import hashlib
from datetime import timedelta

import pytest
from django.utils import timezone
from rest_framework import status

from infrasynth.security.altcha.services import ALTCHAService
from infrasynth.security.models import ALTCHAChallenge


@pytest.fixture
def altcha_service(db):
    return ALTCHAService()


def compute_solution(salt: str, number: int) -> str:
    return hashlib.sha256(f"{salt}{number}".encode()).hexdigest()


class TestChallengeCreation:
    def test_create_challenge_persists(self, altcha_service):
        challenge = altcha_service.create_challenge()
        assert challenge["algorithm"] == "SHA-256"
        assert challenge["difficulty"] == 10000
        assert ALTCHAChallenge.objects.filter(challenge_id=challenge["challenge_id"]).exists()

    def test_create_challenge_fields(self, altcha_service):
        challenge = altcha_service.create_challenge()
        assert challenge["salt"]
        assert challenge["challenge_id"]
        assert challenge["difficulty"] > 0

    def test_challenge_has_expiry(self, altcha_service):
        altcha_service.create_challenge()
        saved = ALTCHAChallenge.objects.get()
        assert saved.expires_at > timezone.now()


class TestVerification:
    def test_verify_correct_solution(self, altcha_service):
        challenge = altcha_service.create_challenge()
        number = 5
        solution = compute_solution(challenge["salt"], number)
        assert altcha_service.verify(challenge["challenge_id"], solution, number) is True

    def test_verify_marks_used(self, altcha_service):
        challenge = altcha_service.create_challenge()
        solution = compute_solution(challenge["salt"], 5)
        assert altcha_service.verify(challenge["challenge_id"], solution, 5) is True
        saved = ALTCHAChallenge.objects.get(challenge_id=challenge["challenge_id"])
        assert saved.is_verified is True

    def test_replay_rejected(self, altcha_service):
        challenge = altcha_service.create_challenge()
        solution = compute_solution(challenge["salt"], 5)
        assert altcha_service.verify(challenge["challenge_id"], solution, 5) is True
        assert altcha_service.verify(challenge["challenge_id"], solution, 5) is False

    def test_wrong_solution_rejected(self, altcha_service):
        challenge = altcha_service.create_challenge()
        wrong = hashlib.sha256(b"nope").hexdigest()
        assert altcha_service.verify(challenge["challenge_id"], wrong, 5) is False

    def test_unknown_challenge_rejected(self, altcha_service):
        assert altcha_service.verify("unknown-id", "abc", 5) is False

    def test_expired_challenge_rejected(self, altcha_service):
        challenge = altcha_service.create_challenge()
        ALTCHAChallenge.objects.filter(challenge_id=challenge["challenge_id"]).update(
            expires_at=timezone.now() - timedelta(minutes=10)
        )
        solution = compute_solution(challenge["salt"], 5)
        assert altcha_service.verify(challenge["challenge_id"], solution, 5) is False


class TestComputeSolution:
    def test_compute_solution_matches_verify(self, altcha_service):
        challenge = altcha_service.create_challenge()
        solution, number = altcha_service.compute_solution(challenge["salt"], challenge["difficulty"])
        assert altcha_service.verify(challenge["challenge_id"], solution, number) is True


class TestALTCHAViews:
    def test_challenge_endpoint(self, api_client):
        resp = api_client.post("/api/auth/altcha/challenge/")
        assert resp.status_code == status.HTTP_200_OK
        data = resp.json()
        assert "challenge_id" in data
        assert "salt" in data
        assert "difficulty" in data

    def test_verify_endpoint_correct(self, api_client):
        svc = ALTCHAService()
        challenge = svc.create_challenge()
        solution = compute_solution(challenge["salt"], 3)
        resp = api_client.post(
            "/api/auth/altcha/verify/",
            {
                "challenge_id": challenge["challenge_id"],
                "solution": solution,
                "number": 3,
            },
            format="json",
        )
        assert resp.status_code == status.HTTP_200_OK
        assert resp.json() == {"verified": True}

    def test_verify_endpoint_wrong(self, api_client):
        svc = ALTCHAService()
        challenge = svc.create_challenge()
        resp = api_client.post(
            "/api/auth/altcha/verify/",
            {
                "challenge_id": challenge["challenge_id"],
                "solution": "deadbeef",
                "number": 1,
            },
            format="json",
        )
        assert resp.json() == {"verified": False}