# This code is part of Qiskit.
#
# (C) Copyright IBM 2018, 2020.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""
iris dataset
"""

import numpy as np
from sklearn import datasets
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler, MinMaxScaler
from sklearn.decomposition import PCA
from qiskit.aqua import MissingOptionalLibraryError


def iris(training_size, test_size, n, plot_data=False):
    """ returns iris dataset """
    class_labels = [r'A', r'B', r'C']
    data, target = datasets.load_iris(return_X_y=True)
    sample_train, sample_test, label_train, label_test = \
        train_test_split(data, target, test_size=1, random_state=42)

    # Now we standardize for gaussian around 0 with unit variance
    std_scale = StandardScaler().fit(sample_train)
    sample_train = std_scale.transform(sample_train)
    sample_test = std_scale.transform(sample_test)

    # Now reduce number of features to number of qubits
    pca = PCA(n_components=n).fit(sample_train)
    sample_train = pca.transform(sample_train)
    sample_test = pca.transform(sample_test)

    # Scale to the range (-1,+1)
    samples = np.append(sample_train, sample_test, axis=0)
    minmax_scale = MinMaxScaler((-1, 1)).fit(samples)
    sample_train = minmax_scale.transform(sample_train)
    sample_test = minmax_scale.transform(sample_test)

    # Pick training size number of samples from each distro
    training_input = {key: (sample_train[label_train == k, :])[:training_size]
                      for k, key in enumerate(class_labels)}
    test_input = {key: (sample_test[label_test == k, :])[:test_size]
                  for k, key in enumerate(class_labels)}

    if plot_data:
        try:
            import matplotlib.pyplot as plt
        except ImportError as ex:
            raise MissingOptionalLibraryError(
                libname='Matplotlib',
                name='iris',
                pip_install='pip install matplotlib') from ex
        for k in range(0, 3):
            plt.scatter(sample_train[label_train == k, 0][:training_size],
                        sample_train[label_train == k, 1][:training_size])

        plt.title("Iris dataset")
        plt.show()

    return sample_train, training_input, test_input, class_labels
