from itertools import chain, product
import warnings

import numpy as np
import scipy.sparse as sp
from scipy.linalg import pinv2
from scipy.sparse.csgraph import laplacian

from sklearn.utils.testing import (assert_equal, assert_raises, assert_true,
                                   assert_almost_equal, assert_array_equal,
                                   SkipTest, assert_raises_regex,
                                   assert_greater_equal, ignore_warnings)
from sklearn.utils import check_random_state
from sklearn.utils import deprecated
from sklearn.utils import resample
from sklearn.utils import safe_mask
from sklearn.utils import column_or_1d
from sklearn.utils import safe_indexing
from sklearn.utils import shuffle
from sklearn.utils import gen_even_slices
from sklearn.utils.extmath import pinvh
from sklearn.utils.arpack import eigsh
from sklearn.utils.mocking import MockDataFrame


def test_make_rng():
    # Check the check_random_state utility function behavior
    assert_true(check_random_state(None) is np.random.mtrand._rand)
    assert_true(check_random_state(np.random) is np.random.mtrand._rand)

    rng_42 = np.random.RandomState(42)
    assert_true(check_random_state(42).randint(100) == rng_42.randint(100))

    rng_42 = np.random.RandomState(42)
    assert_true(check_random_state(rng_42) is rng_42)

    rng_42 = np.random.RandomState(42)
    assert_true(check_random_state(43).randint(100) != rng_42.randint(100))

    assert_raises(ValueError, check_random_state, "some invalid seed")


def test_deprecated():
    # Test whether the deprecated decorator issues appropriate warnings
    # Copied almost verbatim from http://docs.python.org/library/warnings.html

    # First a function...
    with warnings.catch_warnings(record=True) as w:
        warnings.simplefilter("always")

        @deprecated()
        def ham():
            return "spam"

        spam = ham()

        assert_equal(spam, "spam")     # function must remain usable

        assert_equal(len(w), 1)
        assert_true(issubclass(w[0].category, DeprecationWarning))
        assert_true("deprecated" in str(w[0].message).lower())

    # ... then a class.
    with warnings.catch_warnings(record=True) as w:
        warnings.simplefilter("always")

        @deprecated("don't use this")
        class Ham(object):
            SPAM = 1

        ham = Ham()

        assert_true(hasattr(ham, "SPAM"))

        assert_equal(len(w), 1)
        assert_true(issubclass(w[0].category, DeprecationWarning))
        assert_true("deprecated" in str(w[0].message).lower())


def test_resample():
    # Border case not worth mentioning in doctests
    assert_true(resample() is None)

    # Check that invalid arguments yield ValueError
    assert_raises(ValueError, resample, [0], [0, 1])
    assert_raises(ValueError, resample, [0, 1], [0, 1],
                  replace=False, n_samples=3)
    assert_raises(ValueError, resample, [0, 1], [0, 1], meaning_of_life=42)
    # Issue:6581, n_samples can be more when replace is True (default).
    assert_equal(len(resample([1, 2], n_samples=5)), 5)


def test_safe_mask():
    random_state = check_random_state(0)
    X = random_state.rand(5, 4)
    X_csr = sp.csr_matrix(X)
    mask = [False, False, True, True, True]

    mask = safe_mask(X, mask)
    assert_equal(X[mask].shape[0], 3)

    mask = safe_mask(X_csr, mask)
    assert_equal(X_csr[mask].shape[0], 3)


@ignore_warnings  # Test deprecated backport to be removed in 0.21
def test_pinvh_simple_real():
    a = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 10]], dtype=np.float64)
    a = np.dot(a, a.T)
    a_pinv = pinvh(a)
    assert_almost_equal(np.dot(a, a_pinv), np.eye(3))


@ignore_warnings  # Test deprecated backport to be removed in 0.21
def test_pinvh_nonpositive():
    a = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]], dtype=np.float64)
    a = np.dot(a, a.T)
    u, s, vt = np.linalg.svd(a)
    s[0] *= -1
    a = np.dot(u * s, vt)  # a is now symmetric non-positive and singular
    a_pinv = pinv2(a)
    a_pinvh = pinvh(a)
    assert_almost_equal(a_pinv, a_pinvh)


@ignore_warnings  # Test deprecated backport to be removed in 0.21
def test_pinvh_simple_complex():
    a = (np.array([[1, 2, 3], [4, 5, 6], [7, 8, 10]])
         + 1j * np.array([[10, 8, 7], [6, 5, 4], [3, 2, 1]]))
    a = np.dot(a, a.conj().T)
    a_pinv = pinvh(a)
    assert_almost_equal(np.dot(a, a_pinv), np.eye(3))


@ignore_warnings  # Test deprecated backport to be removed in 0.21
def test_arpack_eigsh_initialization():
    # Non-regression test that shows null-space computation is better with
    # initialization of eigsh from [-1,1] instead of [0,1]
    random_state = check_random_state(42)

    A = random_state.rand(50, 50)
    A = np.dot(A.T, A)  # create s.p.d. matrix
    A = laplacian(A) + 1e-7 * np.identity(A.shape[0])
    k = 5

    # Test if eigsh is working correctly
    # New initialization [-1,1] (as in original ARPACK)
    # Was [0,1] before, with which this test could fail
    v0 = random_state.uniform(-1, 1, A.shape[0])
    w, _ = eigsh(A, k=k, sigma=0.0, v0=v0)

    # Eigenvalues of s.p.d. matrix should be nonnegative, w[0] is smallest
    assert_greater_equal(w[0], 0)


def test_column_or_1d():
    EXAMPLES = [
        ("binary", ["spam", "egg", "spam"]),
        ("binary", [0, 1, 0, 1]),
        ("continuous", np.arange(10) / 20.),
        ("multiclass", [1, 2, 3]),
        ("multiclass", [0, 1, 2, 2, 0]),
        ("multiclass", [[1], [2], [3]]),
        ("multilabel-indicator", [[0, 1, 0], [0, 0, 1]]),
        ("multiclass-multioutput", [[1, 2, 3]]),
        ("multiclass-multioutput", [[1, 1], [2, 2], [3, 1]]),
        ("multiclass-multioutput", [[5, 1], [4, 2], [3, 1]]),
        ("multiclass-multioutput", [[1, 2, 3]]),
        ("continuous-multioutput", np.arange(30).reshape((-1, 3))),
    ]

    for y_type, y in EXAMPLES:
        if y_type in ["binary", 'multiclass', "continuous"]:
            assert_array_equal(column_or_1d(y), np.ravel(y))
        else:
            assert_raises(ValueError, column_or_1d, y)


def test_safe_indexing():
    X = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
    inds = np.array([1, 2])
    X_inds = safe_indexing(X, inds)
    X_arrays = safe_indexing(np.array(X), inds)
    assert_array_equal(np.array(X_inds), X_arrays)
    assert_array_equal(np.array(X_inds), np.array(X)[inds])


def test_safe_indexing_pandas():
    try:
        import pandas as pd
    except ImportError:
        raise SkipTest("Pandas not found")
    X = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    X_df = pd.DataFrame(X)
    inds = np.array([1, 2])
    X_df_indexed = safe_indexing(X_df, inds)
    X_indexed = safe_indexing(X_df, inds)
    assert_array_equal(np.array(X_df_indexed), X_indexed)
    # fun with read-only data in dataframes
    # this happens in joblib memmapping
    X.setflags(write=False)
    X_df_readonly = pd.DataFrame(X)
    inds_readonly = inds.copy()
    inds_readonly.setflags(write=False)

    for this_df, this_inds in product([X_df, X_df_readonly],
                                      [inds, inds_readonly]):
        with warnings.catch_warnings(record=True):
            X_df_indexed = safe_indexing(this_df, this_inds)

        assert_array_equal(np.array(X_df_indexed), X_indexed)


def test_safe_indexing_mock_pandas():
    X = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    X_df = MockDataFrame(X)
    inds = np.array([1, 2])
    X_df_indexed = safe_indexing(X_df, inds)
    X_indexed = safe_indexing(X_df, inds)
    assert_array_equal(np.array(X_df_indexed), X_indexed)


def test_shuffle_on_ndim_equals_three():
    def to_tuple(A):    # to make the inner arrays hashable
        return tuple(tuple(tuple(C) for C in B) for B in A)

    A = np.array([[[1, 2], [3, 4]], [[5, 6], [7, 8]]])  # A.shape = (2,2,2)
    S = set(to_tuple(A))
    shuffle(A)  # shouldn't raise a ValueError for dim = 3
    assert_equal(set(to_tuple(A)), S)


def test_shuffle_dont_convert_to_array():
    # Check that shuffle does not try to convert to numpy arrays with float
    # dtypes can let any indexable datastructure pass-through.
    a = ['a', 'b', 'c']
    b = np.array(['a', 'b', 'c'], dtype=object)
    c = [1, 2, 3]
    d = MockDataFrame(np.array([['a', 0],
                                ['b', 1],
                                ['c', 2]],
                      dtype=object))
    e = sp.csc_matrix(np.arange(6).reshape(3, 2))
    a_s, b_s, c_s, d_s, e_s = shuffle(a, b, c, d, e, random_state=0)

    assert_equal(a_s, ['c', 'b', 'a'])
    assert_equal(type(a_s), list)

    assert_array_equal(b_s, ['c', 'b', 'a'])
    assert_equal(b_s.dtype, object)

    assert_equal(c_s, [3, 2, 1])
    assert_equal(type(c_s), list)

    assert_array_equal(d_s, np.array([['c', 2],
                                      ['b', 1],
                                      ['a', 0]],
                                     dtype=object))
    assert_equal(type(d_s), MockDataFrame)

    assert_array_equal(e_s.toarray(), np.array([[4, 5],
                                                [2, 3],
                                                [0, 1]]))


def test_gen_even_slices():
    # check that gen_even_slices contains all samples
    some_range = range(10)
    joined_range = list(chain(*[some_range[slice] for slice in
                                gen_even_slices(10, 3)]))
    assert_array_equal(some_range, joined_range)

    # check that passing negative n_chunks raises an error
    slices = gen_even_slices(10, -1)
    assert_raises_regex(ValueError, "gen_even_slices got n_packs=-1, must be"
                        " >=1", next, slices)
