# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.internet.defer.deferredGenerator} and related APIs.
"""

from __future__ import division, absolute_import

from twisted.internet import reactor

from twisted.trial import unittest

from twisted.internet.defer import waitForDeferred, deferredGenerator, Deferred
from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.internet import defer
from twisted.trial.util import suppress as SUPPRESS
from twisted.python.util import runWithWarningsSuppressed


def getThing():
    d = Deferred()
    reactor.callLater(0, d.callback, "hi")
    return d

def getOwie():
    d = Deferred()
    def CRAP():
        d.errback(ZeroDivisionError('OMG'))
    reactor.callLater(0, CRAP)
    return d

# NOTE: most of the tests in DeferredGeneratorTests are duplicated
# with slightly different syntax for the InlineCallbacksTests below.

class TerminalException(Exception):
    pass

class BaseDefgenTests:
    """
    This class sets up a bunch of test cases which will test both
    deferredGenerator and inlineCallbacks based generators. The subclasses
    DeferredGeneratorTests and InlineCallbacksTests each provide the actual
    generator implementations tested.
    """

    def testBasics(self):
        """
        Test that a normal deferredGenerator works.  Tests yielding a
        deferred which callbacks, as well as a deferred errbacks. Also
        ensures returning a final value works.
        """

        return self._genBasics().addCallback(self.assertEqual, 'WOOSH')

    def testBuggy(self):
        """
        Ensure that a buggy generator properly signals a Failure
        condition on result deferred.
        """
        return self.assertFailure(self._genBuggy(), ZeroDivisionError)

    def testNothing(self):
        """Test that a generator which never yields results in None."""

        return self._genNothing().addCallback(self.assertEqual, None)

    def testHandledTerminalFailure(self):
        """
        Create a Deferred Generator which yields a Deferred which fails and
        handles the exception which results.  Assert that the Deferred
        Generator does not errback its Deferred.
        """
        return self._genHandledTerminalFailure().addCallback(self.assertEqual, None)

    def testHandledTerminalAsyncFailure(self):
        """
        Just like testHandledTerminalFailure, only with a Deferred which fires
        asynchronously with an error.
        """
        d = defer.Deferred()
        deferredGeneratorResultDeferred = self._genHandledTerminalAsyncFailure(d)
        d.errback(TerminalException("Handled Terminal Failure"))
        return deferredGeneratorResultDeferred.addCallback(
            self.assertEqual, None)

    def testStackUsage(self):
        """
        Make sure we don't blow the stack when yielding immediately
        available deferreds.
        """
        return self._genStackUsage().addCallback(self.assertEqual, 0)

    def testStackUsage2(self):
        """
        Make sure we don't blow the stack when yielding immediately
        available values.
        """
        return self._genStackUsage2().addCallback(self.assertEqual, 0)



def deprecatedDeferredGenerator(f):
    """
    Calls L{deferredGenerator} while suppressing the deprecation warning.

    @param f: Function to call
    @return: Return value of function.
    """
    return runWithWarningsSuppressed(
        [ SUPPRESS(message="twisted.internet.defer.deferredGenerator was "
                          "deprecated") ],
        deferredGenerator, f)



class DeferredGeneratorTests(BaseDefgenTests, unittest.TestCase):

    # First provide all the generator impls necessary for BaseDefgenTests
    @deprecatedDeferredGenerator
    def _genBasics(self):

        x = waitForDeferred(getThing())
        yield x
        x = x.getResult()

        self.assertEqual(x, "hi")

        ow = waitForDeferred(getOwie())
        yield ow
        try:
            ow.getResult()
        except ZeroDivisionError as e:
            self.assertEqual(str(e), 'OMG')
        yield "WOOSH"
        return


    @deprecatedDeferredGenerator
    def _genBuggy(self):
        yield waitForDeferred(getThing())
        1//0


    @deprecatedDeferredGenerator
    def _genNothing(self):
        if 0: yield 1


    @deprecatedDeferredGenerator
    def _genHandledTerminalFailure(self):
        x = waitForDeferred(defer.fail(TerminalException("Handled Terminal Failure")))
        yield x
        try:
            x.getResult()
        except TerminalException:
            pass


    @deprecatedDeferredGenerator
    def _genHandledTerminalAsyncFailure(self, d):
        x = waitForDeferred(d)
        yield x
        try:
            x.getResult()
        except TerminalException:
            pass


    def _genStackUsage(self):
        for x in range(5000):
            # Test with yielding a deferred
            x = waitForDeferred(defer.succeed(1))
            yield x
            x = x.getResult()
        yield 0
    _genStackUsage = deprecatedDeferredGenerator(_genStackUsage)

    def _genStackUsage2(self):
        for x in range(5000):
            # Test with yielding a random value
            yield 1
        yield 0
    _genStackUsage2 = deprecatedDeferredGenerator(_genStackUsage2)

    # Tests unique to deferredGenerator

    def testDeferredYielding(self):
        """
        Ensure that yielding a Deferred directly is trapped as an
        error.
        """
        # See the comment _deferGenerator about d.callback(Deferred).
        def _genDeferred():
            yield getThing()
        _genDeferred = deprecatedDeferredGenerator(_genDeferred)

        return self.assertFailure(_genDeferred(), TypeError)

    suppress = [
            SUPPRESS(message='twisted.internet.defer.waitForDeferred was '
                             'deprecated')
            ]

class InlineCallbacksTests(BaseDefgenTests, unittest.TestCase):
    # First provide all the generator impls necessary for BaseDefgenTests

    def _genBasics(self):

        x = yield getThing()

        self.assertEqual(x, "hi")

        try:
            yield getOwie()
        except ZeroDivisionError as e:
            self.assertEqual(str(e), 'OMG')
        returnValue("WOOSH")
    _genBasics = inlineCallbacks(_genBasics)

    def _genBuggy(self):
        yield getThing()
        1/0
    _genBuggy = inlineCallbacks(_genBuggy)


    def _genNothing(self):
        if 0: yield 1
    _genNothing = inlineCallbacks(_genNothing)


    def _genHandledTerminalFailure(self):
        try:
            yield defer.fail(TerminalException("Handled Terminal Failure"))
        except TerminalException:
            pass
    _genHandledTerminalFailure = inlineCallbacks(_genHandledTerminalFailure)


    def _genHandledTerminalAsyncFailure(self, d):
        try:
            yield d
        except TerminalException:
            pass
    _genHandledTerminalAsyncFailure = inlineCallbacks(
        _genHandledTerminalAsyncFailure)


    def _genStackUsage(self):
        for x in range(5000):
            # Test with yielding a deferred
            yield defer.succeed(1)
        returnValue(0)
    _genStackUsage = inlineCallbacks(_genStackUsage)

    def _genStackUsage2(self):
        for x in range(5000):
            # Test with yielding a random value
            yield 1
        returnValue(0)
    _genStackUsage2 = inlineCallbacks(_genStackUsage2)

    # Tests unique to inlineCallbacks

    def testYieldNonDeferred(self):
        """
        Ensure that yielding a non-deferred passes it back as the
        result of the yield expression.

        @return: A L{twisted.internet.defer.Deferred}
        @rtype: L{twisted.internet.defer.Deferred}
        """
        def _test():
            yield 5
            returnValue(5)
        _test = inlineCallbacks(_test)

        return _test().addCallback(self.assertEqual, 5)

    def testReturnNoValue(self):
        """Ensure a standard python return results in a None result."""
        def _noReturn():
            yield 5
            return
        _noReturn = inlineCallbacks(_noReturn)

        return _noReturn().addCallback(self.assertEqual, None)

    def testReturnValue(self):
        """Ensure that returnValue works."""
        def _return():
            yield 5
            returnValue(6)
        _return = inlineCallbacks(_return)

        return _return().addCallback(self.assertEqual, 6)


    def test_nonGeneratorReturn(self):
        """
        Ensure that C{TypeError} with a message about L{inlineCallbacks} is
        raised when a non-generator returns something other than a generator.
        """
        def _noYield():
            return 5
        _noYield = inlineCallbacks(_noYield)

        self.assertIn("inlineCallbacks",
            str(self.assertRaises(TypeError, _noYield)))


    def test_nonGeneratorReturnValue(self):
        """
        Ensure that C{TypeError} with a message about L{inlineCallbacks} is
        raised when a non-generator calls L{returnValue}.
        """
        def _noYield():
            returnValue(5)
        _noYield = inlineCallbacks(_noYield)

        self.assertIn("inlineCallbacks",
            str(self.assertRaises(TypeError, _noYield)))



class DeprecateDeferredGeneratorTests(unittest.SynchronousTestCase):
    """
    Tests that L{DeferredGeneratorTests} and L{waitForDeferred} are
    deprecated.
    """

    def test_deferredGeneratorDeprecated(self):
        """
        L{deferredGenerator} is deprecated.
        """
        @deferredGenerator
        def decoratedFunction():
            yield None

        warnings = self.flushWarnings([self.test_deferredGeneratorDeprecated])
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]['category'], DeprecationWarning)
        self.assertEqual(
            warnings[0]['message'],
            "twisted.internet.defer.deferredGenerator was deprecated in "
            "Twisted 15.0.0; please use "
            "twisted.internet.defer.inlineCallbacks instead")

    def test_waitForDeferredDeprecated(self):
        """
        L{waitForDeferred} is deprecated.
        """
        d = Deferred()
        waitForDeferred(d)

        warnings = self.flushWarnings([self.test_waitForDeferredDeprecated])
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]['category'], DeprecationWarning)
        self.assertEqual(
            warnings[0]['message'],
            "twisted.internet.defer.waitForDeferred was deprecated in "
            "Twisted 15.0.0; please use "
            "twisted.internet.defer.inlineCallbacks instead")
