import math
import mne
import numpy as np
import matplotlib.pyplot as plt

from mne.decoding import SlidingEstimator, cross_val_multiscore, Vectorizer, Scaler
from mne.time_frequency import tfr_morlet

from sklearn.linear_model import LogisticRegression
from sklearn.pipeline import make_pipeline

from utils.file_utils import load_preprocessed_data, get_epochs
from utils.plot_utils import plot_tf_cluster, plot_oscillation_bands

VERBOSE_LEVEL = 'CRITICAL'


def events_to_labels(evts, events_dict, mask=None):  # TODO Test schreiben
    """
    Converts the event labels of epochs to class labels for classification
    :param evts: the event labels to be converted
    :param events_dict: a dictionary of event keys
    :param mask: an optional label mask with 4-entries, where:
        1. entry: 'face intact', 2. entry: 'car intact', 3. entry: 'face scrambled', 4. entry: 'face scrambled'
        If None the entries are [0,1,0,1] i.e. all faces are in class 0 and all cars are in class 1
    :return: The list of class labels
    """
    events = evts.copy()
    if mask is None:
        mask = [0, 1, 0, 1]
    for i in range(len(events)):
        key = list(events_dict.keys())[list(events_dict.values()).index(events[i])]
        k = int(key.split(':')[1])
        if k < 41:
            events[i] = mask[0]  # Face intact
        elif 40 < k < 81:
            events[i] = mask[1]  # Car intact
        elif 100 < k < 141:
            events[i] = mask[2]  # Face scrambled
        elif 140 < k < 181:
            events[i] = mask[3]  # Car scrambled

    return events


def permutation_test(baseline, score, n_iter):
    """
    An implementation of a permutation test for classification scores.

    :param baseline: The classification scores of the baseline, i.e. selection by chance
    :param score: The classification scores which are tested for significance
    :param n_iter: number of permutations
    :return: p-value
    """
    all_data = np.concatenate((baseline, score))

    # Base statistic. The statistic used here is the difference of means
    given_diff = np.mean(score) - np.mean(baseline)
    all_diffs = [given_diff]

    # Permutation iterations
    for i in range(n_iter):
        # Create a permutation of indices and then use indices from index 0 to len(baseline) to get data for baseline.
        # Analogously for scores
        perm_indices = np.random.permutation(list(range(len(all_data))))
        mean_diff = np.mean(all_data[perm_indices[len(baseline):]]) - np.mean(all_data[perm_indices[:len(baseline)]])
        all_diffs.append(mean_diff)

    p_val = len(np.where(np.asarray(all_diffs) >= given_diff)[0]) / (n_iter + 1)

    return p_val


def decoding(dataset, filename, compute_metric=True, mask=None):
    """
    Runs decoding over time for all subjects

    :param dataset: The dataset for which the decoding is done
    :param filename: filename of either the file from which the classifier scores will be loaded
        or to which they will be saved
    :param compute_metric: If True the classifier will be run, else the result will be loaded from a precomputed file
    :param mask: an optional label mask with 4-entries, where:
        1. entry: 'face intact', 2. entry: 'car intact', 3. entry: 'face scrambled', 4. entry: 'face scrambled'
        If None the entries are [0,1,0,1] i.e. all faces are in class 0 and all cars are in class 1
    """
    if mask is None:
        mask = [0, 1, 0, 1]
    times = None
    time_scale = 1100
    metric = []
    p_values = []

    if compute_metric:
        # Computes classifier scores for all subjects
        for i in range(1, 41):
            subj = "0" + str(i)
            if len(str(i)) == 1:
                subj = "0" + subj

            # Load data
            raw = load_preprocessed_data(subj, dataset)
            epochs, events_dict = get_epochs(raw, picks=mne.pick_types(raw.info, eeg=True, eog=False))
            data = epochs.get_data()
            labels = events_to_labels(epochs.events[:, 2], events_dict, mask)

            # Classify
            clf = make_pipeline(Scaler(epochs.info), Vectorizer(), LogisticRegression(solver='lbfgs'))
            time_decode = SlidingEstimator(clf)
            scores = cross_val_multiscore(time_decode, data, labels, cv=10, n_jobs=4)
            metric.append(np.mean(scores, axis=0))

            if times is None:
                times = epochs.times
        np.save('cached_data/decoding_data/' + filename, metric)
        metric = np.asarray(metric)
    else:
        # Dummy time which is created according to epoch.times
        times = np.linspace(-0.09960938, 1, 1127)
        metric = np.load('cached_data/decoding_data/' + filename + '.npy')

    # Compute index of time point 0
    index = math.floor((len(metric[0]) / time_scale) * 100)
    baseline = np.array(metric[:index]).flatten()

    # Plot the result
    plt.plot(np.linspace(-200, 1000, 1127), np.mean(metric, axis=0))
    plt.ylabel('Accuracy (%)')
    plt.xlabel('Time (ms)')
    plt.title('Mean Accuracy over Subjects for Faces vs. Cars')
    plt.show()

    # Compute the permutation tests
    for t in range(len(metric[0][index:])):
        score_t = np.asarray(metric[:, t + index])
        p = permutation_test(baseline, score_t, 1000)
        p_values.append(p)
        if t % 50 == 0:
            print(str(t) + " Out of " + str(len(metric[0][index:])))

    # Plot the result
    plt.plot(times[index:], p_values)
    plt.ylabel('P-Value')
    plt.xlabel('Time (ms)')
    plt.title('P-Values for Faces vs. Cars')
    plt.show()


def create_tfr(raw, condition, freqs, n_cycles, response='induced', baseline=None, plot=False):
    """
    Compute the time frequency representation (TFR) of data for a given condition via Morlet wavelets

    :param raw: the data
    :param condition: the condition for which to compute the TFR. Given as a list of tuples of the form (stimulus, texture)
    :param freqs: the frequencies for which to compute the TFR
    :param n_cycles: the number of cycles used by the Morlet wavelets
    :param response: type of expected TFR. Can be total, induced or evoked. Default is induced,
                    the others were not used for the report, only for exploration
    :param baseline: baseline used to correct the power. A tuple of the form (start, end).
        Default is None and no baseline correction will be applied
    :param plot: True if results should be plotted, else false.
    :return: The TFR or the given data for a given condition. Has type AverageTFR
    """
    epochs, _ = get_epochs(raw, condition, tmin=-0.2, tmax=1)
    print('    ' + str(condition))

    if response == 'total':
        print('    Power Total')
        power = tfr_morlet(epochs, freqs=freqs, n_cycles=n_cycles, return_itc=False, n_jobs=4)
    elif response == 'induced':
        print('    Power Induced')
        power = tfr_morlet(epochs.subtract_evoked(), freqs=freqs, n_cycles=n_cycles, return_itc=False, n_jobs=4)
    else:
        print('    Power Evoked')
        power_total = tfr_morlet(epochs, freqs=freqs, n_cycles=n_cycles, return_itc=False, n_jobs=4)
        power_induced = tfr_morlet(epochs.subtract_evoked(), freqs=freqs, n_cycles=n_cycles, return_itc=False, n_jobs=4)
        power = mne.combine_evoked([power_total, power_induced], weights=[1, -1])
    if plot: power.plot(picks='P7')
    # Apply a baseline correction to the power data
    power.apply_baseline(mode='ratio', baseline=baseline)
    if plot:
        plot_oscillation_bands(power)
        power.plot(picks='P7')
    return power


def time_frequency(dataset, filename, scaling='lin', compute_tfr=True):
    """
    Runs time frequency analysis

    :param dataset: The dataset for which the decoding is done
    :param filename: Filename of either the file from which the TFRs will be loaded
        or to which they will be saved
    :param compute_tfr: If True the TFRs will be created, else the TFRs will be loaded from a precomputed file
    :param scaling: default 'lin' for linear scaling, else can be 'log' for logarithmic scaling
    """
    # Parameters
    if scaling == 'lin':
        freqs = np.linspace(0.1, 50, num=50)  # Use this for linear space scaling
    else:
        freqs = np.logspace(*np.log10([0.1, 50]), num=50)
    n_cycles = freqs / 2
    cond1 = []
    cond2 = []
    times = None

    if compute_tfr:
        for i in range(1, 41):
            subj = "0" + str(i)
            if len(str(i)) == 1:
                subj = "0" + subj
            print("########## SUBJECT " + subj + " ##########")

            # Load data
            raw = load_preprocessed_data(subj, dataset)
            raw.set_channel_types({'HEOG_left': 'eog', 'HEOG_right': 'eog', 'VEOG_lower': 'eog'})
            raw.set_montage('standard_1020', match_case=False)

            # Create the two conditions we want to compare
            # IMPORTANT: If different conditions should be compared you have to change them here, by altering the second
            # argument passed to create_tfr
            power_cond1 = create_tfr(raw, [('face', 'intact')], freqs, n_cycles, 'induced', (-0.2, 0))
            print('    CONDITION 1 LOADED')
            cond1.append(power_cond1)

            power_cond2 = create_tfr(raw, [('face', 'scrambled'), ('car', None)], freqs, n_cycles, 'induced',
                                     (-0.2, 0))
            print('    CONDITION 2 LOADED')
            cond2.append(power_cond2)
            print('    DONE')

        # Save the data so we can access the results more easily
        np.save('cached_data/tf_data/' + filename + '_cond1', cond1)
        np.save('cached_data/tf_data/' + filename + '_cond2', cond2)
    else:
        # If the data should not be recomputed, load the given filename
        cond1 = np.load('cached_data/tf_data/' + filename + '_cond1.npy', allow_pickle=True).tolist()
        cond2 = np.load('cached_data/tf_data/' + filename + '_cond2.npy', allow_pickle=True).tolist()
    if times is None:
        times = cond1[0].times

    # Some plots
    mne.grand_average(cond1).plot(picks=['P7'], vmin=-3, vmax=3, title='Grand Average P7')
    mne.grand_average(cond2).plot(picks=['P7'], vmin=-3, vmax=3, title='Grand Average P7')
    plot_oscillation_bands(mne.grand_average(cond1))
    plot_oscillation_bands(mne.grand_average(cond2))

    # Compute the cluster permutation
    F, clusters, cluster_p_values, h0 = mne.stats.permutation_cluster_test(
        [mne.grand_average(cond1).data, mne.grand_average(cond2).data], n_jobs=4, verbose='INFO',
        seed=123)
    plot_tf_cluster(F, clusters, cluster_p_values, freqs, times, scaling)


if __name__ == '__main__':
    mne.set_log_level(verbose=VERBOSE_LEVEL)
    ds = 'N170'
    decoding(ds, 'faces_vs_cars', True)
    time_frequency(ds, 'face_intact_vs_all_0.1_50hz_ncf2', 'log', True)