"""
管理员OSS文件管理路由

提供管理员上传文件到OSS的接口
"""
from fastapi import APIRouter, UploadFile, File, Depends, HTTPException, Query
from typing import List

import oss2

from app.dependencies.admin_auth import get_current_admin
from app.models.admin import AdminUser
from app.services.oss_service import get_oss_service, OSSService

router = APIRouter(prefix="/api/admin/oss", tags=["管理员OSS文件管理"])

# 文件大小限制配置
MAX_FILE_SIZE_DEFAULT = 20 * 1024 * 1024  # 20MB
MAX_FILE_SIZE_COURSE = 2 * 1024 * 1024 * 1024  # 2GB


def _get_file_size(upload_file: UploadFile) -> int:
    file_obj = upload_file.file
    try:
        current_pos = file_obj.tell()
        file_obj.seek(0, 2)
        size = file_obj.tell()
        file_obj.seek(current_pos)
        return size
    except Exception:
        return 0


@router.post("/upload")
async def upload_file(
    file: UploadFile = File(...),
    prefix: str = Query(default="uploads", description="存储路径前缀"),
    current_admin: AdminUser = Depends(get_current_admin),
    oss_service: OSSService = Depends(get_oss_service)
):
    """上传文件到OSS（管理员）"""
    file_size = _get_file_size(file)
    max_size = MAX_FILE_SIZE_COURSE if prefix.startswith("courses") else MAX_FILE_SIZE_DEFAULT
    max_size_mb = max_size / (1024 * 1024)

    if file_size and file_size > max_size:
        raise HTTPException(
            status_code=400,
            detail=f"文件大小超过{max_size_mb:.0f}MB限制"
        )

    try:
        file.file.seek(0)
        url = oss_service.upload_file_stream(file.file, prefix, file.filename)
        return {
            "url": url,
            "filename": file.filename,
            "size": file_size
        }
    except RuntimeError as e:
        raise HTTPException(status_code=500, detail=str(e))


@router.get("/presigned-url")
async def get_presigned_url(
    prefix: str = Query(default="uploads", description="存储路径前缀"),
    filename: str = Query(default=None, description="原始文件名（用于保留扩展名）"),
    content_type: str = Query(default=None, description="文件 Content-Type"),
    current_admin: AdminUser = Depends(get_current_admin),
    oss_service: OSSService = Depends(get_oss_service)
):
    """生成预签名 PUT 上传 URL，供前端直传 OSS

    前端先请求此接口获取 presigned_url，然后直接 PUT 到 OSS。
    上传完成后，将返回的 object_key 和 public_url 用于业务记录。
    """
    max_size = MAX_FILE_SIZE_COURSE if prefix.startswith("courses") else MAX_FILE_SIZE_DEFAULT
    max_size_mb = max_size / (1024 * 1024)

    try:
        result = oss_service.generate_presigned_put_url(
            prefix=prefix,
            original_filename=filename,
            expires=3600,  # 1小时有效期
            content_type=content_type,
        )
        result["max_size_mb"] = max_size_mb
        return result
    except RuntimeError as e:
        raise HTTPException(status_code=500, detail=str(e))


@router.get("/list-videos")
async def list_oss_videos(
    prefix: str = Query(default="courses/videos", description="OSS路径前缀"),
    current_admin: AdminUser = Depends(get_current_admin),
    oss_service: OSSService = Depends(get_oss_service)
):
    """列出OSS中指定前缀下的视频文件

    优化：先用 ObjectIterator(fetch_stats=True) 快速列出所有文件，
    过滤出视频后，批量并发 head_object 获取元数据，避免逐个串行请求。
    """
    if not oss_service.bucket:
        raise HTTPException(status_code=500, detail="OSS服务未正确配置")

    VIDEO_EXTS = {'.mp4', '.mov', '.avi', '.mkv', '.webm', '.flv', '.wmv', '.m4v'}
    video_keys = []

    try:
        for obj in oss2.ObjectIterator(oss_service.bucket, prefix=prefix):
            key = obj.key
            ext = '.' + key.rsplit('.', 1)[-1].lower() if '.' in key else ''
            if ext not in VIDEO_EXTS:
                continue
            video_keys.append({
                "key": key,
                "size": obj.size,
                "last_modified": obj.last_modified,
                "default_filename": key.rsplit('/', 1)[-1],
            })
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"列举OSS文件失败: {str(e)}")

    if not video_keys:
        return {"items": [], "total": 0}

    # 批量并发获取元数据（避免逐个串行请求）
    import asyncio

    async def _fetch_meta(item: dict) -> dict:
        try:
            head_result = await asyncio.to_thread(
                oss_service.bucket.head_object, item["key"]
            )
            filename = oss_service.get_original_filename_from_headers(
                getattr(head_result, 'headers', None),
                fallback=item["default_filename"],
            )
        except Exception:
            filename = item["default_filename"]

        return {
            "key": item["key"],
            "filename": filename,
            "url": f"https://{oss_service.bucket_domain}/{item['key']}",
            "size": item["size"],
            "last_modified": item["last_modified"],
        }

    try:
        results = await asyncio.gather(*[_fetch_meta(item) for item in video_keys])
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"获取文件元数据失败: {str(e)}")

    results = sorted(results, key=lambda x: x["last_modified"], reverse=True)
    return {"items": results, "total": len(results)}