public async Task VerifyImageLiveness()

in packages/ekyc-api/src/ekyc-api/Utils/LivenessChecker.cs [167:283]
66 lines of code
20 McCabe index (conditional complexity)

        public async Task<string> VerifyImageLiveness(string sessionId)
        {
            AWSXRayRecorder.Instance.BeginSubsegment("LivenessChecker::VerifyImageLiveness");

            var config = new DynamoDBOperationConfig
            {
                OverrideTableName = Globals.SessionTableName
            };

            var session = await dynamoDbContext.LoadAsync<SessionObject>(sessionId, config);

            var imaging = new Imaging(_amazonS3, _documentChecker);

            Image nosePointImage;

            if (session == null)
                return $"Session with ID {sessionId} is not found.";

            if (string.IsNullOrEmpty(session.documentImageKey))
                return $"Document to verify for session {sessionId} is empty.";

            var documentFaceCount = await GetFaceCount(session.documentImageKey, 3);

            if (documentFaceCount == 0)
                return $"No faces found on the document to verify for session {sessionId}.";

            var documentToVerifyImage = await imaging.GetImageFromStorage(session.documentImageKey);

            if (documentToVerifyImage == null)
                return $"Invalid document to verify for session {sessionId}.";


            if (string.IsNullOrEmpty(session.eyesClosedImageKey))
                return $"Eyes closed image for session {sessionId} is empty.";


            var eyesClosedFacesCount = await GetFaceCount(session.eyesClosedImageKey, 3);

            if (eyesClosedFacesCount == 0)
                return $"No faces found on the eyes closed image for session {sessionId}.";

            var eyesClosedImage = await imaging.GetImageFromStorage(session.eyesClosedImageKey);

            if (eyesClosedImage == null)
                return $"Invalid eyes closed image for session {sessionId}.";

            FaceDetail selfieFaceDetails;

            if (string.IsNullOrEmpty(session.selfieImageKey))
                return $"Selfie image for session {sessionId} is empty.";

            var selfieFaceCount = await GetFaceCount(session.selfieImageKey, 2);

            if (selfieFaceCount == 0 || selfieFaceCount > 1)
                return $"There can only be one face on the selfie image for session {sessionId}.";

            var headOnImage = await imaging.GetImageFromStorage(session.selfieImageKey);

            if (headOnImage == null)
                return $"Invalid selfie image for session {sessionId}.";

            selfieFaceDetails = GetFaces(session.selfieImageKey).GetAwaiter().GetResult().FirstOrDefault();

            var selfiePoseError = await VerifySelfieFacePose(selfieFaceDetails);

            if (selfiePoseError != null)
                return selfiePoseError;


            if (string.IsNullOrEmpty(session.nosePointImageKey))
                return $"Nose verification image for session {sessionId} is empty.";


            var nosePointFaceCount = await GetFaceCount(session.nosePointImageKey);

            if (nosePointFaceCount == 0)
                return $"No faces found on the nose point image for session {sessionId}.";

            nosePointImage = await imaging.GetImageFromStorage(session.nosePointImageKey);

            if (nosePointImage == null)
                return $"Invalid nose verification image for session {sessionId}.";


            // Make sure the selfie image matches the document image

            var similarFaces = await CompareFaces(session.selfieImageKey, session.documentImageKey);

            if (!similarFaces.IsMatch)
                return $"The face on the document does not meet the selfie for session {sessionId}.";

            // Check that the eyes are closed on the eyes closed image

            similarFaces = await CompareFaces(session.eyesClosedImageKey, session.selfieImageKey);

            if (!similarFaces.IsMatch)
                return $"Eyes closed image does not match the selfie image for session {sessionId}";

            var eyesClosed = await VerifyClosedEyes(session.eyesClosedImageKey);

            if (!eyesClosed)
                return $"Eyes are not closed for the verification image for session {sessionId}";

            // Check that the nose is in the area of the image

            similarFaces = await CompareFaces(session.nosePointImageKey, session.selfieImageKey);

            if (!similarFaces.IsMatch)
                return $"Nose verification image does not match the selfie image for session {sessionId}";

            var noseVerifyResponse =
                VerifyNoseLocation(session, nosePointImage, selfieFaceDetails).GetAwaiter().GetResult();

            AWSXRayRecorder.Instance.EndSubsegment();

            return noseVerifyResponse;
        }