from __future__ import annotations

from datetime import UTC, datetime, timedelta
from uuid import uuid4

import pytest

from app.domain import InvalidTransitionError, complete_task, start_task
from app.storage import StoredTask


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


def test_start_task_from_backlog_sets_started_at():
    task = make_task(started_at=None, done_at=None)
    before_call = datetime.now(UTC)

    result = start_task(task)

    after_call = datetime.now(UTC)

    assert result.id == task.id
    assert result.title == task.title
    assert result.created_at == task.created_at
    assert result.done_at is None
    assert result.started_at is not None
    assert before_call <= result.started_at <= after_call


def test_start_task_is_idempotent_for_already_started_task():
    started_at = datetime.now(UTC) - timedelta(minutes=5)
    task = make_task(started_at=started_at, done_at=None)

    result = start_task(task)

    assert result == task
    assert result.started_at == started_at


def test_start_task_raises_for_completed_task():
    started_at = datetime.now(UTC) - timedelta(minutes=10)
    done_at = datetime.now(UTC) - timedelta(minutes=1)
    task = make_task(started_at=started_at, done_at=done_at)

    with pytest.raises(InvalidTransitionError, match="invalid_transaction"):
        start_task(task)


def test_complete_task_from_in_progress_sets_done_at():
    started_at = datetime.now(UTC) - timedelta(minutes=10)
    task = make_task(started_at=started_at, done_at=None)
    before_call = datetime.now(UTC)

    result = complete_task(task)

    after_call = datetime.now(UTC)

    assert result.id == task.id
    assert result.title == task.title
    assert result.created_at == task.created_at
    assert result.started_at == started_at
    assert result.done_at is not None
    assert result.started_at <= result.done_at
    assert before_call <= result.done_at <= after_call


def test_complete_task_is_idempotent_for_already_completed_task():
    started_at = datetime.now(UTC) - timedelta(minutes=10)
    done_at = datetime.now(UTC) - timedelta(minutes=1)
    task = make_task(started_at=started_at, done_at=done_at)

    result = complete_task(task)

    assert result == task
    assert result.done_at == done_at


def test_complete_task_raises_for_backlog_task():
    task = make_task(started_at=None, done_at=None)

    with pytest.raises(InvalidTransitionError, match="invalid_transaction"):
        complete_task(task)