documentverification/verifier/views.py

import logging
from rest_framework import status
from rest_framework.response import Response
from rest_framework.views import APIView

# Import engine and vendors to ensure default registration
import verifier.vendors  # noqa: F401
from verifier.engine import engine, registry
from .models import VerificationTransaction, VendorAttemptLog
from .serializers import (
    VerifyDocumentRequestSerializer,
    VerificationTransactionSerializer,
)

logger = logging.getLogger(__name__)


def mask_sensitive_payload(payload: dict) -> dict:
    """Mask sensitive inputs like full aadhaar numbers or passwords for audit safety."""
    masked = dict(payload)
    sensitive_keys = ["aadhaar_number", "aadhaar", "otp", "password", "client_secret"]
    for key in sensitive_keys:
        if key in masked and isinstance(masked[key], str):
            val = masked[key]
            if len(val) > 4:
                masked[key] = f"{val[:2]}****{val[-2:]}"
            else:
                masked[key] = "****"
    return masked


class DocumentVerifyView(APIView):
    """
    POST /api/verify/
    Verifies a document using the vendor waterfall failover engine.
    If the first vendor encounters an error/failure, the engine automatically
    cascades to the next available vendor.
    """

    def post(self, request, *args, **kwargs):
        serializer = VerifyDocumentRequestSerializer(data=request.data)
        if not serializer.is_valid():
            return Response(
                {"is_success": False, "errors": serializer.errors},
                status=status.HTTP_400_BAD_REQUEST,
            )

        doc_type = serializer.validated_data["document_type"]
        input_data = serializer.validated_data["data"]
        preferred_vendor = serializer.validated_data.get("preferred_vendor")
        files = request.FILES if hasattr(request, "FILES") else None

        # Execute waterfall verification
        engine_result = engine.verify(
            document_type=doc_type,
            data=input_data,
            files=files,
            preferred_vendor=preferred_vendor,
        )

        # Persist transaction and audit attempts in DB
        safe_input = mask_sensitive_payload(input_data)
        transaction = VerificationTransaction.objects.create(
            document_type=doc_type,
            status=engine_result.status.value,
            successful_vendor=engine_result.successful_vendor,
            input_payload=safe_input,
            final_data=engine_result.data if engine_result.is_success else {},
            attempts_count=len(engine_result.attempts),
            total_latency_ms=engine_result.total_latency_ms,
        )

        # Persist attempt logs
        for attempt in engine_result.attempts:
            VendorAttemptLog.objects.create(
                transaction=transaction,
                attempt_number=attempt.get("attempt_number", 1),
                vendor_name=attempt.get("vendor_name", "unknown"),
                status=attempt.get("status", "UNKNOWN"),
                is_success=attempt.get("is_success", False),
                data=attempt.get("data", {}),
                raw_response=attempt.get("raw_response"),
                error_code=attempt.get("error_code"),
                error_message=attempt.get("error_message"),
                latency_ms=attempt.get("latency_ms", 0.0),
            )

        response_payload = {
            "reference_id": str(transaction.reference_id),
            "is_success": engine_result.is_success,
            "status": engine_result.status.value,
            "document_type": doc_type,
            "successful_vendor": engine_result.successful_vendor,
            "data": engine_result.data,
            "attempts_count": len(engine_result.attempts),
            "attempts": engine_result.attempts,
            "error_message": engine_result.error_message,
            "total_latency_ms": round(engine_result.total_latency_ms, 2),
        }

        http_status = status.HTTP_200_OK if engine_result.is_success else status.HTTP_422_UNPROCESSABLE_ENTITY
        return Response(response_payload, status=http_status)


class VendorListView(APIView):
    """
    GET /api/vendors/
    Lists all active verification vendors registered with the engine in priority order.
    """

    def get(self, request, *args, **kwargs):
        vendors = registry.get_all_vendors()
        vendor_data = [
            {
                "name": v.name,
                "display_name": getattr(v, "display_name", v.name),
                "priority": v.priority,
                "is_active": v.is_active,
                "supported_documents": v.supported_documents,
            }
            for v in vendors
        ]
        return Response({"count": len(vendor_data), "vendors": vendor_data})


class TransactionDetailView(APIView):
    """
    GET /api/transactions/<uuid:reference_id>/
    Fetch complete audit trail and fallback logs for a transaction.
    """

    def get(self, request, reference_id, *args, **kwargs):
        try:
            tx = VerificationTransaction.objects.prefetch_related("attempts").get(reference_id=reference_id)
        except VerificationTransaction.DoesNotExist:
            return Response(
                {"error": f"Transaction '{reference_id}' not found"},
                status=status.HTTP_404_NOT_FOUND,
            )

        serializer = VerificationTransactionSerializer(tx)
        return Response(serializer.data)