from rest_framework import serializers, status
from rest_framework.response import Response
from rest_framework.views import APIView

from .algorithms import ProcessingError
from .selectors import image_session_get, processing_job_get
from .services import batch_job_create, image_session_create, image_session_process, processing_job_payload


def error_response(message, code=status.HTTP_400_BAD_REQUEST):
    return Response({"detail": message}, status=code)


class ImageUploadView(APIView):
    class InputSerializer(serializers.Serializer):
        image = serializers.ImageField(required=False)
        image_base64 = serializers.CharField(required=False, allow_blank=False)

        def validate(self, attrs):
            if not attrs.get("image") and not attrs.get("image_base64"):
                raise serializers.ValidationError("Provide image or image_base64.")
            return attrs

    def post(self, request):
        serializer = self.InputSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        try:
            payload = image_session_create(
                uploaded_file=serializer.validated_data.get("image"),
                image_base64=serializer.validated_data.get("image_base64"),
            )
            return Response(payload, status=status.HTTP_201_CREATED)
        except ProcessingError as exc:
            return error_response(str(exc))


class ProcessView(APIView):
    class InputSerializer(serializers.Serializer):
        session_id = serializers.UUIDField()
        operation = serializers.CharField()
        params = serializers.DictField(required=False, default=dict)

    def post(self, request):
        serializer = self.InputSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        session = image_session_get(session_id=serializer.validated_data["session_id"])
        if session is None:
            return error_response("Image session does not exist.", status.HTTP_404_NOT_FOUND)

        try:
            payload = image_session_process(
                session=session,
                operation=serializer.validated_data["operation"],
                params=serializer.validated_data.get("params", {}),
            )
            return Response(payload)
        except ProcessingError as exc:
            code = status.HTTP_410_GONE if str(exc) == "Image session has expired." else status.HTTP_400_BAD_REQUEST
            return error_response(str(exc), code)


class BatchView(APIView):
    class InputSerializer(serializers.Serializer):
        operation = serializers.ChoiceField(choices=["average", "subtract"])
        session_ids = serializers.ListField(child=serializers.UUIDField(), min_length=2)
        params = serializers.DictField(required=False, default=dict)

    def post(self, request):
        serializer = self.InputSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        job = batch_job_create(
            operation=serializer.validated_data["operation"],
            session_ids=serializer.validated_data["session_ids"],
            params=serializer.validated_data.get("params", {}),
        )
        return Response({"job_id": str(job.id), "status": job.status}, status=status.HTTP_202_ACCEPTED)


class JobDetailView(APIView):
    def get(self, request, job_id):
        job = processing_job_get(job_id=job_id)
        if job is None:
            return error_response("Job does not exist.", status.HTTP_404_NOT_FOUND)
        return Response(processing_job_payload(job=job))


class HealthView(APIView):
    def get(self, request):
        return Response({"status": "ok"})