import math
import unittest

from reactivex import operators as ops
from reactivex.testing import ReactiveTest, TestScheduler

on_next = ReactiveTest.on_next
on_completed = ReactiveTest.on_completed
on_error = ReactiveTest.on_error
subscribe = ReactiveTest.subscribe
subscribed = ReactiveTest.subscribed
disposed = ReactiveTest.disposed
created = ReactiveTest.created


class RxException(Exception):
    pass


# Helper function for raising exceptions within lambdas
def _raise(ex):
    raise RxException(ex)


class TestDistinctUntilChanged(unittest.TestCase):
    def test_distinct_defaultcomparer_all_distinct(self):
        scheduler = TestScheduler()
        xs = scheduler.create_hot_observable(
            on_next(280, 4),
            on_next(300, 2),
            on_next(350, 1),
            on_next(380, 3),
            on_next(400, 5),
            on_completed(420),
        )

        def create():
            return xs.pipe(ops.distinct())

        results = scheduler.start(create)

        assert results.messages == [
            on_next(280, 4),
            on_next(300, 2),
            on_next(350, 1),
            on_next(380, 3),
            on_next(400, 5),
            on_completed(420),
        ]
        assert xs.subscriptions == [subscribe(200, 420)]

    def test_distinct_default_comparer_some_duplicates(self):
        scheduler = TestScheduler()
        xs = scheduler.create_hot_observable(
            on_next(280, 4),
            on_next(300, 2),
            on_next(350, 2),
            on_next(380, 3),
            on_next(400, 4),
            on_completed(420),
        )

        def create():
            return xs.pipe(ops.distinct())

        results = scheduler.start(create)

        assert results.messages == [
            on_next(280, 4),
            on_next(300, 2),
            on_next(380, 3),
            on_completed(420),
        ]
        assert xs.subscriptions == [subscribe(200, 420)]

    def test_distinct_key_mapper_all_distinct(self):
        scheduler = TestScheduler()
        xs = scheduler.create_hot_observable(
            on_next(280, 8),
            on_next(300, 4),
            on_next(350, 2),
            on_next(380, 6),
            on_next(400, 10),
            on_completed(420),
        )

        def create():
            def key_mapper(x):
                return x / 2

            return xs.pipe(ops.distinct(key_mapper))

        results = scheduler.start(create)

        assert results.messages == [
            on_next(280, 8),
            on_next(300, 4),
            on_next(350, 2),
            on_next(380, 6),
            on_next(400, 10),
            on_completed(420),
        ]
        assert xs.subscriptions == [subscribe(200, 420)]

    def test_distinct_key_mapper_some_duplicates(self):
        scheduler = TestScheduler()
        xs = scheduler.create_hot_observable(
            on_next(280, 4),
            on_next(300, 2),
            on_next(350, 3),
            on_next(380, 7),
            on_next(400, 5),
            on_completed(420),
        )

        def create():
            def key_mapper(x):
                return math.floor(x / 2.0)

            return xs.pipe(ops.distinct(key_mapper))

        results = scheduler.start(create)

        assert results.messages == [
            on_next(280, 4),
            on_next(300, 2),
            on_next(380, 7),
            on_completed(420),
        ]
        assert xs.subscriptions == [subscribe(200, 420)]

    def test_distinct_key_mapper_throws(self):
        ex = "ex"
        scheduler = TestScheduler()
        xs = scheduler.create_hot_observable(
            on_next(280, 3),
            on_next(300, 2),
            on_next(350, 1),
            on_next(380, 0),
            on_next(400, 4),
            on_completed(420),
        )

        def create():
            def key_mapper(x):
                if not x:
                    raise Exception(ex)
                else:
                    return math.floor(x / 2.0)

            return xs.pipe(ops.distinct(key_mapper))

        results = scheduler.start(create)

        assert results.messages == [on_next(280, 3), on_next(350, 1), on_error(380, ex)]
        assert xs.subscriptions == [subscribe(200, 380)]