Fix subquery parsing

Refactor Subquery from Expression into LogicalPlan. Duration parsing is
wip.

Author: costin

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/promql/subquery/Subquery.java

@@ -10,33 +10,27 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.xpack.esql.EsqlIllegalArgumentException;
-import org.elasticsearch.xpack.esql.core.expression.Expression;
-import org.elasticsearch.xpack.esql.core.expression.UnaryExpression;
 import org.elasticsearch.xpack.esql.core.tree.NodeInfo;
 import org.elasticsearch.xpack.esql.core.tree.Source;
-import org.elasticsearch.xpack.esql.core.type.DataType;
-import org.elasticsearch.xpack.esql.expression.promql.types.PromqlDataTypes;
+import org.elasticsearch.xpack.esql.plan.logical.LogicalPlan;
+import org.elasticsearch.xpack.esql.plan.logical.UnaryPlan;
 import org.elasticsearch.xpack.esql.plan.logical.promql.selector.Evaluation;
 
 import java.io.IOException;
 import java.util.Objects;
 
-public class Subquery extends UnaryExpression {
+public class Subquery extends UnaryPlan {
     private final TimeValue range;
     private final TimeValue resolution;
     private final Evaluation evaluation;
 
-    public Subquery(Source source, Expression query, TimeValue range, TimeValue resolution, Evaluation evaluation) {
-        super(source, query);
+    public Subquery(Source source, LogicalPlan child, TimeValue range, TimeValue resolution, Evaluation evaluation) {
+        super(source, child);
         this.range = range;
         this.resolution = resolution;
         this.evaluation = evaluation;
     }
 
-    public Expression query() {
-        return child();
-    }
-
     public TimeValue range() {
         return range;
     }
@@ -50,8 +44,8 @@ public Evaluation evaluation() {
     }
 
     @Override
-    public DataType dataType() {
-        return PromqlDataTypes.RANGE_VECTOR;
+    public boolean expressionsResolved() {
+        return true;
     }
 
     @Override
@@ -60,7 +54,7 @@ protected NodeInfo<Subquery> info() {
     }
 
     @Override
-    protected Subquery replaceChild(Expression newChild) {
+    public Subquery replaceChild(LogicalPlan newChild) {
         return new Subquery(source(), newChild, range, resolution, evaluation);
     }
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/promql/types/PromqlDataTypes.java

@@ -106,7 +106,7 @@ public String visitLabelName(LabelNameContext ctx) {
     @Override
     public Evaluation visitEvaluation(EvaluationContext ctx) {
         if (ctx == null) {
-            return null;
+            return Evaluation.NONE;
         }
 
         TimeValue offset = null;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/promql/PromqlExpressionBuilder.java

@@ -72,6 +72,14 @@ public void testUnsupportedQueries() throws Exception {
         }
     }
 
+    //@AwaitsFix(bugUrl = "placeholder for individual queries")
+    public void testSingleQuery() throws Exception {
+        String query = """
+            rate(http_requests_total[5m])[30m:1m]
+            """;
+        new PromqlParser().createStatement(query);
+    }
+
     static List<Tuple<String, Integer>> readQueries(String source) throws Exception {
         var urls = EsqlTestUtils.classpathResources(source);
         assertThat(urls, not(empty()));