pixelfed/app/Services/FollowerService.php

<?php

namespace App\Services;

use Illuminate\Support\Facades\Redis;
use Cache;
use App\{
	Follower,
	Profile,
	User
};

class FollowerService
{
	const FOLLOWING_KEY = 'pf:services:follow:following:id:';
	const FOLLOWERS_KEY = 'pf:services:follow:followers:id:';

	public static function add($actor, $target)
	{
		Redis::zadd(self::FOLLOWING_KEY . $actor, $target, $target);
		Redis::zadd(self::FOLLOWERS_KEY . $target, $actor, $actor);
	}

	public static function remove($actor, $target)
	{
		Redis::zrem(self::FOLLOWING_KEY . $actor, $target);
		Redis::zrem(self::FOLLOWERS_KEY . $target, $actor);
		Cache::forget('pf:services:follow:audience:' . $actor);
		Cache::forget('pf:services:follow:audience:' . $target);
	}

	public static function followers($id, $start = 0, $stop = 10)
	{
		return Redis::zrange(self::FOLLOWERS_KEY . $id, $start, $stop);
	}

	public static function following($id, $start = 0, $stop = 10)
	{
		return Redis::zrange(self::FOLLOWING_KEY . $id, $start, $stop);
	}

	public static function follows(string $actor, string $target)
	{
		return Follower::whereProfileId($actor)->whereFollowingId($target)->exists();
	}

	public static function audience($profile, $scope = null)
	{
		return (new self)->getAudienceInboxes($profile);
	}

	protected function getAudienceInboxes($profile, $scope = null)
	{
		if(!$profile instanceOf Profile) {
			return [];
		}

		$key = 'pf:services:follow:audience:' . $profile->id;
		return Cache::remember($key, 86400, function() use($profile) {
			return $profile
				->followers()
				->whereLocalProfile(false)
				->get()
				->map(function($follow) {
					return $follow->sharedInbox ?? $follow->inbox_url;
				})
				->unique()
				->values()
				->toArray();
		});
	}

}