#!/usr/bin/env python3
"""Offline regression tests for the selective SRS DNS preflight helper.

All DNS responses are mocked. No live DNS queries, Postfix changes,
or SRS installation operations are performed.
"""

import contextlib
import io
import runpy
import unittest
from pathlib import Path
from unittest.mock import patch


ROOT = Path(__file__).resolve().parents[1]
HELPER = ROOT / "helpers/srs-dns-check.py"

module = runpy.run_path(str(HELPER))
check_server = module["check_server"]


class TestSrsDnsSpf(unittest.TestCase):

    DOMAIN = "srs.example.org"
    HOSTNAME = "mail.example.org"
    IPV4 = "192.0.2.25"
    IPV6 = "2001:db8::25"

    def check_with_spf(self, txt_records):
        answers = {
            (self.DOMAIN, "TXT"): txt_records,
            (self.DOMAIN, "MX"): [
                f"10 {self.HOSTNAME}."
            ],
            (self.HOSTNAME, "A"): [
                self.IPV4
            ],
            (self.HOSTNAME, "AAAA"): [
                self.IPV6
            ],
        }

        def fake_dig(server, name, kind, authoritative=False):
            self.assertEqual(server, "192.0.2.53")
            self.assertTrue(
                authoritative,
                "DNS checks must query authoritative nameservers"
            )
            return answers.get((name, kind), [])

        output = io.StringIO()

        with patch.dict(
            check_server.__globals__,
            {"dig": fake_dig}
        ):
            with contextlib.redirect_stdout(output):
                result = check_server(
                    "ns.example.org",
                    "192.0.2.53",
                    self.DOMAIN,
                    self.HOSTNAME,
                    self.IPV4,
                    self.IPV6,
                )

        return result, output.getvalue()

    def test_valid_spf(self):
        result, output = self.check_with_spf(
            ['"v=spf1 mx -all"']
        )

        self.assertEqual(result, (True, True))
        self.assertIn("[ ok ]", output)

    def test_missing_spf(self):
        result, output = self.check_with_spf([])

        self.assertEqual(result, (False, False))
        self.assertIn("SPF is not the approved", output)
        self.assertIn("[ failed ]", output)

    def test_invalid_spf(self):
        result, output = self.check_with_spf(
            ['"v=spf1 -all"']
        )

        self.assertEqual(result, (False, False))
        self.assertIn("SPF is not the approved", output)
        self.assertIn("[ failed ]", output)

    def test_multiple_spf_records(self):
        result, output = self.check_with_spf([
            '"v=spf1 mx -all"',
            '"v=spf1 ip4:192.0.2.1 -all"',
        ])

        self.assertEqual(result, (False, False))
        self.assertIn("SPF is not the approved", output)
        self.assertIn("[ failed ]", output)


if __name__ == "__main__":
    unittest.main(verbosity=2)