<?php
/**
 * Brave Search API Integration
 *
 * Handles fetching web search results for models that do not natively support web search
 *
 * @package WP_Agentic_Writer
 */

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

class WP_Agentic_Writer_Brave_Search_API {

	/**
	 * Brave Search REST API Endpoint
	 *
	 * @var string
	 */
	private $api_endpoint = 'https://api.search.brave.com/res/v1/web/search';

	/**
	 * Get singleton instance.
	 *
	 * @since 0.1.0
	 * @return WP_Agentic_Writer_Brave_Search_API
	 */
	public static function get_instance() {
		static $instance = null;

		if ( null === $instance ) {
			$instance = new self();
		}

		return $instance;
	}

	/**
	 * Perform a web search.
	 *
	 * @since 0.1.0
	 * @param string $query Required. The user's search query.
	 * @param int    $count Optional. Number of results to return. Default 3.
	 * @return array|WP_Error Array of formatted search results, or WP_Error on failure.
	 */
	public function search( $query, $count = 3 ) {
		$settings = get_option( 'wp_agentic_writer_settings', array() );
		$api_key  = $settings['brave_search_api_key'] ?? '';

		if ( empty( $api_key ) ) {
			return new WP_Error(
				'brave_api_key_missing',
				__( 'Brave Search API Key is missing. Please configure it in WP Agentic Writer settings.', 'wp-agentic-writer' )
			);
		}

		// Check cache first to prevent burning API limits on identical subsequent queries
		$cache_key = 'wpaw_brave_search_' . md5( $query . '_' . $count );
		$cached_results = get_transient( $cache_key );
		if ( false !== $cached_results ) {
			return $cached_results;
		}

		$url = add_query_arg(
			array(
				'q'           => urlencode( $query ),
				'count'       => absint( $count ),
				'text_decorations' => 0, // Disable HTML tags in descriptions
				'spellcheck'  => 1,
			),
			$this->api_endpoint
		);

		$response = wp_remote_get(
			$url,
			array(
				'headers' => array(
					'Accept'            => 'application/json',
					'Accept-Encoding'   => 'gzip',
					'X-Subscription-Token' => $api_key,
				),
				'timeout' => 15,
			)
		);

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

		$http_code = wp_remote_retrieve_response_code( $response );
		$body      = json_decode( wp_remote_retrieve_body( $response ), true );

		if ( 200 !== $http_code ) {
			return new WP_Error(
				'brave_api_error',
				sprintf(
					/* translators: %1$d is HTTP status code, %2$s is error message */
					__( 'Brave Search API Error %1$d: %2$s', 'wp-agentic-writer' ),
					$http_code,
					$body['message'] ?? __( 'Unknown Error', 'wp-agentic-writer' )
				)
			);
		}

		if ( empty( $body['web']['results'] ) ) {
			return array(); // No results found
		}

		$formatted_results = array();
		foreach ( $body['web']['results'] as $result ) {
			$formatted_results[] = array(
				'title'       => $result['title'] ?? '',
				'url'         => $result['url'] ?? '',
				'description' => $result['description'] ?? '',
			);
		}

		// Cache results for 1 hour to prevent redundant API calls
		set_transient( $cache_key, $formatted_results, HOUR_IN_SECONDS );

		return $formatted_results;
	}

	/**
	 * Formats search results into a markdown context block for LLM System Prompt injection.
	 *
	 * @since 0.1.0
	 * @param array  $results Search results array.
	 * @param string $query   Original query.
	 * @return string Formatted markdown context string.
	 */
	public function format_results_for_llm( $results, $query ) {
		if ( empty( $results ) || is_wp_error( $results ) ) {
			return "No reliable web search results found for: {$query}";
		}

		$markdown = "## LIVE WEB SEARCH CONTEXT\n";
		$markdown .= "> You successfully searched the internet for: \"{$query}\"\n";
		$markdown .= "> Please incorporate the following real-time data into your answer:\n\n";

		$counter = 1;
		foreach ( $results as $item ) {
			$markdown .= "{$counter}. **{$item['title']}**\n";
			$markdown .= "   URL: {$item['url']}\n";
			$markdown .= "   Summary: {$item['description']}\n\n";
			$counter++;
		}

		$markdown .= "---------------------------\n";

		return $markdown;
	}
}