import pytest
from fastapi.testclient import TestClient
from sqlalchemy.exc import SQLAlchemyError

from models import Todo
from tests.fakes import FakeSession


@pytest.mark.parametrize(
        "invalid_task",
        [
            "",
            "   ",
            "a" * 201,
        ],
)
def test_create_todo_rejects_invalid_task(
        client: TestClient,
        invalid_task:str,
    ) -> None:
    response = client.post(
        "/todos",
        json={"task": invalid_task},
    )

    assert response.status_code == 422

def test_create_todo_rejects_missing_task(
        client: TestClient,
    ) -> None:
    response = client.post(
        "/todos",
        json={},
    )

    assert response.status_code == 422

    error = response.json()["detail"][0]

    assert error["loc"] == ["body", "task"]
    assert error["type"] == "missing"

def test_create_todo_success(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    response = client.post(
        "/todos",
        json={"task": "学习单元测试"},
    )

    assert response.status_code == 200
    assert response.json() == {
            "id": 1,
            "task": "学习单元测试",
            "completion": False,
        }
    assert fake_session.committed is True
    assert fake_session.added_todo.task == "学习单元测试"
            
def test_patch_missing_todo_returns_404(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = None

    response = client.patch(
        "/todos/999",
        json={"task": "修改后的任务"},
    )

    assert response.status_code == 404
    assert response.json() == {
        "detail": "Todo not found",
    }
    assert fake_session.committed is False
    assert fake_session.rolled_back is False

def test_patch_existing_todo_updates_task(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="旧任务",
        completion=False,
    )

    response = client.patch(
        "/todos/1",
        json={"task": "新任务"},
    )

    assert response.status_code == 200
    assert response.json() == {
            "id": 1,
            "task": "新任务",
            "completion": False,
        }
    assert fake_session.committed is True
    assert fake_session.todo_to_return.task == "新任务"

def test_patch_existing_todo_updates_completion_only(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="保留原任务",
        completion=False,
    )

    response = client.patch(
        "/todos/1",
        json={"completion": True},
    )

    assert response.status_code == 200
    assert response.json() == {
            "id": 1,
            "task": "保留原任务",
            "completion": True,
        }
    assert fake_session.committed is True
    assert fake_session.todo_to_return.task == "保留原任务"
    assert fake_session.todo_to_return.completion is True

def test_delete_existing_todo_success(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    existing_todo = Todo(
        id=1,
        task="准备删除的任务",
        completion=False,
    )
    fake_session.todo_to_return = existing_todo

    response = client.delete("/todos/1")

    assert response.status_code == 200
    assert response.json() == {
            "id": 1,
            "task": "准备删除的任务",
            "completion": False,
        }
    assert fake_session.committed is True
    assert fake_session.deleted_todo is existing_todo

def test_delete_missing_todo_returns_404(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    response = client.delete("/todos/999")

    assert response.status_code == 404
    assert response.json() == {
        "detail": "Todo not found",
    }

    assert fake_session.deleted_todo is None
    assert fake_session.committed is False

def test_create_todo_rolls_back_when_commit_fails(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.should_fail_commit = True

    with pytest.raises(SQLAlchemyError):
        client.post(
            "/todos",
            json={"task": "会提交失败的任务"},
        )

    assert fake_session.rolled_back is True
    assert fake_session.committed is False

def test_patch_todo_rolls_back_when_commit_fails(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="旧任务",
        completion=False,
    )
    fake_session.should_fail_commit = True

    with pytest.raises(SQLAlchemyError):
        client.patch(
            "/todos/1",
            json={"task": "新任务"},
        )

    assert fake_session.rolled_back is True
    assert fake_session.committed is False

def test_delete_todo_rolls_back_when_commit_fails(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    existing_todo = Todo(
        id=1,
        task="准备删除的任务",
        completion=False,
    )
    fake_session.todo_to_return = existing_todo
    fake_session.should_fail_commit = True

    with pytest.raises(SQLAlchemyError):
        client.delete("/todos/1")

    assert fake_session.deleted_todo is existing_todo
    assert fake_session.rolled_back is True
    assert fake_session.committed is False

def test_get_todos_returns_todo_list(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todos_to_return = [
        Todo(
            id=1,
            task="学习单元测试",
            completion=False,
        ),
        Todo(
            id=2,
            task="完成接口测试",
            completion=True,
        ),
    ]

    response = client.get("/todos")

    assert response.status_code == 200
    assert response.json() == [
        {
            "id": 1,
            "task": "学习单元测试",
            "completion": False,
        },
        {
            "id": 2,
            "task": "完成接口测试",
            "completion": True,
        },
    ]

def test_get_todos_returns_empty_list(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todos_to_return = []

    response = client.get("/todos")

    assert response.status_code == 200
    assert response.json() == []

@pytest.mark.parametrize(
    "invalid_task",
    [
        "",
        "   ",
        "a" * 201,
    ],
)
def test_patch_todo_rejects_invalid_task(
    client: TestClient,
    fake_session: FakeSession,
    invalid_task: str,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="原任务",
        completion=False,
    )

    response = client.patch(
        "/todos/1",
        json={"task": invalid_task},
    )

    assert response.status_code == 422

def test_patch_todo_rejects_empty_body(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="原任务",
        completion=False,
    )

    response = client.patch(
        "/todos/1",
        json={},
    )

    assert response.status_code == 422
    assert fake_session.committed is False

def test_patch_todo_accepts_completion_false(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    fake_session.todo_to_return = Todo(
        id=1,
        task="已有任务",
        completion=True,
    )

    response = client.patch(
        "/todos/1",
        json={"completion": False},
    )

    assert response.status_code == 200
    assert fake_session.todo_to_return.completion is False
    assert response.json()["completion"] is False
    assert fake_session.committed is True

def test_patch_todo_updates_task_and_completion(
    client: TestClient,
    fake_session: FakeSession,
) -> None:
    existing_todo = Todo(
        id=1,
        task="原任务",
        completion=False,
    )
    fake_session.todo_to_return = existing_todo

    response = client.patch(
        "/todos/1",
        json={
            "task": "修改后的任务",
            "completion": True,
        },
    )

    assert response.status_code == 200
    assert response.json() == {
            "id": 1,
            "task": "修改后的任务",
            "completion": True,
        }
    assert existing_todo.task == "修改后的任务"
    assert existing_todo.completion is True
    assert fake_session.committed is True