"""D1 回填脚本：把官方补录事件的 `subject_key` 补上商品 ID。

脚本是一次性数据修复，但它是**生产数据**的修复 —— 写错了会污染台账，
所以守住三件事：幂等、只填空值、dry-run 不写库。
"""

from __future__ import annotations

import importlib.util
import sys
from datetime import UTC, datetime
from pathlib import Path

import pytest

from tests.support.db import get_test_engine, make_test_session
from web.backend.models import Account, AccountEvent

SCRIPT_PATH = (
    Path(__file__).resolve().parents[1]
    / "scripts"
    / "backfill_official_exchange_subject_key.py"
)

NOW = datetime(2026, 10, 7, 3, 0, 0, tzinfo=UTC)


def _load_script():
    spec = importlib.util.spec_from_file_location(
        "backfill_official_exchange_subject_key", SCRIPT_PATH
    )
    assert spec and spec.loader
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


@pytest.fixture
def script():
    return _load_script()


def _run(script, monkeypatch, *argv: str) -> int:
    monkeypatch.setattr(sys, "argv", [str(SCRIPT_PATH), *argv])
    return script.main()


class TestBackfillOfficialExchangeSubjectKey:
    def setup_method(self):
        self.engine = get_test_engine()
        self.session = make_test_session(self.engine)
        self.account = Account(
            username="bf-acc", password="p", email="b@e.com", email_password="ep"
        )
        self.session.add(self.account)
        self.session.flush()
        self.account_id = self.account.id

    def teardown_method(self):
        self.session.close()

    def _add_event(self, *, commodity_id: str | None, subject_key: str = "") -> int:
        event = AccountEvent(
            account_id=self.account_id,
            event_type="exchange",
            category="business",
            occurred_at=NOW,
            title="兑换 x",
            amount=-1280,
            subject_type="goods",
            subject_key=subject_key,
            detail=(
                {"source": "official_sync", "commodity_id": commodity_id}
                if commodity_id is not None
                else {"source": "official_sync"}
            ),
            source="official_sync",
        )
        self.session.add(event)
        self.session.commit()
        return event.id

    def _reload(self, event_id: int) -> AccountEvent:
        """重新读一行 —— **必须先 rollback 结束当前事务**。

        脚本用的是**另一个会话**，在 MySQL REPEATABLE READ 下，本会话若沿用旧快照，
        `expire_all()` 也只会拿到事务开始时的老值：脚本改没改都显示没改，
        于是「dry-run 不写库」这类断言会**假绿**。
        """
        self.session.rollback()
        row = self.session.get(AccountEvent, event_id)
        assert row is not None
        return row

    def test_dry_run_writes_nothing(self, script, monkeypatch):
        event_id = self._add_event(commodity_id="20260120QYOOB_bag10")

        assert _run(script, monkeypatch, "--dry-run") == 0

        assert self._reload(event_id).subject_key == "", "dry-run 不该写库"

    def test_apply_fills_subject_key(self, script, monkeypatch):
        event_id = self._add_event(commodity_id="20260120QYOOB_bag10")

        assert _run(script, monkeypatch, "--apply") == 0

        row = self._reload(event_id)
        assert row.subject_key == "20260120QYOOB_bag10"
        assert row.subject_type == "commodity"

    def test_is_idempotent(self, script, monkeypatch):
        event_id = self._add_event(commodity_id="20260120QYOOB_bag10")

        assert _run(script, monkeypatch, "--apply") == 0
        # 第二遍没有可回填的行，应当直接退出且不改动
        assert _run(script, monkeypatch, "--apply") == 0

        assert self._reload(event_id).subject_key == "20260120QYOOB_bag10"

    def test_does_not_overwrite_existing_subject_key(self, script, monkeypatch):
        """只填空值 —— 已有值（哪怕看着不对）不由脚本判断。"""
        event_id = self._add_event(
            commodity_id="20260120QYOOB_bag10", subject_key="手工填的值"
        )

        assert _run(script, monkeypatch, "--apply") == 0

        assert self._reload(event_id).subject_key == "手工填的值"

    def test_skips_events_without_commodity_id(self, script, monkeypatch):
        """没有 `detail.commodity_id` 的行不动，也不该报失败退出码。"""
        event_id = self._add_event(commodity_id=None)

        # 没有可回填的行 → 正常退出（不因为「缺 commodity_id」而误报）
        assert _run(script, monkeypatch, "--apply") == 0

        assert self._reload(event_id).subject_key == ""