Updated SOLID Principles

exec/src/main/java/com/google/fhir/gateway/CustomGenericEndpointExample.java

@@ -25,12 +25,15 @@
 
 import com.auth0.jwt.interfaces.DecodedJWT;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.fhir.gateway.interfaces.ResourceValidator;
+import com.google.fhir.gateway.validators.PatientResourceValidator;
 import jakarta.servlet.ServletException;
 import jakarta.servlet.annotation.WebServlet;
 import jakarta.servlet.http.HttpServlet;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import org.apache.http.HttpStatus;
+import org.springframework.beans.factory.annotation.Autowired;
 import retrofit2.Call;
 import retrofit2.Response;
 
@@ -49,6 +52,8 @@ public class CustomGenericEndpointExample extends HttpServlet {
   private String BASE_URL_FHIR = "chanjo-hapi/fhir/";
   private String BASE_URL_AUTH = "auth/";
 
+  private final ResourceValidatorFactory validatorFactory = new ResourceValidatorFactory();
+
 
   public CustomGenericEndpointExample() throws IOException {
     this.tokenVerifier = TokenVerifier.createFromEnvVars();
@@ -116,61 +121,69 @@ private void forwardRequest(HttpServletRequest req, HttpServletResponse resp, St
         String fhirPractitionerId = dbUser.getFhirPractitionerId();
         String facility = dbUser.getFacility();
 
-        System.out.println("Practitioner Role: " + practitionerRole);
-        System.out.println("Practitioner FHIR ID: " + fhirPractitionerId);
-        System.out.println("Facility: " + facility);
-
         try{
 
           String path = req.getRequestURI().substring(req.getContextPath().length() + "/chanjo-gateway/".length());
           String queryString = req.getQueryString() != null ? "?" + req.getQueryString() : "";
           String targetUrl = BASE_URL_FHIR + path + queryString;
 
-          Call<Object> call = null;
-          switch (method) {
-            case "GET":
-              call = apiService.getResource(targetUrl);
-              break;
-            case "POST":
-              call = apiService.createResource(targetUrl, readRequestBody(req));
-              break;
-            case "PUT":
-              call = apiService.updateResource(targetUrl, readRequestBody(req));
-              break;
-            case "DELETE":
-              call = apiService.deleteResource(targetUrl);
-              break;
-            default:
-          }
+          String resourceType = path.split("/")[0];
+
+          ResourceValidator resourceValidator = validatorFactory.getValidator(resourceType);
+
+          if (resourceValidator != null){
+
+            Call<Object> call = null;
+            switch (method) {
+              case "GET":
+                call = resourceValidator.getResource(practitionerRole, targetUrl);
+                break;
+              case "POST":
+                call = resourceValidator.createResource(practitionerRole, targetUrl, req);
+                break;
+              case "PUT":
+                call = resourceValidator.updateResource(practitionerRole, targetUrl, req);
+                break;
+              case "DELETE":
+                call = resourceValidator.deleteResource(practitionerRole, targetUrl);
+                break;
+              default:
+            }
+
+            if (call == null) {
+              statusCode = HttpServletResponse.SC_UNAUTHORIZED;
+              String responseString = "The resource does not exist or you do not have access to it.";
+              dbResults = new DbResults(responseString);
+            }else {
 
+              Response<Object> response = call.execute();
+              int statusCodeRes = response.code();
 
-          if (call != null) {
-            Response<Object> response = call.execute();
-            int statusCodeRes = response.code();
+              if (response.isSuccessful()) {
+                statusCode = HttpServletResponse.SC_OK;
+                dbResults = new DbResults(response.body());
 
-            if (response.isSuccessful()) {
-              statusCode = HttpServletResponse.SC_OK;
-              dbResults = new DbResults(response.body());
+              } else {
 
-            } else {
+                if (statusCodeRes == 404){
 
-              if (statusCodeRes == 404){
+                  statusCode = HttpServletResponse.SC_NOT_FOUND;
+                  String responseString = "Resource not found";
+                  dbResults = new DbResults(responseString);
 
-                statusCode = HttpServletResponse.SC_NOT_FOUND;
-                String responseString = "Resource not found";
-                dbResults = new DbResults(responseString);
+                }else {
 
-              }else {
+                  String responseString = "Check the request and try again";
+                  dbResults = new DbResults(responseString);
 
-                String responseString = "Check the request and try again";
-                dbResults = new DbResults(responseString);
+                }
 
               }
 
             }
 
           }else {
-            String responseString = "Error while forwarding request";
+            String responseString =  "Check the request and try again";
             dbResults = new DbResults(responseString);
           }
 

exec/src/main/java/com/google/fhir/gateway/ResourceValidatorFactory.java

@@ -0,0 +1,32 @@
+package com.google.fhir.gateway;
+
+import com.google.fhir.gateway.interfaces.ResourceValidator;
+import com.google.fhir.gateway.validators.ImmunizationResourceValidator;
+import com.google.fhir.gateway.validators.PatientResourceValidator;
+import org.springframework.stereotype.Component;
+
+import java.util.Objects;
+
+@Component
+public class ResourceValidatorFactory {
+    public ResourceValidator getValidator(String resourceType) {
+
+        String resourceTypeData = "";
+        if (Objects.equals(resourceType, "Patient")) {
+             resourceTypeData = FHIRResourceTypesData.PATIENT.name();
+        } else if (Objects.equals(resourceType, "Immunization")) {
+            resourceTypeData = FHIRResourceTypesData.IMMUNIZATION.name();
+        }else {
+            resourceTypeData = resourceType;
+        }
+
+        if (Objects.equals(resourceTypeData, FHIRResourceTypesData.PATIENT.name())){
+            return new PatientResourceValidator();
+        }else if (Objects.equals(resourceTypeData, FHIRResourceTypesData.IMMUNIZATION.name())){
+            return new ImmunizationResourceValidator();
+        }else {
+            return null; // or throw an exception here depending on your needs.
+        }
+
+    }
+}

exec/src/main/java/com/google/fhir/gateway/interfaces/ResourceValidator.java

@@ -0,0 +1,12 @@
+package com.google.fhir.gateway.interfaces;
+
+import jakarta.servlet.http.HttpServletRequest;
+import retrofit2.Call;
+
+public interface ResourceValidator {
+    Call<Object> getResource(String role, String targetUrl);
+    Call<Object> createResource(String role, String targetUrl, HttpServletRequest requestBody);
+    Call<Object> updateResource(String role, String targetUrl , HttpServletRequest requestBody);
+    Call<Object> deleteResource(String role, String targetUrl);
+}
+

exec/src/main/java/com/google/fhir/gateway/validators/ImmunizationResourceValidator.java

@@ -0,0 +1,62 @@
+package com.google.fhir.gateway.validators;
+
+import com.google.fhir.gateway.ApiServiceImpl;
+import com.google.fhir.gateway.interfaces.AccessChecker;
+import com.google.fhir.gateway.interfaces.AccessDecision;
+import com.google.fhir.gateway.interfaces.RequestDetailsReader;
+import com.google.fhir.gateway.interfaces.ResourceValidator;
+import jakarta.servlet.http.HttpServletRequest;
+import retrofit2.Call;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class ImmunizationResourceValidator implements AccessChecker, ResourceValidator {
+
+    private final ApiServiceImpl apiService = new ApiServiceImpl();
+
+    @Override
+    public AccessDecision checkAccess(RequestDetailsReader requestDetails) {
+        return null;
+    }
+
+    @Override
+    public Call<Object> getResource(String role, String targetUrl) {
+        return apiService.getResource(targetUrl);
+    }
+
+    @Override
+    public Call<Object> createResource(String role, String targetUrl, HttpServletRequest requestBody) {
+        return apiService.createResource(targetUrl, readRequestBody(requestBody));
+    }
+
+    @Override
+    public Call<Object> updateResource(String role, String targetUrl, HttpServletRequest requestBody) {
+        return apiService.updateResource(targetUrl, readRequestBody(requestBody));
+    }
+
+    @Override
+    public Call<Object> deleteResource(String role, String targetUrl) {
+        return apiService.deleteResource(targetUrl);
+    }
+
+    private String readRequestBody(HttpServletRequest request) {
+
+        try{
+
+            StringBuilder stringBuilder = new StringBuilder();
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(request.getInputStream(), "utf-8"))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    stringBuilder.append(line);
+                }
+            }
+            return stringBuilder.toString();
+
+        }catch (IOException e) {
+            e.printStackTrace();
+            return null;  // or throw an exception here depending on your needs.
+        }
+    }
+}

exec/src/main/java/com/google/fhir/gateway/validators/PatientResourceValidator.java

@@ -0,0 +1,63 @@
+package com.google.fhir.gateway.validators;
+
+import com.google.fhir.gateway.ApiServiceImpl;
+import com.google.fhir.gateway.interfaces.AccessChecker;
+import com.google.fhir.gateway.interfaces.AccessDecision;
+import com.google.fhir.gateway.interfaces.RequestDetailsReader;
+import com.google.fhir.gateway.interfaces.ResourceValidator;
+import jakarta.servlet.http.HttpServletRequest;
+import retrofit2.Call;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class PatientResourceValidator implements AccessChecker, ResourceValidator {
+
+    private final ApiServiceImpl apiService = new ApiServiceImpl();
+
+    @Override
+    public AccessDecision checkAccess(RequestDetailsReader requestDetails) {
+        return null;
+    }
+
+
+    @Override
+    public Call<Object> getResource(String role, String targetUrl) {
+        return apiService.getResource(targetUrl);
+    }
+
+    @Override
+    public Call<Object> createResource(String role, String targetUrl, HttpServletRequest requestBody) {
+        return apiService.createResource(targetUrl, readRequestBody(requestBody));
+    }
+
+    @Override
+    public Call<Object> updateResource(String role, String targetUrl, HttpServletRequest requestBody) {
+        return apiService.updateResource(targetUrl, readRequestBody(requestBody));
+    }
+
+    @Override
+    public Call<Object> deleteResource(String role, String targetUrl) {
+        return apiService.deleteResource(targetUrl);
+    }
+
+    private String readRequestBody(HttpServletRequest request) {
+
+        try{
+
+            StringBuilder stringBuilder = new StringBuilder();
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(request.getInputStream(), "utf-8"))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    stringBuilder.append(line);
+                }
+            }
+            return stringBuilder.toString();
+
+        }catch (IOException e) {
+            e.printStackTrace();
+            return null;  // or throw an exception here depending on your needs.
+        }
+    }
+}

exec/src/main/kotlin/com/google/fhir/gateway/Dataclass.kt

@@ -33,3 +33,10 @@ data class DbUser(
     val country: String,
     val countryName: String
 )
+
+enum class FHIRResourceTypesData {
+    PATIENT,
+    IMMUNIZATION,
+    MEDICATION,
+    ORDER
+}