From b651f4497043db97f46fd721b620633b17a85327 Mon Sep 17 00:00:00 2001
From: Rob Norris <rob_norris@mac.com>
Date: Tue, 25 Apr 2023 09:22:56 -0500
Subject: [PATCH] error extension

---
 modules/core/src/main/scala/problem.scala     | 13 ++++++++++---
 .../src/test/scala/compiler/ProblemSpec.scala | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/modules/core/src/main/scala/problem.scala b/modules/core/src/main/scala/problem.scala
index 493ffbbb..87dde788 100644
--- a/modules/core/src/main/scala/problem.scala
+++ b/modules/core/src/main/scala/problem.scala
@@ -10,7 +10,8 @@ import io.circe.syntax._
 final case class Problem(
   message: String,
   locations: List[(Int, Int)] = Nil,
-  path: List[String] = Nil
+  path: List[String] = Nil,
+  extension: Option[JsonObject] = None,
 ) {
 
   override def toString = {
@@ -23,13 +24,15 @@ final case class Problem(
         if (a == b) a.toString else s"$a..$b"
       } .mkString(", ")
 
-    (path.nonEmpty, locations.nonEmpty) match {
+    val s = (path.nonEmpty, locations.nonEmpty) match {
       case (true, true)   => s"$message (at $pathText: $locationsText)"
       case (true, false)  => s"$message (at $pathText)"
       case (false, true)  => s"$message (at $locationsText)"
       case (false, false) => message
     }
 
+    extension.fold(s)(obj => s"$s, extension: ${obj.asJson.spaces2}")
+
   }
 
 }
@@ -54,10 +57,14 @@ object Problem {
       if (p.path.isEmpty) Nil
       else List(("path" -> p.path.asJson))
 
+    val extensionField: List[(String, Json)] =
+      p.extension.fold(List.empty[(String, Json)])(obj => List("extension" -> obj.asJson))
+
     Json.fromFields(
       "message" -> p.message.asJson ::
       locationsField                :::
-      pathField
+      pathField                     :::
+      extensionField
     )
 
   }
diff --git a/modules/core/src/test/scala/compiler/ProblemSpec.scala b/modules/core/src/test/scala/compiler/ProblemSpec.scala
index 1ec1a9f3..dab3a60a 100644
--- a/modules/core/src/test/scala/compiler/ProblemSpec.scala
+++ b/modules/core/src/test/scala/compiler/ProblemSpec.scala
@@ -7,6 +7,7 @@ import cats.tests.CatsSuite
 import edu.gemini.grackle.syntax._
 import edu.gemini.grackle.Problem
 import io.circe.syntax._
+import io.circe.JsonObject
 
 final class ProblemSpec extends CatsSuite {
 
@@ -106,4 +107,22 @@ final class ProblemSpec extends CatsSuite {
     )
   }
 
+  test("extension") {
+    val p = Problem("foo", extension = Some(JsonObject("bar" -> 42.asJson, "baz" -> List("a", "b").asJson)))
+    assert(
+      p.asJson == json"""
+        {
+          "message" : "foo",
+          "extension" : {
+            "bar" : 42,
+            "baz" : [
+              "a",
+              "b"
+            ]
+          }
+        }
+      """
+    )
+  }
+
 }
\ No newline at end of file