<?php

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the GNU Affero General Public License v3.0.
// See the LICENCE file in the repository root for full licence text.

namespace App\Transformers\Chat;

use App\Models\Chat\Channel;
use App\Models\Chat\Message;
use App\Models\User;
use App\Transformers\TransformerAbstract;

class ChannelTransformer extends TransformerAbstract
{
    const CONVERSATION_INCLUDES = [
        'last_message_id',
        'users',
    ];

    const LISTING_INCLUDES = [
        'current_user_attributes',
        'last_read_id',
        ...self::CONVERSATION_INCLUDES,
    ];

    protected array $availableIncludes = [
        'current_user_attributes',
        'last_message_id',
        'last_read_id', // TODO: deprecated
        'recent_messages', // TODO: deprecated
        'users',
    ];

    private $user;

    public static function forUser(?User $user)
    {
        $transformer = new static();
        $transformer->user = $user;

        return $transformer;
    }

    public function transform(Channel $channel)
    {
        return [
            'channel_id' => $channel->channel_id,
            'description' => $channel->description,
            'icon' => $channel->displayIconFor($this->user),
            'message_length_limit' => $channel->messageLengthLimit(),
            'moderated' => $channel->moderated,
            'name' => $channel->displayNameFor($this->user),
            'type' => $channel->type,
            'uuid' => $channel->uuid,
        ];
    }

    public function includeCurrentUserAttributes(Channel $channel)
    {
        $result = $channel->checkCanMessage($this->user);

        return $this->primitive([
            'can_list_users' => priv_check_user($this->user, 'ChatChannelListUsers', $channel)->can(),
            'can_message' => $result->can(),
            'can_message_error' => $result->message(),
            'last_read_id' => $channel->lastReadIdFor($this->user),
        ]);
    }

    public function includeLastMessageId(Channel $channel)
    {
        return $this->primitive($channel->last_message_id);
    }

    public function includeLastReadId(Channel $channel)
    {
        return $this->primitive($channel->lastReadIdFor($this->user));
    }

    public function includeRecentMessages(Channel $channel)
    {
        if ($channel->exists) {
            $messages = Message::filterBacklogs(
                $channel,
                $channel
                    ->messages()
                    // assumes sender will be included by the Message transformer
                    ->with('sender')
                    ->orderBy('message_id', 'desc')
                    ->limit(50)
                    ->get()
                    ->reverse(),
            );
        } else {
            $messages = [];
        }

        return $this->collection($messages, new MessageTransformer());
    }

    public function includeUsers(Channel $channel)
    {
        return $this->primitive($channel->isPM() ? $channel->userIds() : []);
    }

    public function includeUuid(Channel $channel)
    {
        return $this->primitive($channel->uuid);
    }
}