<?php

namespace App\Console\Commands;

use App\Models\Comment;
use Illuminate\Console\Command;
use Illuminate\Support\Facades\DB;

/**
 * Clean up duplicate comments that pre-date the server-side 60-second dedupe
 * guard. Duplicate = identical (user_id, video_id, parent_id, body) within a
 * configurable gap. Keeps the earliest row, moves any likes onto it, deletes
 * the rest. --dry-run shows what would happen without touching the DB.
 */
class CommentsDedupeCommand extends Command
{
    protected $signature = 'comments:dedupe
        {--window=60 : Treat duplicates as same submission if within N seconds (default 60)}
        {--dry-run : Print what would be removed; do not delete}';

    protected $description = 'Collapse duplicate comments (same user, video, parent, body) into the earliest one';

    public function handle(): int
    {
        $window = max(1, (int) $this->option('window'));
        $dryRun = (bool) $this->option('dry-run');

        // Fetch (user_id, video_id, parent_id, body) groups that appear >1 time.
        // We ignore the window at the SQL layer and apply it per-group in PHP:
        // that avoids a correlated subquery and is fast enough for a one-shot
        // cleanup. For very large tables, chunk by user_id.
        $groups = DB::table('comments')
            ->selectRaw('user_id, video_id, parent_id, body, COUNT(*) as cnt')
            ->groupBy('user_id', 'video_id', 'parent_id', 'body')
            ->havingRaw('COUNT(*) > 1')
            ->get();

        if ($groups->isEmpty()) {
            $this->info('No duplicate (user, video, parent, body) groups found.');
            return self::SUCCESS;
        }

        $totalRemoved = 0;
        $groupsTouched = 0;

        foreach ($groups as $g) {
            $rows = Comment::where('user_id', $g->user_id)
                ->where('video_id', $g->video_id)
                ->where(function ($q) use ($g) {
                    $g->parent_id === null
                        ? $q->whereNull('parent_id')
                        : $q->where('parent_id', $g->parent_id);
                })
                ->where('body', $g->body)
                ->orderBy('created_at')
                ->orderBy('id')
                ->get();

            if ($rows->count() < 2) {
                continue;
            }

            $keeper = $rows->first();
            $cluster = collect([$keeper]);
            $previous = $keeper;

            foreach ($rows->slice(1) as $row) {
                // Same cluster if row is within window of the previous row —
                // which is the behavior the server guard enforces today.
                if ($row->created_at->diffInSeconds($previous->created_at) <= $window) {
                    $cluster->push($row);
                    $previous = $row;
                }
            }

            if ($cluster->count() < 2) {
                continue;
            }

            $toDelete = $cluster->skip(1);
            $groupsTouched++;
            $totalRemoved += $toDelete->count();

            $this->line(sprintf(
                '  user=%d video=%d parent=%s keep=%d remove=%s body="%s"',
                $g->user_id,
                $g->video_id,
                $g->parent_id ?? 'null',
                $keeper->id,
                $toDelete->pluck('id')->join(','),
                mb_strimwidth(preg_replace('/\s+/', ' ', (string) $g->body), 0, 40, '…'),
            ));

            if ($dryRun) {
                continue;
            }

            DB::transaction(function () use ($keeper, $toDelete) {
                $ids = $toDelete->pluck('id')->all();

                // Reparent any replies that were nested under a doomed row.
                Comment::whereIn('parent_id', $ids)->update(['parent_id' => $keeper->id]);

                // Move likes to the keeper, dropping dupes.
                DB::table('comment_likes')
                    ->whereIn('comment_id', $ids)
                    ->update(['comment_id' => $keeper->id]);

                Comment::whereIn('id', $ids)->delete();
            });
        }

        $this->info(sprintf(
            '%s %d duplicate rows across %d groups.',
            $dryRun ? 'Would remove' : 'Removed',
            $totalRemoved,
            $groupsTouched,
        ));

        return self::SUCCESS;
    }
}