feat: expandable accordion in grades module

src/app/_helpers/collections/tree-group.spec.ts

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2022 StApps
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ *  more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {Tree, treeGroupBy} from './tree-group';
+
+interface TestItem {
+  id: number;
+  path?: string[];
+}
+
+describe('tree-group', function () {
+  it('should create a tree', function () {
+    const items: Array<TestItem> = [
+      {
+        id: 1,
+        path: ['a', 'b', 'c'],
+      },
+      {
+        id: 2,
+        path: ['a', 'b', 'd'],
+      },
+    ];
+
+    const tree = treeGroupBy(items, item => item.path ?? []);
+
+    const expectedTree: Tree<TestItem> = {
+      a: {
+        b: {
+          c: {_: [items[0]]},
+          d: {_: [items[1]]},
+        } as Tree<TestItem>,
+      } as Tree<TestItem>,
+    } as Tree<TestItem>;
+
+    expect(tree).toEqual(expectedTree);
+  });
+
+  it('should also sort empty paths', () => {
+    const items: Array<TestItem> = [
+      {
+        id: 1,
+        path: ['a', 'b', 'c'],
+      },
+      {
+        id: 2,
+      },
+    ];
+
+    const tree = treeGroupBy(items, item => item.path ?? []);
+
+    const expectedTree: Tree<TestItem> = {
+      a: {
+        b: {
+          c: {_: [items[0]]},
+        } as Tree<TestItem>,
+      } as Tree<TestItem>,
+      _: [items[1]],
+    } as Tree<TestItem>;
+
+    expect(tree).toEqual(expectedTree);
+  });
+});

src/app/_helpers/collections/tree-group.ts

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2022 StApps
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ *  more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+export type Tree<T> = {
+  [key: string]: Tree<T>;
+} & {
+  _?: T[] | undefined;
+};
+
+/**
+ *
+ */
+export function treeGroupBy<T>(
+  items: T[],
+  transform: (item: T) => string[],
+): Tree<T> {
+  const tree: Tree<T> = {};
+
+  for (const item of items) {
+    let currentTree = tree;
+    const keys = transform(item);
+    if (keys.length === 0) {
+      currentTree._ = currentTree._ || [];
+      currentTree._.push(item);
+    }
+    for (const [i, key] of keys.entries()) {
+      currentTree = currentTree[key] = (currentTree[key] ?? {}) as Tree<T>;
+      if (i === keys.length - 1) {
+        currentTree._ = currentTree._ ?? [];
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        currentTree._.push(item);
+      }
+    }
+  }
+
+  return tree;
+}