You are a senior CKEditor 5 plugin architect.
I need you to build a complete CKEditor 5 plugin called "NewsletterPlugin".
Context:
- This is a migration from a legacy CKEditor 4 plugin.
- Must follow CKEditor 5 architecture strictly.
- Must use CKEditor 5 UI framework and plugin system.
- Must follow documentation:
https://ckeditor.com/docs/ckeditor5/latest/framework/architecture/ui-components.html
https://ckeditor.com/docs/ckeditor5/latest/features/html/general-html-support.html
Environment:
- CKEditor 5 custom build
- ES6 modules
- Typescript preferred (if possible)
- No usage of CKEditor 4 APIs
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FEATURE REQUIREMENTS
========================================
1) Toolbar Button:
- Add a toolbar button named "newsletter"
- Icon: simple SVG placeholder
- When clicked → open a dialog (modal)
2) Dialog Behavior:
The dialog must contain input fields:
- title (text input)
- description (textarea)
- tabs (dynamic list, user can add/remove tab items)
Each tab item:
- tabTitle
- tabContent (HTML allowed)
Buttons:
- Cancel
- OK
3) On OK:
- Generate structured HTML block inside editor
- Structure example:
<div class="newsletter">
<ul class="newsletter-tabs">
<li class="active">
<a href="#tab-1" class="active">Tab 1</a>
</li>
<li>
<a href="#tab-2">Tab 2</a>
</li>
</ul>
<div class="newsletter-content">
<div id="tab-1" class="tab-pane active">
Content 1
</div>
<div id="tab-2" class="tab-pane">
Content 2
</div>
</div>
</div>
4) Behavior inside editor:
- First tab always active by default.
- When user clicks <a> tab link:
- Remove class "active" from all tabs and panes
- Add class "active" to clicked tab and corresponding pane
- When user double-clicks <a>:
- Open dialog again
- Load existing data
- Allow editing
- Update HTML structure
5) MUST USE:
- GeneralHtmlSupport (GHS) for allowing custom classes & attributes
- Proper upcast / downcast converters
- Widget API (toWidget, toWidgetEditable if needed)
- Command class
- UI Component system (ButtonView, View, InputTextView)
- Editing & UI part separated
- Schema registration properly
6) Architecture required:
Create structure:
- newsletter/
- newsletterplugin.ts
- newsletterediting.ts
- newsletterui.ts
- newslettercommand.ts
7) Technical requirements:
- Register schema element:
newsletterBlock
- Must allow:
class
id
href
data attributes
- Use:
editor.model.change()
conversion.for('upcast')
conversion.for('downcast')
- Handle click event via editing view document
- Use editing.view.document.on( 'click', ... )
- Detect double click event
8) Important:
Do NOT use raw DOM manipulation.
All updates must go through editor.model.
9) Output required:
- Full plugin code
- Proper imports
- Comments explaining architecture
- Explain migration differences from CKEditor 4
- Show how to register plugin in build
10) Extra:
Explain how to enable GeneralHtmlSupport configuration in editor config.
========================================
Please produce clean production-ready code.
Do not simplify logic.
Follow CKEditor 5 best practices strictly.