from __future__ import annotations

import json
from datetime import UTC, datetime
from pathlib import Path
from uuid import uuid4

import pytest

from app.storage import DATA_FORMAT_VERSION, StoredTask
from app.storage.repository import JsonFileTaskRepository


def make_task(title: str = "Task") -> StoredTask:
    return StoredTask(
        id=uuid4(),
        title=title,
        created_at=datetime.now(UTC),
        started_at=None,
        done_at=None,
    )


def test_interrupted_save_before_rename_keeps_original_data_intact(tmp_path, monkeypatch):
    file_path = tmp_path / "tasks.json"
    repo = JsonFileTaskRepository(file_path)
    original_task = make_task("Original")
    repo.create_task(original_task)

    replacement_called = False
    real_replace = Path.replace

    def failing_replace(self: Path, target: Path):
        nonlocal replacement_called
        replacement_called = True
        raise RuntimeError("simulated crash before rename")

    monkeypatch.setattr(Path, "replace", failing_replace)

    with pytest.raises(RuntimeError, match="simulated crash before rename"):
        repo.create_task(make_task("New task"))

    assert replacement_called is True

    reloaded_repo = JsonFileTaskRepository(file_path)
    assert reloaded_repo.list_tasks() == [original_task]

    tmp_file = tmp_path / "tasks.json.tmp"
    assert tmp_file.exists()

    monkeypatch.setattr(Path, "replace", real_replace)


def test_normal_save_replaces_file_with_complete_payload(tmp_path):
    file_path = tmp_path / "tasks.json"
    repo = JsonFileTaskRepository(file_path)
    task_1 = make_task("One")
    task_2 = make_task("Two")

    repo.create_task(task_1)
    repo.create_task(task_2)

    payload = json.loads(file_path.read_text(encoding="utf-8"))

    assert payload["version"] == DATA_FORMAT_VERSION
    assert len(payload["tasks"]) == 2
    assert {item["id"] for item in payload["tasks"]} == {str(task_1.id), str(task_2.id)}


def test_stale_tmp_file_does_not_break_startup(tmp_path):
    file_path = tmp_path / "tasks.json"
    repo_1 = JsonFileTaskRepository(file_path)
    task = make_task("Persisted")
    repo_1.create_task(task)

    stale_tmp = tmp_path / "tasks.json.tmp"
    stale_tmp.write_text('{"version": 999, "tasks": "broken"}', encoding="utf-8")

    repo_2 = JsonFileTaskRepository(file_path)

    assert repo_2.list_tasks() == [task]
    assert stale_tmp.exists()