<?php
/**
 * AI-powered image alt text optimizer.
 *
 * Generates descriptive alt text for WooCommerce product images using
 * OpenAI Vision API or WP AI Services API (WP 6.8+).
 *
 * Generated alt text is stored in a separate meta key and injected
 * via filter without modifying the original attachment metadata.
 *
 * @package AICommerce\Content
 */

declare(strict_types=1);

namespace AICommerce\Content;

use AICommerce\Content\Contracts\AIProviderException;
use AICommerce\Core\Encryption;

/**
 * Optimizes product image alt text via AI vision models.
 */
class ImageAltTextOptimizer {

	/**
	 * Meta key for AI-generated alt text on attachments.
	 *
	 * @var string
	 */
	public const META_ALT_TEXT = '_aicommerce_alt_text';

	/**
	 * Encryption helper.
	 *
	 * @var Encryption
	 */
	private Encryption $encryption;

	/**
	 * Static cache for product image lookups.
	 *
	 * @var array<int, bool>
	 */
	private static array $product_image_cache = array();

	/**
	 * Constructor.
	 *
	 * @param Encryption $encryption Encryption helper for API key access.
	 */
	public function __construct( Encryption $encryption ) {
		$this->encryption = $encryption;
	}

	/**
	 * Optimize alt text for all images of a product.
	 *
	 * @param int  $product_id Product ID.
	 * @param bool $overwrite  Whether to overwrite existing AI alt text.
	 *
	 * @return int Number of images processed.
	 */
	public function optimize_product_images( int $product_id, bool $overwrite = false ): int {
		$product = wc_get_product( $product_id );

		if ( ! $product instanceof \WC_Product ) {
			return 0;
		}

		$featured  = get_post_thumbnail_id( $product_id );
		$gallery   = $product->get_gallery_image_ids();
		$all_ids   = array_unique( array_filter( array_merge( array( (int) $featured ), $gallery ) ) );
		$processed = 0;
		$title     = $product->get_name();

		foreach ( $all_ids as $attachment_id ) {
			$attachment_id = (int) $attachment_id;

			if ( ! $overwrite ) {
				$existing = get_post_meta( $attachment_id, self::META_ALT_TEXT, true );
				if ( ! empty( $existing ) ) {
					continue;
				}
			}

			$image_url = wp_get_attachment_url( $attachment_id );

			if ( empty( $image_url ) ) {
				continue;
			}

			$alt_text = $this->generate_alt_text( $image_url, $title );

			if ( ! empty( $alt_text ) ) {
				update_post_meta( $attachment_id, self::META_ALT_TEXT, sanitize_text_field( $alt_text ) );
				// Track that this is a product image.
				self::$product_image_cache[ $attachment_id ] = true;
				++$processed;
			}
		}

		return $processed;
	}

	/**
	 * Generate alt text for a single image using AI.
	 *
	 * Tries WP AI Services API first (WP 6.8+), falls back to OpenAI Vision.
	 *
	 * @param string $image_url     Full URL of the image.
	 * @param string $product_title Product name for context.
	 *
	 * @return string Generated alt text, or empty string on failure.
	 */
	public function generate_alt_text( string $image_url, string $product_title ): string {
		// Priority 1: WP AI Services API (WP 6.8+).
		if ( function_exists( 'ai_get_services' ) ) {
			try {
				$services = ai_get_services();
				if ( $services && method_exists( $services, 'describe_image' ) ) {
					$result = $services->describe_image( $image_url );
					if ( ! empty( $result ) ) {
						return mb_substr( $result, 0, 125 );
					}
				}
			} catch ( \Exception $e ) {
				unset( $e ); // Intentional: fall through to OpenAI Vision on failure.
			}
		}

		// Priority 2: OpenAI Vision API.
		return $this->generate_via_openai_vision( $image_url, $product_title );
	}

	/**
	 * Generate alt text using OpenAI Vision API (gpt-4o-mini).
	 *
	 * @param string $image_url     Image URL.
	 * @param string $product_title Product name.
	 *
	 * @return string Alt text, or empty on failure.
	 */
	private function generate_via_openai_vision( string $image_url, string $product_title ): string {
		$encrypted_key = get_option( 'aicommerce_openai_api_key', '' );

		if ( empty( $encrypted_key ) ) {
			return '';
		}

		$api_key = $this->encryption->decrypt( $encrypted_key );

		if ( empty( $api_key ) ) {
			return '';
		}

		$body = array(
			'model'      => 'gpt-4o-mini',
			'max_tokens' => 60,
			'messages'   => array(
				array(
					'role'    => 'user',
					'content' => array(
						array(
							'type'      => 'image_url',
							'image_url' => array( 'url' => $image_url ),
						),
						array(
							'type' => 'text',
							'text' => sprintf(
								"Describe this product image for alt text. Product name: '%s'. Under 125 characters. Return ONLY the alt text.",
								$product_title
							),
						),
					),
				),
			),
		);

		$response = wp_remote_post(
			'https://api.openai.com/v1/chat/completions', // phpcs:ignore PluginCheck.CodeAnalysis.AIProvider.DirectIntegration -- BYOK integration; WP AI Client requires WP 7.0, this plugin supports WP 6.4+.
			array(
				'timeout' => 30,
				'headers' => array(
					'Authorization' => 'Bearer ' . $api_key,
					'Content-Type'  => 'application/json',
				),
				'body'    => wp_json_encode( $body ),
			)
		);

		if ( is_wp_error( $response ) ) {
			return '';
		}

		$status = wp_remote_retrieve_response_code( $response );

		if ( 200 !== $status ) {
			return '';
		}

		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		$text = trim( $data['choices'][0]['message']['content'] ?? '' );

		return mb_substr( $text, 0, 125 );
	}

	/**
	 * Filter callback: inject AI alt text on product images.
	 *
	 * Hooked to wp_get_attachment_image_attributes.
	 *
	 * @param array    $attr       Image attributes.
	 * @param \WP_Post $attachment Attachment post object.
	 * @param string   $size       Image size.
	 *
	 * @return array Modified attributes.
	 */
	public function inject_alt_text( array $attr, \WP_Post $attachment, $size ): array {
		if ( ! $this->is_product_image( $attachment->ID ) ) {
			return $attr;
		}

		$ai_alt = get_post_meta( $attachment->ID, self::META_ALT_TEXT, true );

		if ( ! empty( $ai_alt ) ) {
			$attr['alt'] = esc_attr( $ai_alt );
		}

		return $attr;
	}

	/**
	 * Check if an attachment is used as a product featured or gallery image.
	 *
	 * @param int $attachment_id Attachment ID.
	 *
	 * @return bool True if used as a product image.
	 */
	private function is_product_image( int $attachment_id ): bool {
		if ( isset( self::$product_image_cache[ $attachment_id ] ) ) {
			return self::$product_image_cache[ $attachment_id ];
		}

		global $wpdb;

		// Check if used as featured image on any product.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
		$is_featured = (int) $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->postmeta} pm
				 INNER JOIN {$wpdb->posts} p ON pm.post_id = p.ID
				 WHERE pm.meta_key = '_thumbnail_id'
				 AND pm.meta_value = %d
				 AND p.post_type = 'product'
				 LIMIT 1",
				$attachment_id
			)
		);

		if ( $is_featured > 0 ) {
			self::$product_image_cache[ $attachment_id ] = true;
			return true;
		}

		// Check if in a product gallery.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
		$in_gallery = (int) $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->postmeta} pm
				 INNER JOIN {$wpdb->posts} p ON pm.post_id = p.ID
				 WHERE pm.meta_key = '_product_image_gallery'
				 AND FIND_IN_SET(%d, pm.meta_value) > 0
				 AND p.post_type = 'product'
				 LIMIT 1",
				$attachment_id
			)
		);

		$result                                      = $in_gallery > 0;
		self::$product_image_cache[ $attachment_id ] = $result;

		return $result;
	}
}