Create userID retrieval Lambda

Allow for the retrieval of userIDs from email (or just generally).

This may need the apigateway passthrough info modified for privacy protection

Lambdas/Lists/User/src/UserGET.java

@@ -0,0 +1,11 @@
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+
+import java.util.Map;
+
+public class UserGET implements RequestHandler<Map<String,Object>, Object> {
+
+    public Object handleRequest(Map<String, Object> inputMap, Context unfilled) {
+        return BasicHandler.handleRequest(inputMap, unfilled, UserGetter.class);
+    }
+}

Lambdas/Lists/User/src/UserGetter.java

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+import com.amazonaws.services.cognitoidp.AWSCognitoIdentityProvider;
+import com.amazonaws.services.cognitoidp.AWSCognitoIdentityProviderClientBuilder;
+import com.amazonaws.services.cognitoidp.model.AttributeType;
+import com.amazonaws.services.cognitoidp.model.ListUsersRequest;
+import com.amazonaws.services.cognitoidp.model.ListUsersResult;
+import com.amazonaws.services.cognitoidp.model.UserType;
+
+import java.io.IOException;
+import java.sql.Connection;
+import java.util.*;
+
+public class UserGetter implements CallHandler {
+    private String cognitoID;
+
+    public UserGetter(Connection connection, String cognitoID) {
+        this.cognitoID = cognitoID;
+    }
+    @Override
+    public Object conductAction(Map<String, Object> bodyMap, HashMap<String, String> queryMap, String cognitoID) {
+        Properties cognitoProperties;
+        try {
+            cognitoProperties = DBConnector.loadProperties("cognitoProperties.json");
+        } catch (IOException e) {
+            e.printStackTrace();
+            return null;
+        }
+        String userPoolId = cognitoProperties.get("userPoolId").toString();
+        System.out.println(userPoolId);
+        ListUsersRequest checkRequest = new ListUsersRequest().withUserPoolId(userPoolId);
+        Object emailObject = bodyMap.get("emailToCheck");
+        if (emailObject != null) {
+            checkRequest.setFilter("email=\"" + emailObject.toString() +"\"");
+        } else {
+            //            checkRequest.setFilter("sub=\"" + cognitoID + "\"");
+            return cognitoID;
+        }
+        System.out.println(checkRequest);
+        AWSCognitoIdentityProvider awsCognitoIdentityProvider = AWSCognitoIdentityProviderClientBuilder.defaultClient();
+        ListUsersResult foundUsersResult = awsCognitoIdentityProvider.listUsers(checkRequest);
+        List<UserType> foundUsers = foundUsersResult.getUsers();
+        if (foundUsers.size() != 1) {
+            System.out.println(foundUsers);
+            if (foundUsers.size() == 0) {
+                throw new InputMismatchException("Not user with given email");
+            }
+            throw new InputMismatchException("Found more than one user with supposedly unique email");
+        }
+        UserType foundUser = foundUsers.get(0);
+        System.out.println(foundUser.getAttributes());
+        String sub = "";
+        for (AttributeType attribute : foundUser.getAttributes()) {
+            if (attribute.getName().equals("sub")) {
+                sub = attribute.getValue();
+                break;
+            }
+            System.out.println(attribute.getName() + ": " + attribute.getValue());
+        }
+        return sub;
+    }
+}