Adding PolicySet parsePoliciesJson method

CedarJava/src/main/java/com/cedarpolicy/model/policy/PolicySet.java

@@ -151,6 +151,46 @@ public static PolicySet parsePolicies(String policiesString) throws InternalExce
         return policySet;
     }
 
+    /**
+     * Parse multiple policies and templates from a JSON file into a PolicySet.
+     *
+     * <p>The file is expected to contain the JSON (EST) representation of a policy set, e.g.
+     * <pre>{@code
+     * {
+     *   "staticPolicies": { "policy0": { ... } },
+     *   "templates": { "template0": { ... } },
+     *   "templateLinks": [ ... ]
+     * }
+     * }</pre>
+     *
+     * @param filePath the path to the JSON file containing the policies
+     * @return a PolicySet containing the parsed policies
+     * @throws InternalException
+     * @throws IOException
+     * @throws NullPointerException
+     */
+    public static PolicySet parsePoliciesJson(Path filePath) throws InternalException, IOException {
+        // Read the file contents into a String
+        String policiesJsonString = Files.readString(filePath);
+        return parsePoliciesJson(policiesJsonString);
+    }
+
+    /**
+     * Parse a JSON string containing multiple policies and templates into a PolicySet.
+     *
+     * <p>The string is expected to be the JSON (EST) representation of a policy set. See
+     * {@link #parsePoliciesJson(Path)} for the expected shape.
+     *
+     * @param policiesJsonString the JSON string containing the policies
+     * @return a PolicySet containing the parsed policies
+     * @throws InternalException
+     * @throws NullPointerException
+     */
+    public static PolicySet parsePoliciesJson(String policiesJsonString) throws InternalException {
+        PolicySet policySet = parsePoliciesJsonJni(policiesJsonString);
+        return policySet;
+    }
+
     // --- Caching support ---
 
     private volatile String cacheId;
@@ -219,6 +259,8 @@ public void run() {
     }
 
     private static native PolicySet parsePoliciesJni(String policiesStr) throws InternalException, NullPointerException;
+    private static native PolicySet parsePoliciesJsonJni(String policiesJsonStr)
+            throws InternalException, NullPointerException;
     private static native String policySetToJson(String policySetStr) throws InternalException, NullPointerException;
     private static native void preparsePolicySetJni(String id, String policiesJson) throws InternalException;
     private static native void removeCachedPolicySetJni(String id);

CedarJava/src/test/java/com/cedarpolicy/PolicySetTests.java

@@ -19,10 +19,13 @@
 import com.cedarpolicy.model.exception.InternalException;
 import com.cedarpolicy.model.policy.Policy;
 import com.cedarpolicy.model.policy.PolicySet;
+import com.cedarpolicy.model.policy.TemplateLink;
+import com.cedarpolicy.value.EntityUID;
 import org.junit.jupiter.api.Test;
 
 import java.io.IOException;
 import java.nio.file.Path;
+import java.util.Map;
 import com.fasterxml.jackson.core.JsonProcessingException;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -79,6 +82,70 @@ public void parseTemplatesTests() throws InternalException, IOException {
         assertEquals(1, policySet.templates.size());
     }
 
+    @Test
+    public void parsePoliciesJsonTests() throws InternalException, IOException {
+        PolicySet policySet = PolicySet.parsePoliciesJson(Path.of(TEST_RESOURCES_DIR + "policies.json"));
+        for (Policy p: policySet.policies) {
+            assertNotNull(p.policySrc);
+        }
+        // Make sure the policy IDs are unique as Policies are made
+        assertEquals(2, policySet.policies.stream().map(p -> p.policyID).distinct().count());
+        assertEquals(2, policySet.policies.size());
+        assertEquals(0, policySet.templates.size());
+    }
+
+    @Test
+    public void parsePoliciesJsonStringTests() throws InternalException {
+        String json = "{\"staticPolicies\":{\"policy0\":{\"effect\":\"permit\","
+                + "\"principal\":{\"op\":\"All\"},\"action\":{\"op\":\"All\"},"
+                + "\"resource\":{\"op\":\"All\"},\"conditions\":[]}},"
+                + "\"templates\":{},\"templateLinks\":[]}";
+        PolicySet policySet = PolicySet.parsePoliciesJson(json);
+        for (Policy p: policySet.policies) {
+            assertNotNull(p.policySrc);
+        }
+        assertEquals(1, policySet.policies.size());
+        assertEquals(0, policySet.templates.size());
+    }
+
+    @Test
+    public void parseTemplatesJsonTests() throws InternalException, IOException {
+        PolicySet policySet = PolicySet.parsePoliciesJson(Path.of(TEST_RESOURCES_DIR + "template.json"));
+        for (Policy p: policySet.policies) {
+            assertNotNull(p.policySrc);
+        }
+        // The two static policies only; the template-linked policy is reported
+        // via templateLinks rather than as a static policy.
+        assertEquals(2, policySet.policies.size());
+
+        for (Policy p: policySet.templates) {
+            assertNotNull(p.policySrc);
+        }
+        assertEquals(1, policySet.templates.size());
+
+        // The template instantiation is preserved as a TemplateLink
+        assertEquals(1, policySet.templateLinks.size());
+        TemplateLink link = policySet.templateLinks.get(0);
+        assertEquals("Template #1", link.getTemplateId());
+        assertEquals("Link #1", link.getResultPolicyId());
+
+        Map<String, EntityUID> linkValues = link.getLinkValues();
+        assertEquals(2, linkValues.size());
+        assertEquals("User::\"Matt\"", linkValues.get("?principal").toString());
+        assertEquals("Album::\"Vacation\"", linkValues.get("?resource").toString());
+    }
+
+    @Test
+    public void parsePoliciesJsonExceptionTests() throws InternalException, IOException {
+        assertThrows(IOException.class, () -> {
+            PolicySet.parsePoliciesJson(Path.of("nonExistentFilePath.json"));
+        });
+        // Cedar policy text, not JSON, should fail to parse as JSON
+        assertThrows(InternalException.class, () -> {
+            PolicySet.parsePoliciesJson("permit(principal, action, resource);");
+        });
+    }
+
     @Test
     public void parsePoliciesExceptionTests() throws InternalException, IOException {
         assertThrows(IOException.class, () -> {

CedarJava/src/test/resources/policies.json

@@ -0,0 +1,37 @@
+{
+  "staticPolicies": {
+    "Policy #1": {
+      "effect": "permit",
+      "principal": {
+        "op": "in",
+        "entity": { "type": "UserGroup", "id": "friends" }
+      },
+      "action": {
+        "op": "==",
+        "entity": { "type": "Action", "id": "view" }
+      },
+      "resource": {
+        "op": "==",
+        "entity": { "type": "Photo", "id": "Husky.jpg" }
+      },
+      "conditions": []
+    },
+    "Policy #2": {
+      "effect": "forbid",
+      "principal": {
+        "op": "==",
+        "entity": { "type": "User", "id": "Matt" }
+      },
+      "action": {
+        "op": "All"
+      },
+      "resource": {
+        "op": "==",
+        "entity": { "type": "Photo", "id": "Husky.jpg" }
+      },
+      "conditions": []
+    }
+  },
+  "templates": {},
+  "templateLinks": []
+}

CedarJava/src/test/resources/template.json

@@ -0,0 +1,62 @@
+{
+  "staticPolicies": {
+    "Policy #1": {
+      "effect": "permit",
+      "principal": {
+        "op": "in",
+        "entity": { "type": "UserGroup", "id": "friends" }
+      },
+      "action": {
+        "op": "==",
+        "entity": { "type": "Action", "id": "view" }
+      },
+      "resource": {
+        "op": "==",
+        "entity": { "type": "Photo", "id": "Husky.jpg" }
+      },
+      "conditions": []
+    },
+    "Policy #2": {
+      "effect": "forbid",
+      "principal": {
+        "op": "==",
+        "entity": { "type": "User", "id": "Matt" }
+      },
+      "action": {
+        "op": "All"
+      },
+      "resource": {
+        "op": "==",
+        "entity": { "type": "Photo", "id": "Husky.jpg" }
+      },
+      "conditions": []
+    }
+  },
+  "templates": {
+    "Template #1": {
+      "effect": "permit",
+      "principal": {
+        "op": "==",
+        "slot": "?principal"
+      },
+      "action": {
+        "op": "All"
+      },
+      "resource": {
+        "op": "in",
+        "slot": "?resource"
+      },
+      "conditions": []
+    }
+  },
+  "templateLinks": [
+    {
+      "newId": "Link #1",
+      "templateId": "Template #1",
+      "values": {
+        "?principal": { "type": "User", "id": "Matt" },
+        "?resource": { "type": "Album", "id": "Vacation" }
+      }
+    }
+  ]
+}