# -*- coding: utf-8 -*-
"""结果交付端点。

端点：
- POST/GET /api/v1/download/result           ↔ Flask /download/result（单曲）
- POST/GET /api/v1/download/batch_zip/result ↔ Flask /download/batch_zip/result（批量 ZIP）

语义对齐要点：
- 任务归属：仅任务本人的站点账号可领取（非本人 403）
- 状态语义：进行中 202 / 暂停 200+提示 / 取消 200+原因 / 失败 500+原因 /
  文件缺失 404（与历史分支逐一对应）
- 交付物：FileResponse 流式发送；Cache-Control: no-store；
  X-Download-Filename（URL 编码，供前端取回原始文件名）
- 文件清理仍由监控线程按 35 分钟保留期统一回收（交付请求不删文件）
"""
import os
from typing import Annotated, Any
from urllib.parse import quote

from fastapi import APIRouter, Depends, Request
from fastapi.responses import FileResponse

from core.state import DOWNLOAD_TASKS, DOWNLOAD_TASKS_LOCK
from web.deps import SiteUser, require_login
from web.request_utils import (
    request_data as _request_data,
)
from web.response import error

router = APIRouter()

LoginUser = Annotated[SiteUser, Depends(require_login)]



def _owned_by(task: dict[str, Any], user: SiteUser) -> bool:
    return int(task.get('user_id') or 0) == int(user.id)


def _file_response(target: str, filename: str, mimetype: str) -> FileResponse:
    resp = FileResponse(target, media_type=mimetype, filename=filename)
    resp.headers['Cache-Control'] = 'no-store'
    resp.headers['X-Download-Filename'] = quote(filename, safe='')
    return resp


@router.api_route('/download/result', methods=['GET', 'POST'])
async def download_result(user: LoginUser, request: Request):
    """单曲下载结果：任务完成后流式返回文件。"""
    data = await _request_data(request)
    task_id = str(data.get('task_id') or '').strip()
    if not task_id:
        return error('缺少 task_id 参数')
    with DOWNLOAD_TASKS_LOCK:
        task = DOWNLOAD_TASKS.get(task_id)
    if not task or task.get('type') != 'single':
        return error('任务不存在或已过期', 404)
    if not _owned_by(task, user):
        return error('无权下载该任务', 403)

    status = task.get('status')
    if status in ('queued', 'running'):
        return error('任务还在进行中，请稍后再试', 202)
    if status == 'paused':
        return error('任务已暂停，请重新打开页面后恢复', 200)

    result = task.get('result') or {}
    target = result.get('zip_path') or result.get('file_path')
    # 微秒级单文件存在性判定，直接同步做（线程调度开销比它本身还大）
    target_exists = bool(target) and os.path.exists(target)  # noqa: ASYNC240
    if status in ('canceled', 'error') and not target_exists:
        return error(task.get('msg') or ('任务已取消' if status == 'canceled' else '任务失败'),
                     200 if status == 'canceled' else 500)
    if not target_exists:
        return error('文件不存在或已被清理', 404)
    filename = result.get('filename') or 'download'
    assert target is not None
    return _file_response(target, filename, result.get('mimetype') or 'application/octet-stream')


@router.api_route('/download/batch_zip/result', methods=['GET', 'POST'])
async def download_batch_zip_result(user: LoginUser, request: Request):
    """批量打包结果：任务完成后流式返回 ZIP。"""
    data = await _request_data(request)
    task_id = str(data.get('task_id') or '').strip()
    if not task_id:
        return error('缺少 task_id 参数')
    with DOWNLOAD_TASKS_LOCK:
        task = DOWNLOAD_TASKS.get(task_id)
    if not task or task.get('type') != 'batch':
        return error('任务不存在或已过期', 404)
    if not _owned_by(task, user):
        return error('无权下载该任务', 403)

    status = task.get('status')
    result = task.get('result') or {}
    zip_path = result.get('zip_path')
    # 同上：微秒级单文件存在性判定
    has_deliverable = bool(zip_path) and os.path.exists(zip_path)  # noqa: ASYNC240
    if status in ('queued', 'running'):
        return error('任务还在进行中，请稍后再试', 202)
    if status == 'paused':
        return error('任务已暂停，请重新打开页面后恢复', 200)
    # 取消/失败但已有部分成果的任务，成果必须可领取
    if status in ('canceled', 'error') and not has_deliverable:
        return error(task.get('msg') or ('任务已取消' if status == 'canceled' else '任务失败'),
                     200 if status == 'canceled' else 500)
    if not has_deliverable:
        return error('打包文件不存在或已被清理', 404)
    zip_name = result.get('filename') or '批量下载.zip'
    assert zip_path is not None
    return _file_response(zip_path, zip_name, 'application/zip')