# -*- coding: utf-8 -*-
"""异步 SQLite 层测试：读写并发、WAL、事务原子性。"""

import asyncio

import pytest

import core.db as db


@pytest.fixture()
def temp_db(tmp_path, monkeypatch):
    """把 DB 指向临时目录，独立于生产 data/site.db。"""
    monkeypatch.setattr(db, 'DATA_DIR', tmp_path)
    monkeypatch.setattr(db, 'DB_PATH', tmp_path / 'site.db')
    return tmp_path / 'site.db'


async def test_write_then_read(temp_db):
    await db.execute('CREATE TABLE t (id INTEGER PRIMARY KEY, v TEXT)')
    rid = await db.execute('INSERT INTO t (v) VALUES (?)', ('hello',))
    assert rid == 1
    row = await db.fetch_one('SELECT v FROM t WHERE id=?', (1,))
    assert row['v'] == 'hello'
    assert await db.fetch_val('SELECT COUNT(*) FROM t') == 1


async def test_wal_mode_enabled(temp_db):
    await db.execute('CREATE TABLE t (id INTEGER PRIMARY KEY)')
    mode = await db.fetch_val('PRAGMA journal_mode')
    assert str(mode).lower() == 'wal'


async def test_concurrent_read_write(temp_db):
    """核心诉求：写的同时读不被阻塞、且读到一致快照（WAL 快照隔离）。"""
    await db.execute('CREATE TABLE nums (id INTEGER PRIMARY KEY, v INTEGER)')

    stop = asyncio.Event()
    read_errors = []
    write_count = 0

    async def writer():
        nonlocal write_count
        for i in range(200):
            await db.execute('INSERT INTO nums (v) VALUES (?)', (i,))
            write_count += 1
        stop.set()

    async def reader():
        # 写入过程中持续读，不应抛 SQLITE_BUSY / 不应被阻塞致死
        while not stop.is_set():
            try:
                n = await db.fetch_val('SELECT COUNT(*) FROM nums')
                assert isinstance(n, int)
            except Exception as e:
                read_errors.append(e)
            await asyncio.sleep(0)

    await asyncio.gather(writer(), *[reader() for _ in range(4)])

    assert not read_errors, f'读期间出现异常: {read_errors[:3]}'
    assert write_count == 200
    assert await db.fetch_val('SELECT COUNT(*) FROM nums') == 200


async def test_write_transaction_commit_and_rollback(temp_db):
    await db.execute('CREATE TABLE t (id INTEGER PRIMARY KEY, v TEXT)')

    async with db.write_transaction() as conn:
        await conn.execute('INSERT INTO t (v) VALUES (?)', ('a',))
        await conn.execute('INSERT INTO t (v) VALUES (?)', ('b',))
    assert await db.fetch_val('SELECT COUNT(*) FROM t') == 2

    with pytest.raises(RuntimeError):
        async with db.write_transaction() as conn:
            await conn.execute('INSERT INTO t (v) VALUES (?)', ('c',))
            raise RuntimeError('boom')
    # 回滚：c 不应落库
    assert await db.fetch_val('SELECT COUNT(*) FROM t') == 2