# -*- coding: utf-8 -*-
"""单曲下载 worker 的行为契约测试（沙箱，不触碰生产 data/）。

为什么：``services/downloads.py::_single_download_worker`` 是单曲下载的**唯一**后台
执行路径（``/download`` 的 file 模式走 ``start_task`` 启动它），177 行 / 圈复杂度 30，
此前**零测试覆盖**。它的三个 except 分支各写一遍「结算 + 删任务目录」，正文里又散着
四处取消检查——改坏任意一处都不会有测试报警。

按惯例：**先在未改动的原始实现上跑绿**，这批测试因此忠实编码了旧行为，重构时本身
即等价性验证器。断言只依赖「调用 worker 后世界里发生了什么」（任务终态、磁盘上的
文件、ZIP 内容、账本行、余额），不引用任何内部函数名，故可跨后续重构复用。

账本口径：一律用 ``reserve_and_open`` 真预扣（``ledger_open`` 只记账不扣款，
会让「退款」凭空给余额加次数，守恒断言就失去意义）。
"""
import asyncio
import threading
import time
import zipfile
from pathlib import Path
from typing import Any

import pytest

import auth_system as auth
import core.db as core_db
from core.state import DOWNLOAD_TASKS, DOWNLOAD_TASKS_LOCK
from music_downloader import DownloadCanceled, DownloadResult, MusicInfo
from services import downloads as downloads_svc
from services.api_service import api_service

PW = 'Passw0rd12'
CREDITS = 50


# ============ 测试替身 ============

class _NullLogger:
    """吞掉 api_service.logger 输出，避免测试往项目根 music_api.log 追加。"""

    def debug(self, *a: Any, **k: Any) -> None: ...
    def info(self, *a: Any, **k: Any) -> None: ...
    def warning(self, *a: Any, **k: Any) -> None: ...
    def error(self, *a: Any, **k: Any) -> None: ...


class _FakeDownloader:
    """可编程下载器替身。

    ``on_download`` 在 ``download_music_file`` 内部被调用，拿到调用时的 kwargs，
    用于在「下载中途」注入取消 / 调用进度回调 / 抛异常。
    ``info_error`` 让 ``get_music_info`` 抛异常（验证未知异常路径）。
    """

    def __init__(self, cache_dir: Path, *, download_ok: bool = True,
                 info_error: Exception | None = None,
                 on_download: Any = None, lyric: str = '[00:01.00]第一行\n[00:02.00]第二行'):
        self.cache_dir = cache_dir
        self.download_ok = download_ok
        self.info_error = info_error
        self.on_download = on_download
        self.lyric = lyric
        self.info_calls = 0
        self.download_calls = 0

    async def get_music_info(self, mid: Any, quality: str, cookies: Any) -> MusicInfo:
        self.info_calls += 1
        if self.info_error is not None:
            raise self.info_error
        return MusicInfo(
            id=int(mid), name='歌名X', artists='歌手A', album='专辑A',
            pic_url='https://pic.example/x.jpg', duration=200, track_number=1,
            download_url='', file_type='mp3', file_size=1024,
            quality='standard', lyric=self.lyric,
        )

    async def download_music_file(self, mid: Any, quality: str, **kw: Any) -> DownloadResult:
        self.download_calls += 1
        if self.on_download is not None:
            self.on_download(kw)
        cancel_ev = kw.get('cancel_event')
        if cancel_ev is not None and cancel_ev.is_set():
            raise DownloadCanceled('任务已取消')
        if not self.download_ok:
            return DownloadResult(success=False, error_message='上游 404')
        path = self.cache_dir / f'{mid}.mp3'
        path.write_bytes(b'ID3\x03\x00\x00\x00' + b'\x00' * 64)
        return DownloadResult(success=True, file_path=str(path),
                              file_size=path.stat().st_size, music_info=kw.get('music_info'))


# ============ 沙箱 ============

@pytest.fixture()
def sandbox(tmp_path, monkeypatch):
    """临时站点库 + 临时下载目录 + 空任务表。"""
    db_path = tmp_path / 'site.db'
    monkeypatch.setattr(auth.db, 'DATA_DIR', tmp_path)
    monkeypatch.setattr(auth.db, 'DB_PATH', db_path)
    monkeypatch.setattr(auth.db, 'BACKUP_DIR', tmp_path / 'backups')
    monkeypatch.setattr(auth.db, 'SECRET_KEY_PATH', tmp_path / 'secret.key')
    monkeypatch.setattr(core_db, 'DATA_DIR', tmp_path)
    monkeypatch.setattr(core_db, 'DB_PATH', db_path)
    asyncio.run(auth.init_db())
    asyncio.run(auth.create_user('payer', PW, email='p@example.com', credits=CREDITS))

    downloads = tmp_path / 'downloads'
    downloads.mkdir()
    cache = downloads / 'cache'
    cache.mkdir()
    monkeypatch.setattr(api_service, 'downloads_path', downloads)
    monkeypatch.setattr(api_service, 'logger', _NullLogger())
    # 封面走网络——测试里默认返回固定字节，个例可覆盖
    async def _cover(_url: str) -> bytes:
        return b'\xff\xd8\xff cover'

    monkeypatch.setattr(downloads_svc, 'fetch_cover_bytes', _cover)
    # 操作记录写进程内共享列表——隔离掉，断言改由个例捕获
    monkeypatch.setattr(downloads_svc, '_record_log', lambda *a: None)

    with DOWNLOAD_TASKS_LOCK:
        DOWNLOAD_TASKS.clear()
    yield {'root': tmp_path, 'downloads': downloads, 'cache': cache}
    with DOWNLOAD_TASKS_LOCK:
        DOWNLOAD_TASKS.clear()


# ============ 工具 ============

def _uid(username: str = 'payer') -> int:
    u = asyncio.run(auth.get_user_by_name(username))
    assert u is not None
    return int(u['id'])


def _balance(username: str = 'payer') -> int:
    u = asyncio.run(auth.get_user_by_name(username))
    assert u is not None
    return int(u['duration_seconds'] or 0)


def _status(task_id: str) -> str:
    with DOWNLOAD_TASKS_LOCK:
        return str(DOWNLOAD_TASKS.get(task_id, {}).get('status') or '')


def _register_single(sandbox, *, music_id: int = 1, user_id: int,
                     reserved: int = 1, **params: Any) -> tuple[str, dict[str, Any]]:
    tid = 's' + str(int(time.time() * 1000000) % 10 ** 10)
    # reserve_and_open：真预扣 + 开账同事务（ledger_open 只记账不扣款，见模块 docstring）
    left = asyncio.run(auth.reserve_and_open(user_id, reserved, tid))
    assert left is not None, '预扣失败（余额不足，检查 fixture 的 credits）'
    task: dict[str, Any] = {
        'type': 'single', 'task_id': tid,
        'user_id': user_id, 'billing_user_id': user_id, 'billing_reserved': reserved,
        'total': 1, 'done': 0, 'failed': 0,
        'status': 'queued', 'start': time.time(), 'msg': '排队中...',
        'cancel': threading.Event(), 'pause': threading.Event(),
        'device_id': 'dev-test', 'result': None,
        'params': {
            'music_id': music_id, 'quality': 'standard',
            'filename_format': 'artist_song', 'write_meta': False,
            'meta_fields': None, 'lyric_format': 'lrc',
            'need_zip': False, 'cookies': {}, 'remote_ip': '1.2.3.4',
            **params,
        },
    }
    with DOWNLOAD_TASKS_LOCK:
        DOWNLOAD_TASKS[tid] = task
    return tid, task


def _run(task_id: str) -> threading.Thread:
    """把 worker 协程跑在独立线程的私有事件循环里（等价于生产的任务循环）。"""
    def _target() -> None:
        asyncio.run(downloads_svc._single_download_worker(task_id))

    th = threading.Thread(target=_target, daemon=True)
    th.start()
    return th


def _zip_names(path: str) -> list[str]:
    with zipfile.ZipFile(path) as zf:
        return zf.namelist()


# ============ 正常路径 ============

def test_single_download_completes(sandbox, monkeypatch):
    """常规单曲（不打包）：终态 done、交付文件落在任务目录、账本按交付结算。"""
    uid = _uid()
    before = _balance()
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    tid, task = _register_single(sandbox, music_id=101, user_id=uid)

    th = _run(tid)
    th.join(timeout=30)
    assert not th.is_alive(), 'worker 未在 30s 内结束'

    assert _status(tid) == 'done', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['msg'] == '下载完成'
    assert task['done'] == 1 and task['completed_at'] > 0
    res = task['result']
    assert res is not None
    assert res['filename'] == '歌手A - 歌名X.mp3'
    assert res['mimetype'] == 'audio/mp3'
    assert res['audio_files'] == [res['file_path']]
    assert 'zip_path' not in res

    # 交付副本在 tasks/<tid>/ 下，与共享缓存分离
    delivered = Path(res['file_path'])
    assert delivered.exists()
    assert delivered.parent == sandbox['downloads'] / 'tasks' / tid
    assert delivered.read_bytes() == (sandbox['cache'] / '101.mp3').read_bytes()
    assert (sandbox['cache'] / '101.mp3').exists(), '共享缓存不应被搬走'

    row = asyncio.run(auth.ledger_get(tid))
    assert row is not None and row['status'] != 'open'
    assert row['delivered'] == 1
    assert _balance() == before - 1, '交付成功：只扣预扣的 1 次，无退款'


def test_single_zip_contains_audio_lyric_cover_and_info(sandbox, monkeypatch):
    """zip=true：包内含音频 + 歌词 + 封面 + info.txt（信息栏四行）。"""
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    tid, task = _register_single(sandbox, music_id=102, user_id=uid, need_zip=True)

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done', f"终态={_status(tid)} msg={task.get('msg')}"
    res = task['result']
    assert res is not None
    assert res['filename'] == '歌手A - 歌名X.zip'
    assert res['mimetype'] == 'application/zip'
    names = sorted(_zip_names(res['zip_path']))
    assert names == ['info.txt', '歌手A - 歌名X.jpg', '歌手A - 歌名X.lrc', '歌手A - 歌名X.mp3'], names

    with zipfile.ZipFile(res['zip_path']) as zf:
        info = zf.read('info.txt').decode('utf-8')
    assert '歌曲: 歌名X' in info
    assert '歌手: 歌手A' in info
    assert '专辑: 专辑A' in info
    assert info.startswith('歌曲: ')


def test_single_zip_lyric_format_srt(sandbox, monkeypatch):
    """lyric_format=srt：歌词条目扩展名随之改变。"""
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    tid, task = _register_single(sandbox, music_id=103, user_id=uid,
                                 need_zip=True, lyric_format='srt')
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done'
    assert '歌手A - 歌名X.srt' in _zip_names(task['result']['zip_path'])


def test_empty_lyric_skips_lyric_entry(sandbox, monkeypatch):
    """上游无歌词（mi.lyric 为空）：不写歌词条目，其余照常。"""
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], lyric=''))
    tid, task = _register_single(sandbox, music_id=104, user_id=uid, need_zip=True)
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done'
    names = _zip_names(task['result']['zip_path'])
    assert not [n for n in names if n.endswith('.lrc')], names
    assert [n for n in names if n.endswith('.mp3')], names


def test_cover_failure_keeps_zip_without_cover(sandbox, monkeypatch):
    """取封面失败：ZIP 仍发布，只是没有封面条目（封面非交付必要条件）。

    注意 ``fetch_cover_bytes`` 的契约是**失败返回 None**（内部已 except Exception），
    所以这里注入的是返回 None，不是抛异常——后者是不存在的形状。
    """
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))

    async def _no_cover(_url: str) -> None:
        return None

    monkeypatch.setattr(downloads_svc, 'fetch_cover_bytes', _no_cover)
    tid, task = _register_single(sandbox, music_id=105, user_id=uid, need_zip=True)
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done', f"终态={_status(tid)} msg={task.get('msg')}"
    names = _zip_names(task['result']['zip_path'])
    assert not [n for n in names if n.endswith('.jpg')], names


def test_filename_format_song_only(sandbox, monkeypatch):
    """filename_format=song：交付名只用歌名。"""
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    tid, task = _register_single(sandbox, music_id=106, user_id=uid,
                                 filename_format='song')
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done'
    assert task['result']['filename'] == '歌名X.mp3'


def test_record_log_gets_song_name(sandbox, monkeypatch):
    """成功交付后按歌名记一条操作记录（IP 取 params.remote_ip）。"""
    uid = _uid()
    logs: list[tuple] = []
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    monkeypatch.setattr(downloads_svc, '_record_log', lambda *a: logs.append(a))
    tid, _ = _register_single(sandbox, music_id=107, user_id=uid)
    th = _run(tid)
    th.join(timeout=30)

    assert logs == [('下载', '1.2.3.4', '歌名X')], logs


def test_remote_ip_defaults_when_missing(sandbox, monkeypatch):
    """params 无 remote_ip：按 '-' 记录，不因缺字段报错。"""
    uid = _uid()
    logs: list[tuple] = []
    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    monkeypatch.setattr(downloads_svc, '_record_log', lambda *a: logs.append(a))
    tid, task = _register_single(sandbox, music_id=108, user_id=uid)
    del task['params']['remote_ip']
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done'
    assert logs == [('下载', '-', '歌名X')]


# ============ 失败与取消 ============

def test_download_failure_marks_error_and_refunds(sandbox, monkeypatch):
    """下载器返回 success=False：转 error、全额退回预扣、任务目录不残留。"""
    uid = _uid()
    before = _balance()
    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], download_ok=False))
    tid, task = _register_single(sandbox, music_id=201, user_id=uid)

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'error', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['msg'] == '上游 404'
    assert task['result'] is None
    assert _balance() == before, '失败应全额退回预扣'
    row = asyncio.run(auth.ledger_get(tid))
    assert row is not None and row['delivered'] == 0 and row['status'] != 'open'
    assert not (sandbox['downloads'] / 'tasks' / tid).exists(), '失败应清掉任务目录'


def test_unexpected_exception_uses_generic_message(sandbox, monkeypatch):
    """非预期异常：用户可见文案泛化（不泄上游细节），原文进日志、余额退回。"""
    uid = _uid()
    before = _balance()
    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'],
                                        info_error=RuntimeError('upstream host=10.0.0.9 refused')))
    tid, task = _register_single(sandbox, music_id=202, user_id=uid)

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'error', f"终态={_status(tid)}"
    assert task['msg'] == '下载失败，请稍后重试'
    assert '10.0.0.9' not in task['msg'], '上游细节不得出现在用户可见文案里'
    assert _balance() == before
    assert not (sandbox['downloads'] / 'tasks' / tid).exists()


def test_cancel_mid_download(sandbox, monkeypatch):
    """下载中被取消：worker 收敛 canceled、全额退费、任务目录清掉。"""
    uid = _uid()
    before = _balance()
    holder: dict[str, Any] = {}

    def _cancel_inside(kw):
        holder['task']['cancel'].set()

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_cancel_inside))
    tid, task = _register_single(sandbox, music_id=203, user_id=uid)
    holder['task'] = task

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'canceled', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['msg'] == '任务已取消'
    assert task['result'] is None
    assert _balance() == before, '取消应全额退回预扣'
    row = asyncio.run(auth.ledger_get(tid))
    assert row is not None and row['delivered'] == 0
    assert not (sandbox['downloads'] / 'tasks' / tid).exists()


def test_cancel_after_download_before_publish(sandbox, monkeypatch):
    """下载已落盘但取消已置位：不发布交付（不发布 result），转 canceled 并退费。"""
    uid = _uid()
    before = _balance()
    holder: dict[str, Any] = {}

    def _cancel_after(kw):
        # 下载返回之后再置位——命中「下载完成后的取消检查」
        def _later():
            holder['task']['cancel'].set()

        threading.Timer(0.0, _later).start()

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_cancel_after))
    tid, task = _register_single(sandbox, music_id=204, user_id=uid)
    holder['task'] = task

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'canceled', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['result'] is None, '取消后不得发布交付'
    assert _balance() == before
    assert not (sandbox['downloads'] / 'tasks' / tid).exists()


def test_cancel_during_zip_stage(sandbox, monkeypatch):
    """打包阶段被取消：ZIP 不发布、转 canceled、退费。"""
    uid = _uid()
    before = _balance()
    holder: dict[str, Any] = {}

    def _cancel_after(kw):
        threading.Timer(0.0, lambda: holder['task']['cancel'].set()).start()

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_cancel_after))
    tid, task = _register_single(sandbox, music_id=205, user_id=uid, need_zip=True)
    holder['task'] = task

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'canceled', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['result'] is None
    assert _balance() == before
    assert not (sandbox['downloads'] / 'tasks' / tid).exists()


def test_terminal_state_not_overwritten_by_late_success(sandbox, monkeypatch):
    """任务已被外部置终态（canceled）时，worker 的成功路径不得覆盖为 done。"""
    uid = _uid()
    before = _balance()
    holder: dict[str, Any] = {}

    def _mark_canceled(kw):
        with DOWNLOAD_TASKS_LOCK:
            holder['task']['status'] = 'canceled'
            holder['task']['completed_at'] = time.time()

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_mark_canceled))
    tid, task = _register_single(sandbox, music_id=206, user_id=uid)
    holder['task'] = task

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'canceled', f"终态={_status(tid)}"
    assert task['result'] is None, '已终态不得被覆盖为 done'
    assert _balance() == before


# ============ 进度上报 ============

def test_progress_callback_writes_live_percent(sandbox, monkeypatch):
    """进度回调写 live_percent 与「下载中 x% · 已收/总量」文案。"""
    uid = _uid()
    seen: dict[str, Any] = {}

    def _emit_progress(kw):
        cb = kw.get('progress_cb')
        if cb is not None:
            cb(512, 1024)
            with DOWNLOAD_TASKS_LOCK:
                t = DOWNLOAD_TASKS.get(seen['tid']) or {}
                seen['live'] = t.get('live_percent')
                seen['msg'] = t.get('msg')

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_emit_progress))
    tid, _task = _register_single(sandbox, music_id=301, user_id=uid)
    seen['tid'] = tid

    th = _run(tid)
    th.join(timeout=30)

    assert seen.get('live') == 50.0, seen
    assert '下载中 50%' in str(seen.get('msg')), seen
    assert _status(tid) == 'done', '进度上报不应影响最终交付'


def test_progress_callback_without_total_uses_received_bytes(sandbox, monkeypatch):
    """总量未知：文案退化为「已接收 <大小>」，不写 live_percent。"""
    uid = _uid()
    seen: dict[str, Any] = {}

    def _emit_progress(kw):
        cb = kw.get('progress_cb')
        if cb is not None:
            cb(2048, 0)
            with DOWNLOAD_TASKS_LOCK:
                t = DOWNLOAD_TASKS.get(seen['tid']) or {}
                seen['live'] = t.get('live_percent')
                seen['msg'] = t.get('msg')

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_emit_progress))
    tid, _task = _register_single(sandbox, music_id=302, user_id=uid)
    seen['tid'] = tid

    th = _run(tid)
    th.join(timeout=30)

    assert '已接收' in str(seen.get('msg')), seen
    assert seen.get('live') is None, seen


def test_progress_callback_errors_do_not_break_download(sandbox, monkeypatch):
    """进度回调自身抛错：被吞掉，下载照常完成。"""
    uid = _uid()

    def _bad_progress(kw):
        cb = kw.get('progress_cb')
        if cb is not None:
            # 回调内部访问非法对象——必须被 except 吞掉
            cb('not-a-number', None)

    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'], on_download=_bad_progress))
    tid, task = _register_single(sandbox, music_id=303, user_id=uid)
    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done', f"终态={_status(tid)} msg={task.get('msg')}"


# ============ 结算兜底 ============

def test_settle_failure_does_not_flip_done_to_error(sandbox, monkeypatch):
    """交付已落定后结算抛错：任务仍为 done（钱由重启对账兜底，不坑已付费用户）。"""
    uid = _uid()

    def _boom(*a, **k):
        raise RuntimeError('库锁超时')

    monkeypatch.setattr(api_service, 'downloader', _FakeDownloader(sandbox['cache']))
    monkeypatch.setattr(downloads_svc.auth_system, 'ledger_settle', _boom)
    tid, task = _register_single(sandbox, music_id=401, user_id=uid)

    th = _run(tid)
    th.join(timeout=30)

    assert _status(tid) == 'done', f"终态={_status(tid)} msg={task.get('msg')}"
    assert task['result'] is not None


def test_ledger_open_when_worker_crashes_before_settle(sandbox, monkeypatch):
    """worker 在结算前崩掉：账本行仍为 open（留给重启对账兜底，不是静默丢失）。"""
    uid = _uid()
    monkeypatch.setattr(api_service, 'downloader',
                        _FakeDownloader(sandbox['cache'],
                                        info_error=RuntimeError('boom')))
    tid, _ = _register_single(sandbox, music_id=402, user_id=uid)

    # 让结算也失败，模拟「连退款都没走成」的极端情况
    monkeypatch.setattr(downloads_svc.auth_system, 'ledger_settle',
                        lambda *a, **k: (_ for _ in ()).throw(RuntimeError('db busy')))
    th = _run(tid)
    th.join(timeout=30)

    row = asyncio.run(auth.ledger_get(tid))
    assert row is not None
    assert row['status'] == 'open', f"应留给对账兜底，实际 status={row['status']}"