<?php

declare(strict_types = 1);

// {{{ 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/>.
// }}}

namespace Plugin\TreeNotes;

use App\Core\Event;
use App\Core\Modules\Plugin;
use App\Entity\Note;
use App\Util\Common;
use App\Util\Formatting;
use Symfony\Component\HttpFoundation\Request;

class TreeNotes extends Plugin
{
    /**
     * Formatting notes without taking a direct reply out of context
     * Show whole conversation in conversation related routes.
     */
    public function onFormatNoteList(array $notes_in, array &$notes_out, Request $request)
    {
        if (str_starts_with($request->get('_route'), 'conversation')) {
            $parents   = $this->conversationFormat($notes_in);
            $notes_out = $this->conversationFormatTree($parents, $notes_in);
        } else {
            $notes_out = $this->feedFormatTree($notes_in);
        }
    }

    /**
     * Formats general Feed view, allowing users to see a Note and its direct replies.
     * These replies are then, shown independently of parent note, making sure that every single Note is shown at least
     * once to users.
     *
     * The list is transversed in reverse to prevent any parent Note from being processed twice. At the same time,
     * this allows all direct replies to be rendered inside the same, respective, parent Note.
     * Moreover, this implies the Entity\Note::getReplies() query will only be performed once, for every Note.
     *
     * @param array $notes The Note list to be formatted, each element has two keys: 'note' (parent/current note),
     *                     and 'replies' (array of notes in the same format)
     */
    private function feedFormatTree(array $notes): array
    {
        $tree                = [];
        $notes               = array_reverse($notes);
        $max_replies_to_show = Common::config('plugin_tree_notes', 'feed_replies');
        foreach ($notes as $note) {
            if (!\is_null($children = $note->getReplies(limit: $max_replies_to_show))) {
                $total_replies = $note->getRepliesCount();
                $show_more     = $total_replies > $max_replies_to_show;
                $notes         = array_filter($notes, fn (Note $n) => !\in_array($n, $children));

                $tree[] = [
                    'note'      => $note,
                    'replies'   => array_map(
                        fn ($n) => [
                            'note'          => $n,
                            'replies'       => [], // We want only one depth level
                            'show_more'     => ($n->getRepliesCount() > $max_replies_to_show),
                            'total_replies' => $n->getRepliesCount(),
                        ],
                        $children,
                    ),
                    'total_replies' => $total_replies,
                    'show_more'     => $show_more,
                ];
            } else {
                $tree[] = ['note' => $note, 'replies' => [], 'show_more' => false];
            }
        }

        return array_reverse($tree);
    }

    /**
     * Filters given Note list off any children, returning only initial Notes of a Conversation.
     *
     * @param array $notes_in Notes to be filtered
     *
     * @return array All initial Conversation Notes in given list
     */
    private function conversationFormat(array $notes_in): array
    {
        return array_filter($notes_in, static fn (Note $note) => \is_null($note->getReplyTo()));
    }

    private function conversationFormatTree(array $parents, array $notes): array
    {
        $subtree = [];
        foreach ($parents as $p) {
            $subtree[] = $this->conversationFormatSubTree($p, $notes);
        }

        return $subtree;
    }

    private function conversationFormatSubTree(Note $parent, array $notes)
    {
        $children = array_filter($notes, fn (Note $note) => $note->getReplyTo() === $parent->getId());

        return [
            'note'      => $parent,
            'replies'   => $this->conversationFormatTree($children, $notes),
            'show_more' => false, // It's always false, we're showing everyone
        ];
    }

    public function onAppendNoteBlock(Request $request, array $conversation, array &$res): bool
    {
        if (\array_key_exists('replies', $conversation)) {
            $res[] = Formatting::twigRenderFile(
                'tree_notes/note_replies_block.html.twig',
                [
                    'nickname'     => $conversation['note']->getActorNickname(),
                    'conversation' => $conversation,
                ],
            );
        }
        return Event::next;
    }
}