Add support for specifying formatter config (cedar-policy#235)

Signed-off-by: Felix Zheng <felix.zheng@mongodb.com>

CedarJava/src/main/java/com/cedarpolicy/formatter/PolicyFormatter.java

@@ -2,6 +2,7 @@
 
 import com.cedarpolicy.loader.LibraryLoader;
 import com.cedarpolicy.model.exception.InternalException;
+import com.cedarpolicy.model.formatter.Config;
 
 public final class PolicyFormatter {
 
@@ -14,4 +15,7 @@ private PolicyFormatter() {
 
   public static native String policiesStrToPretty(String policies)
       throws InternalException, NullPointerException;
+
+  public static native String policiesStrToPrettyWithConfig(String policies, Config config)
+      throws InternalException, NullPointerException;
 }

CedarJava/src/main/java/com/cedarpolicy/model/formatter/Config.java

@@ -0,0 +1,22 @@
+package com.cedarpolicy.model.formatter;
+
+public class Config {
+
+  private final int lineWidth;
+  private final int indentWidth;
+
+  public Config(int lineWidth, int indentWidth) {
+    this.lineWidth = lineWidth;
+    this.indentWidth = indentWidth;
+  }
+
+  @SuppressWarnings("unused")
+  public int getLineWidth() {
+    return lineWidth;
+  }
+
+  @SuppressWarnings("unused")
+  public int getIndentWidth() {
+    return indentWidth;
+  }
+}

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

@@ -2,6 +2,7 @@
 
 import com.cedarpolicy.formatter.PolicyFormatter;
 import com.cedarpolicy.model.exception.InternalException;
+import com.cedarpolicy.model.formatter.Config;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import org.junit.jupiter.api.Test;
@@ -37,4 +38,30 @@ public void testPoliciesStrToPrettyMalformedCedarPolicy() throws Exception {
   public void testPoliciesStrToPrettyNullSafety() {
     assertThrows(NullPointerException.class, () -> PolicyFormatter.policiesStrToPretty(null));
   }
+
+  @Test
+  public void testPoliciesStrToPrettyWithConfigNullSafety() throws Exception {
+    String cedarPolicy = Files.readString(Path.of(TEST_RESOURCES_DIR + "formatted_policy.cedar"));
+
+    assertThrows(NullPointerException.class,
+        () -> PolicyFormatter.policiesStrToPrettyWithConfig(null, null));
+
+    assertThrows(NullPointerException.class,
+        () -> PolicyFormatter.policiesStrToPrettyWithConfig(cedarPolicy, null));
+
+    assertThrows(NullPointerException.class,
+        () -> PolicyFormatter.policiesStrToPrettyWithConfig(null, new Config(120, 4)));
+  }
+
+  @Test
+  public void testPoliciesStrToPrettyWithConfig() throws Exception {
+    String unformattedCedarPolicy = Files.readString(
+        Path.of(TEST_RESOURCES_DIR + "unformatted_policy.cedar"));
+
+    String formattedCedarPolicyWithCustomConfig = Files.readString(
+        Path.of(TEST_RESOURCES_DIR + "formatted_policy_custom_config.cedar"));
+
+    assertEquals(formattedCedarPolicyWithCustomConfig,
+        PolicyFormatter.policiesStrToPrettyWithConfig(unformattedCedarPolicy, new Config(120, 4)));
+  }
 }

CedarJava/src/test/resources/formatted_policy_custom_config.cedar

@@ -0,0 +1,6 @@
+permit (
+    principal,
+    action == Action::"update",
+    resource
+)
+when { resource.owner == principal };

CedarJava/src/test/resources/malformed_policy_set.cedar

@@ -10,4 +10,4 @@ forbid (
   principal == User::"Liam",
   action,
   resource = Photo::"Husky.jpg"
-);
+);

CedarJava/src/test/resources/unformatted_policy.cedar

@@ -3,4 +3,4 @@ permit(
      action
   == Action::"update",
   resource
-) when {resource.owner == principal};
+) when {resource.owner == principal};

CedarJavaFFI/src/interface.rs

@@ -33,6 +33,7 @@ use serde::{Deserialize, Serialize};
 use serde_json::{from_str, Value};
 use std::{collections::HashMap, error::Error, str::FromStr, thread};
 
+use crate::objects::JFormatterConfig;
 use crate::{
     jset::Set,
     objects::{JEntityId, JEntityTypeName, JEntityUID, JPolicy, Object},
@@ -1014,7 +1015,20 @@ pub fn policiesStrToPretty<'a>(
     _: JClass,
     policies_jstr: JString<'a>,
 ) -> jvalue {
-    match policies_str_to_pretty_internal(&mut env, policies_jstr) {
+    match policies_str_to_pretty_internal(&mut env, policies_jstr, None) {
+        Ok(v) => v.as_jni(),
+        Err(e) => jni_failed(&mut env, e.as_ref()),
+    }
+}
+
+#[jni_fn("com.cedarpolicy.formatter.PolicyFormatter")]
+pub fn policiesStrToPrettyWithConfig<'a>(
+    mut env: JNIEnv<'a>,
+    _: JClass,
+    policies_jstr: JString<'a>,
+    config_obj: JObject<'a>,
+) -> jvalue {
+    match policies_str_to_pretty_internal(&mut env, policies_jstr, Some(config_obj)) {
         Ok(v) => v.as_jni(),
         Err(e) => jni_failed(&mut env, e.as_ref()),
     }
@@ -1023,11 +1037,16 @@ pub fn policiesStrToPretty<'a>(
 fn policies_str_to_pretty_internal<'a>(
     env: &mut JNIEnv<'a>,
     policies_jstr: JString<'a>,
+    config_obj: Option<JObject<'a>>,
 ) -> Result<JValueOwned<'a>> {
-    if policies_jstr.is_null() {
+    if policies_jstr.is_null() || config_obj.as_ref().is_some_and(|obj| obj.is_null()) {
         raise_npe(env)
     } else {
-        let config = Config::default();
+        let config = if let Some(obj) = config_obj {
+            JFormatterConfig::cast(env, obj)?.get_rust_repr()
+        } else {
+            Config::default()
+        };
         let policies_str = String::from(env.get_string(&policies_jstr)?);
         match policies_str_to_pretty(&policies_str, &config) {
             Ok(formatted_policies) => Ok(env.new_string(formatted_policies)?.into()),

CedarJavaFFI/src/objects.rs

@@ -5,6 +5,7 @@ use crate::{
 use std::{marker::PhantomData, str::FromStr};
 
 use cedar_policy::{EntityId, EntityTypeName, EntityUid};
+use cedar_policy_formatter::Config;
 use jni::{
     objects::{JObject, JString, JValueGen, JValueOwned},
     sys::jvalue,
@@ -380,3 +381,36 @@ impl<'a> AsRef<JObject<'a>> for JPolicy<'a> {
         &self.obj
     }
 }
+
+pub struct JFormatterConfig<'a> {
+    obj: JObject<'a>,
+    formatter_config: Config,
+}
+
+impl<'a> JFormatterConfig<'a> {
+    pub fn get_rust_repr(&self) -> Config {
+        self.formatter_config.clone()
+    }
+}
+
+impl<'a> AsRef<JObject<'a>> for JFormatterConfig<'a> {
+    fn as_ref(&self) -> &JObject<'a> {
+        &self.obj
+    }
+}
+
+impl<'a> Object<'a> for JFormatterConfig<'a> {
+    fn cast(env: &mut JNIEnv<'a>, obj: JObject<'a>) -> Result<Self> {
+        assert_is_class(env, &obj, "com/cedarpolicy/model/formatter/Config")?;
+        let line_width_jint = env.call_method(&obj, "getLineWidth", "()I", &[])?.i()?;
+        let indent_width_jint = env.call_method(&obj, "getIndentWidth", "()I", &[])?.i()?;
+        let formatter_config = Config {
+            line_width: usize::try_from(line_width_jint)?,
+            indent_width: isize::try_from(indent_width_jint)?,
+        };
+        Ok(Self {
+            obj,
+            formatter_config,
+        })
+    }
+}