import os
import uuid
from django.conf import settings
from rest_framework import viewsets, permissions, status
from rest_framework.decorators import action
from rest_framework.parsers import MultiPartParser, FormParser
from rest_framework.response import Response
from .models import Document, CertificateOfAnalysis, RegulatoryCert
from .serializers import DocumentSerializer, DocumentUploadSerializer, CertificateOfAnalysisSerializer, RegulatoryCertSerializer


class DocumentViewSet(viewsets.ModelViewSet):
    queryset = Document.objects.all()
    serializer_class = DocumentSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        user = self.request.user
        qs = Document.objects.all()
        if user.role == "buyer":
            return qs.filter(visibility__in=["buyer"])
        return qs

    @action(detail=False, methods=["post"], parser_classes=[MultiPartParser, FormParser])
    def upload(self, request):
        serializer = DocumentUploadSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        file = serializer.validated_data["file"]
        batch_id = serializer.validated_data.get("batch_id")
        doc_type = serializer.validated_data["doc_type"]
        visibility = serializer.validated_data.get("visibility", "buyer")

        file_ext = file.name.split(".")[-1].lower()
        allowed = ["pdf", "jpg", "jpeg", "png", "xlsx"]
        if file_ext not in allowed:
            return Response({"error": f"File type .{file_ext} not allowed"}, status=status.HTTP_400_BAD_REQUEST)

        if file.size > 50 * 1024 * 1024:
            return Response({"error": "File exceeds 50MB limit"}, status=status.HTTP_400_BAD_REQUEST)

        batch_dir = os.path.join(settings.MEDIA_ROOT, "ixg-documents", str(batch_id or "uncategorized"))
        os.makedirs(batch_dir, exist_ok=True)

        filename = f"{uuid.uuid4()}_{file.name}"
        filepath = os.path.join(batch_dir, filename)
        with open(filepath, "wb+") as dest:
            for chunk in file.chunks():
                dest.write(chunk)

        doc = Document.objects.create(
            batch_id=batch_id,
            doc_type=doc_type,
            file_url=f"/media/ixg-documents/{batch_id or uncategorized}/{filename}",
            file_name=file.name,
            file_size_bytes=file.size,
            visibility=visibility,
            uploaded_by=request.user,
        )

        return Response(DocumentSerializer(doc).data, status=status.HTTP_201_CREATED)


class CertificateOfAnalysisViewSet(viewsets.ModelViewSet):
    queryset = CertificateOfAnalysis.objects.all()
    serializer_class = CertificateOfAnalysisSerializer
    permission_classes = [permissions.IsAuthenticated]


class RegulatoryCertViewSet(viewsets.ModelViewSet):
    queryset = RegulatoryCert.objects.all()
    serializer_class = RegulatoryCertSerializer
    permission_classes = [permissions.IsAuthenticated]