<?php
/**
 * Vector Index Retrieval Service.
 *
 * @package AISupportAssistant\Chat
 */

namespace AISupportAssistant\Chat;

use AISupportAssistant\Admin\Settings;
use AISupportAssistant\Embeddings\EmbeddingService;
use AISupportAssistant\Helpers\Logger;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Class RetrievalService
 */
class RetrievalService {

	/**
	 * Retrieve top-K relevant chunks for a user question.
	 *
	 * @param string $question User query.
	 * @return array Chunks array.
	 */
	public static function retrieve( string $question ): array {
		if ( empty( trim( $question ) ) ) {
			return array();
		}

		$settings = Settings::get_instance();
		$top_k    = $settings->get( 'top_k', 5 );
		$store    = EmbeddingService::get_vector_store();

		// 1. Generate Query Vector.
		try {
			$query_vector = EmbeddingService::generate( $question );
			if ( empty( $query_vector ) ) {
				Logger::error( 'Retrieval failed: Query vector generation failed.' );
				throw new \RuntimeException( 'Query vector generation returned no embedding.' );
			}
			// 2. Query Vector Store.
			return $store->search( $query_vector, $top_k );
		} catch ( \Throwable $e ) {
			Logger::error( 'Retrieval error: ' . $e->getMessage() );
			throw $e;
		}
	}
}