Add revoke follow feature

- Add new follow revoke module
- Add new hooks: revoke_follow, support_follow, support_revoke_follow
- Add link in contact page action menu

doc/Addons.md

@@ -479,6 +479,22 @@ Hook data:
 - **uid** (input): the user to return the contact data for (can be empty for public contacts).
 - **result** (output): Set by the hook function to indicate a successful detection.
 
+### support_follow
+
+Called to assert whether a connector addon provides follow capabilities.
+
+Hook data:
+- **protocol** (input): shorthand for the protocol. List of values is available in `src/Core/Protocol.php`.
+- **result** (output): should be true if the connector provides follow capabilities, left alone otherwise.
+
+### support_revoke_follow
+
+Called to assert whether a connector addon provides follow revocation capabilities.
+
+Hook data:
+- **protocol** (input): shorthand for the protocol. List of values is available in `src/Core/Protocol.php`.
+- **result** (output): should be true if the connector provides follow revocation capabilities, left alone otherwise.
+
 ### follow
 
 Called before adding a new contact for a user to handle non-native network remote contact (like Twitter).
@@ -497,6 +513,14 @@ Hook data:
 - **two_way** (input): wether to stop sharing with the remote contact as well.
 - **result** (output): wether the unfollowing is successful or not.
 
+### revoke_follow
+
+Called when making a remote contact on a non-native network (like Twitter) unfollow you.
+
+Hook data:
+- **contact** (input): the remote contact (uid = local revoking user id) array.
+- **result** (output): a boolean value indicating wether the operation was successful or not.
+
 ## Complete list of hook callbacks
 
 Here is a complete list of all hook callbacks with file locations (as of 24-Sep-2018). Please see the source for details of any hooks not documented above.
@@ -751,7 +775,11 @@ Here is a complete list of all hook callbacks with file locations (as of 24-Sep-
 
 ### src/Core/Protocol.php
 
+    Hook::callAll('support_follow', $hook_data);
+    Hook::callAll('support_revoke_follow', $hook_data);
     Hook::callAll('unfollow', $hook_data);
+    Kook::callAll('revoke_follow', $hook_data);
+
 ### src/Core/StorageManager
 
     Hook::callAll('storage_instance', $data);

doc/de/Addons.md

@@ -414,7 +414,12 @@ Eine komplette Liste aller Hook-Callbacks mit den zugehörigen Dateien (am 01-Ap
     Hook::callAll('logged_in', $a->user);
 
 ### src/Core/Protocol.php
+
+    Hook::callAll('support_follow', $hook_data);
+    Hook::callAll('support_revoke_follow', $hook_data);
     Hook::callAll('unfollow', $hook_data);
+    Kook::callAll('revoke_follow', $hook_data);
+
 ### src/Core/StorageManager
 
     Hook::callAll('storage_instance', $data);

src/Core/Protocol.php

@@ -71,6 +71,44 @@ class Protocol
 
 	const PHANTOM   = 'unkn';    // Place holder
 
+	/**
+	 * Returns whether the provided protocol supports following
+	 *
+	 * @param $protocol
+	 * @return bool
+	 * @throws HTTPException\InternalServerErrorException
+	 */
+	public static function supportsFollow($protocol): bool
+	{
+		if (in_array($protocol, self::NATIVE_SUPPORT)) {
+			return true;
+		}
+
+		$result = null;
+		Hook::callAll('support_follow', $result);
+
+		return $result === true;
+	}
+
+	/**
+	 * Returns whether the provided protocol supports revoking inbound follows
+	 *
+	 * @param $protocol
+	 * @return bool
+	 * @throws HTTPException\InternalServerErrorException
+	 */
+	public static function supportsRevokeFollow($protocol): bool
+	{
+		if (in_array($protocol, self::NATIVE_SUPPORT)) {
+			return true;
+		}
+
+		$result = null;
+		Hook::callAll('support_revoke_follow', $result);
+
+		return $result === true;
+	}
+
 	/**
 	 * Returns the address string for the provided profile URL
 	 *
@@ -212,7 +250,7 @@ class Protocol
 			return ActivityPub\Transmitter::sendContactUndo($contact['url'], $contact['id'], $user['uid']);
 		}
 
-		// Catch-all addon hook
+		// Catch-all hook for connector addons
 		$hook_data = [
 			'contact' => $contact,
 			'two_way' => $two_way,
@@ -222,4 +260,36 @@ class Protocol
 
 		return $hook_data['result'];
 	}
+
+	/**
+	 * Revoke an incoming follow from the provided contact
+	 *
+	 * @param array $contact Private contact (uid != 0) array
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 * @throws \ImagickException
+	 */
+	public static function revokeFollow(array $contact)
+	{
+		if (empty($contact['network'])) {
+			throw new \InvalidArgumentException('Missing network key in contact array');
+		}
+
+		$protocol = $contact['network'];
+		if ($protocol == Protocol::DFRN && !empty($contact['protocol'])) {
+			$protocol = $contact['protocol'];
+		}
+
+		if ($protocol == Protocol::ACTIVITYPUB) {
+			return ActivityPub\Transmitter::sendContactReject($contact['url'], $contact['hub-verify'], $contact['uid']);
+		}
+
+		// Catch-all hook for connector addons
+		$hook_data = [
+			'contact' => $contact,
+			'result' => null,
+		];
+		Hook::callAll('revoke_follow', $hook_data);
+
+		return $hook_data['result'];
+	}
 }

src/Model/Contact.php

@@ -849,6 +849,36 @@ class Contact
 		return $result;
 	}
 
+	/**
+	 * Revoke follow privileges of the remote user contact
+	 *
+	 * @param array   $contact  Contact unfriended
+	 * @return bool|null Whether the remote operation is successful or null if no remote operation was performed
+	 * @throws HTTPException\InternalServerErrorException
+	 * @throws \ImagickException
+	 */
+	public static function revokeFollow(array $contact): bool
+	{
+		if (empty($contact['network'])) {
+			throw new \InvalidArgumentException('Empty network in contact array');
+		}
+
+		if (empty($contact['uid'])) {
+			throw new \InvalidArgumentException('Unexpected public contact record');
+		}
+
+		$result = Protocol::revokeFollow($contact);
+
+		// A null value here means the remote network doesn't support explicit follow revocation, we can still
+		// break the locally recorded relationship
+		if ($result !== false) {
+			DBA::update('contact', ['rel' => $contact['rel'] == self::FRIEND ? self::SHARING : self::NOTHING], ['id' => $contact['id']]);
+		}
+
+		return $result;
+	}
+
+
 	/**
 	 * Marks a contact for archival after a communication issue delay
 	 *
@@ -1022,7 +1052,7 @@ class Contact
 
 		$follow_link = '';
 		$unfollow_link = '';
-		if (!$contact['self'] && in_array($contact['network'], Protocol::NATIVE_SUPPORT)) {
+		if (!$contact['self'] && Protocol::supportsFollow($contact['network'])) {
 			if ($contact['uid'] && in_array($contact['rel'], [self::SHARING, self::FRIEND])) {
 				$unfollow_link = 'unfollow?url=' . urlencode($contact['url']) . '&auto=1';
 			} elseif(!$contact['pending']) {

src/Module/Contact.php

@@ -1148,6 +1148,16 @@ class Contact extends BaseModule
 		];
 
 		if ($contact['uid'] != 0) {
+			if (Protocol::supportsRevokeFollow($contact['network']) && in_array($contact['rel'], [Model\Contact::FOLLOWER, Model\Contact::FRIEND])) {
+				$contact_actions['revoke_follow'] = [
+					'label' => DI::l10n()->t('Revoke Follow'),
+					'url'   => 'contact/' . $contact['id'] . '/revoke',
+					'title' => DI::l10n()->t('Revoke the follow from this contact'),
+					'sel'   => '',
+					'id'    => 'revoke_follow',
+				];
+			}
+
 			$contact_actions['delete'] = [
 				'label' => DI::l10n()->t('Delete'),
 				'url'   => 'contact/' . $contact['id'] . '/drop?t=' . $formSecurityToken,

src/Module/Contact/Revoke.php

@@ -0,0 +1,108 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2021, the Friendica project
+ *
+ * @license   GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Module\Contact;
+
+use Friendica\BaseModule;
+use Friendica\Content\Nav;
+use Friendica\Core\Protocol;
+use Friendica\Core\Renderer;
+use Friendica\Database\DBA;
+use Friendica\DI;
+use Friendica\Model;
+use Friendica\Module\Contact;
+use Friendica\Module\Security\Login;
+use Friendica\Network\HTTPException;
+
+class Revoke extends BaseModule
+{
+	/** @var array */
+	private static $contact;
+
+	public static function init(array $parameters = [])
+	{
+		if (!local_user()) {
+			return;
+		}
+
+		$data = Model\Contact::getPublicAndUserContactID($parameters['id'], local_user());
+		if (!DBA::isResult($data)) {
+			throw new HTTPException\NotFoundException(DI::l10n()->t('Unknown contact.'));
+		}
+
+		if (empty($data['user'])) {
+			throw new HTTPException\ForbiddenException();
+		}
+
+		self::$contact = Model\Contact::getById($data['user']);
+
+		if (self::$contact['deleted']) {
+			throw new HTTPException\NotFoundException(DI::l10n()->t('Contact is deleted.'));
+		}
+
+		if (!empty(self::$contact['network']) && self::$contact['network'] == Protocol::PHANTOM) {
+			throw new HTTPException\NotFoundException(DI::l10n()->t('Contact is being deleted.'));
+		}
+	}
+
+	public static function post(array $parameters = [])
+	{
+		if (!local_user()) {
+			throw new HTTPException\UnauthorizedException();
+		}
+
+		self::checkFormSecurityTokenRedirectOnError('contact/' . $parameters['id'], 'contact_revoke');
+
+		$result = Model\Contact::revokeFollow(self::$contact);
+		if ($result === true) {
+			notice(DI::l10n()->t('Follow was successfully revoked.'));
+		} elseif ($result === null) {
+			notice(DI::l10n()->t('Follow was successfully revoked, however the remote contact won\'t be aware of this revokation.'));
+		} else {
+			notice(DI::l10n()->t('Unable to revoke follow, please try again later or contact the administrator.'));
+		}
+
+		DI::baseUrl()->redirect('contact/' . $parameters['id']);
+	}
+
+	public static function content(array $parameters = []): string
+	{
+		if (!local_user()) {
+			return Login::form($_SERVER['REQUEST_URI']);
+		}
+
+		Nav::setSelected('contact');
+
+		return Renderer::replaceMacros(Renderer::getMarkupTemplate('contact_drop_confirm.tpl'), [
+			'$l10n' => [
+				'header'  => DI::l10n()->t('Revoke Follow'),
+				'message' => DI::l10n()->t('Do you really want to revoke this contact\'s follow? This cannot be undone and they will have to manually follow you back again.'),
+				'confirm' => DI::l10n()->t('Yes'),
+				'cancel'  => DI::l10n()->t('Cancel'),
+			],
+			'$contact'       => Contact::getContactTemplateVars(self::$contact),
+			'$method'        => 'post',
+			'$confirm_url'   => DI::args()->getCommand(),
+			'$confirm_name'  => 'form_security_token',
+			'$confirm_value' => BaseModule::getFormSecurityToken('contact_revoke'),
+		]);
+	}
+}

src/Protocol/ActivityPub/Transmitter.php

@@ -2047,15 +2047,16 @@ class Transmitter
 	 * @param string  $target Target profile
 	 * @param         $id
 	 * @param integer $uid    User ID
-	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 * @return bool Operation success
+	 * @throws HTTPException\InternalServerErrorException
 	 * @throws \ImagickException
 	 */
-	public static function sendContactReject($target, $id, $uid)
+	public static function sendContactReject($target, $id, $uid): bool
 	{
 		$profile = APContact::getByURL($target);
 		if (empty($profile['inbox'])) {
 			Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
-			return;
+			return false;
 		}
 
 		$owner = User::getOwnerDataById($uid);
@@ -2075,7 +2076,7 @@ class Transmitter
 		Logger::debug('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id);
 
 		$signed = LDSignature::sign($data, $owner);
-		HTTPSignature::transmit($signed, $profile['inbox'], $uid);
+		return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
 	}
 
 	/**

static/routes.config.php

@@ -239,6 +239,7 @@ return [
 		'/{id:\d+}/ignore'            => [Module\Contact::class,           [R::GET]],
 		'/{id:\d+}/poke'              => [Module\Contact\Poke::class,      [R::GET, R::POST]],
 		'/{id:\d+}/posts'             => [Module\Contact::class,           [R::GET]],
+		'/{id:\d+}/revoke'            => [Module\Contact\Revoke::class,    [R::GET, R::POST]],
 		'/{id:\d+}/update'            => [Module\Contact::class,           [R::GET]],
 		'/{id:\d+}/updateprofile'     => [Module\Contact::class,           [R::GET]],
 		'/archived'                   => [Module\Contact::class,           [R::GET]],

view/templates/contact_edit.tpl

@@ -21,6 +21,7 @@
 							<li class="divider"></li>
 							<li role="menuitem"><a href="#" title="{{$contact_actions.block.title}}" onclick="window.location.href='{{$contact_actions.block.url}}'; return false;">{{$contact_actions.block.label}}</a></li>
 							<li role="menuitem"><a href="#" title="{{$contact_actions.ignore.title}}" onclick="window.location.href='{{$contact_actions.ignore.url}}'; return false;">{{$contact_actions.ignore.label}}</a></li>
+							{{if $contact_actions.revoke_follow.url}}<li role="menuitem"><a href="{{$contact_actions.revoke_follow.url}}" title="{{$contact_actions.revoke_follow.title}}">{{$contact_actions.revoke_follow.label}}</a></li>{{/if}}
 							{{if $contact_actions.delete.url}}<li role="menuitem"><a href="{{$contact_actions.delete.url}}" title="{{$contact_actions.delete.title}}" onclick="return confirmDelete();">{{$contact_actions.delete.label}}</a></li> {{/if}}
 						</ul>
 					</div>

view/theme/frio/templates/contact_edit.tpl

@@ -27,6 +27,7 @@
 							{{/if}}
 							<li role="presentation"><a role="menuitem" href="{{$contact_actions.block.url}}" title="{{$contact_actions.block.title}}">{{$contact_actions.block.label}}</a></li>
 							<li role="presentation"><a role="menuitem" href="{{$contact_actions.ignore.url}}" title="{{$contact_actions.ignore.title}}">{{$contact_actions.ignore.label}}</a></li>
+                            {{if $contact_actions.revoke_follow.url}}<li role="presentation"><button role="menuitem" type="button" class="btn-link" title="{{$contact_actions.revoke_follow.title}}" onclick="addToModal('{{$contact_actions.revoke_follow.url}}');">{{$contact_actions.revoke_follow.label}}</button></li>{{/if}}
 							{{if $contact_actions.delete.url}}<li role="presentation"><button role="menuitem" type="button" class="btn-link" title="{{$contact_actions.delete.title}}" onclick="addToModal('{{$contact_actions.delete.url}}&confirm=1');">{{$contact_actions.delete.label}}</button></li>{{/if}}
 						</ul>
 					</li>

view/theme/vier/templates/contact_edit.tpl

@@ -22,6 +22,7 @@
 							<li class="divider"></li>
 							<li role="menuitem"><a href="#" title="{{$contact_actions.block.title}}" onclick="window.location.href='{{$contact_actions.block.url}}'; return false;">{{$contact_actions.block.label}}</a></li>
 							<li role="menuitem"><a href="#" title="{{$contact_actions.ignore.title}}" onclick="window.location.href='{{$contact_actions.ignore.url}}'; return false;">{{$contact_actions.ignore.label}}</a></li>
+							{{if $contact_actions.revoke_follow.url}}<li role="menuitem"><a href="{{$contact_actions.revoke_follow.url}}" title="{{$contact_actions.revoke_follow.title}}">{{$contact_actions.revoke_follow.label}}</a></li>{{/if}}
 							{{if $contact_actions.delete.url}}<li role="menuitem"><a href="{{$contact_actions.delete.url}}" title="{{$contact_actions.delete.title}}" onclick="return confirmDelete();">{{$contact_actions.delete.label}}</a></li>{{/if}}
 						</ul>
 					</div>