Group e-mails by first character in the group creation/edition form

Http/Controllers/CustomersGroupsController.php

@@ -53,6 +53,12 @@ class CustomersGroupsController extends Controller {
 			->pluck('emails')
 			->flatten()
 			->sortBy('email');
+		// Group Emails by their first character.
+		// This is used to display them in collapsible groups.
+		$emails = $emails->mapToGroups(function ($email) {
+			$first_character = substr($email->email, $offset = 0, $length = 1);
+			return [ $first_character => $email ];
+		});
 
 		return view('mmfcustomersgroups::groups/edit', [
 			'mailboxes' => $mailboxes,

Resources/views/groups/partials/edit_form.blade.php

@@ -84,7 +84,14 @@
 					</label>
 					<div class="col-sm-6">
 						<div class="multi-container">
-							@foreach ( $emails as $email )
+							@foreach ( $emails as $first_character => $emails_group )
+								<details>
+									<summary
+										style="display: list-item; counter-increment: list-item 0; list-style: disclosure-closed inside; cursor: pointer;"
+									>
+										{{ $first_character }}…
+									</summary>
+									@foreach ( $emails_group as $email )
 										<div class="control-group">
 											<div class="controls">
 												<label
@@ -106,6 +113,8 @@
 											</div>
 										</div>
 									@endforeach
+								</details>
+							@endforeach
 						</div>
 						{{-- @include('partials/field_error', ['field'=>'emails.*']) --}}
 					</div>