Add a warning for unsupported logical / physical combinations

src/main/scala/eu/neverblink/jelly/cli/command/rdf/RdfToJelly.scala

@@ -82,6 +82,7 @@ object RdfToJelly extends RdfSerDesCommand[RdfToJellyOptions, RdfFormat.Readable
       options.inputFormat,
       remainingArgs.remaining.headOption,
     )
+    if !isQuietMode then checkAndWarnTypeCombination()
 
   override def matchFormatToAction(
       format: RdfFormat.Readable,
@@ -191,6 +192,29 @@ object RdfToJelly extends RdfSerDesCommand[RdfToJellyOptions, RdfFormat.Readable
       }
     }
 
+  private def checkAndWarnTypeCombination(): Unit = {
+    val rdfStreamOptions = getOptions.jellySerializationOptions.asRdfStreamOptions
+
+    val physicalType = rdfStreamOptions.getPhysicalType
+    val isPhysicalTriple = physicalType == PhysicalStreamType.TRIPLES
+
+    val logicalType = rdfStreamOptions.getLogicalType
+    val logicalTripleTypes = Seq(
+      LogicalStreamType.GRAPHS,
+      LogicalStreamType.SUBJECT_GRAPHS,
+      LogicalStreamType.FLAT_TRIPLES,
+    )
+    val isLogicalTriple = logicalTripleTypes.contains(logicalType)
+
+    if isPhysicalTriple != isLogicalTriple then
+      printLine(
+        s"WARNING: Selected combination of logical/physical stream types ($logicalType/$physicalType) is unsupported. " +
+          "Use --quiet to silence this warning.",
+        true,
+      )
+
+  }
+
   /** Check if the logical type is defined and grouped.
     * @param jellyOpt
     *   the Jelly options

src/test/scala/eu/neverblink/jelly/cli/command/rdf/RdfToJellySpec.scala

@@ -685,4 +685,46 @@ class RdfToJellySpec extends AnyWordSpec with TestFixtureHelper with Matchers:
         e.code should be(1)
       }
     }
+
+    "emit a warning" when {
+      "requesting an unsupported logical / physical combination" in withFullJenaFile { f =>
+        val (out, err) =
+          RdfToJelly.runTestCommand(
+            List(
+              "rdf",
+              "to-jelly",
+              "--opt.logical-type=SUBJECT_GRAPHS",
+              "--opt.physical-type=QUADS",
+              f,
+            ),
+          )
+        err should (
+          include("WARNING") and
+            include("unsupported") and
+            include("SUBJECT_GRAPHS/QUADS")
+        )
+      }
+    }
+
+    "not emit a warning" when {
+      "requesting an unsupported logical / physical combination with --quiet flag" in withFullJenaFile {
+        f =>
+          val (out, err) =
+            RdfToJelly.runTestCommand(
+              List(
+                "rdf",
+                "to-jelly",
+                "--quiet",
+                "--opt.logical-type=SUBJECT_GRAPHS",
+                "--opt.physical-type=QUADS",
+                f,
+              ),
+            )
+          err should not(
+            include("WARNING") and
+              include("unsupported") and
+              include("SUBJECT_GRAPHS/QUADS"),
+          )
+      }
+    }
   }