Handle blank mobiledoc in editor

 * Rename Section methods semantically
 * add "simple-card" demo, with "remove" button
 * Clean up cursor detection and embedIntent
 * Add Position.emptyPosition and Range.emptyRange
 * allow mobiledoc to have 0 sections
 * add Post#isBlank
 * Add tests for typing in blank mobiledoc
 * Tests for removing the last item (e.g., card) in a mobiledoc
 * Ensure that replaceSection works when section is undefined
 * Add empty mobiledoc to demo

fixes #125 #35 #71

demo/demo.js

@@ -88,10 +88,13 @@ var selfieCard = {
 var simpleCard = {
   name: 'simple-card',
   display: {
-    setup: function(element) {
+    setup: function(element, options, env) {
       var card = document.createElement('span');
       card.innerHTML = 'Hello, world';
       element.appendChild(card);
+      var button = $('<button>Remove card</button>');
+      button.on('click', env.remove);
+      $(element).append(button);
     }
   }
 };
@@ -284,6 +287,7 @@ function bootEditor(element, mobiledoc) {
   editor = new ContentKit.Editor({
     autofocus: false,
     mobiledoc: mobiledoc,
+    placeholder: 'Write something here...',
     cards: [simpleCard, cardWithEditMode, cardWithInput, selfieCard],
     cardOptions: {
       image: {
@@ -336,6 +340,14 @@ var sampleMobiledocs = {
     ]
   },
 
+  emptyMobiledoc: {
+    version: MOBILEDOC_VERSION,
+    sections: [
+      [],
+      []
+    ]
+  },
+
   simpleMobiledocWithList: {
     version: MOBILEDOC_VERSION,
     sections: [
@@ -408,9 +420,6 @@ var sampleMobiledocs = {
     sections: [
       [],
       [
-        [1, "H2", [
-          [[], 0, "Simple Card"]
-        ]],
         [10, "simple-card"]
       ]
     ]

demo/index.html

@@ -43,7 +43,9 @@ <h2>Try a Demo</h2>
         <select id='select-mobiledoc'>
           <option disabled>Load a new Mobiledoc</option>
           <option value='simpleMobiledoc'>Simple text content</option>
+          <option value='emptyMobiledoc'>Empty mobiledoc</option>
           <option value='simpleMobiledocWithList'>List example</option>
+          <option value='mobileDocWithSimpleCard'>Simple Card</option>
           <option value='mobileDocWithInputCard'>Card with Input</option>
           <option value='mobileDocWithSelfieCard'>Selfie Card</option>
         </select>

src/js/editor/editor.js

@@ -8,7 +8,7 @@ import ImageCard from '../cards/image';
 import Key from '../utils/key';
 import EventEmitter from '../utils/event-emitter';
 
-import MobiledocParser from "../parsers/mobiledoc";
+import MobiledocParser from '../parsers/mobiledoc';
 import PostParser from '../parsers/post';
 import DOMParser from '../parsers/dom';
 import Renderer  from 'content-kit-editor/renderers/editor-dom';
@@ -234,7 +234,7 @@ class Editor {
   }
 
   handleNewline(event) {
-    if (!this.cursor.hasCursor()) { return ;}
+    if (!this.cursor.hasCursor()) { return; }
 
     const range = this.cursor.offsets;
     event.preventDefault();
@@ -570,8 +570,20 @@ class Editor {
     e.preventDefault(); // FIXME for now, just prevent default
   }
 
+  _insertEmptyMarkupSectionAtCursor() {
+    const section = this.run(postEditor => {
+      const section = postEditor.builder.createMarkupSection('p');
+      postEditor.insertSectionBefore(this.post.sections, section);
+      return section;
+    });
+    this.cursor.moveToSection(section);
+  }
+
   handleKeydown(event) {
     if (!this.isEditable) { return; }
+    if (this.post.isBlank) {
+      this._insertEmptyMarkupSectionAtCursor();
+    }
 
     const key = Key.fromEvent(event);
 

src/js/editor/post.js

@@ -1,4 +1,4 @@
-import { MARKUP_SECTION_TYPE, LIST_ITEM_TYPE } from '../models/types';
+import { POST_TYPE, MARKUP_SECTION_TYPE, LIST_ITEM_TYPE } from '../models/types';
 import Position from '../utils/cursor/position';
 import { filter, compact } from '../utils/array-utils';
 import { DIRECTION } from '../utils/key';
@@ -484,11 +484,20 @@ class PostEditor {
   }
 
   /**
+   * @method replaceSection
+   * @param {Section} section
+   * @param {Section} newSection
+   * @return null
    * @public
-   * FIXME: add tests for this
    */
   replaceSection(section, newSection) {
-    return this._replaceSection(section, [newSection]);
+    if (!section) {
+      // The section may be undefined if the user used the embed intent
+      // ("+" icon) to insert a new "ul" section in a blank post
+      this.insertSectionBefore(this.editor.post.sections, newSection);
+    } else {
+      this._replaceSection(section, [newSection]);
+    }
   }
 
   _replaceSection(section, newSections) {
@@ -597,7 +606,8 @@ class PostEditor {
    * @method insertSectionBefore
    * @param {LinkedList} collection The list of sections to insert into
    * @param {Object} section The new section
-   * @param {Object} beforeSection The section "before" is relative to
+   * @param {Object} beforeSection Optional The section "before" is relative to,
+   * if falsy the new section will be appended to the collection
    * @public
    */
   insertSectionBefore(collection, section, beforeSection) {
@@ -637,7 +647,7 @@ class PostEditor {
 
     parent.sections.remove(section);
 
-    if (parent.isBlank) {
+    if (parent.isBlank && parent.type !== POST_TYPE) {
       // If we removed the last child from a parent (e.g. the last li in a ul),
       // also remove the parent
       this.removeSection(parent);

src/js/models/_section.js

@@ -1,19 +1,31 @@
-import { LIST_ITEM_TYPE, LIST_SECTION_TYPE } from './types';
+import { LIST_ITEM_TYPE } from './types';
 import { normalizeTagName } from '../utils/dom-utils';
 import LinkedItem from '../utils/linked-item';
 
 function isMarkerable(section) {
   return !!section.markers;
 }
 
-function isListSection(section) {
-  return section.type === LIST_SECTION_TYPE;
+function getParentSection(section) {
+  return section.parent;
 }
 
-function isListItem(section) {
+function hasSubsections(section) {
+  return !!section.sections;
+}
+
+function isSubsection(section) {
   return section.type === LIST_ITEM_TYPE;
 }
 
+function firstMarkerableChild(section) {
+  return section.items.head;
+}
+
+function lastMarkerableChild(section) {
+  return section.items.tail;
+}
+
 export default class Section extends LinkedItem {
   constructor(type) {
     super();
@@ -34,13 +46,13 @@ export default class Section extends LinkedItem {
     if (next) {
       if (isMarkerable(next)) {
         return next;
-      } else if (isListSection(next)) {
-        const firstListItem = next.items.head;
-        return firstListItem;
+      } else if (hasSubsections(next)) {
+        const firstChild = firstMarkerableChild(next);
+        return firstChild;
       }
-    } else if (isListItem(this)) {
-      const listSection = this.parent;
-      return listSection.immediatelyNextMarkerableSection();
+    } else if (isSubsection(this)) {
+      const parentSection = getParentSection(this);
+      return parentSection.immediatelyNextMarkerableSection();
     }
   }
 
@@ -49,9 +61,9 @@ export default class Section extends LinkedItem {
     if (!prev) { return null; }
     if (isMarkerable(prev)) {
       return prev;
-    } else if (isListSection(prev)) {
-      const lastListItem = prev.items.tail;
-      return lastListItem;
+    } else if (hasSubsections(prev)) {
+      const lastChild = lastMarkerableChild(prev);
+      return lastChild;
     }
   }
 }

src/js/models/post.js

@@ -12,6 +12,10 @@ export default class Post {
     });
   }
 
+  get isBlank() {
+    return this.sections.isEmpty;
+  }
+
   /**
    * @param {Range} range
    * @return {Array} markers that are completely contained by the range

src/js/parsers/mobiledoc.js

@@ -26,11 +26,6 @@ export default class MobiledocParser {
     this.markerTypes = this.parseMarkerTypes(markerTypes);
     this.parseSections(sections, post);
 
-    if (post.sections.isEmpty) {
-      let section = this.builder.createMarkupSection('p');
-      post.sections.append(section);
-    }
-
     return post;
   }
 

src/js/utils/cursor.js

@@ -28,6 +28,8 @@ const Cursor = class Cursor {
   }
 
   isInCard() {
+    if (!this.hasCursor()) { return false; }
+
     const {head, tail} = this.offsets;
     return head && tail && (head._inCard || tail._inCard);
   }
@@ -40,7 +42,7 @@ const Cursor = class Cursor {
    * @return {Range} Cursor#Range object
    */
   get offsets() {
-    if (!this.hasCursor()) { return {}; }
+    if (!this.hasCursor()) { return Range.emptyRange(); }
 
     const { selection, renderTree } = this;
 

src/js/utils/cursor/position.js

@@ -1,4 +1,6 @@
-import { isTextNode, walkTextNodes } from 'content-kit-editor/utils/dom-utils';
+import {
+  isTextNode, findOffsetInElement
+} from 'content-kit-editor/utils/dom-utils';
 import {
   MARKUP_SECTION_TYPE, LIST_ITEM_TYPE, CARD_TYPE
 } from 'content-kit-editor/models/types';
@@ -25,27 +27,26 @@ function findParentSectionFromNode(renderTree, node) {
   }
 }
 
-function findOffsetInElement(elementNode, textNode, offsetInTextNode) {
-  let offset = 0, found = false;
-  walkTextNodes(elementNode, _textNode => {
-    if (found) { return; }
-    if (_textNode === textNode) {
-      found = true;
-      offset += offsetInTextNode;
-    } else {
-      offset += _textNode.textContent.length;
-    }
-  });
-  return offset;
-}
-
 const Position = class Position {
   constructor(section, offset=0) {
     this.section = section;
     this.offset = offset;
     this._inCard = isCardSection(section);
   }
 
+  static emptyPosition() {
+    return {
+      section: null,
+      offset: 0,
+      _inCard: false,
+      marker: null,
+      offsetInTextNode: 0,
+      _isEmpty: true,
+      isEqual(other) { return other._isEmpty; },
+      markerPosition: {}
+    };
+  }
+
   clone() {
     return new Position(this.section, this.offset);
   }
@@ -67,7 +68,7 @@ const Position = class Position {
     if (isTextNode(node)) {
       return Position.fromTextNode(renderTree, node, offset);
     } else {
-      return Position.fromElementNode(renderTree, node, offset);
+      return Position.fromElementNode(renderTree, node);
     }
   }
 
@@ -76,7 +77,7 @@ const Position = class Position {
     let section, offsetInSection;
 
     if (renderNode) {
-      let marker = renderNode.postNode;
+      const marker = renderNode.postNode;
       section = marker.section;
 
       if (!section) { throw new Error(`Could not find parent section for mapped text node "${textNode.textContent}"`); }
@@ -101,6 +102,13 @@ const Position = class Position {
   }
 
   static fromElementNode(renderTree, elementNode) {
+    // The browser may change the reported selection to equal the editor's root
+    // element if the user clicks an element that is immediately removed,
+    // which can happen when clicking to remove a card.
+    if (elementNode === renderTree.rootElement) {
+      return Position.emptyPosition();
+    }
+
     let section, offsetInSection = 0;
 
     section = findParentSectionFromNode(renderTree, elementNode);

src/js/utils/cursor/range.js

@@ -13,6 +13,10 @@ export default class Range {
     );
   }
 
+  static emptyRange() {
+    return new Range(Position.emptyPosition(), Position.emptyPosition());
+  }
+
   /**
    * @param {Markerable} section
    * @return {Range} A range that is constrained to only the part that