<?php

namespace App\Services;

use Carbon\CarbonImmutable;
use Illuminate\Support\Facades\DB;

final class OneYearArticleLikes
{
    /** Each article owns its progress; retries and overlapping workers cannot pay twice. */
    public function sync(): int
    {
        $total = 0;
        DB::table('articles')->where('iStatus', 1)
            ->whereColumn('iYearLikeTarget', '>', 'iYearLikeAdded')
            ->select('id')->chunkById(100, function ($articles) use (&$total) {
                foreach ($articles as $article) {
                    $total += $this->syncArticle($article->id);
                }
            });

        return $total;
    }

    public function syncArticle(int $id): int
    {
        return DB::transaction(function () use ($id) {
            $article = DB::table('articles')->where('id', $id)->lockForUpdate()->first();
            if (! $article || (int) $article->iStatus !== 1
                || $article->iYearLikeTarget <= $article->iYearLikeAdded) {
                return 0;
            }

            $now = CarbonImmutable::now();
            if (! $article->sYearLikeStartedAt) {
                DB::table('articles')->where('id', $id)->update(['sYearLikeStartedAt' => $now]);

                return 0;
            }

            $start = CarbonImmutable::parse($article->sYearLikeStartedAt);
            $end = $start->addYearNoOverflow();
            $duration = $end->getTimestamp() - $start->getTimestamp();
            $elapsed = max(0, min($duration, $now->getTimestamp() - $start->getTimestamp()));
            $due = intdiv((int) $article->iYearLikeTarget * $elapsed, $duration);
            $add = max(0, $due - (int) $article->iYearLikeAdded);
            if ($add > 0) {
                // Query-builder arithmetic preserves real/other automatic likes and content timestamps.
                DB::table('articles')->where('id', $id)->update([
                    'iLikeCount' => DB::raw('iLikeCount + '.$add),
                    'iYearLikeAdded' => DB::raw('iYearLikeAdded + '.$add),
                    'sLastLikedAt' => $now,
                ]);
            }

            return $add;
        }, 3);
    }
}