import numpy as np
import scipy.sparse as sp
from itertools import product
import pytest

from scipy.sparse import issparse
from scipy.sparse import csc_matrix
from scipy.sparse import csr_matrix
from scipy.sparse import coo_matrix
from scipy.sparse import dok_matrix
from scipy.sparse import lil_matrix

from sklearn.utils._testing import assert_array_equal
from sklearn.utils._testing import assert_array_almost_equal
from sklearn.utils._testing import assert_allclose
from sklearn.utils.estimator_checks import _NotAnArray
from sklearn.utils.fixes import parse_version

from sklearn.utils.multiclass import unique_labels
from sklearn.utils.multiclass import is_multilabel
from sklearn.utils.multiclass import type_of_target
from sklearn.utils.multiclass import class_distribution
from sklearn.utils.multiclass import check_classification_targets
from sklearn.utils.multiclass import _ovr_decision_function

from sklearn.utils.metaestimators import _safe_split
from sklearn.model_selection import ShuffleSplit
from sklearn.svm import SVC
from sklearn import datasets


EXAMPLES = {
    'multilabel-indicator': [
        # valid when the data is formatted as sparse or dense, identified
        # by CSR format when the testing takes place
        csr_matrix(np.random.RandomState(42).randint(2, size=(10, 10))),
        [[0, 1], [1, 0]],
        [[0, 1]],
        csr_matrix(np.array([[0, 1], [1, 0]])),
        csr_matrix(np.array([[0, 1], [1, 0]], dtype=np.bool)),
        csr_matrix(np.array([[0, 1], [1, 0]], dtype=np.int8)),
        csr_matrix(np.array([[0, 1], [1, 0]], dtype=np.uint8)),
        csr_matrix(np.array([[0, 1], [1, 0]], dtype=np.float)),
        csr_matrix(np.array([[0, 1], [1, 0]], dtype=np.float32)),
        csr_matrix(np.array([[0, 0], [0, 0]])),
        csr_matrix(np.array([[0, 1]])),
        # Only valid when data is dense
        [[-1, 1], [1, -1]],
        np.array([[-1, 1], [1, -1]]),
        np.array([[-3, 3], [3, -3]]),
        _NotAnArray(np.array([[-3, 3], [3, -3]])),
    ],
    'multiclass': [
        [1, 0, 2, 2, 1, 4, 2, 4, 4, 4],
        np.array([1, 0, 2]),
        np.array([1, 0, 2], dtype=np.int8),
        np.array([1, 0, 2], dtype=np.uint8),
        np.array([1, 0, 2], dtype=np.float),
        np.array([1, 0, 2], dtype=np.float32),
        np.array([[1], [0], [2]]),
        _NotAnArray(np.array([1, 0, 2])),
        [0, 1, 2],
        ['a', 'b', 'c'],
        np.array(['a', 'b', 'c']),
        np.array(['a', 'b', 'c'], dtype=object),
        np.array(['a', 'b', 'c'], dtype=object),
    ],
    'multiclass-multioutput': [
        [[1, 0, 2, 2], [1, 4, 2, 4]],
        [['a', 'b'], ['c', 'd']],
        np.array([[1, 0, 2, 2], [1, 4, 2, 4]]),
        np.array([[1, 0, 2, 2], [1, 4, 2, 4]], dtype=np.int8),
        np.array([[1, 0, 2, 2], [1, 4, 2, 4]], dtype=np.uint8),
        np.array([[1, 0, 2, 2], [1, 4, 2, 4]], dtype=np.float),
        np.array([[1, 0, 2, 2], [1, 4, 2, 4]], dtype=np.float32),
        np.array([['a', 'b'], ['c', 'd']]),
        np.array([['a', 'b'], ['c', 'd']]),
        np.array([['a', 'b'], ['c', 'd']], dtype=object),
        np.array([[1, 0, 2]]),
        _NotAnArray(np.array([[1, 0, 2]])),
    ],
    'binary': [
        [0, 1],
        [1, 1],
        [],
        [0],
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1]),
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1], dtype=np.bool),
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1], dtype=np.int8),
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1], dtype=np.uint8),
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1], dtype=np.float),
        np.array([0, 1, 1, 1, 0, 0, 0, 1, 1, 1], dtype=np.float32),
        np.array([[0], [1]]),
        _NotAnArray(np.array([[0], [1]])),
        [1, -1],
        [3, 5],
        ['a'],
        ['a', 'b'],
        ['abc', 'def'],
        np.array(['abc', 'def']),
        ['a', 'b'],
        np.array(['abc', 'def'], dtype=object),
    ],
    'continuous': [
        [1e-5],
        [0, .5],
        np.array([[0], [.5]]),
        np.array([[0], [.5]], dtype=np.float32),
    ],
    'continuous-multioutput': [
        np.array([[0, .5], [.5, 0]]),
        np.array([[0, .5], [.5, 0]], dtype=np.float32),
        np.array([[0, .5]]),
    ],
    'unknown': [
        [[]],
        [()],
        # sequence of sequences that weren't supported even before deprecation
        np.array([np.array([]), np.array([1, 2, 3])], dtype=object),
        [np.array([]), np.array([1, 2, 3])],
        [{1, 2, 3}, {1, 2}],
        [frozenset([1, 2, 3]), frozenset([1, 2])],

        # and also confusable as sequences of sequences
        [{0: 'a', 1: 'b'}, {0: 'a'}],

        # empty second dimension
        np.array([[], []]),

        # 3d
        np.array([[[0, 1], [2, 3]], [[4, 5], [6, 7]]]),
    ]
}

NON_ARRAY_LIKE_EXAMPLES = [
    {1, 2, 3},
    {0: 'a', 1: 'b'},
    {0: [5], 1: [5]},
    'abc',
    frozenset([1, 2, 3]),
    None,
]

MULTILABEL_SEQUENCES = [
    [[1], [2], [0, 1]],
    [(), (2), (0, 1)],
    np.array([[], [1, 2]], dtype='object'),
    _NotAnArray(np.array([[], [1, 2]], dtype='object'))
]


def test_unique_labels():
    # Empty iterable
    with pytest.raises(ValueError):
        unique_labels()

    # Multiclass problem
    assert_array_equal(unique_labels(range(10)), np.arange(10))
    assert_array_equal(unique_labels(np.arange(10)), np.arange(10))
    assert_array_equal(unique_labels([4, 0, 2]), np.array([0, 2, 4]))

    # Multilabel indicator
    assert_array_equal(unique_labels(np.array([[0, 0, 1],
                                               [1, 0, 1],
                                               [0, 0, 0]])),
                       np.arange(3))

    assert_array_equal(unique_labels(np.array([[0, 0, 1],
                                               [0, 0, 0]])),
                       np.arange(3))

    # Several arrays passed
    assert_array_equal(unique_labels([4, 0, 2], range(5)),
                       np.arange(5))
    assert_array_equal(unique_labels((0, 1, 2), (0,), (2, 1)),
                       np.arange(3))

    # Border line case with binary indicator matrix
    with pytest.raises(ValueError):
        unique_labels([4, 0, 2], np.ones((5, 5)))
    with pytest.raises(ValueError):
        unique_labels(np.ones((5, 4)), np.ones((5, 5)))

    assert_array_equal(unique_labels(np.ones((4, 5)), np.ones((5, 5))),
                       np.arange(5))


def test_unique_labels_non_specific():
    # Test unique_labels with a variety of collected examples

    # Smoke test for all supported format
    for format in ["binary", "multiclass", "multilabel-indicator"]:
        for y in EXAMPLES[format]:
            unique_labels(y)

    # We don't support those format at the moment
    for example in NON_ARRAY_LIKE_EXAMPLES:
        with pytest.raises(ValueError):
            unique_labels(example)

    for y_type in ["unknown", "continuous", 'continuous-multioutput',
                   'multiclass-multioutput']:
        for example in EXAMPLES[y_type]:
            with pytest.raises(ValueError):
                unique_labels(example)


def test_unique_labels_mixed_types():
    # Mix with binary or multiclass and multilabel
    mix_clf_format = product(EXAMPLES["multilabel-indicator"],
                             EXAMPLES["multiclass"] +
                             EXAMPLES["binary"])

    for y_multilabel, y_multiclass in mix_clf_format:
        with pytest.raises(ValueError):
            unique_labels(y_multiclass, y_multilabel)
        with pytest.raises(ValueError):
            unique_labels(y_multilabel, y_multiclass)

    with pytest.raises(ValueError):
        unique_labels([[1, 2]], [["a", "d"]])

    with pytest.raises(ValueError):
        unique_labels(["1", 2])

    with pytest.raises(ValueError):
        unique_labels([["1", 2], [1, 3]])

    with pytest.raises(ValueError):
        unique_labels([["1", "2"], [2, 3]])


def test_is_multilabel():
    for group, group_examples in EXAMPLES.items():
        if group in ['multilabel-indicator']:
            dense_exp = True
        else:
            dense_exp = False

        for example in group_examples:
            # Only mark explicitly defined sparse examples as valid sparse
            # multilabel-indicators
            if group == 'multilabel-indicator' and issparse(example):
                sparse_exp = True
            else:
                sparse_exp = False

            if (issparse(example) or
                (hasattr(example, '__array__') and
                 np.asarray(example).ndim == 2 and
                 np.asarray(example).dtype.kind in 'biuf' and
                 np.asarray(example).shape[1] > 0)):
                examples_sparse = [sparse_matrix(example)
                                   for sparse_matrix in [coo_matrix,
                                                         csc_matrix,
                                                         csr_matrix,
                                                         dok_matrix,
                                                         lil_matrix]]
                for exmpl_sparse in examples_sparse:
                    assert sparse_exp == is_multilabel(exmpl_sparse), (
                            'is_multilabel(%r) should be %s'
                            % (exmpl_sparse, sparse_exp))

            # Densify sparse examples before testing
            if issparse(example):
                example = example.toarray()

            assert dense_exp == is_multilabel(example), (
                    'is_multilabel(%r) should be %s'
                    % (example, dense_exp))


def test_check_classification_targets():
    for y_type in EXAMPLES.keys():
        if y_type in ["unknown", "continuous", 'continuous-multioutput']:
            for example in EXAMPLES[y_type]:
                msg = 'Unknown label type: '
                with pytest.raises(ValueError, match=msg):
                    check_classification_targets(example)
        else:
            for example in EXAMPLES[y_type]:
                check_classification_targets(example)


# @ignore_warnings
def test_type_of_target():
    for group, group_examples in EXAMPLES.items():
        for example in group_examples:
            assert type_of_target(example) == group, (
                'type_of_target(%r) should be %r, got %r'
                % (example, group, type_of_target(example)))

    for example in NON_ARRAY_LIKE_EXAMPLES:
        msg_regex = r'Expected array-like \(array or non-string sequence\).*'
        with pytest.raises(ValueError, match=msg_regex):
            type_of_target(example)

    for example in MULTILABEL_SEQUENCES:
        msg = ('You appear to be using a legacy multi-label data '
               'representation. Sequence of sequences are no longer supported;'
               ' use a binary array or sparse matrix instead.')
        with pytest.raises(ValueError, match=msg):
            type_of_target(example)


def test_type_of_target_pandas_sparse():
    pd = pytest.importorskip("pandas")

    if parse_version(pd.__version__) >= parse_version('0.25'):
        pd_sparse_array = pd.arrays.SparseArray
    else:
        pd_sparse_array = pd.SparseArray

    y = pd_sparse_array([1, np.nan, np.nan, 1, np.nan])
    msg = "y cannot be class 'SparseSeries' or 'SparseArray'"
    with pytest.raises(ValueError, match=msg):
        type_of_target(y)


def test_class_distribution():
    y = np.array([[1, 0, 0, 1],
                  [2, 2, 0, 1],
                  [1, 3, 0, 1],
                  [4, 2, 0, 1],
                  [2, 0, 0, 1],
                  [1, 3, 0, 1]])
    # Define the sparse matrix with a mix of implicit and explicit zeros
    data = np.array([1, 2, 1, 4, 2, 1, 0, 2, 3, 2, 3, 1, 1, 1, 1, 1, 1])
    indices = np.array([0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 5, 0, 1, 2, 3, 4, 5])
    indptr = np.array([0, 6, 11, 11, 17])
    y_sp = sp.csc_matrix((data, indices, indptr), shape=(6, 4))

    classes, n_classes, class_prior = class_distribution(y)
    classes_sp, n_classes_sp, class_prior_sp = class_distribution(y_sp)
    classes_expected = [[1, 2, 4],
                        [0, 2, 3],
                        [0],
                        [1]]
    n_classes_expected = [3, 3, 1, 1]
    class_prior_expected = [[3/6, 2/6, 1/6],
                            [1/3, 1/3, 1/3],
                            [1.0],
                            [1.0]]

    for k in range(y.shape[1]):
        assert_array_almost_equal(classes[k], classes_expected[k])
        assert_array_almost_equal(n_classes[k], n_classes_expected[k])
        assert_array_almost_equal(class_prior[k], class_prior_expected[k])

        assert_array_almost_equal(classes_sp[k], classes_expected[k])
        assert_array_almost_equal(n_classes_sp[k], n_classes_expected[k])
        assert_array_almost_equal(class_prior_sp[k], class_prior_expected[k])

    # Test again with explicit sample weights
    (classes,
     n_classes,
     class_prior) = class_distribution(y, [1.0, 2.0, 1.0, 2.0, 1.0, 2.0])
    (classes_sp,
     n_classes_sp,
     class_prior_sp) = class_distribution(y, [1.0, 2.0, 1.0, 2.0, 1.0, 2.0])
    class_prior_expected = [[4/9, 3/9, 2/9],
                            [2/9, 4/9, 3/9],
                            [1.0],
                            [1.0]]

    for k in range(y.shape[1]):
        assert_array_almost_equal(classes[k], classes_expected[k])
        assert_array_almost_equal(n_classes[k], n_classes_expected[k])
        assert_array_almost_equal(class_prior[k], class_prior_expected[k])

        assert_array_almost_equal(classes_sp[k], classes_expected[k])
        assert_array_almost_equal(n_classes_sp[k], n_classes_expected[k])
        assert_array_almost_equal(class_prior_sp[k], class_prior_expected[k])


def test_safe_split_with_precomputed_kernel():
    clf = SVC()
    clfp = SVC(kernel="precomputed")

    iris = datasets.load_iris()
    X, y = iris.data, iris.target
    K = np.dot(X, X.T)

    cv = ShuffleSplit(test_size=0.25, random_state=0)
    train, test = list(cv.split(X))[0]

    X_train, y_train = _safe_split(clf, X, y, train)
    K_train, y_train2 = _safe_split(clfp, K, y, train)
    assert_array_almost_equal(K_train, np.dot(X_train, X_train.T))
    assert_array_almost_equal(y_train, y_train2)

    X_test, y_test = _safe_split(clf, X, y, test, train)
    K_test, y_test2 = _safe_split(clfp, K, y, test, train)
    assert_array_almost_equal(K_test, np.dot(X_test, X_train.T))
    assert_array_almost_equal(y_test, y_test2)


def test_ovr_decision_function():
    # test properties for ovr decision function

    predictions = np.array([[0, 1, 1],
                            [0, 1, 0],
                            [0, 1, 1],
                            [0, 1, 1]])

    confidences = np.array([[-1e16, 0, -1e16],
                            [1., 2., -3.],
                            [-5., 2., 5.],
                            [-0.5, 0.2, 0.5]])

    n_classes = 3

    dec_values = _ovr_decision_function(predictions, confidences, n_classes)

    # check that the decision values are within 0.5 range of the votes
    votes = np.array([[1, 0, 2],
                      [1, 1, 1],
                      [1, 0, 2],
                      [1, 0, 2]])

    assert_allclose(votes, dec_values, atol=0.5)

    # check that the prediction are what we expect
    # highest vote or highest confidence if there is a tie.
    # for the second sample we have a tie (should be won by 1)
    expected_prediction = np.array([2, 1, 2, 2])
    assert_array_equal(np.argmax(dec_values, axis=1), expected_prediction)

    # third and fourth sample have the same vote but third sample
    # has higher confidence, this should reflect on the decision values
    assert (dec_values[2, 2] > dec_values[3, 2])

    # assert subset invariance.
    dec_values_one = [_ovr_decision_function(np.array([predictions[i]]),
                                             np.array([confidences[i]]),
                                             n_classes)[0] for i in range(4)]

    assert_allclose(dec_values, dec_values_one, atol=1e-6)