"""Payments retention (PR #2754) — "12 месяцев" text sync guard.

WHY:
    mera-public/content.ts declares itself as the ONE place product promises
    live (docstring at the top of that file: "ни одного утверждения, которого
    не делает код"). The public retention promise ("оплаченный отчёт хранится
    N месяцев") has THREE places it could quietly drift: the backend setting
    (`settings.trade_in_paid_retention_days`), the frontend constant
    (`PAID_REPORT_RETENTION_MONTHS` in content.ts), and any page that renders
    it (today: privacy/page.tsx). Deep-review finding 2026-08-06 MEDIUM on
    PR #2754 caught exactly this: a comment claimed the number "reads from the
    same setting" while the page actually hardcoded a `12 месяцев` literal --
    a comment cannot fail CI, same lesson as
    test_consent_text_frontend_sync.py's _CONSENT_TEXT_SNAPSHOT guard (which
    this file mirrors).

WHAT:
    1. privacy/page.tsx imports PAID_REPORT_RETENTION_MONTHS from content.ts
       and does NOT hardcode a "N месяцев" literal of its own.
    2. The frontend months constant and the backend days setting stay within
       a sane calendar tolerance of each other (28-31 days per month) -- this
       does NOT enforce byte-identity (days and months are different units by
       design, see content.ts docstring), only that nobody silently changes
       one without the other drifting out of "still honestly ~12 months".
"""

from __future__ import annotations

import os
import re
from pathlib import Path

os.environ.setdefault("DATABASE_URL", "postgresql+psycopg://test:test@localhost:5432/test")

_FRONTEND_CONTENT = (
    Path(__file__).resolve().parents[2] / "frontend" / "src" / "app" / "mera-public" / "content.ts"
)
_FRONTEND_PRIVACY_PAGE = (
    Path(__file__).resolve().parents[2]
    / "frontend"
    / "src"
    / "app"
    / "mera-public"
    / "privacy"
    / "page.tsx"
)

_MONTHS_CONST_RE = re.compile(r"PAID_REPORT_RETENTION_MONTHS\s*=\s*(\d+)\s*;")
_LITERAL_MONTHS_RE = re.compile(r'"?\d+ месяцев"?')


def _extract_months_constant(content_ts_source: str) -> int:
    match = _MONTHS_CONST_RE.search(content_ts_source)
    assert match is not None, (
        "PAID_REPORT_RETENTION_MONTHS not found in content.ts -- "
        "constant renamed/removed without updating this test"
    )
    return int(match.group(1))


def test_frontend_files_exist() -> None:
    assert _FRONTEND_CONTENT.is_file(), f"missing frontend file: {_FRONTEND_CONTENT}"
    assert _FRONTEND_PRIVACY_PAGE.is_file(), f"missing frontend file: {_FRONTEND_PRIVACY_PAGE}"


def test_privacy_page_imports_retention_constant_not_hardcoded() -> None:
    """The whole point: FAILS if privacy/page.tsx stops importing the shared
    constant and goes back to a hardcoded '12 месяцев' literal (exactly the
    drift the deep-review finding caught -- comment said 'reads from content.ts',
    code said otherwise)."""
    src = _FRONTEND_PRIVACY_PAGE.read_text(encoding="utf-8")
    assert "PAID_REPORT_RETENTION_MONTHS" in src, (
        "privacy/page.tsx no longer references PAID_REPORT_RETENTION_MONTHS -- "
        "the retention promise must be rendered from the shared content.ts "
        "constant, not written out again by hand"
    )
    assert re.search(r'from\s+"\.\./content"', src), (
        "privacy/page.tsx must import from '../content' (content.ts), where "
        "PAID_REPORT_RETENTION_MONTHS is declared"
    )
    literal_hits = _LITERAL_MONTHS_RE.findall(src)
    assert not literal_hits, (
        "privacy/page.tsx contains a hardcoded 'N месяцев' literal -- render the "
        "PAID_REPORT_RETENTION_MONTHS constant instead: "
        f"{literal_hits!r}"
    )


def test_backend_days_setting_matches_frontend_months_within_calendar_tolerance() -> None:
    """Not byte-identity (days vs months are different units, deliberately --
    see content.ts docstring on PAID_REPORT_RETENTION_MONTHS): just a sanity
    bound that `trade_in_paid_retention_days` still honestly rounds to the
    number of months the public page promises (28-31 days/month, generous)."""
    from app.core.config import settings

    days = settings.trade_in_paid_retention_days
    months = _extract_months_constant(_FRONTEND_CONTENT.read_text(encoding="utf-8"))

    assert 28 * months <= days <= 31 * months, (
        f"settings.trade_in_paid_retention_days={days} no longer honestly rounds to "
        f"content.ts PAID_REPORT_RETENTION_MONTHS={months} -- update both together "
        "(and the offer text, when it exists) so the public promise stays true"
    )