s = channel_idxs[name][0]
    cidx_f = channel_idxs[name][1]
    for cname in conditions_all[name]:
      cidxs = np.argwhere(all_conditions_list == cname)
      if cidxs.shape[0] > 0:
        cidx = cidxs[0][0]
        all_tidxs = np.arange(0, ntime+1) + cidx*ntime
        all_data_nxtc[cidx_s:cidx_f, all_tidxs[0]:all_tidxs[-1]] = \
            avg_data_all[name][cname].T

  # A bit of filtering. We don't care about spectral properties, or
  # filtering artifacts, simply correlate time steps a bit.
  filt_len = 6
  bc_filt = np.ones([filt_len])/float(filt_len)
  for c in range(nchannels_all):
    all_data_nxtc[c,:] = scipy.signal.filtfilt(bc_filt, [1.0], all_data_nxtc[c,:])

  # Compute the PCs.
  all_data_mean_nx1 = np.mean(all_data_nxtc, axis=1, keepdims=True)
  all_data_zm_nxtc = all_data_nxtc - all_data_mean_nx1
  corr_mat_nxn = np.dot(all_data_zm_nxtc, all_data_zm_nxtc.T)
  evals_n, evecs_nxn = np.linalg.eigh(corr_mat_nxn)
  sidxs = np.flipud(np.argsort(evals_n)) # sort such that 0th is highest
  evals_n = evals_n[sidxs]
  evecs_nxn = evecs_nxn[:,sidxs]

  # Project all the channels data onto the low-D PCA basis, where
  # low-d is the npcs parameter.
  all_data_pca_pxtc = np.dot(evecs_nxn[:, 0:npcs].T, all_data_zm_nxtc)

  # Now for each dataset, we regress the channel data onto the top
  # pcs, and this will be our alignment matrix for that dataset.
  # |B - A*W|^2
  for name, dataset in datasets.items():
    cidx_s = channel_idxs[name][0]
    cidx_f = channel_idxs[name][1]
    all_data_zm_chxtc = all_data_zm_nxtc[cidx_s:cidx_f,:] # ch for channel
    W_chxp, _, _, _ = \
        np.linalg.lstsq(all_data_zm_chxtc.T, all_data_pca_pxtc.T)
    dataset['alignment_matrix_cxf'] = W_chxp

  do_debug_plot = False
  if do_debug_plot:
    pc_vecs = evecs_nxn[:,0:npcs]
    ntoplot = 400

    plt.figure()
    plt.plot(np.log10(evals_n), '-x')
    plt.figure()
    plt.subplot(311)
    plt.imshow(all_data_pca_pxtc)
    plt.colorbar()

    plt.subplot(312)
    plt.imshow(np.dot(W_chxp.T, all_data_zm_chxtc))
    plt.colorbar()

    plt.subplot(313)
    plt.imshow(np.dot(all_data_zm_chxtc.T, W_chxp).T - all_data_pca_pxtc)
    plt.colorbar()

    import pdb
    pdb.set_trace()

  return datasets
