From ed41a884bc38c5eb0a8f3531f0c899d7b6082ae3 Mon Sep 17 00:00:00 2001
From: Arman Ozak <arman@armanozak.com>
Date: Tue, 16 Jun 2020 11:25:09 +0300
Subject: [PATCH] feat: add tree utils to core

---
 .../core/src/lib/tests/tree-utils.spec.ts     | 68 +++++++++++++++++++
 .../packages/core/src/lib/utils/index.ts      |  1 +
 .../packages/core/src/lib/utils/tree-utils.ts | 51 ++++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 npm/ng-packs/packages/core/src/lib/tests/tree-utils.spec.ts
 create mode 100644 npm/ng-packs/packages/core/src/lib/utils/tree-utils.ts

diff --git a/npm/ng-packs/packages/core/src/lib/tests/tree-utils.spec.ts b/npm/ng-packs/packages/core/src/lib/tests/tree-utils.spec.ts
new file mode 100644
index 0000000000..454c1c6891
--- /dev/null
+++ b/npm/ng-packs/packages/core/src/lib/tests/tree-utils.spec.ts
@@ -0,0 +1,68 @@
+import { createTreeFromList, TreeNode } from '../utils/tree-utils';
+
+const LIST_1 = [
+  { id: 1, pid: null },
+  { id: 2, pid: 1 },
+];
+const LIST_2 = [
+  { id: 1, pid: null },
+  { id: 2, pid: 1 },
+  { id: 3, pid: 1 },
+];
+const LIST_3 = [
+  { id: 1, pid: null },
+  { id: 2, pid: 1 },
+  { id: 3, pid: 2 },
+];
+const TREE_1 = [
+  { id: 1, pid: null, isLeaf: false, children: [{ id: 2, pid: 1, isLeaf: true, children: [] }] },
+];
+const TREE_2 = [
+  {
+    id: 1,
+    pid: null,
+    isLeaf: false,
+    children: [
+      { id: 2, pid: 1, isLeaf: true, children: [] },
+      { id: 3, pid: 1, isLeaf: true, children: [] },
+    ],
+  },
+];
+const TREE_3 = [
+  {
+    id: 1,
+    pid: null,
+    isLeaf: false,
+    children: [
+      { id: 2, pid: 1, isLeaf: false, children: [{ id: 3, pid: 2, isLeaf: true, children: [] }] },
+    ],
+  },
+];
+describe('Tree Utils', () => {
+  describe('createTreeFromList', () => {
+    test.each`
+      list      | expected
+      ${LIST_1} | ${TREE_1}
+      ${LIST_2} | ${TREE_2}
+      ${LIST_3} | ${TREE_3}
+    `('should return $expected when given $list', ({ list, expected }: TestCreateTreeFromList) => {
+      expect(
+        createTreeFromList(
+          list,
+          x => x.id,
+          x => x.pid,
+        ),
+      ).toEqual(expected);
+    });
+  });
+});
+
+interface TestCreateTreeFromList {
+  list: ModelA[];
+  expected: TreeNode<ModelA>[];
+}
+
+interface ModelA {
+  id: 1;
+  pid: null;
+}
diff --git a/npm/ng-packs/packages/core/src/lib/utils/index.ts b/npm/ng-packs/packages/core/src/lib/utils/index.ts
index ce89b4dddb..6f6136b195 100644
--- a/npm/ng-packs/packages/core/src/lib/utils/index.ts
+++ b/npm/ng-packs/packages/core/src/lib/utils/index.ts
@@ -9,3 +9,4 @@ export * from './localization-utils';
 export * from './number-utils';
 export * from './route-utils';
 export * from './rxjs-utils';
+export * from './tree-utils';
diff --git a/npm/ng-packs/packages/core/src/lib/utils/tree-utils.ts b/npm/ng-packs/packages/core/src/lib/utils/tree-utils.ts
new file mode 100644
index 0000000000..86844a4375
--- /dev/null
+++ b/npm/ng-packs/packages/core/src/lib/utils/tree-utils.ts
@@ -0,0 +1,51 @@
+export class TreeNode<T extends any> {
+  children: TreeNode<T>[] = [];
+  isLeaf = true;
+
+  constructor(props: T) {
+    Object.assign(this, props);
+  }
+}
+
+export function createTreeFromList<T extends object, R extends BranchOrLeaf<T>>(
+  list: T[],
+  keySelector: (item: T) => NodeKey,
+  parentKeySelector: (item: T) => NodeKey,
+  valueMapper = (item: T) => new TreeNode(item) as R,
+) {
+  const map = createMapFromList(list, keySelector, valueMapper);
+  const tree: ReturnType<typeof valueMapper>[] = [];
+
+  list.forEach(row => {
+    const id = keySelector(row);
+    const parentId = parentKeySelector(row);
+    const node = map.get(id);
+
+    if (parentId) {
+      const parent = map.get(parentId);
+      parent.children.push(node);
+      parent.isLeaf = false;
+    } else {
+      tree.push(node);
+    }
+  });
+
+  return tree;
+}
+
+export function createMapFromList<T extends object, R extends BranchOrLeaf<T>>(
+  list: T[],
+  keySelector: (item: T) => NodeKey,
+  valueMapper = (item: T) => new TreeNode(item) as R,
+) {
+  const map = new Map<ReturnType<typeof keySelector>, ReturnType<typeof valueMapper>>();
+  list.forEach(row => map.set(keySelector(row), valueMapper(row)));
+  return map;
+}
+
+type NodeKey = number | string | Symbol;
+
+interface BranchOrLeaf<T> {
+  children: BranchOrLeaf<T>[];
+  isLeaf: boolean;
+}