<?php

declare(strict_types=1);

namespace App\Console\Commands;

use App\Models\Artwork;
use Illuminate\Console\Command;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

final class BackfillArtworkPrimaryCategoryCommand extends Command
{
    protected $signature = 'artworks:backfill-primary-category
        {--dry-run : Report without writing (default unless --apply is passed)}
        {--report : Print category-count distribution and conflicts}
        {--apply : Write primary_category_id for artworks with exactly one category}
        {--force : Overwrite existing primary_category_id values}';

    protected $description = 'Backfill artworks.primary_category_id from unique artwork_category memberships';

    public function handle(): int
    {
        $apply = (bool) $this->option('apply');
        $force = (bool) $this->option('force');
        $report = (bool) $this->option('report') || ! $apply;

        if ($report) {
            $this->printDistribution();
        }

        $conflicts = $this->conflictArtworkIds();
        $zeros = $this->zeroCategoryArtworkIds();
        $eligible = $this->eligibleArtworkIds($force);

        $this->info('Zero-category artworks: '.$zeros->count());
        $this->info('Single-category eligible for backfill: '.$eligible->count());
        $this->info('Multi-category conflicts (not auto-resolved): '.$conflicts->count());

        if ($conflicts->isNotEmpty()) {
            $this->warn('Multi-category artwork IDs (first 50): '.$conflicts->take(50)->implode(', '));
        }

        if (! $apply) {
            $this->comment('Dry run only. Re-run with --apply to write primary_category_id for single-category artworks.');

            return self::SUCCESS;
        }

        $updated = 0;
        foreach ($eligible->chunk(500) as $chunk) {
            $rows = DB::table('artwork_category')
                ->select('artwork_id', 'category_id')
                ->whereIn('artwork_id', $chunk->all())
                ->get()
                ->groupBy('artwork_id');

            foreach ($rows as $artworkId => $memberships) {
                if ($memberships->count() !== 1) {
                    continue;
                }

                $query = Artwork::query()->where('id', (int) $artworkId);
                if (! $force) {
                    $query->whereNull('primary_category_id');
                }

                $updated += $query->update([
                    'primary_category_id' => (int) $memberships->first()->category_id,
                ]);
            }
        }

        $this->info("Updated {$updated} artwork(s).");

        return self::SUCCESS;
    }

    private function printDistribution(): void
    {
        $distribution = DB::query()
            ->fromSub(function ($query): void {
                $query->from('artwork_category')
                    ->select('artwork_id', DB::raw('COUNT(*) as category_count'))
                    ->groupBy('artwork_id');
            }, 'x')
            ->select('category_count', DB::raw('COUNT(*) as artworks'))
            ->groupBy('category_count')
            ->orderBy('category_count')
            ->get();

        $this->table(['category_count', 'artworks'], $distribution->map(fn ($row): array => [
            (int) $row->category_count,
            (int) $row->artworks,
        ])->all());
    }

    /**
     * @return Collection<int, int>
     */
    private function eligibleArtworkIds(bool $force)
    {
        $query = DB::table('artwork_category')
            ->select('artwork_id')
            ->groupBy('artwork_id')
            ->havingRaw('COUNT(*) = 1');

        if (! $force) {
            $query->whereIn('artwork_id', Artwork::query()->whereNull('primary_category_id')->select('id'));
        }

        return $query->pluck('artwork_id')->map(fn ($id): int => (int) $id);
    }

    /**
     * @return Collection<int, int>
     */
    private function conflictArtworkIds()
    {
        return DB::table('artwork_category')
            ->select('artwork_id')
            ->groupBy('artwork_id')
            ->havingRaw('COUNT(*) > 1')
            ->orderByRaw('COUNT(*) DESC')
            ->pluck('artwork_id')
            ->map(fn ($id): int => (int) $id);
    }

    /**
     * @return Collection<int, int>
     */
    private function zeroCategoryArtworkIds()
    {
        return Artwork::query()
            ->whereDoesntHave('categories')
            ->pluck('id')
            ->map(fn ($id): int => (int) $id);
    }
}