<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Builds prompts from scan findings and caches the AI's responses so the
 * same finding isn't re-explained (and re-billed) on every page load.
 */
class CGARD_AI_Explainer {

	const CACHE_TTL = 30 * DAY_IN_SECONDS;

	/** @var CGARD_AI_Client */
	private $client;

	public function __construct() {
		$this->client = new CGARD_AI_Client();
	}

	/**
	 * @param array $finding One row from CGARD_Db::get_findings().
	 * @return string|WP_Error
	 */
	public function explain_finding( array $finding ) {
		$cache_key = 'cgard_ai_explain_' . md5( $finding['check_key'] . $finding['description'] );
		$cached    = get_transient( $cache_key );

		if ( false !== $cached ) {
			return $cached;
		}

		$result = $this->client->complete( $this->build_finding_prompt( $finding ), 500 );

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

		set_transient( $cache_key, $result, self::CACHE_TTL );

		return $result;
	}

	/**
	 * @param array  $findings Open findings, as from CGARD_Db::get_findings( 'open' ).
	 * @param string $site_name
	 * @return string|WP_Error
	 */
	public function generate_incident_report( array $findings, $site_name ) {
		if ( empty( $findings ) ) {
			return sprintf(
				/* translators: %s: site name */
				__( '%s currently has no open security findings — nothing to report.', 'clarityguard' ),
				$site_name
			);
		}

		$cache_key = 'cgard_ai_report_' . md5( $site_name . wp_json_encode( wp_list_pluck( $findings, 'check_key' ) ) );
		$cached    = get_transient( $cache_key );

		if ( false !== $cached ) {
			return $cached;
		}

		$result = $this->client->complete( $this->build_report_prompt( $findings, $site_name ), 900 );

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

		set_transient( $cache_key, $result, self::CACHE_TTL );

		return $result;
	}

	private function build_finding_prompt( array $finding ) {
		return sprintf(
			"You are a security assistant helping a non-technical WordPress site owner understand one scan finding.\n\n" .
			"Finding: %s\nSeverity: %s\nTechnical description: %s\nStandard fix already shown to the user: %s\n\n" .
			"Write a short, friendly explanation (about 100-150 words) covering: (1) what this actually means in plain " .
			"language, (2) a realistic worst-case scenario if it's left unfixed, and (3) how urgent it really is relative " .
			"to the stated severity. Do not repeat the fix steps verbatim — the user already has those above. " .
			"Write 2-3 short plain-text paragraphs, no markdown headers or bullet points.",
			$finding['title'],
			strtoupper( $finding['severity'] ),
			$finding['description'],
			$finding['fix_steps']
		);
	}

	private function build_report_prompt( array $findings, $site_name ) {
		$lines = array();

		foreach ( $findings as $finding ) {
			$lines[] = sprintf( '- [%s] %s: %s', strtoupper( $finding['severity'] ), $finding['title'], $finding['description'] );
		}

		return sprintf(
			"Write a short, professional security incident report that an agency could hand directly to a client, based " .
			"on the following WordPress security scan findings for the site \"%s\".\n\n" .
			"Structure it as: a one-paragraph executive summary; a prioritized list of issues (most urgent first) each " .
			"with a one-sentence business-risk explanation; and a short closing recommendation paragraph. Keep the whole " .
			"thing under 400 words, plain text (no markdown headers), professional but not alarmist tone.\n\nFindings:\n%s",
			$site_name,
			implode( "\n", $lines )
		);
	}
}