"""通用媒体上传：图片与文件统一入口，按 category 分子目录存储。"""

import re
import uuid
from pathlib import Path

from django.conf import settings
from rest_framework import permissions, status
from rest_framework.parsers import FormParser, MultiPartParser
from rest_framework.response import Response
from rest_framework.views import APIView

ALLOWED_IMAGE_EXT = {".jpg", ".jpeg", ".png", ".gif", ".webp", ".svg"}
ALLOWED_FILE_EXT = ALLOWED_IMAGE_EXT | {
    ".pdf",
    ".doc",
    ".docx",
    ".xls",
    ".xlsx",
    ".ppt",
    ".pptx",
    ".zip",
    ".rar",
    ".7z",
    ".txt",
    ".csv",
}
MAX_IMAGE_BYTES = 8 * 1024 * 1024
MAX_FILE_BYTES = 50 * 1024 * 1024
# 仅允许字母数字、下划线、连字符，防止路径穿越
CATEGORY_RE = re.compile(r"^[a-zA-Z0-9_-]{1,32}$")


class MediaUploadView(APIView):
    """POST /uploads/  表单字段: file, category(可选), kind=image|file(可选)"""

    permission_classes = [permissions.IsAdminUser]
    parser_classes = [MultiPartParser, FormParser]

    def post(self, request):
        file = request.FILES.get("file")
        if not file:
            return Response({"detail": "请选择文件"}, status=status.HTTP_400_BAD_REQUEST)

        category = (request.data.get("category") or "misc").strip()
        if not CATEGORY_RE.match(category):
            return Response(
                {"detail": "category 仅允许字母、数字、下划线与连字符"},
                status=status.HTTP_400_BAD_REQUEST,
            )

        kind = (request.data.get("kind") or "").strip().lower()
        ext = Path(file.name).suffix.lower()
        if not kind:
            kind = "image" if ext in ALLOWED_IMAGE_EXT else "file"

        if kind == "image":
            allowed = ALLOWED_IMAGE_EXT
            max_bytes = MAX_IMAGE_BYTES
            size_label = "8MB"
        else:
            allowed = ALLOWED_FILE_EXT
            max_bytes = MAX_FILE_BYTES
            size_label = "50MB"

        if file.size > max_bytes:
            return Response(
                {"detail": f"文件不能超过 {size_label}"},
                status=status.HTTP_400_BAD_REQUEST,
            )
        if ext not in allowed:
            return Response(
                {
                    "detail": f"不支持的格式，请上传 {', '.join(sorted(allowed))}",
                },
                status=status.HTTP_400_BAD_REQUEST,
            )

        filename = f"{uuid.uuid4().hex}{ext}"
        rel_dir = Path(category)
        abs_dir = Path(settings.MEDIA_ROOT) / rel_dir
        abs_dir.mkdir(parents=True, exist_ok=True)
        abs_path = abs_dir / filename
        with open(abs_path, "wb") as out:
            for chunk in file.chunks():
                out.write(chunk)

        url = f"/{settings.MEDIA_URL.strip('/')}/{rel_dir.as_posix()}/{filename}"
        return Response({"url": url, "name": file.name, "kind": kind})