"""快照与正交维度模型的不变量。

重点覆盖那些"容易被合并成单一状态枚举"的维度：进度、失败原因、请求动作。
"""

from __future__ import annotations

import dataclasses
from datetime import UTC, datetime

import pytest

from chongming_task.models import (
    AttemptRecord,
    Failure,
    FailureKind,
    Progress,
    RequestedAction,
    TaskSnapshot,
    TimeoutScope,
)
from chongming_task.states import TaskStatus


def test_progress_fraction_is_none_when_total_unknown() -> None:
    """total 未知必须返回 None 而非 0.0——后者会被渲染成"尚未开始"。"""
    assert Progress(done=5).fraction is None
    assert Progress(done=0, total=0).fraction is None
    assert Progress(done=25, total=100).fraction == 0.25


def test_progress_rejects_done_beyond_total() -> None:
    with pytest.raises(ValueError, match="不能超过"):
        Progress(done=11, total=10)


def test_progress_rejects_negative_values() -> None:
    with pytest.raises(ValueError, match="不能为负"):
        Progress(done=-1)
    with pytest.raises(ValueError, match="不能为负"):
        Progress(total=-1)


def test_timeout_scope_maps_to_failure_kind() -> None:
    """超时是失败原因而非生命周期状态，两者的对应关系必须稳定。"""
    assert FailureKind.for_timeout(TimeoutScope.START) is FailureKind.TIMEOUT_START
    assert FailureKind.for_timeout(TimeoutScope.ATTEMPT) is FailureKind.TIMEOUT_ATTEMPT
    assert FailureKind.for_timeout(TimeoutScope.IDLE) is FailureKind.TIMEOUT_IDLE


def test_attempt_record_numbering_starts_at_one() -> None:
    now = datetime(2026, 1, 1, tzinfo=UTC)
    with pytest.raises(ValueError, match="从 1 开始"):
        AttemptRecord(task_id="t1", attempt=0, started_at=now)


def test_snapshot_requires_identity() -> None:
    with pytest.raises(ValueError, match="task_id"):
        TaskSnapshot(task_id="", name="x")
    with pytest.raises(ValueError, match="name"):
        TaskSnapshot(task_id="t1", name="")


def test_snapshot_rejects_attempt_beyond_max_attempts() -> None:
    with pytest.raises(ValueError, match="max_attempts"):
        TaskSnapshot(task_id="t1", name="x", attempt=3, max_attempts=2)


def test_snapshot_is_frozen() -> None:
    """快照不可变，才能安全跨线程/协程传递并直接作为持久化记录。"""
    snap = TaskSnapshot(task_id="t1", name="x")
    with pytest.raises(dataclasses.FrozenInstanceError):
        snap.status = TaskStatus.RUNNING  # type: ignore[misc]


def test_validate_flags_terminal_missing_ended_at() -> None:
    snap = TaskSnapshot(task_id="t1", name="x", status=TaskStatus.SUCCEEDED)
    assert any("ended_at" in problem for problem in snap.validate())


def test_validate_flags_leftover_requested_action_on_terminal() -> None:
    """终态残留请求会让 UI 永远显示"停止中"。"""
    now = datetime(2026, 1, 1, tzinfo=UTC)
    snap = TaskSnapshot(
        task_id="t1",
        name="x",
        status=TaskStatus.STOPPED,
        ended_at=now,
        requested_action=RequestedAction.STOP,
    )
    assert any("requested_action" in problem for problem in snap.validate())


def test_retry_wait_may_carry_failure() -> None:
    """RETRY_WAIT 必须能携带上次失败原因，否则界面无法回答"它为什么在等"。"""
    snap = TaskSnapshot(
        task_id="t1",
        name="x",
        status=TaskStatus.RETRY_WAIT,
        failure=Failure(kind=FailureKind.EXCEPTION, message="boom"),
    )
    assert snap.validate() == ()


def test_retry_wait_without_failure_is_inconsistent() -> None:
    snap = TaskSnapshot(task_id="t1", name="x", status=TaskStatus.RETRY_WAIT)
    assert any("RETRY_WAIT" in problem for problem in snap.validate())


def test_success_must_not_carry_failure() -> None:
    now = datetime(2026, 1, 1, tzinfo=UTC)
    snap = TaskSnapshot(
        task_id="t1",
        name="x",
        status=TaskStatus.SUCCEEDED,
        ended_at=now,
        failure=Failure(kind=FailureKind.EXCEPTION, message="boom"),
    )
    assert any("SUCCEEDED" in problem for problem in snap.validate())


def test_consistent_terminal_snapshot_validates_clean() -> None:
    now = datetime(2026, 1, 1, tzinfo=UTC)
    snap = TaskSnapshot(
        task_id="t1",
        name="x",
        status=TaskStatus.FAILED,
        ended_at=now,
        attempt=1,
        max_attempts=1,
        failure=Failure(kind=FailureKind.EXCEPTION, message="boom"),
    )
    assert snap.validate() == ()
    assert snap.is_terminal
    assert snap.is_revivable


def test_running_snapshot_requires_started_at_only_on_validate() -> None:
    """时间线完整性刻意不放在 __post_init__，以免逐步构造快照时处处受限。"""
    snap = TaskSnapshot(task_id="t1", name="x", status=TaskStatus.RUNNING)
    assert any("started_at" in problem for problem in snap.validate())
    # 但构造本身不报错
    assert snap.status is TaskStatus.RUNNING