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

"""
Tests for L{twisted.application.runner._pidfile}.
"""

import errno
from functools import wraps
from os import getpid, name as SYSTEM_NAME
from typing import Any, Callable, Optional

from zope.interface.verify import verifyObject

from typing import NoReturn

import twisted.trial.unittest
from twisted.python.filepath import FilePath
from twisted.python.runtime import platform
from twisted.trial.unittest import SkipTest
from ...runner import _pidfile
from .._pidfile import (
    AlreadyRunningError,
    InvalidPIDFileError,
    IPIDFile,
    NonePIDFile,
    NoPIDFound,
    PIDFile,
    StalePIDFileError,
)


def ifPlatformSupported(f: Callable[..., Any]) -> Callable[..., Any]:
    """
    Decorator for tests that are not expected to work on all platforms.

    Calling L{PIDFile.isRunning} currently raises L{NotImplementedError} on
    non-POSIX platforms.

    On an unsupported platform, we expect to see any test that calls
    L{PIDFile.isRunning} to raise either L{NotImplementedError}, L{SkipTest},
    or C{self.failureException}.
    (C{self.failureException} may occur in a test that checks for a specific
    exception but it gets NotImplementedError instead.)

    @param f: The test method to decorate.

    @return: The wrapped callable.
    """

    @wraps(f)
    def wrapper(self: Any, *args: Any, **kwargs: Any) -> Any:
        supported = platform.getType() == "posix"

        if supported:
            return f(self, *args, **kwargs)
        else:
            e = self.assertRaises(
                (NotImplementedError, SkipTest, self.failureException),
                f,
                self,
                *args,
                **kwargs,
            )
            if isinstance(e, NotImplementedError):
                self.assertTrue(str(e).startswith("isRunning is not implemented on "))

    return wrapper


class PIDFileTests(twisted.trial.unittest.TestCase):
    """
    Tests for L{PIDFile}.
    """

    def filePath(self, content: Optional[bytes] = None) -> FilePath[str]:
        filePath = FilePath(self.mktemp())
        if content is not None:
            filePath.setContent(content)
        return filePath

    def test_interface(self) -> None:
        """
        L{PIDFile} conforms to L{IPIDFile}.
        """
        pidFile = PIDFile(self.filePath())
        verifyObject(IPIDFile, pidFile)

    def test_formatWithPID(self) -> None:
        """
        L{PIDFile._format} returns the expected format when given a PID.
        """
        self.assertEqual(PIDFile._format(pid=1337), b"1337\n")

    def test_readWithPID(self) -> None:
        """
        L{PIDFile.read} returns the PID from the given file path.
        """
        pid = 1337

        pidFile = PIDFile(self.filePath(PIDFile._format(pid=pid)))

        self.assertEqual(pid, pidFile.read())

    def test_readEmptyPID(self) -> None:
        """
        L{PIDFile.read} raises L{InvalidPIDFileError} when given an empty file
        path.
        """
        pidValue = b""
        pidFile = PIDFile(self.filePath(b""))

        e = self.assertRaises(InvalidPIDFileError, pidFile.read)
        self.assertEqual(str(e), f"non-integer PID value in PID file: {pidValue!r}")

    def test_readWithBogusPID(self) -> None:
        """
        L{PIDFile.read} raises L{InvalidPIDFileError} when given an empty file
        path.
        """
        pidValue = b"$foo!"
        pidFile = PIDFile(self.filePath(pidValue))

        e = self.assertRaises(InvalidPIDFileError, pidFile.read)
        self.assertEqual(str(e), f"non-integer PID value in PID file: {pidValue!r}")

    def test_readDoesntExist(self) -> None:
        """
        L{PIDFile.read} raises L{NoPIDFound} when given a non-existing file
        path.
        """
        pidFile = PIDFile(self.filePath())

        e = self.assertRaises(NoPIDFound, pidFile.read)
        self.assertEqual(str(e), "PID file does not exist")

    def test_readOpenRaisesOSErrorNotENOENT(self) -> None:
        """
        L{PIDFile.read} re-raises L{OSError} if the associated C{errno} is
        anything other than L{errno.ENOENT}.
        """

        def oops(mode: str = "r") -> NoReturn:
            raise OSError(errno.EIO, "I/O error")

        self.patch(FilePath, "open", oops)

        pidFile = PIDFile(self.filePath())

        error = self.assertRaises(OSError, pidFile.read)
        self.assertEqual(error.errno, errno.EIO)

    def test_writePID(self) -> None:
        """
        L{PIDFile._write} stores the given PID.
        """
        pid = 1995

        pidFile = PIDFile(self.filePath())
        pidFile._write(pid)

        self.assertEqual(pidFile.read(), pid)

    def test_writePIDInvalid(self) -> None:
        """
        L{PIDFile._write} raises L{ValueError} when given an invalid PID.
        """
        pidFile = PIDFile(self.filePath())

        self.assertRaises(ValueError, pidFile._write, "burp")

    def test_writeRunningPID(self) -> None:
        """
        L{PIDFile.writeRunningPID} stores the PID for the current process.
        """
        pidFile = PIDFile(self.filePath())
        pidFile.writeRunningPID()

        self.assertEqual(pidFile.read(), getpid())

    def test_remove(self) -> None:
        """
        L{PIDFile.remove} removes the PID file.
        """
        pidFile = PIDFile(self.filePath(b""))
        self.assertTrue(pidFile.filePath.exists())

        pidFile.remove()
        self.assertFalse(pidFile.filePath.exists())

    @ifPlatformSupported
    def test_isRunningDoesExist(self) -> None:
        """
        L{PIDFile.isRunning} returns true for a process that does exist.
        """
        pidFile = PIDFile(self.filePath())
        pidFile._write(1337)

        def kill(pid: int, signal: int) -> None:
            return  # Don't actually kill anything

        self.patch(_pidfile, "kill", kill)

        self.assertTrue(pidFile.isRunning())

    @ifPlatformSupported
    def test_isRunningThis(self) -> None:
        """
        L{PIDFile.isRunning} returns true for this process (which is running).

        @note: This differs from L{PIDFileTests.test_isRunningDoesExist} in
        that it actually invokes the C{kill} system call, which is useful for
        testing of our chosen method for probing the existence of a process.
        """
        pidFile = PIDFile(self.filePath())
        pidFile.writeRunningPID()

        self.assertTrue(pidFile.isRunning())

    @ifPlatformSupported
    def test_isRunningDoesNotExist(self) -> None:
        """
        L{PIDFile.isRunning} raises L{StalePIDFileError} for a process that
        does not exist (errno=ESRCH).
        """
        pidFile = PIDFile(self.filePath())
        pidFile._write(1337)

        def kill(pid: int, signal: int) -> None:
            raise OSError(errno.ESRCH, "No such process")

        self.patch(_pidfile, "kill", kill)

        self.assertRaises(StalePIDFileError, pidFile.isRunning)

    @ifPlatformSupported
    def test_isRunningNotAllowed(self) -> None:
        """
        L{PIDFile.isRunning} returns true for a process that we are not allowed
        to kill (errno=EPERM).
        """
        pidFile = PIDFile(self.filePath())
        pidFile._write(1337)

        def kill(pid: int, signal: int) -> None:
            raise OSError(errno.EPERM, "Operation not permitted")

        self.patch(_pidfile, "kill", kill)

        self.assertTrue(pidFile.isRunning())

    @ifPlatformSupported
    def test_isRunningInit(self) -> None:
        """
        L{PIDFile.isRunning} returns true for a process that we are not allowed
        to kill (errno=EPERM).

        @note: This differs from L{PIDFileTests.test_isRunningNotAllowed} in
        that it actually invokes the C{kill} system call, which is useful for
        testing of our chosen method for probing the existence of a process
        that we are not allowed to kill.

        @note: In this case, we try killing C{init}, which is process #1 on
        POSIX systems, so this test is not portable.  C{init} should always be
        running and should not be killable by non-root users.
        """
        if SYSTEM_NAME != "posix":
            raise SkipTest("This test assumes POSIX")

        pidFile = PIDFile(self.filePath())
        pidFile._write(1)  # PID 1 is init on POSIX systems

        self.assertTrue(pidFile.isRunning())

    @ifPlatformSupported
    def test_isRunningUnknownErrno(self) -> None:
        """
        L{PIDFile.isRunning} re-raises L{OSError} if the attached C{errno}
        value from L{os.kill} is not an expected one.
        """
        pidFile = PIDFile(self.filePath())
        pidFile.writeRunningPID()

        def kill(pid: int, signal: int) -> None:
            raise OSError(errno.EEXIST, "File exists")

        self.patch(_pidfile, "kill", kill)

        self.assertRaises(OSError, pidFile.isRunning)

    def test_isRunningNoPIDFile(self) -> None:
        """
        L{PIDFile.isRunning} returns false if the PID file doesn't exist.
        """
        pidFile = PIDFile(self.filePath())

        self.assertFalse(pidFile.isRunning())

    def test_contextManager(self) -> None:
        """
        When used as a context manager, a L{PIDFile} will store the current pid
        on entry, then removes the PID file on exit.
        """
        pidFile = PIDFile(self.filePath())
        self.assertFalse(pidFile.filePath.exists())

        with pidFile:
            self.assertTrue(pidFile.filePath.exists())
            self.assertEqual(pidFile.read(), getpid())

        self.assertFalse(pidFile.filePath.exists())

    @ifPlatformSupported
    def test_contextManagerDoesntExist(self) -> None:
        """
        When used as a context manager, a L{PIDFile} will replace the
        underlying PIDFile rather than raising L{AlreadyRunningError} if the
        contained PID file exists but refers to a non-running PID.
        """
        pidFile = PIDFile(self.filePath())
        pidFile._write(1337)

        def kill(pid: int, signal: int) -> None:
            raise OSError(errno.ESRCH, "No such process")

        self.patch(_pidfile, "kill", kill)

        e = self.assertRaises(StalePIDFileError, pidFile.isRunning)
        self.assertEqual(str(e), "PID file refers to non-existing process")

        with pidFile:
            self.assertEqual(pidFile.read(), getpid())

    @ifPlatformSupported
    def test_contextManagerAlreadyRunning(self) -> None:
        """
        When used as a context manager, a L{PIDFile} will raise
        L{AlreadyRunningError} if the there is already a running process with
        the contained PID.
        """
        pidFile = PIDFile(self.filePath())
        pidFile._write(1337)

        def kill(pid: int, signal: int) -> None:
            return  # Don't actually kill anything

        self.patch(_pidfile, "kill", kill)

        self.assertTrue(pidFile.isRunning())

        self.assertRaises(AlreadyRunningError, pidFile.__enter__)


class NonePIDFileTests(twisted.trial.unittest.TestCase):
    """
    Tests for L{NonePIDFile}.
    """

    def test_interface(self) -> None:
        """
        L{NonePIDFile} conforms to L{IPIDFile}.
        """
        pidFile = NonePIDFile()
        verifyObject(IPIDFile, pidFile)

    def test_read(self) -> None:
        """
        L{NonePIDFile.read} raises L{NoPIDFound}.
        """
        pidFile = NonePIDFile()

        e = self.assertRaises(NoPIDFound, pidFile.read)
        self.assertEqual(str(e), "PID file does not exist")

    def test_write(self) -> None:
        """
        L{NonePIDFile._write} raises L{OSError} with an errno of L{errno.EPERM}.
        """
        pidFile = NonePIDFile()

        error = self.assertRaises(OSError, pidFile._write, 0)
        self.assertEqual(error.errno, errno.EPERM)

    def test_writeRunningPID(self) -> None:
        """
        L{NonePIDFile.writeRunningPID} raises L{OSError} with an errno of
        L{errno.EPERM}.
        """
        pidFile = NonePIDFile()

        error = self.assertRaises(OSError, pidFile.writeRunningPID)
        self.assertEqual(error.errno, errno.EPERM)

    def test_remove(self) -> None:
        """
        L{NonePIDFile.remove} raises L{OSError} with an errno of L{errno.EPERM}.
        """
        pidFile = NonePIDFile()

        error = self.assertRaises(OSError, pidFile.remove)
        self.assertEqual(error.errno, errno.ENOENT)

    def test_isRunning(self) -> None:
        """
        L{NonePIDFile.isRunning} returns L{False}.
        """
        pidFile = NonePIDFile()

        self.assertEqual(pidFile.isRunning(), False)

    def test_contextManager(self) -> None:
        """
        When used as a context manager, a L{NonePIDFile} doesn't raise, despite
        not existing.
        """
        pidFile = NonePIDFile()

        with pidFile:
            pass