import os.path as op
import numpy as np
import matplotlib.pyplot as plt

import mne
from mne.forward import make_forward_dipole
from mne.evoked import combine_evoked
from mne.simulation import simulate_evoked

from nilearn.plotting import plot_anat
from nilearn.datasets import load_mni152_template

data_path = mne.datasets.sample.data_path()
subjects_dir = op.join(data_path, 'subjects')
fname_ave = op.join(data_path, 'MEG', 'sample', 'sample_audvis-ave.fif')
fname_cov = op.join(data_path, 'MEG', 'sample', 'sample_audvis-cov.fif')
fname_bem = op.join(subjects_dir, 'sample', 'bem', 'sample-5120-bem-sol.fif')
fname_trans = op.join(data_path, 'MEG', 'sample',
                      'sample_audvis_raw-trans.fif')
fname_surf_lh = op.join(subjects_dir, 'sample', 'surf', 'lh.white')

"""
Explanation: Source localization with equivalent current dipole (ECD) fit
This shows how to fit a dipole :footcite:Sarvas1987 using mne-python.
For a comparison of fits between MNE-C and MNE-Python, see
this gist_.
End of explanation
"""


evoked = mne.read_evokeds(fname_ave, condition='Right Auditory',
                          baseline=(None, 0))
evoked.pick_types(meg=True, eeg=False)
evoked_full = evoked.copy()
evoked.crop(0.07, 0.08)

# Fit a dipole
dip = mne.fit_dipole(evoked, fname_cov, fname_bem, fname_trans)[0]

# Plot the result in 3D brain with the MRI image.
dip.plot_locations(fname_trans, 'sample', subjects_dir, mode='orthoview')

"""
Explanation: Let's localize the N100m (using MEG only)
End of explanation
"""


subject = 'sample'
mni_pos = dip.to_mni(subject=subject, trans=fname_trans,
                     subjects_dir=subjects_dir)

mri_pos = dip.to_mri(subject=subject, trans=fname_trans,
                     subjects_dir=subjects_dir)

# Find an anatomical label for the best fitted dipole
best_dip_idx = dip.gof.argmax()
label = dip.to_volume_labels(fname_trans, subject=subject,
                             subjects_dir=subjects_dir,
                             aseg='aparc.a2009s+aseg')[best_dip_idx]

# Draw dipole position on MRI scan and add anatomical label from parcellation
t1_fname = op.join(subjects_dir, subject, 'mri', 'T1.mgz')
fig_T1 = plot_anat(t1_fname, cut_coords=mri_pos[0],
                   title=f'Dipole location: {label}')

try:
    template = load_mni152_template(resolution=1)
except TypeError:  # in nilearn < 0.8.1 this did not exist
    template = load_mni152_template()
fig_template = plot_anat(template, cut_coords=mni_pos[0],
                         title='Dipole loc. (MNI Space)')

"""
Explanation: Plot the result in 3D brain with the MRI image using Nilearn
In MRI coordinates and in MNI coordinates (template brain)
End of explanation
"""


fwd, stc = make_forward_dipole(dip, fname_bem, evoked.info, fname_trans)
pred_evoked = simulate_evoked(fwd, stc, evoked.info, cov=None, nave=np.inf)

# find time point with highest GOF to plot
best_idx = np.argmax(dip.gof)
best_time = dip.times[best_idx]
print('Highest GOF %0.1f%% at t=%0.1f ms with confidence volume %0.1f cm^3'
      % (dip.gof[best_idx], best_time * 1000,
         dip.conf['vol'][best_idx] * 100 ** 3))
# remember to create a subplot for the colorbar
fig, axes = plt.subplots(nrows=1, ncols=4, figsize=[10., 3.4],
                         gridspec_kw=dict(width_ratios=[1, 1, 1, 0.1],
                                          top=0.85))
vmin, vmax = -400, 400  # make sure each plot has same colour range

# first plot the topography at the time of the best fitting (single) dipole
plot_params = dict(times=best_time, ch_type='mag', outlines='skirt',
                   colorbar=False, time_unit='s')
evoked.plot_topomap(time_format='Measured field', axes=axes[0], **plot_params)

# compare this to the predicted field
pred_evoked.plot_topomap(time_format='Predicted field', axes=axes[1],
                         **plot_params)

# Subtract predicted from measured data (apply equal weights)
diff = combine_evoked([evoked, pred_evoked], weights=[1, -1])
plot_params['colorbar'] = True
diff.plot_topomap(time_format='Difference', axes=axes[2:], **plot_params)
fig.suptitle('Comparison of measured and predicted fields '
             'at {:.0f} ms'.format(best_time * 1000.), fontsize=16)
fig.tight_layout()

"""
Explanation: Calculate and visualise magnetic field predicted by dipole with maximum GOF
and compare to the measured data, highlighting the ipsilateral (right) source
End of explanation
"""


dip_fixed = mne.fit_dipole(evoked_full, fname_cov, fname_bem, fname_trans,
                           pos=dip.pos[best_idx], ori=dip.ori[best_idx])[0]
dip_fixed.plot(time_unit='s')

"""
Explanation: Estimate the time course of a single dipole with fixed position and
orientation (the one that maximized GOF) over the entire interval
End of explanation
"""


