Dropping node descendants function add

Author: nikitaeverywhere

package.json

@@ -1,6 +1,6 @@
 {
   "name": "iknow-entity-browser",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "Visualizer for iKnow entities",
   "main": "gulpfile.babel.js",
   "scripts": {

src/static/js/controls.js

@@ -1,7 +1,8 @@
 /**
  * This file describes on-screen controls like UI link/remove buttons, etc.
  */
-import { onSelectionUpdate } from "./selection";
+import { onSelectionUpdate, updateSelection } from "./selection";
+import { dropDescendants } from "./model";
 
 let dropChildrenButton = null,
     removeButton = null,
@@ -14,17 +15,25 @@ onSelectionUpdate((sel) => {
 
 function updateButtons () {
     let display = selection.length ? "block" : "none";
-    dropChildrenButton.style.display = removeButton.style.display = display;
+    dropChildrenButton.style.display = display;
+    removeButton.classList.add("disabled"); // temporary
 }
 
 function deleteSelection () {
 
 }
 
+function dropChildren () {
+    if (!selection.length)
+        return;
+    dropDescendants(selection);
+    updateSelection();
+}
+
 export function init () {
     dropChildrenButton = document.getElementById(`dropChildrenButton`);
-    (removeButton = document.getElementById(`removeButton`)).addEventListener("click",
-        () => deleteSelection()
-    );
+    dropChildrenButton.addEventListener("click", () => dropChildren());
+    removeButton = document.getElementById(`removeButton`);
+    removeButton.addEventListener("click", () => deleteSelection());
     updateButtons();
 }

src/static/js/model/index.js

@@ -228,9 +228,9 @@ function resetChildrenPosition (parent, children = []) {
 // }
 
 /**
- * Unfold the node
+ * Unfold the folder by specified amount of nodes.
  * @param node - Node to unfold
- * @param [children] - Number of nodes to unfold
+ * @param [children=20] - Number of nodes to unfold
  * @returns {number} - Number of nodes left to unfold
  */
 export function unfold (node, children = 20) {
@@ -263,4 +263,54 @@ export function unfold (node, children = 20) {
         }
     });
     return res.left;
+}
+
+/**
+ * Delete all node's descendants.
+ * @param {Array|*} nodes - Node to unfold
+ * @returns {number} - Number of nodes unlinked
+ */
+export function dropDescendants (nodes) {
+
+    if (!(nodes instanceof Array))
+        nodes = [nodes];
+
+    let toDrop = 0;
+    for (let node of nodes) {
+        toDrop += (node.children ? node.children.length : 0)
+            + (node._children ? node._children.length : 0);
+    }
+    if (toDrop === 0)
+        return 0;
+
+    let restore = nodes.slice().map(node => {
+        return {
+            node: node,
+            children: node.children,
+            _children: node._children
+        };
+    });
+
+    function f () {
+        for (let node of nodes) {
+            node.children = [];
+            node._children = [];
+        }
+        dataUpdated();
+    }
+    f();
+
+    history.createState({
+        redo: f,
+        undo: () => {
+            for (let res of restore) {
+                res.node.children = res.children;
+                res.node._children = res._children;
+            }
+            dataUpdated();
+        }
+    });
+
+    return toDrop;
+
 }