Loki: Add support for distinct operation in autocomplete and query builder (#69003)

* Loki Autocomplete: add support for suggesting distinct

* Loki query builder: add distinct as format operation

* Remove unused import

* Loki visual query: add support to parse distinct filters

* Query builder: use label param editor for distinct

* Loki Autocomplete: Improve distinct label suggestions

* Query Builder: improve distinct parsing

* Fix tests

* Update tests

public/app/plugins/datasource/loki/querybuilder/parsing.ts

@@ -8,6 +8,8 @@ import {
   By,
   ConvOp,
   Decolorize,
+  DistinctFilter,
+  DistinctLabel,
   Filter,
   FilterOp,
   Grouping,
@@ -205,6 +207,11 @@ export function handleExpression(expr: string, node: SyntaxNode, context: Contex
       break;
     }
 
+    case DistinctFilter: {
+      visQuery.operations.push(handleDistinctFilter(expr, node, context));
+      break;
+    }
+
     default: {
       // Any other nodes we just ignore and go to its children. This should be fine as there are lots of wrapper
       // nodes that can be skipped.
@@ -422,6 +429,7 @@ function handleUnwrapExpr(
 
   return {};
 }
+
 function handleRangeAggregation(expr: string, node: SyntaxNode, context: Context) {
   const nameNode = node.getChild(RangeOp);
   const funcName = getString(expr, nameNode);
@@ -632,3 +640,20 @@ function isEmptyQuery(query: LokiVisualQuery) {
   }
   return false;
 }
+
+function handleDistinctFilter(expr: string, node: SyntaxNode, context: Context): QueryBuilderOperation {
+  const labels: string[] = [];
+  let exploringNode = node.getChild(DistinctLabel);
+  while (exploringNode) {
+    const label = getString(expr, exploringNode.getChild(Identifier));
+    if (label) {
+      labels.push(label);
+    }
+    exploringNode = exploringNode?.getChild(DistinctLabel);
+  }
+  labels.reverse();
+  return {
+    id: LokiOperationId.Distinct,
+    params: labels,
+  };
+}