"""app/test_db.py —— SQLite 层单测（aiosqlite + WAL，幂等迁移，JSON 编解码）。

覆盖：connect 建表/索引、重复 connect 幂等、外键级联删除、JSON 编解码容错。
"""
from __future__ import annotations

import pytest

from app.db import Database, dumps_json, loads_json


async def test_connect_creates_schema_and_wal(tmp_path):
    db = Database(tmp_path / "t1" / "plantai.db")
    await db.connect()
    try:
        # WAL 模式
        row = await db.fetchone("PRAGMA journal_mode")
        assert row[0].lower() == "wal"
        # 表存在
        tables = await db.fetchall("SELECT name FROM sqlite_master WHERE type='table'")
        names = {t["name"] for t in tables}
        assert {"sessions", "messages"} <= names
        # 索引存在
        indexes = await db.fetchall(
            "SELECT name FROM sqlite_master WHERE type='index' AND name LIKE 'idx_%'"
        )
        inames = {i["name"] for i in indexes}
        assert "idx_messages_session" in inames
        assert "idx_sessions_updated" in inames
    finally:
        await db.close()


async def test_connect_idempotent(tmp_path):
    db = Database(tmp_path / "t2" / "plantai.db")
    await db.connect()
    await db.close()
    await db.connect()  # 二次迁移不报错
    await db.close()


async def test_cascade_delete_messages(tmp_path):
    db = Database(tmp_path / "t3" / "plantai.db")
    await db.connect()
    try:
        await db.execute(
            "INSERT INTO sessions (id, title, status, meta, created_at, updated_at) "
            "VALUES ('s1', 't', 'idle', '{}', '2026-01-01T00:00:00Z', '2026-01-01T00:00:00Z')"
        )
        await db.execute(
            "INSERT INTO messages (id, session_id, role, kind, status, blocks, raw, text, "
            "created_at, updated_at) VALUES "
            "('m1', 's1', 'user', 'qa', 'done', '[]', NULL, 'hi', "
            "'2026-01-01T00:00:00Z', '2026-01-01T00:00:00Z')"
        )
        row = await db.fetchone("SELECT COUNT(*) AS n FROM messages WHERE session_id='s1'")
        assert row["n"] == 1
        await db.execute("DELETE FROM sessions WHERE id='s1'")
        row = await db.fetchone("SELECT COUNT(*) AS n FROM messages WHERE session_id='s1'")
        assert row["n"] == 0  # ON DELETE CASCADE
    finally:
        await db.close()


def test_dumps_loads_json_roundtrip():
    payload = {"a": 1, "b": [1, 2], "c": {"d": "中文"}}
    assert loads_json(dumps_json(payload)) == payload
    assert loads_json(None, default=[]) == []
    assert loads_json("not-json", default={}) == {}


def test_dumps_json_fallback_on_unserializable():
    import threading

    assert dumps_json({"lock": threading.Lock()}, default=None) == "null"