From 7778ddc2925941ee5f3794091589c4d098374679 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 3 Jun 2020 17:09:07 +0200
Subject: [PATCH 01/15] Add manual test for link protocol.

---
 .../ckeditor5-link/tests/manual/protocol.html | 52 +++++++++++++++++++
 .../ckeditor5-link/tests/manual/protocol.js   | 49 +++++++++++++++++
 .../ckeditor5-link/tests/manual/protocol.md   |  8 +++
 3 files changed, 109 insertions(+)
 create mode 100644 packages/ckeditor5-link/tests/manual/protocol.html
 create mode 100644 packages/ckeditor5-link/tests/manual/protocol.js
 create mode 100644 packages/ckeditor5-link/tests/manual/protocol.md

diff --git a/packages/ckeditor5-link/tests/manual/protocol.html b/packages/ckeditor5-link/tests/manual/protocol.html
new file mode 100644
index 00000000000..5ea3e8230d9
--- /dev/null
+++ b/packages/ckeditor5-link/tests/manual/protocol.html
@@ -0,0 +1,52 @@
+<style>
+	code {
+		background: hsl(0, 0%, 90%);
+	}
+
+	sup {
+		position: relative;
+	}
+
+	.ck-editor__editable sup:after {
+		content: '';
+		display: inline-block;
+		position: absolute;
+		width: 14px;
+		height: 14px;
+		left: 1px;
+    top: 1px;
+		background: hsla(207, 87%, 55%, 0.5);
+		border-radius: 50px;
+		animation: pulse 2s linear infinite;
+	}
+
+	@keyframes pulse {
+		0% {
+			transform: scale(1);
+		}
+
+		50% {
+			transform: scale(2);
+		}
+
+		100% {
+			transform: scale(1);
+		}
+	}
+</style>
+
+<h2>The default configuration for the link protocol has been set to <code id="default-protocol"></code>.</h2>
+
+<h3>...but you can change it:</h3>
+<form id="protocol-settings" style="margin: 20px 0;">
+	<label for="http"><input type="radio" name="option" id="http" value="http://" />HTTP</label>
+	<label for="https"><input type="radio" name="option" id="https" value="https://" />HTTPS</label>
+	<label for="mailto"><input type="radio" name="option" id="mailto" value="mailto:" />MAILTO</label>
+	<label for="file"><input type="radio" name="option" id="file" value="file://" />FILE</label>
+</form>
+
+<div id="editor">
+	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com <sup class="indicator">[1]</sup>.</p>
+</div>
+
+<p><sup>[1]</sup> Copy the email address and create a link with it (<code>mailto:</code> protocol will be added automatically).</p>
diff --git a/packages/ckeditor5-link/tests/manual/protocol.js b/packages/ckeditor5-link/tests/manual/protocol.js
new file mode 100644
index 00000000000..c99580b4256
--- /dev/null
+++ b/packages/ckeditor5-link/tests/manual/protocol.js
@@ -0,0 +1,49 @@
+/**
+ * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/* globals console:false, window, document */
+
+import ClassicEditor from '@ckeditor/ckeditor5-editor-classic/src/classiceditor';
+import Enter from '@ckeditor/ckeditor5-enter/src/enter';
+import Typing from '@ckeditor/ckeditor5-typing/src/typing';
+import Link from '../../src/link';
+import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph';
+import Undo from '@ckeditor/ckeditor5-undo/src/undo';
+import Superscript from '@ckeditor/ckeditor5-basic-styles/src/superscript';
+
+ClassicEditor
+	.create( document.querySelector( '#editor' ), {
+		plugins: [ Link, Typing, Paragraph, Undo, Enter, Superscript ],
+		toolbar: [ 'link', 'undo', 'redo' ],
+		link: {
+			addTargetToExternalLinks: true,
+			defaultProtocol: 'http://'
+		}
+	} )
+	.then( editor => {
+		window.editor = editor;
+
+		const LinkUIPlugin = editor.plugins.get( 'LinkUI' );
+		const formView = LinkUIPlugin.formView;
+		const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
+
+		document.getElementById( 'default-protocol' ).innerText = defaultProtocol;
+
+		document.querySelectorAll( '#protocol-settings input[type="radio"]' ).forEach( radio => {
+			radio.checked = radio.value === defaultProtocol;
+
+			radio.addEventListener( 'click', ( {
+				target: { value: protocol }
+			} ) => {
+				editor.config.set( 'link.defaultProtocol', protocol );
+
+				// Change input placeholder just for manual test's case to provide more dynamic behavior.
+				formView.urlInputView.fieldView.placeholder = protocol + 'example.com';
+			} );
+		} );
+	} )
+	.catch( err => {
+		console.error( err.stack );
+	} );
diff --git a/packages/ckeditor5-link/tests/manual/protocol.md b/packages/ckeditor5-link/tests/manual/protocol.md
new file mode 100644
index 00000000000..2a5266c561a
--- /dev/null
+++ b/packages/ckeditor5-link/tests/manual/protocol.md
@@ -0,0 +1,8 @@
+## Link protocol
+
+This test checks whether:
+- `config.link.defaultProtocol` applies.
+- user is able to dynamically change the link protocol (just as an extended example of usage).
+- the plugin dynamically change link protocol to `mailto:` when email address was detected.
+
+When you dynamically change the value of the link protocol, the form input placeholder should change as well.

From 79a31afe5e5a2a662b5099c82de8dce3f2ec06a5 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 3 Jun 2020 17:10:46 +0200
Subject: [PATCH 02/15] Add default link protocol automatically.

---
 packages/ckeditor5-link/src/linkui.js          | 16 +++++++++++++---
 packages/ckeditor5-link/src/ui/linkformview.js | 13 ++++++++-----
 packages/ckeditor5-link/src/utils.js           |  7 +++++++
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index 68370115999..7318f3203f3 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -9,7 +9,7 @@
 
 import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
 import ClickObserver from '@ckeditor/ckeditor5-engine/src/view/observer/clickobserver';
-import { isLinkElement } from './utils';
+import { isLinkElement, DEFAULT_PROTOCOL } from './utils';
 import ContextualBalloon from '@ckeditor/ckeditor5-ui/src/panel/balloon/contextualballoon';
 
 import clickOutsideHandler from '@ckeditor/ckeditor5-ui/src/bindings/clickoutsidehandler';
@@ -143,8 +143,9 @@ export default class LinkUI extends Plugin {
 	_createFormView() {
 		const editor = this.editor;
 		const linkCommand = editor.commands.get( 'link' );
+		const defaultProtocol = editor.config.get( 'link.defaultProtocol' ) || DEFAULT_PROTOCOL;
 
-		const formView = new LinkFormView( editor.locale, linkCommand );
+		const formView = new LinkFormView( editor.locale, linkCommand, defaultProtocol );
 
 		formView.urlInputView.fieldView.bind( 'value' ).to( linkCommand, 'value' );
 
@@ -154,7 +155,16 @@ export default class LinkUI extends Plugin {
 
 		// Execute link command after clicking the "Save" button.
 		this.listenTo( formView, 'submit', () => {
-			editor.execute( 'link', formView.urlInputView.fieldView.element.value, formView.getDecoratorSwitchesState() );
+			const { value } = formView.urlInputView.fieldView.element;
+			const hasProtocol = ( /\w+:\/\//gmi ).test( value );
+			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
+
+			// It's good to check config second time on submit for more dynamic cases
+			// when protocol might change after the element rendered.
+			const protocol = isEmail && 'mailto:' || editor.config.get( 'link.defaultProtocol' ) || defaultProtocol;
+			const parsedValue = !hasProtocol && value ? protocol + value : value;
+
+			editor.execute( 'link', parsedValue, formView.getDecoratorSwitchesState() );
 			this._closeFormView();
 		} );
 
diff --git a/packages/ckeditor5-link/src/ui/linkformview.js b/packages/ckeditor5-link/src/ui/linkformview.js
index 2b050ee8e25..12fb97d865a 100644
--- a/packages/ckeditor5-link/src/ui/linkformview.js
+++ b/packages/ckeditor5-link/src/ui/linkformview.js
@@ -21,6 +21,8 @@ import FocusTracker from '@ckeditor/ckeditor5-utils/src/focustracker';
 import FocusCycler from '@ckeditor/ckeditor5-ui/src/focuscycler';
 import KeystrokeHandler from '@ckeditor/ckeditor5-utils/src/keystrokehandler';
 
+import { DEFAULT_PROTOCOL } from '../utils';
+
 import checkIcon from '@ckeditor/ckeditor5-core/theme/icons/check.svg';
 import cancelIcon from '@ckeditor/ckeditor5-core/theme/icons/cancel.svg';
 import '../../theme/linkform.css';
@@ -40,8 +42,9 @@ export default class LinkFormView extends View {
 	 *
 	 * @param {module:utils/locale~Locale} [locale] The localization services instance.
 	 * @param {module:link/linkcommand~LinkCommand} linkCommand Reference to {@link module:link/linkcommand~LinkCommand}.
+	 * @param {String} [protocol] A value of a protocol to be displayed in the input's placeholder.
 	 */
-	constructor( locale, linkCommand ) {
+	constructor( locale, linkCommand, protocol ) {
 		super( locale );
 
 		const t = locale.t;
@@ -67,7 +70,7 @@ export default class LinkFormView extends View {
 		 *
 		 * @member {module:ui/labeledfield/labeledfieldview~LabeledFieldView}
 		 */
-		this.urlInputView = this._createUrlInput();
+		this.urlInputView = this._createUrlInput( protocol );
 
 		/**
 		 * The Save button view.
@@ -207,15 +210,15 @@ export default class LinkFormView extends View {
 	 * Creates a labeled input view.
 	 *
 	 * @private
+	 * @param {module:link/utils~DefaultProtocol} [protocol=http://] A value of a protocol to be displayed in the input's placeholder.
 	 * @returns {module:ui/labeledfield/labeledfieldview~LabeledFieldView} Labeled field view instance.
 	 */
-	_createUrlInput() {
+	_createUrlInput( protocol = DEFAULT_PROTOCOL ) {
 		const t = this.locale.t;
-
 		const labeledInput = new LabeledFieldView( this.locale, createLabeledInputText );
 
 		labeledInput.label = t( 'Link URL' );
-		labeledInput.fieldView.placeholder = 'https://example.com';
+		labeledInput.fieldView.placeholder = protocol + 'example.com';
 
 		return labeledInput;
 	}
diff --git a/packages/ckeditor5-link/src/utils.js b/packages/ckeditor5-link/src/utils.js
index 4c80d39e9c0..4eafb2be35a 100644
--- a/packages/ckeditor5-link/src/utils.js
+++ b/packages/ckeditor5-link/src/utils.js
@@ -12,6 +12,13 @@ import { upperFirst } from 'lodash-es';
 const ATTRIBUTE_WHITESPACES = /[\u0000-\u0020\u00A0\u1680\u180E\u2000-\u2029\u205f\u3000]/g; // eslint-disable-line no-control-regex
 const SAFE_URL = /^(?:(?:https?|ftps?|mailto):|[^a-z]|[a-z+.-]+(?:[^a-z+.:-]|$))/i;
 
+/**
+ * A default link protocol value.
+ * @typedef {String} module:link/utils~DefaultProtocol
+ * @default 'http://'
+ */
+export const DEFAULT_PROTOCOL = 'http://';
+
 /**
  * Returns `true` if a given view node is the link element.
  *

From 96e8d9e5207a6d79ee628607da1da30edb834dc0 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 3 Jun 2020 17:11:04 +0200
Subject: [PATCH 03/15] Add tests for the link protocol.

---
 packages/ckeditor5-link/tests/linkui.js       | 62 ++++++++++++++++++-
 .../ckeditor5-link/tests/ui/linkformview.js   |  4 +-
 2 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/packages/ckeditor5-link/tests/linkui.js b/packages/ckeditor5-link/tests/linkui.js
index 48c6b18f511..602320bcafc 100644
--- a/packages/ckeditor5-link/tests/linkui.js
+++ b/packages/ckeditor5-link/tests/linkui.js
@@ -8,7 +8,7 @@
 import ClassicTestEditor from '@ckeditor/ckeditor5-core/tests/_utils/classictesteditor';
 import testUtils from '@ckeditor/ckeditor5-core/tests/_utils/utils';
 import { keyCodes } from '@ckeditor/ckeditor5-utils/src/keyboard';
-import { setData as setModelData } from '@ckeditor/ckeditor5-engine/src/dev-utils/model';
+import { setData as setModelData, getData as getModelData } from '@ckeditor/ckeditor5-engine/src/dev-utils/model';
 import { getData as getViewData } from '@ckeditor/ckeditor5-engine/src/dev-utils/view';
 
 import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph';
@@ -21,6 +21,8 @@ import ContextualBalloon from '@ckeditor/ckeditor5-ui/src/panel/balloon/contextu
 import ButtonView from '@ckeditor/ckeditor5-ui/src/button/buttonview';
 import View from '@ckeditor/ckeditor5-ui/src/view';
 
+import { DEFAULT_PROTOCOL } from '../src/utils';
+
 import ClickObserver from '@ckeditor/ckeditor5-engine/src/view/observer/clickobserver';
 
 describe( 'LinkUI', () => {
@@ -905,6 +907,62 @@ describe( 'LinkUI', () => {
 			expect( editor.ui.focusTracker.isFocused ).to.be.true;
 		} );
 
+		describe( 'link protocol', () => {
+			beforeEach( () => {
+				editor.model.schema.extend( '$text', {
+					allowIn: '$root',
+					allowAttributes: 'linkHref'
+				} );
+			} );
+
+			it( 'should use a default link protocol from the `config.link.defaultProtocol` when provided', () => {
+				return ClassicTestEditor
+					.create( editorElement, {
+						link: {
+							defaultProtocol: 'https://'
+						}
+					} )
+					.then( editor => {
+						const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
+
+						expect( defaultProtocol ).to.equal( 'https://' );
+
+						editorElement.remove();
+						editor.destroy();
+					} );
+			} );
+
+			it( 'should use `http://` as a default link protocol without any configuration', () => {
+				formView.urlInputView.fieldView.value = 'ckeditor.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://ckeditor.com' );
+			} );
+
+			it( 'should propagate the protocol to the link\'s `linkHref` attribute in model', () => {
+				setModelData( editor.model, '[ckeditor.com]' );
+
+				formView.urlInputView.fieldView.value = 'ckeditor.com';
+				formView.fire( 'submit' );
+
+				expect( getModelData( editor.model ) ).to.equal(
+					'[<$text linkHref="http://ckeditor.com">ckeditor.com</$text>]'
+				);
+			} );
+
+			it( 'should detect an email on submitting the form and add "mailto:" protocol automatically to the provided value', () => {
+				setModelData( editor.model, '[email@example.com]' );
+
+				formView.urlInputView.fieldView.value = 'email@example.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:email@example.com' );
+				expect( getModelData( editor.model ) ).to.equal(
+					'[<$text linkHref="mailto:email@example.com">email@example.com</$text>]'
+				);
+			} );
+		} );
+
 		describe( 'binding', () => {
 			beforeEach( () => {
 				setModelData( editor.model, '<paragraph>f[o]o</paragraph>' );
@@ -1062,7 +1120,7 @@ describe( 'LinkUI', () => {
 					formView.fire( 'submit' );
 
 					expect( executeSpy.calledOnce ).to.be.true;
-					expect( executeSpy.calledWithExactly( 'link', 'url', { linkIsFoo: true } ) ).to.be.true;
+					expect( executeSpy.calledWithExactly( 'link', DEFAULT_PROTOCOL + 'url', { linkIsFoo: true } ) ).to.be.true;
 				} );
 
 				it( 'should reset switch state when form view is closed', () => {
diff --git a/packages/ckeditor5-link/tests/ui/linkformview.js b/packages/ckeditor5-link/tests/ui/linkformview.js
index 402274d89c7..b4c511dec43 100644
--- a/packages/ckeditor5-link/tests/ui/linkformview.js
+++ b/packages/ckeditor5-link/tests/ui/linkformview.js
@@ -21,6 +21,8 @@ import Link from '../../src/link';
 import ObservableMixin from '@ckeditor/ckeditor5-utils/src/observablemixin';
 import mix from '@ckeditor/ckeditor5-utils/src/mix';
 
+import { DEFAULT_PROTOCOL } from '../../src/utils';
+
 describe( 'LinkFormView', () => {
 	let view;
 
@@ -83,7 +85,7 @@ describe( 'LinkFormView', () => {
 
 		describe( 'url input view', () => {
 			it( 'has placeholder', () => {
-				expect( view.urlInputView.fieldView.placeholder ).to.equal( 'https://example.com' );
+				expect( view.urlInputView.fieldView.placeholder ).to.equal( DEFAULT_PROTOCOL + 'example.com' );
 			} );
 		} );
 

From cd7f08cf4e57d50c9cd79afc374395dd89602211 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 3 Jun 2020 18:12:08 +0200
Subject: [PATCH 04/15] Add API docs.

---
 packages/ckeditor5-link/src/link.js | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/packages/ckeditor5-link/src/link.js b/packages/ckeditor5-link/src/link.js
index 2fa90aabe23..2c29edd5bc7 100644
--- a/packages/ckeditor5-link/src/link.js
+++ b/packages/ckeditor5-link/src/link.js
@@ -57,6 +57,25 @@ export default class Link extends Plugin {
  * @interface LinkConfig
  */
 
+/**
+ * When set, the editor will add the given protocol to the link when the user creates a link without one.
+ * In case no configuration is provided, the value defaults to `http://`.
+ * For example, when the user is creating a link and types `ckeditor.com` in the link form input — during link submission —
+ * the editor will automatically add the `http://` protocol, so the link will be as follows: `http://ckeditor.com`.
+ *
+ * 		ClassicEditor
+ *			.create( editorElement, {
+ * 				link: {
+ * 					defaultProtocol: 'http://'
+ * 				}
+ *			} )
+ *			.then( ... )
+ *			.catch( ... );
+ *
+ * @default 'http://'
+ * @member {String} module:link/link~LinkConfig#defaultProtocol
+ */
+
 /**
  * When set to `true`, the `target="blank"` and `rel="noopener noreferrer"` attributes are automatically added to all external links
  * in the editor. "External links" are all links in the editor content starting with `http`, `https`, or `//`.

From f3fa2f4961992f5fd363381d0991e99184e0a0f6 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 3 Jun 2020 18:15:24 +0200
Subject: [PATCH 05/15] Fix whitespaces.

---
 packages/ckeditor5-link/tests/manual/protocol.html | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/ckeditor5-link/tests/manual/protocol.html b/packages/ckeditor5-link/tests/manual/protocol.html
index 5ea3e8230d9..6b5a4bd693d 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.html
+++ b/packages/ckeditor5-link/tests/manual/protocol.html
@@ -14,7 +14,7 @@
 		width: 14px;
 		height: 14px;
 		left: 1px;
-    top: 1px;
+		top: 1px;
 		background: hsla(207, 87%, 55%, 0.5);
 		border-radius: 50px;
 		animation: pulse 2s linear infinite;

From 08c8db327800a893cf7f13949ab3f7b27fcda5c6 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:31:54 +0200
Subject: [PATCH 06/15] Update documentation (API, guide).

---
 packages/ckeditor5-link/docs/features/link.md | 24 +++++++++++++++++++
 packages/ckeditor5-link/src/link.js           |  7 ++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/packages/ckeditor5-link/docs/features/link.md b/packages/ckeditor5-link/docs/features/link.md
index 4aa62b8189d..66ecf68396d 100644
--- a/packages/ckeditor5-link/docs/features/link.md
+++ b/packages/ckeditor5-link/docs/features/link.md
@@ -147,6 +147,30 @@ ClassicEditor
 	.catch( ... );
 ```
 
+#### Adding default link protocol for the external links
+
+Default link protocol can be usefull when user forget to type a full URL address to an external source, site etc. Sometimes copying the text, like for example `ckeditor.com` and converting it to a link may cause some issues. When you do this, the created link will direct you to `yourdomain.com/ckeditor.com`, because you forgot to pass the right protocol which makes the link relative to the site where it appears.
+
+Enabling the `{@link module:link/link~LinkConfig#defaultProtocol config.link.defaultProtocol}`, the {@link module:link/link~Link} feature will handle this issue for you. By default it doesn't fix the passed link value, but when you set `{@link module:link/link~LinkConfig#defaultProtocol config.link.defaultProtocol}` to — for example — `http://`, the plugin will add the given protocol to the every link that may need it (like `ckeditor.com`, `example.com` etc. where `[protocol://]example.com` is missing). Here's the basic configuration example:
+
+```js
+ClassicEditor
+	.create( document.querySelector( '#editor' ), {
+		// ...
+		link: {
+			defaultProtocol: 'http://'
+		}
+	} )
+	.then( ... )
+	.catch( ... );
+```
+
+<info-box>
+	Having `config.link.defaultProtocol` enabled you are still able to link things locally using `#` or `/`. Protocol won't be added to those links.
+
+	Enabled feature also gives you an **email addresses auto-detection** feature. When you submit `hello@example.com`, the plugin will change it automatically to `mailto:hello@example.com`.
+</info-box>
+
 #### Adding attributes to links based on pre–defined rules (automatic decorators)
 
 Automatic link decorators match all links in the editor content against a {@link module:link/link~LinkDecoratorAutomaticDefinition function} which decides whether the link should receive some set of attributes, considering the URL (`href`) of the link. These decorators work silently and are being applied during the {@link framework/guides/architecture/editing-engine#conversion data downcast} only.
diff --git a/packages/ckeditor5-link/src/link.js b/packages/ckeditor5-link/src/link.js
index 2c29edd5bc7..96f8e9f9897 100644
--- a/packages/ckeditor5-link/src/link.js
+++ b/packages/ckeditor5-link/src/link.js
@@ -59,10 +59,12 @@ export default class Link extends Plugin {
 
 /**
  * When set, the editor will add the given protocol to the link when the user creates a link without one.
- * In case no configuration is provided, the value defaults to `http://`.
  * For example, when the user is creating a link and types `ckeditor.com` in the link form input — during link submission —
  * the editor will automatically add the `http://` protocol, so the link will be as follows: `http://ckeditor.com`.
  *
+ * The feature also comes with an email auto-detection. When you submit `hello@example.com`
+ * the plugin will automatically change it to `mailto:hello@example.com`.
+ *
  * 		ClassicEditor
  *			.create( editorElement, {
  * 				link: {
@@ -72,7 +74,8 @@ export default class Link extends Plugin {
  *			.then( ... )
  *			.catch( ... );
  *
- * @default 'http://'
+ * **NOTE:** In case no configuration is provided, the editor won't auto-fix the links.
+ *
  * @member {String} module:link/link~LinkConfig#defaultProtocol
  */
 

From e51d83e50c0f7cff804b3e5ae05414c3f30dcf00 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:32:40 +0200
Subject: [PATCH 07/15] Change manual test.

---
 packages/ckeditor5-link/tests/manual/protocol.html | 6 +++---
 packages/ckeditor5-link/tests/manual/protocol.js   | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/ckeditor5-link/tests/manual/protocol.html b/packages/ckeditor5-link/tests/manual/protocol.html
index 6b5a4bd693d..8ed4a7d7a4e 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.html
+++ b/packages/ckeditor5-link/tests/manual/protocol.html
@@ -37,16 +37,16 @@
 
 <h2>The default configuration for the link protocol has been set to <code id="default-protocol"></code>.</h2>
 
-<h3>...but you can change it:</h3>
+<h3>...but you can dynamically change it:</h3>
 <form id="protocol-settings" style="margin: 20px 0;">
+	<label for="none"><input type="radio" name="option" id="none" value="none" />DISABLE FEATURE</label>
 	<label for="http"><input type="radio" name="option" id="http" value="http://" />HTTP</label>
 	<label for="https"><input type="radio" name="option" id="https" value="https://" />HTTPS</label>
 	<label for="mailto"><input type="radio" name="option" id="mailto" value="mailto:" />MAILTO</label>
-	<label for="file"><input type="radio" name="option" id="file" value="file://" />FILE</label>
 </form>
 
 <div id="editor">
 	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com <sup class="indicator">[1]</sup>.</p>
 </div>
 
-<p><sup>[1]</sup> Copy the email address and create a link with it (<code>mailto:</code> protocol will be added automatically).</p>
+<p><sup>[1]</sup><strong>When feature enabled:</strong> copy the email address and create a link with it (<code>mailto:</code> protocol will be added automatically).</p>
diff --git a/packages/ckeditor5-link/tests/manual/protocol.js b/packages/ckeditor5-link/tests/manual/protocol.js
index c99580b4256..d2d75b0724a 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.js
+++ b/packages/ckeditor5-link/tests/manual/protocol.js
@@ -37,10 +37,10 @@ ClassicEditor
 			radio.addEventListener( 'click', ( {
 				target: { value: protocol }
 			} ) => {
-				editor.config.set( 'link.defaultProtocol', protocol );
+				editor.config.set( 'link.defaultProtocol', protocol === 'none' ? undefined : protocol );
 
 				// Change input placeholder just for manual test's case to provide more dynamic behavior.
-				formView.urlInputView.fieldView.placeholder = protocol + 'example.com';
+				formView.urlInputView.fieldView.placeholder = protocol === 'none' ? 'https://example.com' : protocol + 'example.com';
 			} );
 		} );
 	} )

From 3926be33a44c1c4ecad06c42ed50d55b7d3241a9 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:33:53 +0200
Subject: [PATCH 08/15] Remove DEFAULT_PROTOCOL and fix the script for better
 handling link values.

---
 packages/ckeditor5-link/src/linkui.js         | 13 ++--
 .../ckeditor5-link/src/ui/linkformview.js     |  6 +-
 packages/ckeditor5-link/src/utils.js          |  7 --
 packages/ckeditor5-link/tests/linkui.js       | 65 +++++++++++++++++--
 .../ckeditor5-link/tests/ui/linkformview.js   |  4 +-
 5 files changed, 72 insertions(+), 23 deletions(-)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index 7318f3203f3..d74bc131bf1 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -9,7 +9,7 @@
 
 import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
 import ClickObserver from '@ckeditor/ckeditor5-engine/src/view/observer/clickobserver';
-import { isLinkElement, DEFAULT_PROTOCOL } from './utils';
+import { isLinkElement } from './utils';
 import ContextualBalloon from '@ckeditor/ckeditor5-ui/src/panel/balloon/contextualballoon';
 
 import clickOutsideHandler from '@ckeditor/ckeditor5-ui/src/bindings/clickoutsidehandler';
@@ -143,7 +143,7 @@ export default class LinkUI extends Plugin {
 	_createFormView() {
 		const editor = this.editor;
 		const linkCommand = editor.commands.get( 'link' );
-		const defaultProtocol = editor.config.get( 'link.defaultProtocol' ) || DEFAULT_PROTOCOL;
+		const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
 
 		const formView = new LinkFormView( editor.locale, linkCommand, defaultProtocol );
 
@@ -156,13 +156,16 @@ export default class LinkUI extends Plugin {
 		// Execute link command after clicking the "Save" button.
 		this.listenTo( formView, 'submit', () => {
 			const { value } = formView.urlInputView.fieldView.element;
-			const hasProtocol = ( /\w+:\/\//gmi ).test( value );
+
+			const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
+
+			const isProtocolNeeded = !!defaultProtocol && !( /^((\w+:(\/{2,})?)|(\W))/gmi ).test( value );
 			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
 
 			// It's good to check config second time on submit for more dynamic cases
 			// when protocol might change after the element rendered.
-			const protocol = isEmail && 'mailto:' || editor.config.get( 'link.defaultProtocol' ) || defaultProtocol;
-			const parsedValue = !hasProtocol && value ? protocol + value : value;
+			const protocol = isEmail && 'mailto:' || defaultProtocol;
+			const parsedValue = value && isProtocolNeeded ? protocol + value : value;
 
 			editor.execute( 'link', parsedValue, formView.getDecoratorSwitchesState() );
 			this._closeFormView();
diff --git a/packages/ckeditor5-link/src/ui/linkformview.js b/packages/ckeditor5-link/src/ui/linkformview.js
index 12fb97d865a..e20a747e8d0 100644
--- a/packages/ckeditor5-link/src/ui/linkformview.js
+++ b/packages/ckeditor5-link/src/ui/linkformview.js
@@ -21,8 +21,6 @@ import FocusTracker from '@ckeditor/ckeditor5-utils/src/focustracker';
 import FocusCycler from '@ckeditor/ckeditor5-ui/src/focuscycler';
 import KeystrokeHandler from '@ckeditor/ckeditor5-utils/src/keystrokehandler';
 
-import { DEFAULT_PROTOCOL } from '../utils';
-
 import checkIcon from '@ckeditor/ckeditor5-core/theme/icons/check.svg';
 import cancelIcon from '@ckeditor/ckeditor5-core/theme/icons/cancel.svg';
 import '../../theme/linkform.css';
@@ -210,10 +208,10 @@ export default class LinkFormView extends View {
 	 * Creates a labeled input view.
 	 *
 	 * @private
-	 * @param {module:link/utils~DefaultProtocol} [protocol=http://] A value of a protocol to be displayed in the input's placeholder.
+	 * @param {String} [protocol=http://] A value of a protocol to be displayed in the input's placeholder.
 	 * @returns {module:ui/labeledfield/labeledfieldview~LabeledFieldView} Labeled field view instance.
 	 */
-	_createUrlInput( protocol = DEFAULT_PROTOCOL ) {
+	_createUrlInput( protocol = 'https://' ) {
 		const t = this.locale.t;
 		const labeledInput = new LabeledFieldView( this.locale, createLabeledInputText );
 
diff --git a/packages/ckeditor5-link/src/utils.js b/packages/ckeditor5-link/src/utils.js
index 4eafb2be35a..4c80d39e9c0 100644
--- a/packages/ckeditor5-link/src/utils.js
+++ b/packages/ckeditor5-link/src/utils.js
@@ -12,13 +12,6 @@ import { upperFirst } from 'lodash-es';
 const ATTRIBUTE_WHITESPACES = /[\u0000-\u0020\u00A0\u1680\u180E\u2000-\u2029\u205f\u3000]/g; // eslint-disable-line no-control-regex
 const SAFE_URL = /^(?:(?:https?|ftps?|mailto):|[^a-z]|[a-z+.-]+(?:[^a-z+.:-]|$))/i;
 
-/**
- * A default link protocol value.
- * @typedef {String} module:link/utils~DefaultProtocol
- * @default 'http://'
- */
-export const DEFAULT_PROTOCOL = 'http://';
-
 /**
  * Returns `true` if a given view node is the link element.
  *
diff --git a/packages/ckeditor5-link/tests/linkui.js b/packages/ckeditor5-link/tests/linkui.js
index 602320bcafc..ae7c422e57a 100644
--- a/packages/ckeditor5-link/tests/linkui.js
+++ b/packages/ckeditor5-link/tests/linkui.js
@@ -21,8 +21,6 @@ import ContextualBalloon from '@ckeditor/ckeditor5-ui/src/panel/balloon/contextu
 import ButtonView from '@ckeditor/ckeditor5-ui/src/button/buttonview';
 import View from '@ckeditor/ckeditor5-ui/src/view';
 
-import { DEFAULT_PROTOCOL } from '../src/utils';
-
 import ClickObserver from '@ckeditor/ckeditor5-engine/src/view/observer/clickobserver';
 
 describe( 'LinkUI', () => {
@@ -932,14 +930,61 @@ describe( 'LinkUI', () => {
 					} );
 			} );
 
-			it( 'should use `http://` as a default link protocol without any configuration', () => {
+			it( 'should not add a protocol without the configuration', () => {
+				formView.urlInputView.fieldView.value = 'ckeditor.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'ckeditor.com' );
+			} );
+
+			it( 'should not add a protocol to the local links even when `config.link.defaultProtocol` configured', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
+				formView.urlInputView.fieldView.value = '#test';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( '#test' );
+			} );
+
+			it( 'should not add a protocol to the relative links even when `config.link.defaultProtocol` configured', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
+				formView.urlInputView.fieldView.value = '/test.html';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( '/test.html' );
+			} );
+
+			it( 'should not add a protocol when given provided wihitn the value even when `config.link.defaultProtocol` configured', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
+				formView.urlInputView.fieldView.value = 'http://example.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://example.com' );
+			} );
+
+			it( 'should use the "http://" protocol when it\'s configured', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
 				formView.urlInputView.fieldView.value = 'ckeditor.com';
 				formView.fire( 'submit' );
 
 				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://ckeditor.com' );
 			} );
 
+			it( 'should use the "http://" protocol when it\'s configured and form input value contains "www."', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
+				formView.urlInputView.fieldView.value = 'www.ckeditor.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://www.ckeditor.com' );
+			} );
+
 			it( 'should propagate the protocol to the link\'s `linkHref` attribute in model', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
 				setModelData( editor.model, '[ckeditor.com]' );
 
 				formView.urlInputView.fieldView.value = 'ckeditor.com';
@@ -951,6 +996,8 @@ describe( 'LinkUI', () => {
 			} );
 
 			it( 'should detect an email on submitting the form and add "mailto:" protocol automatically to the provided value', () => {
+				editor.config.set( 'link.defaultProtocol', 'http://' );
+
 				setModelData( editor.model, '[email@example.com]' );
 
 				formView.urlInputView.fieldView.value = 'email@example.com';
@@ -961,6 +1008,16 @@ describe( 'LinkUI', () => {
 					'[<$text linkHref="mailto:email@example.com">email@example.com</$text>]'
 				);
 			} );
+
+			it( 'should not add an email protocol when given provided wihitn the value' +
+				'even when `config.link.defaultProtocol` configured', () => {
+				editor.config.set( 'link.defaultProtocol', 'mailto:' );
+
+				formView.urlInputView.fieldView.value = 'mailto:test@example.com';
+				formView.fire( 'submit' );
+
+				expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:test@example.com' );
+			} );
 		} );
 
 		describe( 'binding', () => {
@@ -1120,7 +1177,7 @@ describe( 'LinkUI', () => {
 					formView.fire( 'submit' );
 
 					expect( executeSpy.calledOnce ).to.be.true;
-					expect( executeSpy.calledWithExactly( 'link', DEFAULT_PROTOCOL + 'url', { linkIsFoo: true } ) ).to.be.true;
+					expect( executeSpy.calledWithExactly( 'link', 'url', { linkIsFoo: true } ) ).to.be.true;
 				} );
 
 				it( 'should reset switch state when form view is closed', () => {
diff --git a/packages/ckeditor5-link/tests/ui/linkformview.js b/packages/ckeditor5-link/tests/ui/linkformview.js
index b4c511dec43..402274d89c7 100644
--- a/packages/ckeditor5-link/tests/ui/linkformview.js
+++ b/packages/ckeditor5-link/tests/ui/linkformview.js
@@ -21,8 +21,6 @@ import Link from '../../src/link';
 import ObservableMixin from '@ckeditor/ckeditor5-utils/src/observablemixin';
 import mix from '@ckeditor/ckeditor5-utils/src/mix';
 
-import { DEFAULT_PROTOCOL } from '../../src/utils';
-
 describe( 'LinkFormView', () => {
 	let view;
 
@@ -85,7 +83,7 @@ describe( 'LinkFormView', () => {
 
 		describe( 'url input view', () => {
 			it( 'has placeholder', () => {
-				expect( view.urlInputView.fieldView.placeholder ).to.equal( DEFAULT_PROTOCOL + 'example.com' );
+				expect( view.urlInputView.fieldView.placeholder ).to.equal( 'https://example.com' );
 			} );
 		} );
 

From 1c60eae3fd64ea71fb832e45f9be5a71a294bcbf Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:44:40 +0200
Subject: [PATCH 09/15] Fix dev comment.

---
 packages/ckeditor5-link/src/linkui.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index d74bc131bf1..f4bb1e4de95 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -157,13 +157,13 @@ export default class LinkUI extends Plugin {
 		this.listenTo( formView, 'submit', () => {
 			const { value } = formView.urlInputView.fieldView.element;
 
+			// It's good to check the config for the second time on submit.
+			// This will cover more dynamic cases, when protocol might change after the element has been rendered.
 			const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
 
 			const isProtocolNeeded = !!defaultProtocol && !( /^((\w+:(\/{2,})?)|(\W))/gmi ).test( value );
 			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
 
-			// It's good to check config second time on submit for more dynamic cases
-			// when protocol might change after the element rendered.
 			const protocol = isEmail && 'mailto:' || defaultProtocol;
 			const parsedValue = value && isProtocolNeeded ? protocol + value : value;
 

From 6c03572a0ddfa4ba1eab327a64c80d0984403dd0 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:52:25 +0200
Subject: [PATCH 10/15] Add dev comment for the regex part.

---
 packages/ckeditor5-link/src/linkui.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index f4bb1e4de95..3a44a96ee77 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -161,6 +161,7 @@ export default class LinkUI extends Plugin {
 			// This will cover more dynamic cases, when protocol might change after the element has been rendered.
 			const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
 
+			// The regex checks for the protocol syntax ('xxxx://') or non-word charecters at the begining of the link ('/', '#' etc.).
 			const isProtocolNeeded = !!defaultProtocol && !( /^((\w+:(\/{2,})?)|(\W))/gmi ).test( value );
 			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
 

From 60d498feb6cb7cbac715e7a17469ab27e96012fe Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 14:53:53 +0200
Subject: [PATCH 11/15] Fix dev comment.

---
 packages/ckeditor5-link/src/linkui.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index 3a44a96ee77..96d692aa573 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -161,7 +161,8 @@ export default class LinkUI extends Plugin {
 			// This will cover more dynamic cases, when protocol might change after the element has been rendered.
 			const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
 
-			// The regex checks for the protocol syntax ('xxxx://') or non-word charecters at the begining of the link ('/', '#' etc.).
+			// The regex checks for the protocol syntax ('xxxx://' or 'xxxx:')
+			// or non-word charecters at the begining of the link ('/', '#' etc.).
 			const isProtocolNeeded = !!defaultProtocol && !( /^((\w+:(\/{2,})?)|(\W))/gmi ).test( value );
 			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
 

From a653407cca29e21940c45b8c7e9a2bb3703a5577 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Thu, 4 Jun 2020 15:35:12 +0200
Subject: [PATCH 12/15] Add @ckeditor/ckeditor5-basic-styles

---
 packages/ckeditor5-link/package.json | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/ckeditor5-link/package.json b/packages/ckeditor5-link/package.json
index 1c1b25dc39a..f250e83759e 100644
--- a/packages/ckeditor5-link/package.json
+++ b/packages/ckeditor5-link/package.json
@@ -16,6 +16,7 @@
     "lodash-es": "^4.17.15"
   },
   "devDependencies": {
+    "@ckeditor/ckeditor5-basic-styles": "^19.0.1",
     "@ckeditor/ckeditor5-block-quote": "^19.0.1",
     "@ckeditor/ckeditor5-clipboard": "^19.0.1",
     "@ckeditor/ckeditor5-editor-classic": "^19.0.1",

From de6f4d9d3c2f80ec3abd3fb7774c19c5f345deff Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 10 Jun 2020 14:25:01 +0200
Subject: [PATCH 13/15] Fix code and tests.

---
 packages/ckeditor5-link/src/linkui.js   |  12 +--
 packages/ckeditor5-link/tests/linkui.js | 123 +++++++++++++++---------
 2 files changed, 81 insertions(+), 54 deletions(-)

diff --git a/packages/ckeditor5-link/src/linkui.js b/packages/ckeditor5-link/src/linkui.js
index 96d692aa573..1e78a65f05e 100644
--- a/packages/ckeditor5-link/src/linkui.js
+++ b/packages/ckeditor5-link/src/linkui.js
@@ -21,6 +21,8 @@ import LinkActionsView from './ui/linkactionsview';
 import linkIcon from '../theme/icons/link.svg';
 
 const linkKeystroke = 'Ctrl+K';
+const protocolRegExp = /^((\w+:(\/{2,})?)|(\W))/i;
+const emailRegExp = /[\w-]+@[\w-]+\.+[\w-]+/i;
 
 /**
  * The link UI plugin. It introduces the `'link'` and `'unlink'` buttons and support for the <kbd>Ctrl+K</kbd> keystroke.
@@ -157,16 +159,12 @@ export default class LinkUI extends Plugin {
 		this.listenTo( formView, 'submit', () => {
 			const { value } = formView.urlInputView.fieldView.element;
 
-			// It's good to check the config for the second time on submit.
-			// This will cover more dynamic cases, when protocol might change after the element has been rendered.
-			const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
-
 			// The regex checks for the protocol syntax ('xxxx://' or 'xxxx:')
 			// or non-word charecters at the begining of the link ('/', '#' etc.).
-			const isProtocolNeeded = !!defaultProtocol && !( /^((\w+:(\/{2,})?)|(\W))/gmi ).test( value );
-			const isEmail = ( /[\w-]+@[\w-]+\.+[\w-]+/gmi ).test( value );
+			const isProtocolNeeded = !!defaultProtocol && !protocolRegExp.test( value );
+			const isEmail = emailRegExp.test( value );
 
-			const protocol = isEmail && 'mailto:' || defaultProtocol;
+			const protocol = isEmail ? 'mailto:' : defaultProtocol;
 			const parsedValue = value && isProtocolNeeded ? protocol + value : value;
 
 			editor.execute( 'link', parsedValue, formView.getDecoratorSwitchesState() );
diff --git a/packages/ckeditor5-link/tests/linkui.js b/packages/ckeditor5-link/tests/linkui.js
index ae7c422e57a..9d4b57afe4b 100644
--- a/packages/ckeditor5-link/tests/linkui.js
+++ b/packages/ckeditor5-link/tests/linkui.js
@@ -891,6 +891,27 @@ describe( 'LinkUI', () => {
 	describe( 'link form view', () => {
 		let focusEditableSpy;
 
+		const createEditorWithDefaultProtocol = defaultProtocol => {
+			return ClassicTestEditor
+				.create( editorElement, {
+					plugins: [ LinkEditing, LinkUI, Paragraph, BlockQuote ],
+					link: { defaultProtocol }
+				} )
+				.then( editor => {
+					const linkUIFeature = editor.plugins.get( LinkUI );
+					const formView = linkUIFeature.formView;
+
+					formView.render();
+
+					editor.model.schema.extend( '$text', {
+						allowIn: '$root',
+						allowAttributes: 'linkHref'
+					} );
+
+					return { editor, formView };
+				} );
+		};
+
 		beforeEach( () => {
 			focusEditableSpy = testUtils.sinon.spy( editor.editing.view, 'focus' );
 		} );
@@ -906,13 +927,6 @@ describe( 'LinkUI', () => {
 		} );
 
 		describe( 'link protocol', () => {
-			beforeEach( () => {
-				editor.model.schema.extend( '$text', {
-					allowIn: '$root',
-					allowAttributes: 'linkHref'
-				} );
-			} );
-
 			it( 'should use a default link protocol from the `config.link.defaultProtocol` when provided', () => {
 				return ClassicTestEditor
 					.create( editorElement, {
@@ -925,7 +939,6 @@ describe( 'LinkUI', () => {
 
 						expect( defaultProtocol ).to.equal( 'https://' );
 
-						editorElement.remove();
 						editor.destroy();
 					} );
 			} );
@@ -938,85 +951,101 @@ describe( 'LinkUI', () => {
 			} );
 
 			it( 'should not add a protocol to the local links even when `config.link.defaultProtocol` configured', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = '#test';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = '#test';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( '#test' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( '#test' );
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should not add a protocol to the relative links even when `config.link.defaultProtocol` configured', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = '/test.html';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = '/test.html';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( '/test.html' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( '/test.html' );
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should not add a protocol when given provided wihitn the value even when `config.link.defaultProtocol` configured', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = 'http://example.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'http://example.com';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( 'http://example.com' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://example.com' );
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should use the "http://" protocol when it\'s configured', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = 'ckeditor.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'ckeditor.com';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( 'http://ckeditor.com' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://ckeditor.com' );
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should use the "http://" protocol when it\'s configured and form input value contains "www."', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = 'www.ckeditor.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'www.ckeditor.com';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( 'http://www.ckeditor.com' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( 'http://www.ckeditor.com' );
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should propagate the protocol to the link\'s `linkHref` attribute in model', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					setModelData( editor.model, '[ckeditor.com]' );
 
-				setModelData( editor.model, '[ckeditor.com]' );
+					formView.urlInputView.fieldView.value = 'ckeditor.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'ckeditor.com';
-				formView.fire( 'submit' );
+					expect( getModelData( editor.model ) ).to.equal(
+						'[<$text linkHref="http://ckeditor.com">ckeditor.com</$text>]'
+					);
 
-				expect( getModelData( editor.model ) ).to.equal(
-					'[<$text linkHref="http://ckeditor.com">ckeditor.com</$text>]'
-				);
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should detect an email on submitting the form and add "mailto:" protocol automatically to the provided value', () => {
-				editor.config.set( 'link.defaultProtocol', 'http://' );
+				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
+					setModelData( editor.model, '[email@example.com]' );
 
-				setModelData( editor.model, '[email@example.com]' );
+					formView.urlInputView.fieldView.value = 'email@example.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'email@example.com';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:email@example.com' );
+					expect( getModelData( editor.model ) ).to.equal(
+						'[<$text linkHref="mailto:email@example.com">email@example.com</$text>]'
+					);
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:email@example.com' );
-				expect( getModelData( editor.model ) ).to.equal(
-					'[<$text linkHref="mailto:email@example.com">email@example.com</$text>]'
-				);
+					editor.destroy();
+				} );
 			} );
 
 			it( 'should not add an email protocol when given provided wihitn the value' +
 				'even when `config.link.defaultProtocol` configured', () => {
-				editor.config.set( 'link.defaultProtocol', 'mailto:' );
+				return createEditorWithDefaultProtocol( 'mailto:' ).then( ( { editor, formView } ) => {
+					formView.urlInputView.fieldView.value = 'mailto:test@example.com';
+					formView.fire( 'submit' );
 
-				formView.urlInputView.fieldView.value = 'mailto:test@example.com';
-				formView.fire( 'submit' );
+					expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:test@example.com' );
 
-				expect( formView.urlInputView.fieldView.value ).to.equal( 'mailto:test@example.com' );
+					editor.destroy();
+				} );
 			} );
 		} );
 

From e9b938eabbf4327cd8e9f49f91f5ea02a0229138 Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 10 Jun 2020 14:53:49 +0200
Subject: [PATCH 14/15] Change manual test.

---
 .../ckeditor5-link/tests/manual/protocol.html | 25 +++++----
 .../ckeditor5-link/tests/manual/protocol.js   | 54 ++++++++-----------
 .../ckeditor5-link/tests/manual/protocol.md   |  4 +-
 3 files changed, 38 insertions(+), 45 deletions(-)

diff --git a/packages/ckeditor5-link/tests/manual/protocol.html b/packages/ckeditor5-link/tests/manual/protocol.html
index 8ed4a7d7a4e..1a2d083bcb5 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.html
+++ b/packages/ckeditor5-link/tests/manual/protocol.html
@@ -35,18 +35,25 @@
 	}
 </style>
 
-<h2>The default configuration for the link protocol has been set to <code id="default-protocol"></code>.</h2>
 
-<h3>...but you can dynamically change it:</h3>
-<form id="protocol-settings" style="margin: 20px 0;">
-	<label for="none"><input type="radio" name="option" id="none" value="none" />DISABLE FEATURE</label>
-	<label for="http"><input type="radio" name="option" id="http" value="http://" />HTTP</label>
-	<label for="https"><input type="radio" name="option" id="https" value="https://" />HTTPS</label>
-	<label for="mailto"><input type="radio" name="option" id="mailto" value="mailto:" />MAILTO</label>
-</form>
+<h2><code>Feature is disabled</code></h2>
+<div id="editor0">
+	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com.</p>
+</div>
 
-<div id="editor">
+<h2><code>http://</code></h2>
+<div id="editor1">
 	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com <sup class="indicator">[1]</sup>.</p>
 </div>
 
 <p><sup>[1]</sup><strong>When feature enabled:</strong> copy the email address and create a link with it (<code>mailto:</code> protocol will be added automatically).</p>
+
+<h2><code>https://</code></h2>
+<div id="editor2">
+	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com.</p>
+</div>
+
+<h2><code>mailto:</code></h2>
+<div id="editor3">
+	<p>This is <a href="http://ckeditor.com">CKEditor5</a> from <a href="http://cksource.com">CKSource</a>. If you need more information please contact us at support@example.com.</p>
+</div>
diff --git a/packages/ckeditor5-link/tests/manual/protocol.js b/packages/ckeditor5-link/tests/manual/protocol.js
index d2d75b0724a..9f33f4b3409 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.js
+++ b/packages/ckeditor5-link/tests/manual/protocol.js
@@ -13,37 +13,25 @@ import Paragraph from '@ckeditor/ckeditor5-paragraph/src/paragraph';
 import Undo from '@ckeditor/ckeditor5-undo/src/undo';
 import Superscript from '@ckeditor/ckeditor5-basic-styles/src/superscript';
 
-ClassicEditor
-	.create( document.querySelector( '#editor' ), {
-		plugins: [ Link, Typing, Paragraph, Undo, Enter, Superscript ],
-		toolbar: [ 'link', 'undo', 'redo' ],
-		link: {
-			addTargetToExternalLinks: true,
-			defaultProtocol: 'http://'
-		}
-	} )
-	.then( editor => {
-		window.editor = editor;
-
-		const LinkUIPlugin = editor.plugins.get( 'LinkUI' );
-		const formView = LinkUIPlugin.formView;
-		const defaultProtocol = editor.config.get( 'link.defaultProtocol' );
-
-		document.getElementById( 'default-protocol' ).innerText = defaultProtocol;
-
-		document.querySelectorAll( '#protocol-settings input[type="radio"]' ).forEach( radio => {
-			radio.checked = radio.value === defaultProtocol;
-
-			radio.addEventListener( 'click', ( {
-				target: { value: protocol }
-			} ) => {
-				editor.config.set( 'link.defaultProtocol', protocol === 'none' ? undefined : protocol );
-
-				// Change input placeholder just for manual test's case to provide more dynamic behavior.
-				formView.urlInputView.fieldView.placeholder = protocol === 'none' ? 'https://example.com' : protocol + 'example.com';
-			} );
+createEditorWithDefaultProtocol( '#editor0' );
+createEditorWithDefaultProtocol( '#editor1', 'http://' );
+createEditorWithDefaultProtocol( '#editor2', 'https://' );
+createEditorWithDefaultProtocol( '#editor3', 'mailto:' );
+
+function createEditorWithDefaultProtocol( editor, defaultProtocol ) {
+	return ClassicEditor
+		.create( document.querySelector( editor ), {
+			plugins: [ Link, Typing, Paragraph, Undo, Enter, Superscript ],
+			toolbar: [ 'link', 'undo', 'redo' ],
+			link: {
+				addTargetToExternalLinks: true,
+				...defaultProtocol && { defaultProtocol }
+			}
+		} )
+		.then( editor => {
+			window.editor = editor;
+		} )
+		.catch( err => {
+			console.error( err.stack );
 		} );
-	} )
-	.catch( err => {
-		console.error( err.stack );
-	} );
+}
diff --git a/packages/ckeditor5-link/tests/manual/protocol.md b/packages/ckeditor5-link/tests/manual/protocol.md
index 2a5266c561a..5c4f80f84fe 100644
--- a/packages/ckeditor5-link/tests/manual/protocol.md
+++ b/packages/ckeditor5-link/tests/manual/protocol.md
@@ -2,7 +2,5 @@
 
 This test checks whether:
 - `config.link.defaultProtocol` applies.
-- user is able to dynamically change the link protocol (just as an extended example of usage).
+- when input value starts with a protocol-like syntax (like `http://` etc.) or any non-word (like `#` or `/`) then `defaultProtocol` won't be applied.
 - the plugin dynamically change link protocol to `mailto:` when email address was detected.
-
-When you dynamically change the value of the link protocol, the form input placeholder should change as well.

From e5bf396a5a51b03853ca13982a01a8cd84122cbb Mon Sep 17 00:00:00 2001
From: panr <radoslaw.koziel@gmail.com>
Date: Wed, 10 Jun 2020 14:56:57 +0200
Subject: [PATCH 15/15] Fix typos.

---
 packages/ckeditor5-link/tests/linkui.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/ckeditor5-link/tests/linkui.js b/packages/ckeditor5-link/tests/linkui.js
index 9d4b57afe4b..1f09e43f672 100644
--- a/packages/ckeditor5-link/tests/linkui.js
+++ b/packages/ckeditor5-link/tests/linkui.js
@@ -972,7 +972,7 @@ describe( 'LinkUI', () => {
 				} );
 			} );
 
-			it( 'should not add a protocol when given provided wihitn the value even when `config.link.defaultProtocol` configured', () => {
+			it( 'should not add a protocol when given provided within the value even when `config.link.defaultProtocol` configured', () => {
 				return createEditorWithDefaultProtocol( 'http://' ).then( ( { editor, formView } ) => {
 					formView.urlInputView.fieldView.value = 'http://example.com';
 					formView.fire( 'submit' );
@@ -1036,7 +1036,7 @@ describe( 'LinkUI', () => {
 				} );
 			} );
 
-			it( 'should not add an email protocol when given provided wihitn the value' +
+			it( 'should not add an email protocol when given provided within the value' +
 				'even when `config.link.defaultProtocol` configured', () => {
 				return createEditorWithDefaultProtocol( 'mailto:' ).then( ( { editor, formView } ) => {
 					formView.urlInputView.fieldView.value = 'mailto:test@example.com';