from rest_framework.views import APIView
#from rest_framework.generics import GenericAPIView
from rest_framework.response import Response
from rest_framework import status

from .models import GaiaSource
from .serializers import GaiaSourceSerializer

from drf_spectacular.utils import extend_schema, OpenApiResponse, OpenApiParameter

import numpy as np
import healpy as hp
from astropy.coordinates import SkyCoord
from astropy import units as u




class ConeSearchView(APIView):

    serializer_class = GaiaSourceSerializer

    @extend_schema(

        description = "GAIA DR3 cone search using healpix indexation. ra, dec, radius in decimal degrees.",

        summary = "GAIA DR3 cone search.",
  
        responses = {
            200: OpenApiResponse(response=GaiaSourceSerializer(many=True), description="Successful Response"),
            400: OpenApiResponse(description="Bad Request"),
            404: OpenApiResponse(description="Not Found")
        },

        # parameters=[
        #     OpenApiParameter(
        #         name='ra', description='Right Ascension in decimal degrees', required=True, type=float
        #     ),
        #     OpenApiParameter(
        #         name='dec', description='Declination in decimal degrees', required=True, type=float
        #     ),
        #     OpenApiParameter(
        #         name='radius', description='Search radius in decimal degrees', required=True, type=float
        #     )
        # ],
        tags=["GAIA"],
        
    )

    

    def get(self, request): # ra, dec, radius):
        
        try:
            ra = float(request.query_params.get('ra'))
            dec = float(request.query_params.get('dec'))
            radius = float(request.query_params.get('radius'))
        except (TypeError, ValueError):
            return Response({"error": "Invalid parameters"}, status=status.HTTP_400_BAD_REQUEST)
        # radius = float(radius)
        # ra = float(ra)
        # dec = float(dec)
        nside = 2048

        #create skycoord for the center of search
        center = SkyCoord(ra=ra*u.deg, dec=dec*u.deg, frame='icrs')

        #fetch healpix indices in the specified disc
        healpix_indices = self.get_healpix_indices(ra, dec, radius, nside)
        #fetch all objects from those healpixes
        objects = GaiaSource.objects.filter(healpix_ring_index__in=healpix_indices)

        results = [] #initialize the results list

        for obj in objects:
            
            source_coordinates = SkyCoord(
                ra=obj.ra*u.deg, 
                dec=obj.dec*u.deg, 
                frame='icrs'
            )
            
            separation = center.separation(source_coordinates)

            if separation.degree <= radius:

                results.append(obj)           

        serializer = GaiaSourceSerializer(results, many=True)

        return Response(serializer.data, status=status.HTTP_200_OK)

    

    @staticmethod
    def get_healpix_indices(ra, dec, radius, nside):

        # Convert the input coordinates to a SkyCoord object
        center = SkyCoord(ra=ra*u.deg, dec=dec*u.deg, frame='icrs')

        # Convert the center coordinates to HEALPix vector
        vec = hp.ang2vec(center.ra.deg, center.dec.deg, lonlat=True) 

        # Find the pixels within the given radius
        indices = hp.query_disc(nside, vec, np.radians(radius))        
        return indices