# -*- coding: utf-8 -*-
"""aria2 下载后端的单元测试（用假 api 驱动，不需要真实 aria2c 二进制）。

覆盖：
- aria2c 缺失时 get_backend 静默降级且失败结果被记忆
- 正常完成路径的进度回调与自动清理
- 取消 / 体积超限 连带删除残片；任务失败 / 总超时 保留残片供续传
- 提交失败与 RPC 抖动统一上报为可重试异常
"""
from __future__ import annotations

import threading

import pytest

import music_downloader._aria2 as a2
from core.sync_http import RequestException
from music_downloader import DownloadCanceled, DownloadException


class _FakeDownload:
    """按预设步进产出状态，模拟 aria2 的 tellStatus 轮询。"""

    def __init__(self, steps):
        self.gid = 'g1'
        self._steps = list(steps)
        self._i = 0
        self.completed_length = 0
        self.total_length = 100
        self.is_complete = False
        self.has_failed = False
        self.error_message = ''
        self.status = 'active'

    def update(self):
        idx = min(self._i, len(self._steps) - 1)
        done, complete, failed = self._steps[idx]
        self._i += 1
        self.completed_length = done
        self.is_complete = complete
        self.has_failed = failed
        if failed:
            self.status = 'error'
            self.error_message = 'boom'


class _FakeAPI:
    def __init__(self, download, fail_submit=False, fail_update=False):
        self.download = download
        self.removed: list[tuple[str, bool, bool]] = []
        self.submitted: tuple[list[str], dict[str, str]] | None = None
        self._fail_submit = fail_submit
        self._fail_update = fail_update

    def add_uris(self, uris, options=None):
        if self._fail_submit:
            raise RuntimeError('rpc down')
        self.submitted = (list(uris), options or {})
        return self.download

    def remove(self, downloads, force=False, files=False):
        self.removed.append((downloads[0].gid, force, files))


class _FailUpdateDownload(_FakeDownload):
    def update(self):
        raise RuntimeError('rpc jitter')


class _FakeProc:
    def poll(self):
        return 0

    def terminate(self):
        pass

    def kill(self):
        pass

    def wait(self, timeout=None):
        return 0


def _backend(monkeypatch, steps, **kw):
    monkeypatch.setattr(a2.time, 'sleep', lambda _s: None)
    dl = _FailUpdateDownload([]) if kw.get('fail_update') else _FakeDownload(steps)
    api = _FakeAPI(dl, fail_submit=kw.get('fail_submit', False))
    return a2.Aria2Backend(api, _FakeProc(), 6800), api


# ---------- 降级 ----------

def test_get_backend_degrades_without_binary(monkeypatch):
    monkeypatch.setattr(a2.shutil, 'which', lambda _n: None)
    monkeypatch.setattr(a2, '_backend', None)
    monkeypatch.setattr(a2, '_unavailable', False)
    assert a2.get_backend() is None
    assert a2.get_backend() is None      # 失败结果被记忆，不反复拉起进程


def test_free_port_is_in_valid_range():
    assert 0 < a2._free_port() < 65536


# ---------- 完成路径 ----------

def test_fetch_reports_progress_and_completes(monkeypatch, tmp_path):
    be, api = _backend(monkeypatch, [(50, False, False), (100, True, False)])
    seen = []
    be.fetch('http://x/y.mp3', tmp_path / 'y.part',
             progress_cb=lambda done, total: seen.append((done, total)))
    assert seen == [(50, 100), (100, 100)]
    assert api.removed == []                                  # 完成不需要中止
    assert not (tmp_path / 'y.part.aria2').exists()           # 控制文件已兜底清理
    submitted = api.submitted
    assert submitted is not None
    options = submitted[1]
    assert options['continue'] == 'true'                      # 续传选项已下发
    assert options['max-connection-per-server'] == str(a2._SPLIT)


def test_progress_callback_exception_is_swallowed(monkeypatch, tmp_path):
    be, _api = _backend(monkeypatch, [(100, True, False)])

    def boom(_d, _t):
        raise RuntimeError('cb')

    be.fetch('http://x/y.mp3', tmp_path / 'y.part', progress_cb=boom)   # 不应抛出


# ---------- 取消 / 守卫 / 失败 ----------

def test_fetch_maps_cancel_and_drops_partial(monkeypatch, tmp_path):
    be, api = _backend(monkeypatch, [(10, False, False)])
    ev = threading.Event()
    ev.set()
    with pytest.raises(DownloadCanceled):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part', cancel_event=ev)
    assert api.removed == [('g1', True, True)]


def test_fetch_guards_size_and_drops_partial(monkeypatch, tmp_path):
    be, api = _backend(monkeypatch, [(700, False, False)])
    with pytest.raises(DownloadException):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part', max_bytes=500)
    assert api.removed == [('g1', True, True)]


def test_fetch_failure_is_retryable_and_keeps_partial(monkeypatch, tmp_path):
    be, api = _backend(monkeypatch, [(10, False, True)])
    with pytest.raises(RequestException):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part')
    assert api.removed == []                                  # 残片保留，供下轮续传


def test_fetch_timeout_is_retryable(monkeypatch, tmp_path):
    be, api = _backend(monkeypatch, [(10, False, False)])     # 永不完成
    with pytest.raises(RequestException):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part', timeout=-1)
    assert api.removed == [('g1', True, False)]               # 超时中止但保留残片


def test_fetch_submit_failure_is_retryable(monkeypatch, tmp_path):
    be, _api = _backend(monkeypatch, [], fail_submit=True)
    with pytest.raises(RequestException):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part')


def test_fetch_update_failure_is_retryable(monkeypatch, tmp_path):
    be, _api = _backend(monkeypatch, [], fail_update=True)
    with pytest.raises(RequestException):
        be.fetch('http://x/y.mp3', tmp_path / 'y.part')


def test_close_is_idempotent(monkeypatch):
    be, _api = _backend(monkeypatch, [])
    be.close()
    be.close()