Add first_over_time (#127656)

This change adds support for first_over_time for time-series data 
streams, similar to last_over_time.

Author: dnhatn

x-pack/plugin/esql/compute/build.gradle

@@ -79,6 +79,14 @@ def prop(Name, Type, type, Wrapper, TYPE, BYTES, Array, Hash) {
   ]
 }
 
+def addOccurrence(props, Occurrence) {
+  def newProps = props.collectEntries { [(it.key): it.value] }
+  newProps["Occurrence"] = Occurrence
+  newProps["First"] = Occurrence == "First" ? "true" : ""
+  newProps["Last"] = Occurrence == "Last" ? "true" : ""
+  return newProps
+}
+
 tasks.named('stringTemplates').configure {
   var intProperties = prop("Int", "Int", "int", "Integer", "INT", "Integer.BYTES", "IntArray", "LongHash")
   var floatProperties = prop("Float", "Float", "float", "Float", "FLOAT", "Float.BYTES", "FloatArray", "LongHash")
@@ -862,27 +870,30 @@ tasks.named('stringTemplates').configure {
     it.outputFile = "org/elasticsearch/xpack/compute/operator/lookup/EnrichResultBuilderForBoolean.java"
   }
 
-  // TODO: add last_over_time for other types: boolean, bytes_refs
-  File lastOverTimeAggregatorInputFile = file("src/main/java/org/elasticsearch/compute/aggregation/X-LastOverTimeAggregator.java.st")
-  template {
-    it.properties = intProperties
-    it.inputFile = lastOverTimeAggregatorInputFile
-    it.outputFile = "org/elasticsearch/compute/aggregation/LastOverTimeIntAggregator.java"
-  }
-  template {
-    it.properties = longProperties
-    it.inputFile = lastOverTimeAggregatorInputFile
-    it.outputFile = "org/elasticsearch/compute/aggregation/LastOverTimeLongAggregator.java"
+  // TODO: add {value}_over_time for other types: boolean, bytes_refs
+  File valueOverTimeAggregatorInputFile = file("src/main/java/org/elasticsearch/compute/aggregation/X-ValueOverTimeAggregator.java.st")
+  ["First", "Last"].forEach { Occurrence ->
+    {
+      template {
+        it.properties = addOccurrence(intProperties, Occurrence)
+        it.inputFile = valueOverTimeAggregatorInputFile
+        it.outputFile = "org/elasticsearch/compute/aggregation/${Occurrence}OverTimeIntAggregator.java"
+      }
+      template {
+        it.properties = addOccurrence(longProperties, Occurrence)
+        it.inputFile = valueOverTimeAggregatorInputFile
+        it.outputFile = "org/elasticsearch/compute/aggregation/${Occurrence}OverTimeLongAggregator.java"
+      }
+      template {
+        it.properties = addOccurrence(floatProperties, Occurrence)
+        it.inputFile = valueOverTimeAggregatorInputFile
+        it.outputFile = "org/elasticsearch/compute/aggregation/${Occurrence}OverTimeFloatAggregator.java"
+      }
+      template {
+        it.properties = addOccurrence(doubleProperties, Occurrence)
+        it.inputFile = valueOverTimeAggregatorInputFile
+        it.outputFile = "org/elasticsearch/compute/aggregation/${Occurrence}OverTimeDoubleAggregator.java"
+      }
+    }
   }
-  template {
-    it.properties = floatProperties
-    it.inputFile = lastOverTimeAggregatorInputFile
-    it.outputFile = "org/elasticsearch/compute/aggregation/LastOverTimeFloatAggregator.java"
-  }
-  template {
-    it.properties = doubleProperties
-    it.inputFile = lastOverTimeAggregatorInputFile
-    it.outputFile = "org/elasticsearch/compute/aggregation/LastOverTimeDoubleAggregator.java"
-  }
-
 }