array(
					'comment.id'                => $comment_id,
					'commenter.id'              => $commenter_id,
					'usermessage'               => wp_strip_all_tags( $content ),
					'original_activity.user_id' => $original_activity->user_id,
					'poster.name'               => $poster_name,
					'thread.url'                => esc_url( $thread_link ),
					'unsubscribe'               => esc_url( bp_email_get_unsubscribe_link( $unsubscribe_args ) ),
				),
			);

			bp_send_email( 'activity-comment', $original_activity->user_id, $args );
		}

		/**
		 * Fires at the point that notifications should be sent for activity comments.
		 *
		 * @since 2.6.0
		 *
		 * @param BP_Activity_Activity $original_activity The original activity.
		 * @param int                  $comment_id        ID for the newly received comment.
		 * @param int                  $commenter_id      ID of the user who made the comment.
		 * @param array                $params            Arguments used with the original activity comment.
		 */
		do_action( 'bp_activity_sent_reply_to_update_notification', $original_activity, $comment_id, $commenter_id, $params );
	}


	/*
	 * If this is a reply to another comment, send an email notification to the
	 * author of the immediate parent comment.
	 */
	if ( empty( $params['parent_id'] ) || ( $params['activity_id'] == $params['parent_id'] ) ) {
		return;
	}

	$parent_comment = new BP_Activity_Activity( $params['parent_id'] );

	if ( $parent_comment->user_id != $commenter_id && $original_activity->user_id != $parent_comment->user_id ) {

		// Send an email if the user hasn't opted-out.
		if ( 'no' != bp_get_user_meta( $parent_comment->user_id, 'notification_activity_new_reply', true ) ) {

			$unsubscribe_args = array(
				'user_id'           => $parent_comment->user_id,
				'notification_type' => 'activity-comment-author',
			);

			$args = array(
				'tokens' => array(
					'comment.id'             => $comment_id,
					'commenter.id'           => $commenter_id,
					'usermessage'            => wp_strip_all_tags( $content ),
					'parent-comment-user.id' => $parent_comment->user_id,
					'poster.name'            => $poster_name,
					'thread.url'             => esc_url( $thread_link ),
					'unsubscribe'            => esc_url( bp_email_get_unsubscribe_link( $unsubscribe_args ) ),
				),
			);

			bp_send_email( 'activity-comment-author', $parent_comment->user_id, $args );
		}

		/**
		 * Fires at the point that notifications should be sent for comments on activity replies.
		 *
		 * @since 2.6.0
		 *
		 * @param BP_Activity_Activity $parent_comment The parent activity.
		 * @param int                  $comment_id     ID for the newly received comment.
		 * @param int                  $commenter_id   ID of the user who made the comment.
		 * @param array                $params         Arguments used with the original activity comment.
		 */
		do_action( 'bp_activity_sent_reply_to_reply_notification', $parent_comment, $comment_id, $commenter_id, $params );
	}
}

/**
 * Helper method to map action arguments to function parameters.
 *
 * @since 1.9.0
 *
 * @param int   $comment_id ID of the comment being notified about.
 * @param array $params     Parameters to use with notification.
 */
function bp_activity_new_comment_notification_helper( $comment_id, $params ) {
	bp_activity_new_comment_notification( $comment_id, $params['user_id'], $params );
}
add_action( 'bp_activity_comment_posted', 'bp_activity_new_comment_notification_helper', 10, 2 );

/** Embeds *******************************************************************/

/**
 * Set up activity oEmbed cache during the activity loop.
 *
 * During an activity loop, this function sets up the hooks necessary to grab
 * each item's embeds from the cache, or put them in the cache if they are
 * not there yet.
 *
 * This does not cover recursive activity comments, as they do not use a real loop.
 * For that, see {@link bp_activity_comment_embed()}.
 *
 * @since 1.5.0
 *
 * @see BP_Embed
 * @see bp_embed_activity_cache()
 * @see bp_embed_activity_save_cache()
 *
 */
function bp_activity_embed() {
	add_filter( 'embed_post_id',         'bp_get_activity_id'                  );
	add_filter( 'oembed_dataparse',      'bp_activity_oembed_dataparse', 10, 2 );
	add_filter( 'bp_embed_get_cache',    'bp_embed_activity_cache',      10, 3 );
	add_action( 'bp_embed_update_cache', 'bp_embed_activity_save_cache', 10, 3 );
}
add_action( 'activity_loop_start', 'bp_activity_embed' );

/**
 * Cache full oEmbed response from oEmbed.
 *
 * @since 2.6.0
 *
 * @param string $retval Current oEmbed result.
 * @param object $data   Full oEmbed response.
 * @param string $url    URL used for the oEmbed request.
 * @return string
 */
function bp_activity_oembed_dataparse( $retval, $data ) {
	buddypress()->activity->oembed_response = $data;

	return $retval;
}

/**
 * Set up activity oEmbed cache while recursing through activity comments.
 *
 * While crawling through an activity comment tree
 * ({@link bp_activity_recurse_comments}), this function sets up the hooks
 * necessary to grab each comment's embeds from the cache, or put them in
 * the cache if they are not there yet.
 *
 * @since 1.5.0
 *
 * @see BP_Embed
 * @see bp_embed_activity_cache()
 * @see bp_embed_activity_save_cache()
 *
 */
function bp_activity_comment_embed() {
	add_filter( 'embed_post_id',         'bp_get_activity_comment_id'          );
	add_filter( 'bp_embed_get_cache',    'bp_embed_activity_cache',      10, 3 );
	add_action( 'bp_embed_update_cache', 'bp_embed_activity_save_cache', 10, 3 );
}
add_action( 'bp_before_activity_comment', 'bp_activity_comment_embed' );

/**
 * When a user clicks on a "Read More" item, make sure embeds are correctly parsed and shown for the expanded content.
 *
 * @since 1.5.0
 *
 * @see BP_Embed
 *
 * @param object $activity The activity that is being expanded.
 */
function bp_dtheme_embed_read_more( $activity ) {
	buddypress()->activity->read_more_id = $activity->id;

	add_filter( 'embed_post_id',         function () { return buddypress()->activity->read_more_id; } );
	add_filter( 'bp_embed_get_cache',    'bp_embed_activity_cache',      10, 3 );
	add_action( 'bp_embed_update_cache', 'bp_embed_activity_save_cache', 10, 3 );
}
add_action( 'bp_dtheme_get_single_activity_content',       'bp_dtheme_embed_read_more' );
add_action( 'bp_legacy_theme_get_single_activity_content', 'bp_dtheme_embed_read_more' );

/**
 * Clean up 'embed_post_id' filter after comment recursion.
 *
 * This filter must be removed so that the non-comment filters take over again
 * once the comments are done being processed.
 *
 * @since 1.5.0
 *
 * @see bp_activity_comment_embed()
 */
function bp_activity_comment_embed_after_recurse() {
	remove_filter( 'embed_post_id', 'bp_get_activity_comment_id' );
}
add_action( 'bp_after_activity_comment', 'bp_activity_comment_embed_after_recurse' );

/**
 * Fetch an activity item's cached embeds.
 *
 * Used during {@link BP_Embed::parse_oembed()} via {@link bp_activity_embed()}.
 *
 * @since 1.5.0
 *
 * @see BP_Embed::parse_oembed()
 *
 * @param string $cache    An empty string passed by BP_Embed::parse_oembed() for
 *                         functions like this one to filter.
 * @param int    $id       The ID of the activity item.
 * @param string $cachekey The cache key generated in BP_Embed::parse_oembed().
 * @return mixed The cached embeds for this activity item.
 */
function bp_embed_activity_cache( $cache, $id, $cachekey ) {
	return bp_activity_get_meta( $id, $cachekey );
}

/**
 * Set an activity item's embed cache.
 *
 * Used during {@link BP_Embed::parse_oembed()} via {@link bp_activity_embed()}.
 *
 * @since 1.5.0
 *
 * @see BP_Embed::parse_oembed()
 *
 * @param string $cache    An empty string passed by BP_Embed::parse_oembed() for
 *                         functions like this one to filter.
 * @param string $cachekey The cache key generated in BP_Embed::parse_oembed().
 * @param int    $id       The ID of the activity item.
 */
function bp_embed_activity_save_cache( $cache, $cachekey, $id ) {
	bp_activity_update_meta( $id, $cachekey, $cache );

	// Cache full oEmbed response.
	if ( true === isset( buddypress()->activity->oembed_response ) ) {
		$cachekey = str_replace( '_oembed', '_oembed_response', $cachekey );
		bp_activity_update_meta( $id, $cachekey, buddypress()->activity->oembed_response );
	}
}

/**
 * Should we use Heartbeat to refresh activities?
 *
 * @since 2.0.0
 *
 * @return bool True if activity heartbeat is enabled, otherwise false.
 */
function bp_activity_do_heartbeat() {
	$retval = false;

	if ( bp_is_activity_heartbeat_active() && ( bp_is_activity_directory() || bp_is_group_activity() ) ) {
		$retval = true;
	}

	/**
	 * Filters whether the heartbeat feature in the activity stream should be active.
	 *
	 * @since 2.8.0
	 *
	 * @param bool $retval Whether or not activity heartbeat is active.
	 */
	return (bool) apply_filters( 'bp_activity_do_heartbeat', $retval );
}

/**
 * Detect a change in post type status, and initiate an activity update if necessary.
 *
 * @since 2.2.0
 *
 * @todo Support untrashing better.
 *
 * @param string $new_status New status for the post.
 * @param string $old_status Old status for the post.
 * @param object $post       Post data.
 */
function bp_activity_catch_transition_post_type_status( $new_status, $old_status, $post ) {
	if ( ! post_type_supports( $post->post_type, 'buddypress-activity' ) ) {
		return;
	}

	// This is an edit.
	if ( $new_status === $old_status ) {
		// An edit of an existing post should update the existing activity item.
		if ( $new_status == 'publish' ) {
			$edit = bp_activity_post_type_update( $post );

			// Post was never recorded into activity stream, so record it now!
			if ( null === $edit ) {
				bp_activity_post_type_publish( $post->ID, $post );
			}

		// Allow plugins to eventually deal with other post statuses.
		} else {
			/**
			 * Fires when editing the post and the new status is not 'publish'.
			 *
			 * This is a variable filter that is dependent on the post type
			 * being untrashed.
			 *
			 * @since 2.5.0
			 *
			 * @param WP_Post $post Post data.
			 * @param string $new_status New status for the post.
			 * @param string $old_status Old status for the post.
			 */
			do_action( 'bp_activity_post_type_edit_' . $post->post_type, $post, $new_status, $old_status );
		}

		return;
	}

	// Publishing a previously unpublished post.
	if ( 'publish' === $new_status ) {
		// Untrashing the post type - nothing here yet.
		if ( 'trash' == $old_status ) {

			/**
			 * Fires if untrashing post in a post type.
			 *
			 * This is a variable filter that is dependent on the post type
			 * being untrashed.
			 *
			 * @since 2.2.0
			 *
			 * @param WP_Post $post Post data.
			 */
			do_action( 'bp_activity_post_type_untrash_' . $post->post_type, $post );
		} else {
			// Record the post.
			bp_activity_post_type_publish( $post->ID, $post );
		}

	// Unpublishing a previously published post.
	} elseif ( 'publish' === $old_status ) {
		// Some form of pending status - only remove the activity entry.
		bp_activity_post_type_unpublish( $post->ID, $post );

	// For any other cases, allow plugins to eventually deal with it.
	} else {
		/**
		 * Fires when the old and the new post status are not 'publish'.
		 *
		 * This is a variable filter that is dependent on the post type
		 * being untrashed.
		 *
		 * @since 2.5.0
		 *
		 * @param WP_Post $post Post data.
		 * @param string $new_status New status for the post.
		 * @param string $old_status Old status for the post.
		 */
		do_action( 'bp_activity_post_type_transition_status_' . $post->post_type, $post, $new_status, $old_status );
	}
}
add_action( 'transition_post_status', 'bp_activity_catch_transition_post_type_status', 10, 3 );

/**
 * When a post type comment status transition occurs, update the relevant activity's status.
 *
 * @since 2.5.0
 *
 * @param string     $new_status New comment status.
 * @param string     $old_status Previous comment status.
 * @param WP_Comment $comment Comment data.
 */
function bp_activity_transition_post_type_comment_status( $new_status, $old_status, $comment ) {
	$post_type = get_post_type( $comment->comment_post_ID );
	if ( ! $post_type ) {
		return;
	}

	// Get the post type tracking args.
	$activity_post_object = bp_activity_get_post_type_tracking_args( $post_type );

	// Bail if the activity type does not exist.
	if ( empty( $activity_post_object->comments_tracking->action_id ) ) {
		return false;

	// Set the $activity_comment_object.
	} else {
		$activity_comment_object = $activity_post_object->comments_tracking;
	}

	// Init an empty activity ID.
	$activity_id = 0;

	/**
	 * Activity currently doesn't have any concept of a trash, or an unapproved/approved state.
	 *
	 * If a blog comment transitions to a "delete" or "hold" status, delete the activity item.
	 * If a blog comment transitions to trashed, or spammed, mark the activity as spam.
	 * If a blog comment transitions to approved (and the activity exists), mark the activity as ham.
	 * If a blog comment transitions to unapproved (and the activity exists), mark the activity as spam.
	 * Otherwise, record the comment into the activity stream.
	 */

	// This clause handles delete/hold.
	if ( in_array( $new_status, array( 'delete', 'hold' ) ) ) {
		return bp_activity_post_type_remove_comment( $comment->comment_ID, $activity_post_object );

	// These clauses handle trash, spam, and un-spams.
	} elseif ( in_array( $new_status, array( 'trash', 'spam', 'unapproved' ) ) ) {
		$action = 'spam_activity';
	} elseif ( 'approved' == $new_status ) {
		$action = 'ham_activity';
	}

	// Get the activity.
	if ( bp_disable_blogforum_comments() ) {
		$activity_id = bp_activity_get_activity_id( array(
			'component'         => $activity_comment_object->component_id,
			'item_id'           => get_current_blog_id(),
			'secondary_item_id' => $comment->comment_ID,
			'type'              => $activity_comment_object->action_id,
		) );
	} else {
		$activity_id = get_comment_meta( $comment->comment_ID, 'bp_activity_comment_id', true );
	}

	/**
	 * Leave a chance to plugins to manage activity comments differently.
	 *
	 * @since  2.5.0
	 *
	 * @param bool        $value       True to override BuddyPress management.
	 * @param string      $post_type   The post type name.
	 * @param int         $activity_id The post type activity (0 if not found).
	 * @param string      $new_status  The new status of the post type comment.
	 * @param string      $old_status  The old status of the post type comment.
	 * @param WP_Comment  $comment Comment data.
	 */
	if ( true === apply_filters( 'bp_activity_pre_transition_post_type_comment_status', false, $post_type, $activity_id, $new_status, $old_status, $comment ) ) {
		return false;
	}

	// Check activity item exists.
	if ( empty( $activity_id ) ) {
		// If no activity exists, but the comment has been approved, record it into the activity table.
		if ( 'approved' == $new_status ) {
			return bp_activity_post_type_comment( $comment->comment_ID, true, $activity_post_object );
		}

		return;
	}

	// Create an activity object.
	$activity = new BP_Activity_Activity( $activity_id );
	if ( empty( $activity->component ) ) {
		return;
	}

	// Spam/ham the activity if it's not already in that state.
	if ( 'spam_activity' === $action && ! $activity->is_spam ) {
		bp_activity_mark_as_spam( $activity );
	} elseif ( 'ham_activity' == $action) {
		bp_activity_mark_as_ham( $activity );
	}

	// Add "new_post_type_comment" to the allowed activity types, so that the activity's Akismet history is generated.
	$post_type_comment_action = $activity_comment_object->action_id;
	$comment_akismet_history = function ( $activity_types ) use ( $post_type_comment_action ) {
		$activity_types[] = $post_type_comment_action;

		return $activity_types;
	};
	add_filter( 'bp_akismet_get_activity_types', $comment_akismet_history );

	// Make sure the activity change won't edit the comment if sync is on.
	remove_action( 'bp_activity_before_save', 'bp_blogs_sync_activity_edit_to_post_comment', 20 );

	// Save the updated activity.
	$activity->save();

	// Restore the action.
	add_action( 'bp_activity_before_save', 'bp_blogs_sync_activity_edit_to_post_comment', 20 );

	// Remove the dynamic permitting of the "new_blog_comment" activity type so we don't break anything.
	remove_filter( 'bp_akismet_get_activity_types', $comment_akismet_history );
}
add_action( 'transition_comment_status', 'bp_activity_transition_post_type_comment_status', 10, 3 );

/**
 * Finds and exports personal data associated with an email address from the Activity tables.
 *
 * @since 4.0.0
 *
 * @param string $email_address  The user's email address.
 * @param int    $page           Batch number.
 * @return array An array of personal data.
 */
function bp_activity_personal_data_exporter( $email_address, $page ) {
	$number              = 50;
	$email_address       = trim( $email_address );
	$user_data_to_export = array();

	$user = get_user_by( 'email', $email_address );

	if ( ! $user ) {
		return array(
			'data' => array(),
			'done' => true,
		);
	}

	$activities = bp_activity_get( array(
		'display_comments' => 'stream',
		'per_page'         => $number,
		'page'             => $page,
		'show_hidden'      => true,
		'filter'           => array(
			'user_id' => $user->ID,
		),
	) );

	$activity_actions    = bp_activity_get_actions();

	foreach ( $activities['activities'] as $activity ) {
		if ( ! empty( $activity_actions->{$activity->component}->{$activity->type}['format_callback'] ) ) {
			$description = call_user_func( $activity_actions->{$activity->component}->{$activity->type}['format_callback'], '', $activity );
		} elseif ( ! empty( $activity->action ) ) {
			$description = $activity->action;
		} else {
			$description = $activity->type;
		}

		$item_data = array(
			array(
				'name'  => __( 'Activity Date', 'buddypress' ),
				'value' => $activity->date_recorded,
			),
			array(
				'name'  => __( 'Activity Description', 'buddypress' ),
				'value' => $description,
			),
			array(
				'name'  => __( 'Activity URL', 'buddypress' ),
				'value' => bp_activity_get_permalink( $activity->id, $activity ),
			),
		);

		if ( ! empty( $activity->content ) ) {
			$item_data[] = array(
				'name'  => __( 'Activity Content', 'buddypress' ),
				'value' => $activity->content,
			);
		}

		/**
		 * Filters the data associated with an activity item when assembled for a WP personal data export.
		 *
		 * Plugins that register activity types whose `action` string doesn't adequately
		 * describe the activity item for the purposes of data export may filter the activity
		 * item data here.
		 *
		 * @since 4.0.0
		 *
		 * @param array                $item_data Array of data describing the activity item.
		 * @param BP_Activity_Activity $activity  Activity item.
		 */
		$item_data = apply_filters( 'bp_activity_personal_data_export_item_data', $item_data, $activity );

		$user_data_to_export[] = array(
			'group_id'    => 'bp_activity',
			'group_label' => __( 'Activity', 'buddypress' ),
			'item_id'     => "bp-activity-{$activity->id}",
			'data'        => $item_data,
		);
	}

	// Tell core if we have more items to process.
	$done = count( $activities['activities'] ) < $number;

	return array(
		'data' => $user_data_to_export,
		'done' => $done,
	);
}

/**
 * Checks whether an activity feed is enabled.
 *
 * @since 8.0.0
 * @since 12.0.0 Added bp_current_user_can( 'bp_view' ) check.
 *
 * @param string $feed_id The feed identifier. Possible values are:
 *                        'sitewide', 'personal', 'friends', 'mygroups', 'mentions', 'favorites'.
 */
function bp_activity_is_feed_enable( $feed_id = '' ) {
	$retval = bp_current_user_can( 'bp_view', array( 'bp_component' => 'activity' ) );

	/**
	 * Filters if BuddyPress should consider feeds enabled. If disabled, it will return early.
	 *
	 * @since 1.8.0
	 * @since 8.0.0 Adds the `$feed_id` parameter.
	 *
	 * @param bool   $retval  Whether this feed is enabled or not.
	 * @param string $feed_id The feed identifier.
	 */
	return (bool) apply_filters( 'bp_activity_enable_feeds', $retval, $feed_id );
}
<br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function bp_activity_do_mentions() in /home/nimaghor/public_html/wp-content/plugins/buddypress/bp-activity/classes/class-bp-activity-component.php:280
Stack trace:
#0 /home/nimaghor/public_html/wp-includes/class-wp-hook.php(324): BP_Activity_Component-&gt;register_nav(Array)
#1 /home/nimaghor/public_html/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters(NULL, Array)
#2 /home/nimaghor/public_html/wp-includes/plugin.php(517): WP_Hook-&gt;do_action(Array)
#3 /home/nimaghor/public_html/wp-content/plugins/buddypress/bp-core/bp-core-dependency.php(169): do_action('bp_register_nav')
#4 /home/nimaghor/public_html/wp-includes/class-wp-hook.php(324): bp_register_nav('')
#5 /home/nimaghor/public_html/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters(NULL, Array)
#6 /home/nimaghor/public_html/wp-includes/plugin.php(517): WP_Hook-&gt;do_action(Array)
#7 /home/nimaghor/public_html/wp-content/plugins/buddypress/bp-core/bp-core-dependency.php(291): do_action('bp_init')
#8 /home/nima in <b>/home/nimaghor/public_html/wp-content/plugins/buddypress/bp-activity/classes/class-bp-activity-component.php</b> on line <b>280</b><br />