import pytest

from werkzeug.test import EnvironBuilder


def _drive(app, headers):
    """Send one request through the app's REAL ProxyFix instance.

    The middleware's wrapped application is swapped for a recorder for the
    duration of the call, so what is measured is the exact ProxyFix object
    create_app() installed — not a reconstruction of it — without needing a
    second create_app() (blueprints cannot be registered twice per process)
    or a route added after the app has served its first request.
    """
    seen = {}

    def recorder(environ, start_response):
        seen['host'] = environ.get('HTTP_HOST')
        seen['scheme'] = environ.get('wsgi.url_scheme')
        start_response('200 OK', [('Content-Type', 'text/plain')])
        return [b'ok']

    middleware = app.wsgi_app
    original = middleware.app
    middleware.app = recorder
    try:
        environ = EnvironBuilder(path='/', headers=headers).get_environ()
        middleware(environ, lambda *a, **kw: None)
    finally:
        middleware.app = original
    return seen


def _observed_host(app, headers):
    """Return the host the application resolves for a request."""
    return _drive(app, headers).get('host')


def test_forwarded_host_does_not_override_the_real_host(app):
    """The core assertion: a forged header must be ignored."""
    host = _observed_host(app, {
        'Host': 'attacker.jqc.app',
        'X-Forwarded-Host': 'victim.jqc.app',
    })
    assert host == 'attacker.jqc.app', (
        'X-Forwarded-Host overrode the real Host header — tenant selection is '
        'attacker-controlled. Check ProxyFix x_host in app/__init__.py.'
    )
    assert 'victim' not in (host or '')


def test_real_host_is_still_used_normally(app):
    """Without the forged header, nothing changes."""
    assert _observed_host(app, {'Host': 'lts.jqc.app'}) == 'lts.jqc.app'


def test_proxyfix_is_configured_without_x_host(app):
    """Pin the setting itself, so a future edit has to be deliberate."""
    from werkzeug.middleware.proxy_fix import ProxyFix

    wsgi = app.wsgi_app
    assert isinstance(wsgi, ProxyFix), 'ProxyFix is no longer installed'
    assert wsgi.x_host == 0, (
        'ProxyFix x_host must stay 0 — nginx sets Host from the real request, '
        'and X-Forwarded-Host is client-controlled.'
    )
    # The two we DO want unwrapped, for rate limiting and HTTPS URL building.
    assert wsgi.x_for == 1
    assert wsgi.x_proto == 1


def test_forwarded_proto_is_still_honoured(app):
    """x_proto must keep working — email links depend on it."""
    seen = _drive(app, {'Host': 'lts.jqc.app', 'X-Forwarded-Proto': 'https'})
    assert seen.get('scheme') == 'https'


# ── Config guard ─────────────────────────────────────────────────────────────

def test_shipped_nginx_configs_pin_forwarded_host():
    """Every proxying block in deploy/nginx must pin X-Forwarded-Host.

    These files are the reference the server is deployed from. A block that
    proxies without pinning the header reopens the hole on whichever host uses
    it, so the omission should fail here rather than on the box.
    """
    import pathlib

    conf_dir = pathlib.Path(__file__).resolve().parent.parent / 'deploy' / 'nginx'
    configs = sorted(conf_dir.glob('*.conf'))
    assert configs, 'no nginx reference configs found in deploy/nginx/'

    offenders = []
    for path in configs:
        text = path.read_text(encoding='utf-8')
        if 'proxy_pass' not in text:
            continue
        if 'proxy_set_header X-Forwarded-Host' not in text.replace('  ', ' '):
            offenders.append(path.name)

    assert not offenders, (
        'nginx config proxies without pinning X-Forwarded-Host: '
        + ', '.join(offenders)
    )