<?php

declare(strict_types=1);

namespace App\Jobs;

use App\Models\Artwork;
use App\Models\ArtworkEmbedding;
use App\Services\Vision\ArtworkEmbeddingClient;
use App\Services\Vision\ArtworkVectorIndexService;
use App\Services\Vision\ArtworkVisionImageUrl;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Foundation\Bus\Dispatchable;
use Illuminate\Queue\InteractsWithQueue;
use Illuminate\Queue\SerializesModels;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Redis;

final class GenerateArtworkEmbeddingJob implements ShouldQueue
{
    use Dispatchable;
    use InteractsWithQueue;
    use Queueable;
    use SerializesModels;

    public int $tries = 3;

    public int $timeout = 20;

    public function __construct(
        private readonly int $artworkId,
        private readonly ?string $sourceHash = null,
        private readonly bool $force = false,
    ) {
        $queue = (string) config('recommendations.queue', config('vision.queue', 'default'));
        if ($queue !== '') {
            $this->onQueue($queue);
        }
    }

    public function backoff(): array
    {
        return [2, 10, 30];
    }

    public function handle(
        ArtworkEmbeddingClient $client,
        ArtworkVisionImageUrl $imageUrlBuilder,
        ArtworkVectorIndexService $vectors,
    ): void {
        if (! (bool) config('recommendations.embedding.enabled', true)) {
            return;
        }

        $artwork = Artwork::query()
            ->with(['categories' => fn ($categories) => $categories->with('contentType')->orderBy('sort_order')->orderBy('name')])
            ->find($this->artworkId);
        if (! $artwork) {
            return;
        }

        $sourceHash = strtolower((string) preg_replace('/[^a-z0-9]/', '', (string) ($this->sourceHash ?? $artwork->hash ?? '')));
        if ($sourceHash === '') {
            return;
        }

        $model = (string) config('recommendations.embedding.model', 'clip');
        $modelVersion = (string) config('recommendations.embedding.model_version', 'v1');
        $algoVersion = (string) config('recommendations.embedding.algo_version', 'clip-cosine-v1');

        if (! $this->force) {
            $existing = ArtworkEmbedding::query()
                ->where('artwork_id', $artwork->id)
                ->where('model', $model)
                ->where('model_version', $modelVersion)
                ->first();

            if (
                $existing
                && (string) ($existing->source_hash ?? '') === $sourceHash
                && $this->vectorIndexCoversEmbedding(
                    $artwork,
                    $existing
                )
            ) {
                return;
            }
        }

        $lockKey = $this->lockKey(
            $artwork->id,
            $model,
            $modelVersion
        );

        if (! $this->acquireLock($lockKey)) {
            return;
        }

        try {
            /*
             * Another worker may have generated or indexed the
             * embedding between our first read and lock acquisition.
             * Re-read both records under the lock.
             */
            if (! $this->force) {
                $artwork->refresh();

                $existing = ArtworkEmbedding::query()
                    ->where('artwork_id', $artwork->id)
                    ->where('model', $model)
                    ->where('model_version', $modelVersion)
                    ->first();

                if (
                    $existing
                    && (string) ($existing->source_hash ?? '')
                        === $sourceHash
                ) {
                    if (
                        $this->vectorIndexCoversEmbedding(
                            $artwork,
                            $existing
                        )
                    ) {
                        return;
                    }

                    $storedVector = $this->decodeStoredVector(
                        $existing
                    );

                    if ($storedVector !== []) {
                        $this->upsertVectorIndex(
                            $vectors,
                            $artwork,
                            $storedVector
                        );

                        return;
                    }
                }
            }

            $imageUrl = $imageUrlBuilder->fromArtwork($artwork);
            if ($imageUrl === null) {
                return;
            }

            $vector = $client->embed($imageUrl, (int) $artwork->id, $sourceHash);
            if ($vector === []) {
                return;
            }

            $normalized = $this->normalize($vector);

            ArtworkEmbedding::query()->updateOrCreate(
                [
                    'artwork_id' => (int) $artwork->id,
                    'model' => $model,
                    'model_version' => $modelVersion,
                ],
                [
                    'algo_version' => $algoVersion,
                    'dim' => count($normalized),
                    'embedding_json' => json_encode($normalized, JSON_THROW_ON_ERROR),
                    'source_hash' => $sourceHash,
                    'is_normalized' => true,
                    'generated_at' => now(),
                    'meta' => [
                        'source' => 'clip',
                        'image_variant' => (string) config('vision.image_variant', 'md'),
                    ],
                ]
            );

            $this->upsertVectorIndex(
                $vectors,
                $artwork,
                $normalized
            );
        } finally {
            $this->releaseLock($lockKey);
        }
    }

    /**
     * @param  array<int, float>  $vector
     */
    private function upsertVectorIndex(
        ArtworkVectorIndexService $vectors,
        Artwork $artwork,
        array $vector
    ): void {
        if (! $vectors->isConfigured()) {
            return;
        }

        try {
            $vectors->upsertArtworkVector(
                $artwork,
                $vector
            );
        } catch (\Throwable $e) {
            Log::warning('GenerateArtworkEmbeddingJob vector upsert failed', [
                'artwork_id' => (int) $artwork->id,
                'error' => $e->getMessage(),
            ]);
        }
    }

    private function vectorIndexCoversEmbedding(
        Artwork $artwork,
        ArtworkEmbedding $embedding
    ): bool {
        $indexedAt = $artwork->last_vector_indexed_at;
        $generatedAt = $embedding->generated_at;

        if ($indexedAt === null || $generatedAt === null) {
            return false;
        }

        return $indexedAt->greaterThanOrEqualTo(
            $generatedAt
        );
    }

    /**
     * @return array<int, float>
     */
    private function decodeStoredVector(
        ArtworkEmbedding $embedding
    ): array {
        try {
            $decoded = json_decode(
                (string) $embedding->embedding_json,
                true,
                512,
                JSON_THROW_ON_ERROR
            );
        } catch (\Throwable) {
            return [];
        }

        if (! is_array($decoded) || $decoded === []) {
            return [];
        }

        $vector = [];

        foreach ($decoded as $value) {
            if (! is_int($value) && ! is_float($value)) {
                return [];
            }

            $value = (float) $value;

            if (! is_finite($value)) {
                return [];
            }

            $vector[] = $value;
        }

        $count = count($vector);

        $minDim = max(
            1,
            (int) config(
                'recommendations.embedding.min_dim',
                64
            )
        );

        $maxDim = max(
            $minDim,
            (int) config(
                'recommendations.embedding.max_dim',
                4096
            )
        );

        if (
            $count < $minDim
            || $count > $maxDim
        ) {
            return [];
        }

        if (
            (int) $embedding->dim > 0
            && $count !== (int) $embedding->dim
        ) {
            return [];
        }

        return $vector;
    }

    /**
     * @param  array<int, float>  $vector
     * @return array<int, float>
     */
    private function normalize(array $vector): array
    {
        $sumSquares = 0.0;
        foreach ($vector as $value) {
            $sumSquares += ($value * $value);
        }

        if ($sumSquares <= 0.0) {
            return $vector;
        }

        $norm = sqrt($sumSquares);

        return array_map(static fn (float $value): float => $value / $norm, $vector);
    }

    private function lockKey(int $artworkId, string $model, string $version): string
    {
        return 'artwork-embedding:lock:'.$artworkId.':'.$model.':'.$version;
    }

    private function acquireLock(string $key): bool
    {
        try {
            $didSet = Redis::setnx($key, 1);
            if ($didSet) {
                Redis::expire($key, 1800);
            }

            return (bool) $didSet;
        } catch (\Throwable) {
            return true;
        }
    }

    private function releaseLock(string $key): void
    {
        try {
            Redis::del($key);
        } catch (\Throwable) {
            // ignore
        }
    }
}