import os
import re
import json
import hashlib
from pathlib import Path
from django.http import HttpResponse, JsonResponse, FileResponse
from django.views import View
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.permissions import AllowAny


class IPInfoView(APIView):
    permission_classes = [AllowAny]

    def get(self, request):
        x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR', '')
        ip = x_forwarded_for.split(',')[0].strip() if x_forwarded_for else request.META.get('REMOTE_ADDR', '')
        return Response({'code': 0, 'data': {'ip': ip}})


class AssetDownloadView(View):
    """文件资产下载（按 SHA1）

    取物理文件的顺序（先新后旧）：
      1. FileAsset.StoragePath —— 当前上传链路（/API/Asset/Upload*）的落地位置
         （MEDIA_ROOT/assets/<uploadId>_<原始文件名>）
      2. ./resource/<aa>/<bb>/<cc>/<sha1> —— Flask 期遗留布局，保持向后兼容

    历史问题：上传写 MEDIA_ROOT/assets，而本视图原先只读 ./resource 布局，
    导致上传成功却下载 404（资产管理页与 Talk 图片/文件消息均受影响）。
    """

    def get(self, request, sha1):
        # 验证 sha1 参数格式，防止路径遍历
        if not re.match(r'^[0-9a-fA-F]{40}$', sha1):
            return HttpResponse('Invalid hash', status=400)

        resolved = _ResolveAssetFile(sha1)
        if resolved is None:
            return JsonResponse({'code': 404, 'msg': '文件不存在'}, status=404)

        file_path, file_name = resolved
        return FileResponse(open(file_path, 'rb'), as_attachment=True, filename=file_name or sha1)


#: 允许下载的目录白名单（解析后必须落在其中，防路径遍历）
def _ResolveAssetFile(sha1):
    """解析资产物理文件：返回 (Path, 下载文件名)；找不到返回 None

    先在 FileAsset 表按 SHA1 查 StoragePath（并校验路径落在允许目录内），
    再回退到 ./resource 分段布局。
    """
    from django.conf import settings as _settings

    media_root = Path(getattr(_settings, 'MEDIA_ROOT', '.')).resolve()
    resource_root = Path('./resource').resolve()
    allowed_roots = (media_root, resource_root)

    def _InAllowed(p):
        try:
            resolved = p.resolve()
        except OSError:
            return None
        for root in allowed_roots:
            try:
                resolved.relative_to(root)
                return resolved
            except ValueError:
                continue
        return None

    # 1) 当前上传链路：FileAsset.StoragePath
    try:
        from gvsds.apps.gerp.models import FileAsset

        asset = FileAsset.objects.filter(FileSHA1=sha1).first()
        if asset and asset.StoragePath:
            stored = Path(asset.StoragePath)
            for candidate in (stored, (media_root / str(asset.StoragePath).lstrip('/\\'))):
                safe = _InAllowed(candidate)
                if safe is not None and safe.is_file():
                    return safe, asset.FileName or sha1
    except Exception:
        # 查库失败不能影响旧布局回退（保持下载可用）
        import logging

        logging.getLogger(__name__).warning('资产按 StoragePath 定位失败：%s', sha1, exc_info=True)

    # 2) Flask 期遗留布局：./resource/<aa>/<bb>/<cc>/<sha1>
    legacy = _InAllowed(resource_root / sha1[0:2] / sha1[2:4] / sha1[4:6] / sha1)
    if legacy is not None and legacy.is_file():
        return legacy, sha1
    return None


class HealthCheckView(APIView):
    permission_classes = [AllowAny]

    def get(self, request):
        return Response({'code': 0, 'msg': 'ok', 'service': 'gvsds-django'})