Revert "Explore: Remove support for legacy, compact format URLs (#49350)" (#50873)

This reverts commit a9cc3225ba.

Co-authored-by: Elfo404 <me@giordanoricci.com>

public/app/core/utils/explore.ts

@@ -165,6 +165,16 @@ export function buildQueryTransaction(
 
 export const clearQueryKeys: (query: DataQuery) => DataQuery = ({ key, ...rest }) => rest;
 
+const isSegment = (segment: { [key: string]: string }, ...props: string[]) =>
+  props.some((prop) => segment.hasOwnProperty(prop));
+
+enum ParseUrlStateIndex {
+  RangeFrom = 0,
+  RangeTo = 1,
+  Datasource = 2,
+  SegmentsStart = 3,
+}
+
 export const safeParseJson = (text?: string): any | undefined => {
   if (!text) {
     return;
@@ -219,7 +229,25 @@ export function parseUrlState(initial: string | undefined): ExploreUrlState {
     return errorResult;
   }
 
-  return parsed;
+  if (!Array.isArray(parsed)) {
+    return parsed;
+  }
+
+  if (parsed.length <= ParseUrlStateIndex.SegmentsStart) {
+    console.error('Error parsing compact URL state for Explore.');
+    return errorResult;
+  }
+
+  const range = {
+    from: parsed[ParseUrlStateIndex.RangeFrom],
+    to: parsed[ParseUrlStateIndex.RangeTo],
+  };
+  const datasource = parsed[ParseUrlStateIndex.Datasource];
+  const parsedSegments = parsed.slice(ParseUrlStateIndex.SegmentsStart);
+  const queries = parsedSegments.filter((segment) => !isSegment(segment, 'ui', 'mode', '__panelsState'));
+
+  const panelsState = parsedSegments.find((segment) => isSegment(segment, '__panelsState'))?.__panelsState;
+  return { datasource, queries, range, panelsState };
 }
 
 export function generateKey(index = 0): string {