import json
from django.shortcuts import render
from django.http import JsonResponse
from django.views.decorators.csrf import csrf_exempt
from rest_framework.decorators import api_view
from rest_framework.response import Response
from rest_framework import status

from .services.cashfree_client import CashfreeSecureIDClient

def get_cashfree_client(request):
    """
    Instantiate client using session-stored override credentials if available,
    otherwise fallback to environment variables.
    """
    client_id = request.session.get('CASHFREE_CLIENT_ID')
    client_secret = request.session.get('CASHFREE_CLIENT_SECRET')
    environment = request.session.get('CASHFREE_ENV', 'TEST')
    
    return CashfreeSecureIDClient(
        client_id=client_id,
        client_secret=client_secret,
        environment=environment
    )

def index_view(request):
    """
    Main Web Application Dashboard UI.
    """
    client = get_cashfree_client(request)
    context = {
        "client_id": client.client_id,
        "environment": client.environment,
        "has_credentials": client.has_credentials(),
    }
    return render(request, "verifier/index.html", context)

@api_view(['GET', 'POST'])
def config_api_view(request):
    """
    API to fetch or update active Cashfree credentials and environment configuration.
    """
    if request.method == 'GET':
        client = get_cashfree_client(request)
        return Response({
            "client_id": client.client_id,
            "has_credentials": client.has_credentials(),
            "environment": client.environment,
            "base_url": client.base_url
        })
    elif request.method == 'POST':
        data = request.data or {}
        client_id = data.get('client_id', '').strip()
        client_secret = data.get('client_secret', '').strip()
        environment = data.get('environment', 'TEST').upper()

        request.session['CASHFREE_CLIENT_ID'] = client_id
        request.session['CASHFREE_CLIENT_SECRET'] = client_secret
        request.session['CASHFREE_ENV'] = environment

        client = CashfreeSecureIDClient(client_id=client_id, client_secret=client_secret, environment=environment)
        verify_res = client.verify_credentials() if client.has_credentials() else {"success": False, "message": "No credentials provided"}

        return Response({
            "message": "Configuration updated successfully",
            "client_id": client.client_id,
            "environment": client.environment,
            "has_credentials": client.has_credentials(),
            "credential_check": verify_res
        })

@api_view(['POST'])
def verify_pan_api(request):
    """
    POST /api/verify/pan/
    Verify PAN details (Individual / Business).
    """
    data = request.data or {}
    pan = data.get('pan', '')
    name = data.get('name', '')
    pan_type = data.get('type', 'INDIVIDUAL')

    if not pan:
        return Response({
            "error": "PAN parameter is required.",
            "field": "pan"
        }, status=status.HTTP_400_BAD_REQUEST)

    client = get_cashfree_client(request)
    result = client.verify_pan(pan=pan, name=name, pan_type=pan_type)
    return Response(result)

@api_view(['POST'])
def verify_aadhaar_api(request):
    """
    POST /api/verify/aadhaar/
    Verify Aadhaar details or execute Aadhaar masking.
    """
    data = request.data or {}
    aadhaar_number = data.get('aadhaar_number', '')
    action = data.get('action', 'verify') # 'verify' or 'mask'

    if not aadhaar_number:
        return Response({
            "error": "Aadhaar number parameter is required.",
            "field": "aadhaar_number"
        }, status=status.HTTP_400_BAD_REQUEST)

    client = get_cashfree_client(request)
    result = client.verify_aadhaar(aadhaar_number=aadhaar_number, action=action)
    return Response(result)

@api_view(['POST'])
def verify_gstin_api(request):
    """
    POST /api/verify/gstin/
    Verify Goods and Services Tax Identification Number (GSTIN).
    """
    data = request.data or {}
    gstin = data.get('gstin', '')

    if not gstin:
        return Response({
            "error": "GSTIN parameter is required.",
            "field": "gstin"
        }, status=status.HTTP_400_BAD_REQUEST)

    client = get_cashfree_client(request)
    result = client.verify_gstin(gstin=gstin)
    return Response(result)

@api_view(['POST'])
def verify_ifsc_api(request):
    """
    POST /api/verify/ifsc/
    Lookup bank details, branch address, and supported payment modes using IFSC code.
    """
    data = request.data or {}
    ifsc = data.get('ifsc', '')

    if not ifsc:
        return Response({
            "error": "IFSC code parameter is required.",
            "field": "ifsc"
        }, status=status.HTTP_400_BAD_REQUEST)

    client = get_cashfree_client(request)
    result = client.verify_ifsc(ifsc=ifsc)
    return Response(result)

@api_view(['POST'])
def verify_bank_account_api(request):
    """
    POST /api/verify/bank-account/
    Synchronous Bank Account Verification (BAV Sync).
    """
    data = request.data or {}
    bank_account = data.get('bank_account', '')
    ifsc = data.get('ifsc', '')
    name = data.get('name', '')
    phone = data.get('phone', '')

    if not bank_account or not ifsc:
        return Response({
            "error": "Both bank_account and ifsc parameters are required.",
            "fields": ["bank_account", "ifsc"]
        }, status=status.HTTP_400_BAD_REQUEST)

    client = get_cashfree_client(request)
    result = client.verify_bank_account(bank_account=bank_account, ifsc=ifsc, name=name, phone=phone)
    return Response(result)