import numpy as np
import pytest

import pandas as pd
from pandas import RangeIndex
import pandas._testing as tm


class TestGetIndexer:
    def test_get_indexer(self):
        index = RangeIndex(start=0, stop=20, step=2)
        target = RangeIndex(10)
        indexer = index.get_indexer(target)
        expected = np.array([0, -1, 1, -1, 2, -1, 3, -1, 4, -1], dtype=np.intp)
        tm.assert_numpy_array_equal(indexer, expected)

    def test_get_indexer_pad(self):
        index = RangeIndex(start=0, stop=20, step=2)
        target = RangeIndex(10)
        indexer = index.get_indexer(target, method="pad")
        expected = np.array([0, 0, 1, 1, 2, 2, 3, 3, 4, 4], dtype=np.intp)
        tm.assert_numpy_array_equal(indexer, expected)

    def test_get_indexer_backfill(self):
        index = RangeIndex(start=0, stop=20, step=2)
        target = RangeIndex(10)
        indexer = index.get_indexer(target, method="backfill")
        expected = np.array([0, 1, 1, 2, 2, 3, 3, 4, 4, 5], dtype=np.intp)
        tm.assert_numpy_array_equal(indexer, expected)

    def test_get_indexer_limit(self):
        # GH#28631
        idx = RangeIndex(4)
        target = RangeIndex(6)
        result = idx.get_indexer(target, method="pad", limit=1)
        expected = np.array([0, 1, 2, 3, 3, -1], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)

    @pytest.mark.parametrize("stop", [0, -1, -2])
    def test_get_indexer_decreasing(self, stop):
        # GH#28678
        index = RangeIndex(7, stop, -3)
        result = index.get_indexer(range(9))
        expected = np.array([-1, 2, -1, -1, 1, -1, -1, 0, -1], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)


class TestTake:
    def test_take_preserve_name(self):
        index = RangeIndex(1, 5, name="foo")
        taken = index.take([3, 0, 1])
        assert index.name == taken.name

    def test_take_fill_value(self):
        # GH#12631
        idx = pd.RangeIndex(1, 4, name="xxx")
        result = idx.take(np.array([1, 0, -1]))
        expected = pd.Int64Index([2, 1, 3], name="xxx")
        tm.assert_index_equal(result, expected)

        # fill_value
        msg = "Unable to fill values because RangeIndex cannot contain NA"
        with pytest.raises(ValueError, match=msg):
            idx.take(np.array([1, 0, -1]), fill_value=True)

        # allow_fill=False
        result = idx.take(np.array([1, 0, -1]), allow_fill=False, fill_value=True)
        expected = pd.Int64Index([2, 1, 3], name="xxx")
        tm.assert_index_equal(result, expected)

        msg = "Unable to fill values because RangeIndex cannot contain NA"
        with pytest.raises(ValueError, match=msg):
            idx.take(np.array([1, 0, -2]), fill_value=True)
        with pytest.raises(ValueError, match=msg):
            idx.take(np.array([1, 0, -5]), fill_value=True)

        msg = "index -5 is out of bounds for (axis 0 with )?size 3"
        with pytest.raises(IndexError, match=msg):
            idx.take(np.array([1, -5]))
