"""Content Security Policy, and the migration away from 'unsafe-inline'.

SEC-WEB-001 / OPS-010. script-src still carries 'unsafe-inline', which is
why the stored XSS of SEC-XSS-001 executed instead of being blocked.

Removing it is not a one-line change. A nonce authorises `<script>`
elements; it can do nothing for `onclick="..."` attributes, and there are
dozens of those across the templates. Under CSP level 3 a browser also
ignores 'unsafe-inline' the moment a nonce appears, so the two cannot
coexist as a gradual transition — the switch is atomic.

The counts below are a ratchet: they may only go down. Migrating a
template and lowering the number is a deliberate act, recorded in the
diff. Adding a new inline handler turns the suite red.
"""

import os
import re

import pytest

from app.app import build_csp

TEMPLATE_ROOT = os.path.join(
    os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
    'app', 'templates',
)

#: Attributes a nonce can never authorise.
INLINE_HANDLER = re.compile(
    r'\son(?:click|change|submit|input|load|keyup|keydown|mouseover|focus|blur)\s*=',
    re.I,
)

#: Remaining inline handlers, per template. Lower these as you migrate;
#: never raise one. Templates absent from this map must have none.
HANDLER_BUDGET = {
    'pages/match_form.html': 13,
    'pages/calendar.html': 11,
    'pages/teams.html': 11,
    'pages/evaluate_player.html': 9,
    'pages/view_tryout.html': 8,
}

#: What the ratchet is counting down to.
TOTAL_BUDGET = sum(HANDLER_BUDGET.values())


def _templates():
    for root, _dirs, files in os.walk(TEMPLATE_ROOT):
        for name in files:
            if name.endswith('.html'):
                full = os.path.join(root, name)
                rel = os.path.relpath(full, TEMPLATE_ROOT).replace(os.sep, '/')
                yield rel, full


def _count_handlers(path):
    with open(path, encoding='utf-8') as handle:
        return len(INLINE_HANDLER.findall(handle.read()))


class TestPolicyHeader:
    def test_the_current_policy_still_allows_inline_script(self, client):
        """Documents where we are, not where we want to be."""
        csp = client.get('/auth/login').headers['Content-Security-Policy']
        assert "'unsafe-inline'" in csp

    def test_the_policy_pins_the_dangerous_directives(self, client):
        csp = client.get('/auth/login').headers['Content-Security-Policy']

        assert "default-src 'self'" in csp
        assert "frame-ancestors 'none'" in csp
        assert "base-uri 'self'" in csp
        assert "form-action 'self'" in csp
        assert "object-src" not in csp or "object-src 'none'" in csp

    def test_no_nonce_is_emitted_while_inline_script_is_allowed(self, client):
        """Emitting both would silently drop every inline script in modern
        browsers, since a nonce makes them ignore 'unsafe-inline'."""
        csp = client.get('/auth/login').headers['Content-Security-Policy']
        assert 'nonce-' not in csp

    def test_the_hardened_policy_carries_a_nonce_and_no_unsafe_inline(self):
        csp = build_csp(allow_inline_script=False, nonce='abc123')

        assert "'nonce-abc123'" in csp
        assert "'unsafe-inline'" not in csp.split('style-src')[0]

    def test_each_request_gets_a_distinct_nonce(self, app):
        """A reused nonce is worth no more than 'unsafe-inline'."""
        application = app
        application.config['CSP_ALLOW_INLINE_SCRIPT'] = False
        client = application.test_client()

        seen = set()
        for _ in range(5):
            csp = client.get('/auth/login').headers['Content-Security-Policy']
            seen.add(re.search(r"'nonce-([^']+)'", csp).group(1))

        assert len(seen) == 5


class TestInlineHandlerRatchet:
    @pytest.mark.parametrize('relative,full', list(_templates()))
    def test_a_template_never_gains_an_inline_handler(self, relative, full):
        allowed = HANDLER_BUDGET.get(relative, 0)
        found = _count_handlers(full)

        assert found <= allowed, (
            f'{relative} has {found} inline event handler(s), budget is '
            f'{allowed}. A nonce cannot authorise these — use '
            f'data-action="..." and the delegated listener in main.js.'
        )

    def test_the_budget_map_has_no_stale_entries(self):
        """Lower an entry to zero and it must be deleted, so the map keeps
        reflecting the real remaining work."""
        actual = {rel: _count_handlers(full) for rel, full in _templates()}

        stale = [rel for rel, allowed in HANDLER_BUDGET.items()
                 if actual.get(rel, 0) < allowed]

        assert not stale, (
            f'Budget is now higher than reality for {stale}. Lower or remove '
            f'these entries so the count keeps meaning something.'
        )

    def test_the_shared_layout_is_already_free_of_them(self):
        """base.html and macros.html render on every single page, so they
        were migrated first."""
        for relative in ('layouts/base.html', 'layouts/macros.html'):
            full = os.path.join(TEMPLATE_ROOT, *relative.split('/'))
            assert _count_handlers(full) == 0, f'{relative} regressed'

    def test_progress_is_recorded(self):
        """Fails when the total drops, as a reminder to update the budget
        and, once it reaches zero, to flip CSP_ALLOW_INLINE_SCRIPT."""
        total = sum(_count_handlers(full) for _rel, full in _templates())

        assert total <= TOTAL_BUDGET
        assert total == TOTAL_BUDGET, (
            f'{TOTAL_BUDGET - total} handler(s) removed since the budget was '
            f'last updated — lower HANDLER_BUDGET to {total}. At zero, set '
            f'CSP_ALLOW_INLINE_SCRIPT to false and delete this ratchet.'
        )