Remove quotation marks from url (CATcher-org#345)

Quotation marks and null parameters are present for
filters saved in url.

Quotation marks are unnecessary and empty filters
can be removed from the URL in order to make it
more readable and editable by advanced users.

Let's remove null params and remove quotation marks
from the url.

src/app/core/services/filters.service.ts

@@ -72,20 +72,53 @@ export class FiltersService {
   ) {}
 
   private pushFiltersToUrl(): void {
-    const queryParams = {};
+    const queryParams = { ...this.route.snapshot.queryParams };
+
     for (const filterName of Object.keys(this.filter$.value)) {
-      if (this.filter$.value[filterName] instanceof Set) {
-        queryParams[filterName] = JSON.stringify([...this.filter$.value[filterName]]);
-      } else {
-        queryParams[filterName] = JSON.stringify(this.filter$.value[filterName]);
+      const filterValue = this.filter$.value[filterName];
+
+      // Don't include empty or null filters
+      // Intended behaviour to reset to default if 0 of a certain filter are selected
+      switch (filterName) {
+        // Strings
+        case 'title':
+        case 'type':
+          if (!filterValue) {
+            delete queryParams[filterName];
+            continue;
+          }
+          queryParams[filterName] = filterValue;
+          break;
+        // Arrays
+        case 'status':
+        case 'labels':
+        case 'milestones':
+          if (filterValue.length === 0) {
+            delete queryParams[filterName];
+            continue;
+          }
+          queryParams[filterName] = filterValue;
+          break;
+        // Sets
+        case 'selectedLabels':
+        case 'deselectedLabels':
+          if (filterValue.size === 0) {
+            delete queryParams[filterName];
+          }
+          queryParams[filterName] = [...filterValue];
+          break;
+        // Objects
+        case 'sort':
+          queryParams[filterName] = JSON.stringify(filterValue);
+          break;
+        default:
       }
     }
     queryParams[FiltersService.PRESET_VIEW_QUERY_PARAM_KEY] = this.presetView$.value;
 
     this.router.navigate([], {
       relativeTo: this.route,
       queryParams,
-      queryParamsHandling: 'merge',
       replaceUrl: true
     });
   }
@@ -100,7 +133,6 @@ export class FiltersService {
     const queryParams = this.route.snapshot.queryParamMap;
     try {
       const presetView = queryParams.get(FiltersService.PRESET_VIEW_QUERY_PARAM_KEY);
-
       // Use preset view if set in url
       if (presetView && this.presetViews.hasOwnProperty(presetView) && presetView !== 'custom') {
         this.updatePresetView(presetView);
@@ -114,16 +146,35 @@ export class FiltersService {
       }
 
       for (const filterName of Object.keys(nextFilter)) {
-        const stringifiedFilterData = queryParams.get(filterName);
-        if (!stringifiedFilterData) {
+        // Check if there is no such param in url
+        if (queryParams.get(filterName) === null) {
           continue;
         }
-        const filterData = JSON.parse(stringifiedFilterData);
 
-        if (nextFilter[filterName] instanceof Set) {
-          nextFilter[filterName] = new Set(filterData);
-        } else {
-          nextFilter[filterName] = filterData;
+        const filterData = queryParams.getAll(filterName);
+
+        switch (filterName) {
+          // Strings
+          case 'title':
+          case 'type':
+            nextFilter[filterName] = filterData[0];
+            break;
+          // Arrays
+          case 'status':
+          case 'labels':
+          case 'milestones':
+            nextFilter[filterName] = filterData;
+            break;
+          // Sets
+          case 'selectedLabels':
+          case 'deselectedLabels':
+            nextFilter[filterName] = new Set(filterData);
+            break;
+          // Objects
+          case 'sort':
+            nextFilter[filterName] = JSON.parse(filterData[0]);
+            break;
+          default:
         }
       }
       this.updateFilters(nextFilter);