<?php

declare(strict_types=1);

namespace App\Services;

use App\Enums\ReactionType;
use Illuminate\Support\Facades\DB;

/**
 * Bulk reaction read model for artwork comment trees.
 *
 * The returned value intentionally matches ReactionController's `totals`
 * contract so SSR and API comment payloads can hydrate ReactionBar directly.
 */
final class CommentReactionService
{
    /**
     * @param  iterable<int|string>  $commentIds
     * @return array<int, array<string, array{emoji:string, label:string, count:int, mine:bool}>>
     */
    public function forComments(iterable $commentIds, ?int $userId = null): array
    {
        $ids = collect($commentIds)
            ->map(static fn ($id): int => (int) $id)
            ->filter(static fn (int $id): bool => $id > 0)
            ->unique()
            ->values()
            ->all();

        if ($ids === []) {
            return [];
        }

        $counts = DB::table('comment_reactions')
            ->whereIn('comment_id', $ids)
            ->selectRaw('comment_id, reaction, COUNT(*) as total')
            ->groupBy('comment_id', 'reaction')
            ->get()
            ->groupBy('comment_id');

        $mine = collect();
        if ($userId !== null) {
            $mine = DB::table('comment_reactions')
                ->whereIn('comment_id', $ids)
                ->where('user_id', $userId)
                ->get(['comment_id', 'reaction'])
                ->groupBy('comment_id');
        }

        $result = [];
        foreach ($ids as $commentId) {
            $commentCounts = $counts->get($commentId, collect())->keyBy('reaction');
            $commentMine = $mine->get($commentId, collect())->pluck('reaction')->flip();

            $totals = [];
            foreach (ReactionType::cases() as $type) {
                $slug = $type->value;
                $totals[$slug] = [
                    'emoji' => $type->emoji(),
                    'label' => $type->label(),
                    'count' => (int) ($commentCounts->get($slug)->total ?? 0),
                    'mine' => $commentMine->has($slug),
                ];
            }

            $result[$commentId] = $totals;
        }

        return $result;
    }
}