<?php

// {{{ License

// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social 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.
//
// GNU social 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 GNU social.  If not, see <http://www.gnu.org/licenses/>.

// }}}

/**
 * ActivityPub's Remote Actor
 *
 * @category  Plugin
 * @package   GNUsocial
 *
 * @author    Diogo Cordeiro <diogo@fc.up.pt>
 * @author    Hugo Sales <hugo@fc.up.pt>
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */

namespace Plugin\ActivityPub\Entity;

class ActivityPubActor
{
    // {{{ Autocode
    // }}} Autocode

    /**
     * Generates a pretty profile from a Profile object
     *
     * @param Profile $profile
     *
     * @throws InvalidUrlException
     * @throws ServerException
     * @throws Exception
     *
     * @return array array to be used in a response
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public static function profile_to_array(Profile $profile): array
    {
        $uri        = $profile->getUri();
        $id         = $profile->getID();
        $rsa        = new Activitypub_rsa();
        $public_key = $rsa->ensure_public_key($profile);
        unset($rsa);
        $res = [
            '@context' => [
                'https://www.w3.org/ns/activitystreams',
                'https://w3id.org/security/v1',
                [
                    'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers',
                ],
            ],
            'id'                        => $uri,
            'type'                      => 'Person',
            'following'                 => common_local_url('apActorFollowing', ['id' => $id]),
            'followers'                 => common_local_url('apActorFollowers', ['id' => $id]),
            'liked'                     => common_local_url('apActorLiked', ['id' => $id]),
            'inbox'                     => common_local_url('apInbox', ['id' => $id]),
            'outbox'                    => common_local_url('apActorOutbox', ['id' => $id]),
            'preferredUsername'         => $profile->getNickname(),
            'name'                      => $profile->getBestName(),
            'summary'                   => ($desc = $profile->getDescription()) == null ? '' : $desc,
            'url'                       => $profile->getUrl(),
            'manuallyApprovesFollowers' => false,
            'publicKey'                 => [
                'id'           => $uri . '#public-key',
                'owner'        => $uri,
                'publicKeyPem' => $public_key,
            ],
            'tag'        => [],
            'attachment' => [],
            'icon'       => [
                'type'      => 'Image',
                'mediaType' => 'image/png',
                'height'    => AVATAR_PROFILE_SIZE,
                'width'     => AVATAR_PROFILE_SIZE,
                'url'       => $profile->avatarUrl(AVATAR_PROFILE_SIZE),
            ],
        ];

        if ($profile->isLocal()) {
            $res['endpoints']['sharedInbox'] = common_local_url('apInbox');
        } else {
            $aprofile                        = new Activitypub_profile();
            $aprofile                        = $aprofile->from_profile($profile);
            $res['endpoints']['sharedInbox'] = $aprofile->sharedInboxuri;
        }

        return $res;
    }

    /**
     * Insert the current object variables into the database
     *
     * @throws ServerException
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function do_insert(): void
    {
        // Does any other protocol have this remote entity we're about to add ?
        Event::handle('StartTFNLookup', [$this->uri, get_class($this), &$profile_id]);
        if (!is_null($profile_id)) {
            // Yes! Avoid creating a new profile
            $this->profile_id = $profile_id;
            $this->created    = $this->modified    = common_sql_now();

            if ($this->insert() === false) {
                $this->query('ROLLBACK');
                throw new ServerException('Cannot save ActivityPub profile.');
            }

            // Update existing profile with received data
            $profile = Profile::getKV('id', $profile_id);
            self::update_local_profile($profile, $this);

            // Ask TFN to handle profile duplication
            Event::handle('EndTFNLookup', [get_class($this), $profile_id]);
        } else {
            // No, create both a new profile and remote profile
            $profile          = new Profile();
            $profile->created = $this->created = $this->modified = common_sql_now();
            self::update_local_profile($profile, $this);

            $this->profile_id = $profile->insert();
            if ($this->profile_id === false) {
                $profile->query('ROLLBACK');
                throw new ServerException('Profile insertion failed.');
            }

            $ok = $this->insert();

            if ($ok === false) {
                $profile->query('ROLLBACK');
                $this->query('ROLLBACK');
                throw new ServerException('Cannot save ActivityPub profile.');
            }
        }
    }

    /**
     * Fetch the locally stored profile for this Activitypub_profile
     *
     * @throws NoProfileException if it was not found
     *
     * @return Profile
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function local_profile(): Profile
    {
        $profile = Profile::getKV('id', $this->profile_id);
        if (!$profile instanceof Profile) {
            throw new NoProfileException($this->profile_id);
        }
        return $profile;
    }

    /**
     * Generates an Activitypub_profile from a Profile
     *
     * @param Profile $profile
     *
     * @throws Exception if no Activitypub_profile exists for given Profile
     *
     * @return Activitypub_profile
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public static function from_profile(Profile $profile): Activitypub_profile
    {
        $profile_id = $profile->getID();

        $aprofile = self::getKV('profile_id', $profile_id);
        if (!$aprofile instanceof Activitypub_profile) {
            // No Activitypub_profile for this profile_id,
            if (!$profile->isLocal()) {
                // create one!
                $aprofile = self::create_from_local_profile($profile);
            } else {
                throw new Exception('No Activitypub_profile for Profile ID: ' . $profile_id . ', this is a local user.');
            }
        }

        // extend the ap_profile with some information we
        // don't store in the database
        $fields = [
            'nickname' => 'nickname',
            'fullname' => 'fullname',
            'bio'      => 'bio',
        ];

        foreach ($fields as $af => $pf) {
            $aprofile->{$af} = $profile->{$pf};
        }

        return $aprofile;
    }

    /**
     * Travels an array of Profile and returns an array of Activitypub_profile
     *
     * @param array of Profile $profiles
     *
     * @return array of Activitypub_profile
     */
    public static function from_profile_collection(array $profiles): array
    {
        $ap_profiles = [];

        foreach ($profiles as $profile) {
            try {
                $ap_profiles[] = self::from_profile($profile);
            } catch (Exception $e) {
                // Don't mind local profiles
            }
        }

        return $ap_profiles;
    }

    /**
     * Given an existent local profile creates an ActivityPub profile.
     * One must be careful not to give a user profile to this function
     * as only remote users have ActivityPub_profiles on local instance
     *
     * @param Profile $profile
     *
     * @throws HTTP_Request2_Exception
     * @throws Exception
     * @throws Exception
     *
     * @return Activitypub_profile
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    private static function create_from_local_profile(Profile $profile): Activitypub_profile
    {
        $aprofile = new Activitypub_profile();

        $url     = $profile->getUri();
        $inboxes = Activitypub_explorer::get_actor_inboxes_uri($url);
        if ($inboxes === false) {
            throw new Exception('This is not an ActivityPub user thus AProfile is politely refusing to proceed.');
        }

        $aprofile->created = $aprofile->modified = common_sql_now();

        $aprofile                 = new Activitypub_profile;
        $aprofile->profile_id     = $profile->getID();
        $aprofile->uri            = $url;
        $aprofile->nickname       = $profile->getNickname();
        $aprofile->fullname       = $profile->getFullname();
        $aprofile->bio            = substr($profile->getDescription(), 0, 1000);
        $aprofile->inboxuri       = $inboxes['inbox'];
        $aprofile->sharedInboxuri = $inboxes['sharedInbox'];

        $aprofile->insert();

        return $aprofile;
    }

    /**
     * Returns sharedInbox if possible, inbox otherwise
     *
     * @return string Inbox URL
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function get_inbox(): string
    {
        if (is_null($this->sharedInboxuri)) {
            return $this->inboxuri;
        }

        return $this->sharedInboxuri;
    }

    /**
     * Getter for uri property
     *
     * @return string URI
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function getUri(): string
    {
        return $this->uri;
    }

    /**
     * Getter for url property
     *
     * @return string URL
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function getUrl(): string
    {
        return $this->getUri();
    }

    /**
     * Getter for id property
     *
     * @return int
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public function getID(): int
    {
        return $this->profile_id;
    }

    /**
     * Ensures a valid Activitypub_profile when provided with a valid URI.
     *
     * @param string $url
     * @param bool   $grab_online whether to try online grabbing, defaults to true
     *
     * @throws Exception if it isn't possible to return an Activitypub_profile
     *
     * @return Activitypub_profile
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public static function fromUri(string $url, bool $grab_online = true): Activitypub_profile
    {
        try {
            return self::from_profile(Activitypub_explorer::get_profile_from_url($url, $grab_online));
        } catch (Exception $e) {
            throw new Exception('No valid ActivityPub profile found for given URI.');
        }
    }

    /**
     * Look up, and if necessary create, an Activitypub_profile for the remote
     * entity with the given WebFinger address.
     * This should never return null -- you will either get an object or
     * an exception will be thrown.
     *
     * @param string $addr WebFinger address
     *
     * @throws Exception on error conditions
     *
     * @return Activitypub_profile
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     * @author GNU social
     */
    public static function ensure_webfinger(string $addr): Activitypub_profile
    {
        // Normalize $addr, i.e. add 'acct:' if missing
        $addr = Discovery::normalize($addr);

        // Try the cache
        $uri = self::cacheGet(sprintf('activitypub_profile:webfinger:%s', $addr));

        if ($uri !== false) {
            if (is_null($uri)) {
                // Negative cache entry
                // TRANS: Exception.
                throw new Exception(_m('Not a valid WebFinger address (via cache).'));
            }
            try {
                return self::fromUri($uri);
            } catch (Exception $e) {
                common_log(LOG_ERR, sprintf(__METHOD__ . ': WebFinger address cache inconsistent with database, did not find Activitypub_profile uri==%s', $uri));
                self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), false);
            }
        }

        // Now, try some discovery

        $disco = new Discovery();

        try {
            $xrd = $disco->lookup($addr);
        } catch (Exception $e) {
            // Save negative cache entry so we don't waste time looking it up again.
            // @todo FIXME: Distinguish temporary failures?
            self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), null);
            // TRANS: Exception.
            throw new Exception(_m('Not a valid WebFinger address.'));
        }

        $hints = array_merge(
            ['webfinger' => $addr],
            DiscoveryHints::fromXRD($xrd)
        );

        // If there's an Hcard, let's grab its info
        if (array_key_exists('hcard', $hints)) {
            if (!array_key_exists('profileurl', $hints) || $hints['hcard'] != $hints['profileurl']) {
                $hcardHints = DiscoveryHints::fromHcardUrl($hints['hcard']);
                $hints      = array_merge($hcardHints, $hints);
            }
        }

        // If we got a profile page, try that!
        $profileUrl = null;
        if (array_key_exists('profileurl', $hints)) {
            $profileUrl = $hints['profileurl'];
            try {
                common_log(LOG_INFO, "Discovery on acct:{$addr} with profile URL {$profileUrl}");
                $aprofile = self::fromUri($hints['profileurl']);
                self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), $aprofile->getUri());
                return $aprofile;
            } catch (Exception $e) {
                common_log(LOG_WARNING, "Failed creating profile from profile URL '{$profileUrl}': " . $e->getMessage());
                // keep looking
                //
                // @todo FIXME: This means an error discovering from profile page
                // may give us a corrupt entry using the webfinger URI, which
                // will obscure the correct page-keyed profile later on.
            }
        }

        // XXX: try hcard
        // XXX: try FOAF

        // TRANS: Exception. %s is a WebFinger address.
        throw new Exception(sprintf(_m('Could not find a valid profile for "%s".'), $addr));
    }

    /**
     * Update local profile with info from some AP profile
     *
     * @param Profile             $profile
     * @param Activitypub_profile $aprofile
     *
     * @return void
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public static function update_local_profile(Profile $profile, Activitypub_profile $aprofile): void
    {
        $fields = [
            'profileurl' => 'profileurl',
            'nickname'   => 'nickname',
            'fullname'   => 'fullname',
            'bio'        => 'bio',
        ];

        $orig = clone $profile;

        foreach ($fields as $af => $pf) {
            $profile->{$pf} = $aprofile->{$af};
        }

        if ($profile->id) {
            common_debug('Updating local Profile:' . $profile->id . ' from remote ActivityPub profile');
            $profile->modified = common_sql_now();
            $profile->update($orig);
        }
    }

    /**
     * Update remote user profile in local instance
     *
     * @param Activitypub_profile $aprofile
     * @param array|false         $res      remote response, if array it updates, if false it deletes
     *
     * @throws NoProfileException
     *
     * @return Profile remote Profile object
     *
     * @author Diogo Cordeiro <diogo@fc.up.pt>
     */
    public static function update_profile(Activitypub_profile $aprofile, $res): Profile
    {
        if ($res === false) {
            $profile = $aprofile->local_profile();
            $id      = $profile->getID();
            $profile->delete();
            throw new NoProfileException($id, '410 Gone');
        }

        if (!is_array($res)) {
            throw new InvalidArgumentException('TypeError: Argument 2 passed to Activitypub_profile::update_profile() must be of the type array or bool(false).');
        }

        // ActivityPub Profile
        $aprofile->uri            = $res['id'];
        $aprofile->nickname       = $res['preferredUsername'];
        $aprofile->fullname       = $res['name'] ?? null;
        $aprofile->bio            = isset($res['summary']) ? substr(strip_tags($res['summary']), 0, 1000) : null;
        $aprofile->inboxuri       = $res['inbox'];
        $aprofile->sharedInboxuri = $res['endpoints']['sharedInbox'] ?? $res['inbox'];
        $aprofile->profileurl     = $res['url']                      ?? $aprofile->uri;
        $aprofile->modified       = common_sql_now();

        $profile = $aprofile->local_profile();

        // Profile
        self::update_local_profile($profile, $aprofile);
        $aprofile->update();

        // Public Key
        Activitypub_rsa::update_public_key($profile, $res['publicKey']['publicKeyPem']);

        // Avatar
        if (isset($res['icon']['url'])) {
            try {
                Activitypub_explorer::update_avatar($profile, $res['icon']['url']);
            } catch (Exception $e) {
                // Let the exception go, it isn't a serious issue
                common_debug('An error ocurred while grabbing remote avatar' . $e->getMessage());
            }
        }

        return $profile;
    }

    /**
     * Update remote user profile URI in local instance
     *
     * @param string $uri
     *
     * @throws Exception (if the update fails)
     *
     * @return void
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public function updateUri(string $uri): void
    {
        $orig      = clone $this;
        $this->uri = $uri;
        $this->updateWithKeys($orig);
    }

    /**
     * Getter for the number of subscribers of a
     * given local profile
     *
     * @param Profile $profile profile object
     *
     * @return int number of subscribers
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function subscriberCount(Profile $profile): int
    {
        $cnt = self::cacheGet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id));

        if ($cnt !== false && is_int($cnt)) {
            return $cnt;
        }

        $user_table      = common_database_tablename('user');
        $sub             = new Subscription();
        $sub->subscribed = $profile->id;
        $sub->_join .= "\n" . <<<END
            INNER JOIN (
              SELECT id AS subscriber FROM {$user_table}
              UNION ALL
              SELECT profile_id FROM activitypub_profile
            ) AS t1 USING (subscriber)
            END;
        $sub->whereAdd('subscriber <> subscribed');
        $cnt = $sub->count('DISTINCT subscriber');

        self::cacheSet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id), $cnt);

        return $cnt;
    }

    /**
     * Getter for the number of subscriptions of a
     * given local profile
     *
     * @param Profile $profile profile object
     *
     * @return int number of subscriptions
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function subscriptionCount(Profile $profile): int
    {
        $cnt = self::cacheGet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id));

        if ($cnt !== false && is_int($cnt)) {
            return $cnt;
        }

        $user_table      = common_database_tablename('user');
        $sub             = new Subscription();
        $sub->subscriber = $profile->id;
        $sub->_join .= "\n" . <<<END
            INNER JOIN (
              SELECT id AS subscribed FROM {$user_table}
              UNION ALL
              SELECT profile_id FROM activitypub_profile
            ) AS t1 USING (subscribed)
            END;
        $sub->whereAdd('subscriber <> subscribed');
        $cnt = $sub->count('DISTINCT subscribed');

        self::cacheSet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id), $cnt);

        return $cnt;
    }

    /**
     * Increment or decrement subscriber count
     *
     * @param Profile $profile
     * @param $adder
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function updateSubscriberCount(Profile $profile, $adder): void
    {
        $cnt = self::cacheGet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id));

        if ($cnt !== false && is_int($cnt)) {
            self::cacheSet(sprintf('activitypub_profile:subscriberCount:%d', $profile->id), $cnt + $adder);
        }
    }

    /**
     * Increment or decrement subscription count
     *
     * @param Profile $profile
     * @param $adder
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function updateSubscriptionCount(Profile $profile, $adder): void
    {
        $cnt = self::cacheGet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id));

        if ($cnt !== false && is_int($cnt)) {
            self::cacheSet(sprintf('activitypub_profile:subscriptionCount:%d', $profile->id), $cnt + $adder);
        }
    }

    /**
     * Getter for the subscriber profiles of a
     * given local profile
     *
     * @param Profile  $profile profile object
     * @param int      $offset  [optional] index of the starting row to fetch from
     * @param null|int $limit   [optional] maximum number of rows allowed for fetching. If it is omitted,
     *                          then the sequence will have everything
     *                          from offset up until the end.
     *
     * @return array subscriber profile objects
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function getSubscribers(Profile $profile, int $offset = 0, ?int $limit = null): array
    {
        $cache = false;
        if ($offset + $limit <= Subscription::CACHE_WINDOW) {
            $subs = self::cacheGet(sprintf('activitypub_profile:subscriberCollection:%d', $profile->id));
            if ($subs !== false && is_array($subs)) {
                return array_slice($subs, $offset, $limit);
            }

            $cache = true;
        }

        $subs     = Subscription::getSubscriberIDs($profile->id, $offset, $limit);
        $profiles = [];

        $users = User::multiGet('id', $subs);
        foreach ($users->fetchAll() as $user) {
            $profiles[$user->id] = $user->getProfile();
        }

        $ap_profiles = Activitypub_profile::multiGet('profile_id', $subs);
        foreach ($ap_profiles->fetchAll() as $ap) {
            $profiles[$ap->getID()] = $ap->local_profile();
        }

        if ($cache) {
            self::cacheSet(sprintf('activitypub_profile:subscriberCollection:%d', $profile->id), $profiles);
        }

        return $profiles;
    }

    /**
     * Getter for the subscribed profiles of a
     * given local profile
     *
     * @param Profile  $profile profile object
     * @param int      $offset  index of the starting row to fetch from
     * @param null|int $limit   maximum number of rows allowed for fetching
     *
     * @return array subscribed profile objects
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function getSubscribed(Profile $profile, int $offset = 0, ?int $limit = null): array
    {
        $cache = false;
        if ($offset + $limit <= Subscription::CACHE_WINDOW) {
            $subs = self::cacheGet(sprintf('activitypub_profile:subscribedCollection:%d', $profile->id));
            if (is_array($subs)) {
                return array_slice($subs, $offset, $limit);
            }

            $cache = true;
        }

        $subs = Subscription::getSubscribedIDs($profile->id, $offset, $limit);

        $profiles = [];

        $users = User::multiGet('id', $subs);
        foreach ($users->fetchAll() as $user) {
            $profiles[$user->id] = $user->getProfile();
        }

        $ap_profiles = Activitypub_profile::multiGet('profile_id', $subs);
        foreach ($ap_profiles->fetchAll() as $ap) {
            $profiles[$ap->getID()] = $ap->local_profile();
        }

        if ($cache) {
            self::cacheSet(sprintf('activitypub_profile:subscribedCollection:%d', $profile->id), $profiles);
        }

        return $profiles;
    }

    /**
     * Update cached values that are relevant to
     * the users involved in a subscription
     *
     * @param Profile $actor subscriber profile object
     * @param Profile $other subscribed profile object
     *
     * @throws Exception
     *
     * @return void
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function subscribeCacheUpdate(Profile $actor, Profile $other): void
    {
        self::blow('activitypub_profile:subscribedCollection:%d', $actor->getID());
        self::blow('activitypub_profile:subscriberCollection:%d', $other->id);
        self::updateSubscriptionCount($actor, +1);
        self::updateSubscriberCount($other, +1);
    }

    /**
     * Update cached values that are relevant to
     * the users involved in an unsubscription
     *
     * @param Profile $actor subscriber profile object
     * @param Profile $other subscribed profile object
     *
     * @throws Exception
     *
     * @return void
     *
     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
     */
    public static function unsubscribeCacheUpdate(Profile $actor, Profile $other): void
    {
        self::blow('activitypub_profile:subscribedCollection:%d', $actor->getID());
        self::blow('activitypub_profile:subscriberCollection:%d', $other->id);
        self::updateSubscriptionCount($actor, -1);
        self::updateSubscriberCount($other, -1);
    }

    public static function schemaDef()
    {
        return [
            'name'        => 'activitypub_actor',
            'description' => 'remote actor profiles',
            'fields'      => [
                'uri'            => ['type' => 'text', 'not null' => true],
                'profile_id'     => ['type' => 'int', 'not null' => true],
                'inboxuri'       => ['type' => 'text', 'not null' => true],
                'sharedInboxuri' => ['type' => 'text'],
                'created'        => ['type' => 'datetime', 'description' => 'date this record was created'],
                'modified'       => ['type' => 'timestamp', 'not null' => true, 'description' => 'date this record was modified'],
            ],
            'primary key'  => ['profile_id'],
            'foreign keys' => [
                'activitypub_profile_profile_id_fkey' => ['profile', ['profile_id' => 'id']],
            ],
        ];
    }
}