"""Tests for the get_conn dependency helper."""

from __future__ import annotations

import pytest

from app.db import db, get_conn


pytestmark = pytest.mark.asyncio


class _FakeConnection:
    def __init__(self, idx: int) -> None:
        self.idx = idx


class _AcquireContext:
    def __init__(self, conn: _FakeConnection, tracker: "_FakePool") -> None:
        self._conn = conn
        self._tracker = tracker

    async def __aenter__(self) -> _FakeConnection:
        self._tracker.active += 1
        return self._conn

    async def __aexit__(self, exc_type, exc, tb) -> None:
        self._tracker.active -= 1


class _FakePool:
    def __init__(self) -> None:
        self.acquire_calls = 0
        self.active = 0

    def acquire(self) -> _AcquireContext:
        conn = _FakeConnection(self.acquire_calls)
        self.acquire_calls += 1
        return _AcquireContext(conn, self)


async def _collect_single_connection():
    connection = None
    async for conn in get_conn():
        connection = conn
    return connection


async def test_get_conn_reuses_connection_within_scope():
    original_pool = db.pool
    fake_pool = _FakePool()
    db.pool = fake_pool
    try:
        captured: list[_FakeConnection] = []

        async for outer in get_conn():
            captured.append(outer)
            async for inner in get_conn():
                captured.append(inner)

        assert len(captured) == 2
        assert captured[0] is captured[1]
        assert fake_pool.acquire_calls == 1
    finally:
        db.pool = original_pool


async def test_get_conn_acquires_new_connection_per_root_scope():
    original_pool = db.pool
    fake_pool = _FakePool()
    db.pool = fake_pool
    try:
        first = await _collect_single_connection()
        second = await _collect_single_connection()

        assert first is not None and second is not None
        assert first is not second
        assert fake_pool.acquire_calls == 2
    finally:
        db.pool = original_pool