# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
from __future__ import annotations

import email.message
import email.parser
from email.message import Message
from io import BytesIO, StringIO
from typing import IO, AnyStr, Callable

from twisted.mail import bounce
from twisted.trial import unittest


class BounceTests(unittest.TestCase):
    """
    Bounce message generation
    """

    def test_bounceMessageUnicode(self) -> None:
        """
        L{twisted.mail.bounce.generateBounce} can accept L{unicode}.
        """
        fromAddress, to, s = bounce.generateBounce(
            StringIO(
                """\
From: Moshe Zadka <moshez@example.com>
To: nonexistent@example.org
Subject: test

"""
            ),
            "moshez@example.com",
            "nonexistent@example.org",
        )
        self.assertEqual(fromAddress, b"")
        self.assertEqual(to, b"moshez@example.com")
        emailParser = email.parser.Parser()
        mess = emailParser.parse(StringIO(s.decode("utf-8")))
        self.assertEqual(mess["To"], "moshez@example.com")
        self.assertEqual(mess["From"], "postmaster@example.org")
        self.assertEqual(mess["subject"], "Returned Mail: see transcript for details")

    def test_bounceMessageBytes(self) -> None:
        """
        L{twisted.mail.bounce.generateBounce} can accept L{bytes}.
        """
        fromAddress, to, s = bounce.generateBounce(
            BytesIO(
                b"""\
From: Moshe Zadka <moshez@example.com>
To: nonexistent@example.org
Subject: test

"""
            ),
            b"moshez@example.com",
            b"nonexistent@example.org",
        )
        self.assertEqual(fromAddress, b"")
        self.assertEqual(to, b"moshez@example.com")
        emailParser = email.parser.Parser()
        mess = emailParser.parse(StringIO(s.decode("utf-8")))
        self.assertEqual(mess["To"], "moshez@example.com")
        self.assertEqual(mess["From"], "postmaster@example.org")
        self.assertEqual(mess["subject"], "Returned Mail: see transcript for details")

    def test_bounceMessageCustomTranscript(self) -> None:
        """
        Pass a custom transcript message to L{twisted.mail.bounce.generateBounce}.
        """
        fromAddress, to, s = bounce.generateBounce(
            BytesIO(
                b"""\
From: Moshe Zadka <moshez@example.com>
To: nonexistent@example.org
Subject: test

"""
            ),
            b"moshez@example.com",
            b"nonexistent@example.org",
            "Custom transcript",
        )
        self.assertEqual(fromAddress, b"")
        self.assertEqual(to, b"moshez@example.com")
        emailParser = email.parser.Parser()
        mess = emailParser.parse(StringIO(s.decode("utf-8")))
        self.assertEqual(mess["To"], "moshez@example.com")
        self.assertEqual(mess["From"], "postmaster@example.org")
        self.assertEqual(mess["subject"], "Returned Mail: see transcript for details")
        self.assertTrue(mess.is_multipart())
        parts: list[Message] = mess.get_payload()  # type:ignore[assignment]
        self.assertEqual(
            parts[0].get_payload(),
            "Custom transcript\n",
        )

    def _bounceBigMessage(
        self, header: AnyStr, message: AnyStr, ioType: Callable[[AnyStr], IO[AnyStr]]
    ) -> None:
        """
        Pass a really big message to L{twisted.mail.bounce.generateBounce}.
        """
        fromAddress, to, s = bounce.generateBounce(
            ioType(header + message), "moshez@example.com", "nonexistent@example.org"
        )
        emailParser = email.parser.Parser()
        mess = emailParser.parse(StringIO(s.decode("utf-8")))
        self.assertEqual(mess["To"], "moshez@example.com")
        self.assertEqual(mess["From"], "postmaster@example.org")
        self.assertEqual(mess["subject"], "Returned Mail: see transcript for details")
        self.assertTrue(mess.is_multipart())
        parts: list[Message] = mess.get_payload()  # type:ignore[assignment]
        innerMessage: list[Message] = parts[1].get_payload()  # type:ignore[assignment]
        if isinstance(message, bytes):
            messageText = message.decode("utf-8")
        else:
            messageText = message
        pl: str = innerMessage[0].get_payload()  # type:ignore[assignment]
        self.assertEqual(pl + "\n", messageText)

    def test_bounceBigMessage(self) -> None:
        """
        L{twisted.mail.bounce.generateBounce} with big L{unicode} and
        L{bytes} messages.
        """
        header = b"""\
From: Moshe Zadka <moshez@example.com>
To: nonexistent@example.org
Subject: test

"""
        self._bounceBigMessage(header, b"Test test\n" * 10000, BytesIO)
        self._bounceBigMessage(header.decode("utf-8"), "More test\n" * 10000, StringIO)