import re

from fastapi.testclient import TestClient
from sqlalchemy import select
from sqlalchemy.orm import Session

from app.config import Settings
from app.database import get_engine
from app.main import create_app
from app.models import EmailServerConfig, User


def _build_settings(db_url: str, **overrides) -> Settings:
    values = {
        "APP_ENV": "test",
        "DB_URL": db_url,
        "SESSION_SECRET": "test-secret",
        "COOKIE_SECURE": False,
        "COOKIE_SAMESITE": "lax",
        "LOGIN_RATE_LIMIT_ATTEMPTS": 5,
        "LOGIN_RATE_LIMIT_WINDOW_MINUTES": 15,
    }
    values.update(overrides)
    return Settings(**values)


def _extract_csrf(html: str) -> str:
    match = re.search(r'name="csrf_token" value="([^"]+)"', html)
    assert match is not None
    return match.group(1)


def _find_latest_link(sent_mails: list[dict[str, str]], path_fragment: str) -> str:
    pattern = re.compile(rf"https?://[^\s]+{re.escape(path_fragment)}[^\s]*")
    for mail in reversed(sent_mails):
        match = pattern.search(mail["body"])
        if match is not None:
            return match.group(0)
    raise AssertionError(f"no mail with link containing {path_fragment!r}")


def _insert_mail_config() -> None:
    with Session(get_engine()) as db:
        db.add(
            EmailServerConfig(
                smtp_host="smtp.test.local",
                smtp_port=587,
                from_email="noreply@test.local",
                from_name="Stundenfuchs",
                use_starttls=True,
                use_ssl=False,
                verify_tls=False,
                registration_mails_enabled=False,
                password_reset_mails_enabled=True,
            )
        )
        db.commit()


def test_login_rate_limit_ignores_spoofed_x_forwarded_for(app):
    email = "rate-limit@example.com"
    password = "strongpasswordRate1"

    with TestClient(app) as register_client:
        register = register_client.post(
            "/auth/register",
            json={"email": email, "password": password},
        )
        assert register.status_code == 200

    with TestClient(app) as attacker:
        for idx in range(5):
            response = attacker.post(
                "/auth/login",
                headers={"x-forwarded-for": f"198.51.100.{idx}"},
                json={"email": email, "password": "wrong-password"},
            )
            assert response.status_code == 401

        blocked = attacker.post(
            "/auth/login",
            headers={"x-forwarded-for": "203.0.113.77"},
            json={"email": email, "password": "wrong-password"},
        )
        assert blocked.status_code == 429


def test_password_reset_new_request_invalidates_previous_token(tmp_path, monkeypatch):
    db_path = tmp_path / "reset-rotation.db"
    app = create_app(_build_settings(f"sqlite:///{db_path}"))
    sent_mails: list[dict[str, str]] = []

    def fake_send_email(*, settings, to_email: str, subject: str, text_body: str) -> None:
        sent_mails.append({"to": to_email, "subject": subject, "body": text_body})

    monkeypatch.setattr("app.main.send_email", fake_send_email)
    _insert_mail_config()

    with TestClient(app) as auth_client:
        register = auth_client.post(
            "/auth/register",
            json={"email": "reset-user@example.com", "password": "strongpasswordReset1"},
        )
        assert register.status_code == 200

    with TestClient(app) as reset_client:
        request_page = reset_client.get("/password-reset/request")
        request_csrf = _extract_csrf(request_page.text)
        first_request = reset_client.post(
            "/password-reset/request",
            data={"email": "reset-user@example.com", "csrf_token": request_csrf},
        )
        assert first_request.status_code == 200
        first_link = _find_latest_link(sent_mails, "/password-reset/confirm?token=")

        request_page_again = reset_client.get("/password-reset/request")
        request_csrf_again = _extract_csrf(request_page_again.text)
        second_request = reset_client.post(
            "/password-reset/request",
            data={"email": "reset-user@example.com", "csrf_token": request_csrf_again},
        )
        assert second_request.status_code == 200
        second_link = _find_latest_link(sent_mails, "/password-reset/confirm?token=")

        assert first_link != second_link
        first_token_page = reset_client.get(first_link)
        assert first_token_page.status_code == 400

        second_token_page = reset_client.get(second_link)
        assert second_token_page.status_code == 200
        assert 'name="token"' in second_token_page.text


def test_password_change_invalidates_existing_reset_tokens(tmp_path, monkeypatch):
    db_path = tmp_path / "reset-password-change.db"
    app = create_app(_build_settings(f"sqlite:///{db_path}"))
    sent_mails: list[dict[str, str]] = []

    def fake_send_email(*, settings, to_email: str, subject: str, text_body: str) -> None:
        sent_mails.append({"to": to_email, "subject": subject, "body": text_body})

    monkeypatch.setattr("app.main.send_email", fake_send_email)
    _insert_mail_config()

    password = "strongpasswordReset2"
    with TestClient(app) as user_client, TestClient(app) as reset_client:
        register = user_client.post(
            "/auth/register",
            json={"email": "password-change@example.com", "password": password},
        )
        assert register.status_code == 200
        csrf_token = register.json()["csrf_token"]

        request_page = reset_client.get("/password-reset/request")
        request_csrf = _extract_csrf(request_page.text)
        reset_request = reset_client.post(
            "/password-reset/request",
            data={"email": "password-change@example.com", "csrf_token": request_csrf},
        )
        assert reset_request.status_code == 200
        reset_link = _find_latest_link(sent_mails, "/password-reset/confirm?token=")

        change_password = user_client.post(
            "/settings/password",
            data={
                "current_password": password,
                "new_password": "strongpasswordReset3",
                "new_password_repeat": "strongpasswordReset3",
                "csrf_token": csrf_token,
            },
            follow_redirects=False,
        )
        assert change_password.status_code == 303
        assert change_password.headers["location"] == "/settings?msg=password_updated"

        expired_reset = reset_client.get(reset_link)
        assert expired_reset.status_code == 400


def test_email_change_requires_reverification_and_clears_session(tmp_path, monkeypatch):
    db_path = tmp_path / "email-change.db"
    app = create_app(
        _build_settings(
            f"sqlite:///{db_path}",
            EMAIL_VERIFICATION_REQUIRED=True,
        )
    )
    sent_mails: list[dict[str, str]] = []

    def fake_send_email(*, settings, to_email: str, subject: str, text_body: str) -> None:
        sent_mails.append({"to": to_email, "subject": subject, "body": text_body})

    monkeypatch.setattr("app.main.send_email", fake_send_email)
    _insert_mail_config()

    password = "strongpasswordVerify2"
    with TestClient(app) as client:
        register_page = client.get("/register")
        register_csrf = _extract_csrf(register_page.text)
        register_submit = client.post(
            "/register",
            data={
                "email": "verified-before-change@example.com",
                "password": password,
                "csrf_token": register_csrf,
            },
            follow_redirects=False,
        )
        assert register_submit.status_code == 303
        assert register_submit.headers["location"] == "/login?msg=email_verification_sent"

        verify_link = _find_latest_link(sent_mails, "/verify-email?token=")
        verify_response = client.get(verify_link, follow_redirects=False)
        assert verify_response.status_code == 303

        login_page = client.get("/login")
        login_csrf = _extract_csrf(login_page.text)
        login_submit = client.post(
            "/login",
            data={
                "email": "verified-before-change@example.com",
                "password": password,
                "csrf_token": login_csrf,
            },
            follow_redirects=False,
        )
        assert login_submit.status_code == 303

        settings_page = client.get("/settings")
        settings_csrf = _extract_csrf(settings_page.text)
        profile_update = client.post(
            "/settings/profile",
            data={
                "email": "changed-address@example.com",
                "current_password": password,
                "csrf_token": settings_csrf,
            },
            follow_redirects=False,
        )
        assert profile_update.status_code == 303
        assert profile_update.headers["location"] == "/login?msg=email_verification_sent"

        me_after_change = client.get("/me")
        assert me_after_change.status_code == 401

        login_page_after_change = client.get("/login")
        login_csrf_after_change = _extract_csrf(login_page_after_change.text)
        blocked_login = client.post(
            "/login",
            data={
                "email": "changed-address@example.com",
                "password": password,
                "csrf_token": login_csrf_after_change,
            },
            follow_redirects=False,
        )
        assert blocked_login.status_code == 403

    assert sent_mails[-1]["to"] == "changed-address@example.com"

    with Session(get_engine()) as db:
        updated_user = db.execute(select(User).where(User.email == "changed-address@example.com")).scalar_one()
        assert updated_user.email_verified is False


def test_api_mfa_resend_respects_cooldown(tmp_path, monkeypatch):
    db_path = tmp_path / "mfa-resend.db"
    app = create_app(_build_settings(f"sqlite:///{db_path}"))
    sent_mails: list[dict[str, str]] = []

    def fake_send_email(*, settings, to_email: str, subject: str, text_body: str) -> None:
        sent_mails.append({"to": to_email, "subject": subject, "body": text_body})

    monkeypatch.setattr("app.main.send_email", fake_send_email)
    _insert_mail_config()

    password = "strongpasswordMfa1"
    with TestClient(app) as client:
        register = client.post(
            "/auth/register",
            json={"email": "mfa-resend@example.com", "password": password},
        )
        assert register.status_code == 200
        csrf_token = register.json()["csrf_token"]

        enable_email_mfa = client.post(
            "/settings/mfa",
            data={
                "csrf_token": csrf_token,
                "mfa_method": "email",
                "current_password": password,
            },
            follow_redirects=False,
        )
        assert enable_email_mfa.status_code == 303

        logout = client.post("/auth/logout", headers={"x-csrf-token": csrf_token})
        assert logout.status_code == 200

        login = client.post("/auth/login", json={"email": "mfa-resend@example.com", "password": password})
        assert login.status_code == 200
        assert login.json()["mfa_required"] is True
        pending_csrf = login.json()["csrf_token"]

        resend = client.post("/auth/mfa/resend", headers={"x-csrf-token": pending_csrf})
        assert resend.status_code == 429
        assert "Bitte kurz warten" in resend.text