refactor: build next filter state for each category (#440)

Author: Fran McDade

src/common/categories/models/range/utils.ts

@@ -1,4 +1,4 @@
-import { SelectedFilter } from "../../../entities";
+import { CategoryValueKey, SelectedFilter } from "../../../entities";
 import { isSelectedRange } from "./typeGuards";
 import { SelectedRange } from "./types";
 
@@ -13,6 +13,28 @@ export function assertIsRange(value: unknown): asserts value is SelectedRange {
   }
 }
 
+/**
+ * Build the next filter state for the given range category.
+ * @param nextCategorySelectedFilter - Next filter state for the range category.
+ * @param selectedValue - Selected value for the range category.
+ * @param selected - Whether the category value is selected.
+ */
+export function buildNextRangeFilterState(
+  nextCategorySelectedFilter: SelectedFilter,
+  selectedValue: CategoryValueKey,
+  selected: boolean
+): void {
+  if (selected) {
+    // Assert that the selected value is a range.
+    assertIsRange(selectedValue);
+    // Set the selected range.
+    nextCategorySelectedFilter.value = selectedValue;
+  } else {
+    // Remove the selected range.
+    nextCategorySelectedFilter.value = [];
+  }
+}
+
 /**
  * Get the selected values for the given category, if any.
  * Handles type checking for selected range.

src/common/categories/models/select/utils.ts

@@ -0,0 +1,23 @@
+import { CategoryValueKey, SelectedFilter } from "../../../entities";
+
+/**
+ * Build the next filter state for the given select category.
+ * @param nextCategorySelectedFilter - Next filter state for the select category.
+ * @param selectedValue - Selected value for the select category.
+ * @param selected - Whether the category value is selected.
+ */
+export function buildNextSelectFilterState(
+  nextCategorySelectedFilter: SelectedFilter,
+  selectedValue: CategoryValueKey,
+  selected: boolean
+): void {
+  if (selected) {
+    // Set the selected value.
+    nextCategorySelectedFilter.value.push(selectedValue);
+  } else {
+    // Remove the selected value from the selected set of values.
+    nextCategorySelectedFilter.value = nextCategorySelectedFilter.value.filter(
+      (value: CategoryValueKey) => value !== selectedValue
+    );
+  }
+}

src/hooks/useCategoryFilter.ts

@@ -1,7 +1,8 @@
 import { CategoryConfig } from "../common/categories/config/types";
 import { findSelectCategoryConfig } from "../common/categories/config/utils";
 import { isRangeCategory } from "../common/categories/models/range/typeGuards";
-import { assertIsRange } from "../common/categories/models/range/utils";
+import { buildNextRangeFilterState } from "../common/categories/models/range/utils";
+import { buildNextSelectFilterState } from "../common/categories/models/select/utils";
 import { Category } from "../common/categories/models/types";
 import { buildRangeCategoryView } from "../common/categories/views/range/utils";
 import { CategoryView, VIEW_KIND } from "../common/categories/views/types";
@@ -174,28 +175,21 @@ export function buildNextFilterState(
     value: categorySelectedFilter ? [...categorySelectedFilter.value] : [],
   };
 
-  // Handle case where category value is selected.
-  if (selected) {
-    if (viewKind === VIEW_KIND.RANGE) {
-      // Assert that the selected value is a range.
-      assertIsRange(selectedValue);
-      // Set the selected range.
-      nextCategorySelectedFilter.value = selectedValue;
-    } else {
-      // Set the selected value.
-      nextCategorySelectedFilter.value.push(selectedValue);
-    }
-  }
-  // Otherwise, category value has been de-selected; remove the selected value from the selected set of values.
-  else {
-    if (viewKind === VIEW_KIND.RANGE) {
-      nextCategorySelectedFilter.value = [];
-    } else {
-      nextCategorySelectedFilter.value =
-        nextCategorySelectedFilter.value.filter(
-          (value: CategoryValueKey) => value !== selectedValue
-        );
-    }
+  // Build next filter state for category.
+  if (viewKind === VIEW_KIND.RANGE) {
+    // Handle range category.
+    buildNextRangeFilterState(
+      nextCategorySelectedFilter,
+      selectedValue,
+      selected
+    );
+  } else {
+    // Handle select category.
+    buildNextSelectFilterState(
+      nextCategorySelectedFilter,
+      selectedValue,
+      selected
+    );
   }
 
   // Add the new selected filter for this category to the set of selected filters, if there are selected values for it.