"""Milestone 0.7 — retention scaffold and schema-drift guard."""

from __future__ import annotations

import dataclasses
import importlib.util
import json
from collections.abc import Iterator
from datetime import UTC, date, datetime, timedelta
from pathlib import Path
from typing import Any

import pytest
from alembic import command
from alembic.autogenerate import compare_metadata
from alembic.config import Config
from alembic.runtime.migration import MigrationContext
from sqlalchemy import create_engine, select
from sqlalchemy.orm import Session, sessionmaker

import ypms.retention_classes as catalog
from ypms.audit.models import AuditLog
from ypms.db import Base
from ypms.framework import retention
from ypms.framework.retention import (
    RETENTION_RUN_ACTION,
    Disposal,
    RetentionPolicy,
    mapped_models,
    resolve_policy,
    run_retention,
)
from ypms.settings import get_settings
from ypms.stub_models import FosterIndicator
from ypms.youth.models import Registrant

ROOT = Path(__file__).resolve().parents[2]
NOW = datetime(2026, 10, 1, tzinfo=UTC)

# ---------------- policy coverage ----------------


def test_every_mapped_table_has_a_policy() -> None:
    missing = [m.__tablename__ for m in mapped_models() if resolve_policy(m) is None]
    assert missing == []


def test_entity_models_declare_policy_on_the_class() -> None:
    """Framework tables may use the name map; YPMS entities must not."""
    framework = set(catalog.FRAMEWORK_TABLE_POLICIES)
    for m in mapped_models():
        if m.__tablename__ not in framework:
            assert "retention_policy" in vars(m), m.__tablename__


def test_unset_policies_cite_poam() -> None:
    for m in mapped_models():
        p = resolve_policy(m)
        assert p is not None
        if p.status == "unset":
            assert "POAM" in p.authority, m.__tablename__


def test_nothing_is_approved_before_records_officer_signoff() -> None:
    # Flip deliberately when YPMS-POAM-054 closes; update this test with it.
    assert not any(p.approved for p in _all_policies())


def test_anchor_columns_exist() -> None:
    for m in mapped_models():
        p = resolve_policy(m)
        assert p is not None
        if p.period_days is not None:
            assert p.anchor in m.__table__.columns, (m.__tablename__, p.anchor)


@pytest.mark.parametrize(
    ("policy", "status"),
    [
        (RetentionPolicy("x", Disposal.RETAIN, None), "retain"),
        (RetentionPolicy("x", Disposal.RETAIN, 10), "retain"),
        (RetentionPolicy("x", Disposal.TOMBSTONE, None), "unset"),
        (RetentionPolicy("x", Disposal.TOMBSTONE, 10), "interim"),
        (RetentionPolicy("x", Disposal.TOMBSTONE, 10, approved=True), "approved"),
    ],
)
def test_policy_status(policy: RetentionPolicy, status: str) -> None:
    assert policy.status == status


def _all_policies() -> list[RetentionPolicy]:
    return [v for v in vars(catalog).values() if isinstance(v, RetentionPolicy)]


# ---------------- job ----------------


def _registrant(db: Session, *, updated_at: datetime) -> Registrant:
    r = Registrant(first_name="A", last_name="B", dob=date(2009, 1, 1))
    db.add(r)
    db.flush()
    r.updated_at = updated_at
    db.flush()
    return r


def test_empty_run_reports_zero_and_audits(db: Session) -> None:
    report = run_retention(db, now=NOW)
    assert report.to_purge == 0
    assert report.dry_run is True
    assert {t.table for t in report.tables} == {m.__tablename__ for m in mapped_models()}
    assert "consent_records" in report.tables_with("unset")
    assert "permissions" in report.tables_with("retain")

    (row,) = db.execute(select(AuditLog).where(AuditLog.action == RETENTION_RUN_ACTION)).scalars()
    assert row.actor_id is None
    assert row.after == report.summary()


def test_interim_policy_counts_but_never_purges(db: Session) -> None:
    old = _registrant(db, updated_at=NOW - timedelta(days=8 * 365))
    _registrant(db, updated_at=NOW - timedelta(days=30))

    report = run_retention(db, now=NOW)

    reg = next(t for t in report.tables if t.table == "registrants")
    assert (reg.status, reg.interim_eligible, reg.to_purge) == ("interim", 1, 0)
    assert report.to_purge == 0
    assert db.get(Registrant, old.id) is not None
    assert old.deleted_at is None


def test_approved_policy_counts_to_purge_but_phase0_still_reports_only(
    db: Session, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setattr(
        Registrant, "retention_policy",
        dataclasses.replace(catalog.PARTICIPATION, approved=True),
    )
    old = _registrant(db, updated_at=NOW - timedelta(days=8 * 365))

    report = run_retention(db, now=NOW)

    reg = next(t for t in report.tables if t.table == "registrants")
    assert (reg.status, reg.to_purge) == ("approved", 1)
    assert report.to_purge == 1
    assert db.get(Registrant, old.id) is not None and old.deleted_at is None


def test_annual_ingest_classes_use_two_year_window(db: Session) -> None:
    for days in (800, 100):
        f = FosterIndicator()
        db.add(f)
        db.flush()
        f.created_at = NOW - timedelta(days=days)
    db.flush()
    report = run_retention(db, now=NOW)
    foster = next(t for t in report.tables if t.table == "foster_indicators")
    assert foster.interim_eligible == 1


def test_missing_policy_is_an_error(db: Session, monkeypatch: pytest.MonkeyPatch) -> None:
    trimmed = {k: v for k, v in catalog.FRAMEWORK_TABLE_POLICIES.items() if k != "roles"}
    monkeypatch.setattr(catalog, "FRAMEWORK_TABLE_POLICIES", trimmed)
    with pytest.raises(LookupError, match="roles"):
        run_retention(db, now=NOW)


def test_main_runs_commits_and_prints_summary(
    db: Session, monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]
) -> None:
    import ypms.db

    bind = db.get_bind()
    monkeypatch.setattr(ypms.db, "session_factory", lambda: sessionmaker(bind=bind))
    assert retention.main() == 0
    out = json.loads(capsys.readouterr().out.strip().splitlines()[-1])
    assert out["to_purge"] == 0 and out["dry_run"] is True
    assert db.execute(select(AuditLog).where(AuditLog.action == RETENTION_RUN_ACTION)).first()


# ---------------- migrations ----------------


def _load_migration(name: str) -> Any:
    spec = importlib.util.spec_from_file_location(name, ROOT / "migrations" / "versions" / f"{name}.py")
    assert spec and spec.loader
    mod = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(mod)
    return mod


def test_stub_migration_matches_stub_models() -> None:
    import ypms.stub_models as stubs

    tables = {
        v.__tablename__ for v in vars(stubs).values()
        if isinstance(v, type) and issubclass(v, Base) and v is not Base
    }
    assert set(_load_migration("0004_stub_entity_tables").TABLES) == tables


# Pre-existing in 0002 (immutable): named unique constraints duplicated by the
# unique indexes the models declare. Follow-up tracked in PHASE0_STATUS.md.
KNOWN_0002_DRIFT = {("roles", "code"), ("users", "email"), ("users", "username")}

# Mapped only when tests/framework/_fixtures.py is imported; never migrated.
TEST_ONLY_TABLES = {"things"}


@pytest.fixture
def migrated_url(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Iterator[str]:
    url = f"sqlite:///{tmp_path / 'drift.db'}"
    monkeypatch.setenv("DATABASE_URL", url)
    get_settings.cache_clear()
    try:
        command.upgrade(Config(str(ROOT / "alembic.ini")), "head")
        yield url
    finally:
        monkeypatch.undo()
        get_settings.cache_clear()


def test_migrations_match_models(migrated_url: str) -> None:
    engine = create_engine(migrated_url)
    with engine.connect() as conn:
        diff = compare_metadata(MigrationContext.configure(conn), Base.metadata)
    engine.dispose()

    unexpected = []
    for op in diff:
        if op[0] == "add_table" and op[1].name in TEST_ONLY_TABLES:
            continue
        if op[0] == "remove_constraint":
            uc = op[1]
            cols = [c.name for c in uc.columns]
            if len(cols) == 1 and (uc.table.name, cols[0]) in KNOWN_0002_DRIFT:
                continue
        unexpected.append(op)
    assert unexpected == []