<?php
/**
 * Audit log for REST API activity.
 *
 * Records every write to the wc-edm REST API and every rejected request,
 * so unauthorized access attempts are visible after the fact.
 *
 * @package WC_Email_Discount_Manager
 */

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

/**
 * Writes and maintains the audit log.
 */
class WC_EDM_Audit_Log {

	/**
	 * Cron hook used for pruning old entries.
	 */
	const CRON_HOOK = 'wc_edm_prune_audit_log';

	/**
	 * Hook the daily prune job.
	 */
	public function __construct() {
		add_action( self::CRON_HOOK, array( __CLASS__, 'prune' ) );
		add_action( 'init', array( __CLASS__, 'schedule_prune' ) );
	}

	/**
	 * Make sure the daily prune job is scheduled.
	 */
	public static function schedule_prune() {
		if ( ! wp_next_scheduled( self::CRON_HOOK ) ) {
			wp_schedule_event( time() + HOUR_IN_SECONDS, 'daily', self::CRON_HOOK );
		}
	}

	/**
	 * Remove the scheduled prune job (used on deactivation).
	 */
	public static function unschedule_prune() {
		$timestamp = wp_next_scheduled( self::CRON_HOOK );

		if ( $timestamp ) {
			wp_unschedule_event( $timestamp, self::CRON_HOOK );
		}
	}

	/**
	 * Whether audit logging is enabled.
	 *
	 * @return bool
	 */
	public static function is_enabled() {
		/**
		 * Filter whether REST activity is written to the audit log.
		 *
		 * @param bool $enabled Default true.
		 */
		return (bool) apply_filters( 'wc_edm_audit_log_enabled', true );
	}

	/**
	 * How many days entries are kept.
	 *
	 * @return int
	 */
	public static function retention_days() {
		/**
		 * Filter the audit log retention period in days.
		 *
		 * @param int $days Default 30.
		 */
		return max( 1, (int) apply_filters( 'wc_edm_audit_log_retention_days', 30 ) );
	}

	/**
	 * Resolve the client IP address.
	 *
	 * The shop may sit behind a reverse proxy (e.g. Cloudflare), where
	 * REMOTE_ADDR is the proxy rather than the visitor. Proxy headers are
	 * only trustworthy when the proxy is guaranteed to set them, so this is
	 * filterable for setups that need different handling.
	 *
	 * @return string
	 */
	public static function get_client_ip() {
		$ip = '';

		if ( ! empty( $_SERVER['HTTP_CF_CONNECTING_IP'] ) ) {
			$ip = sanitize_text_field( wp_unslash( $_SERVER['HTTP_CF_CONNECTING_IP'] ) );
		} elseif ( ! empty( $_SERVER['REMOTE_ADDR'] ) ) {
			$ip = sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ) );
		}

		$ip = filter_var( $ip, FILTER_VALIDATE_IP ) ? $ip : '';

		/**
		 * Filter the resolved client IP used for logging and rate limiting.
		 *
		 * @param string $ip Resolved IP address.
		 */
		return (string) apply_filters( 'wc_edm_client_ip', $ip );
	}

	/**
	 * Record an entry.
	 *
	 * @param string $outcome One of allowed|denied|rate_limited.
	 * @param string $method  HTTP method.
	 * @param string $route   REST route.
	 * @param int    $status  HTTP status code.
	 * @param array  $details Optional extra context.
	 * @return void
	 */
	public static function record( $outcome, $method, $route, $status = 0, $details = array() ) {
		if ( ! self::is_enabled() ) {
			return;
		}

		if ( ! in_array( $outcome, array( 'allowed', 'denied', 'rate_limited' ), true ) ) {
			$outcome = 'allowed';
		}

		$user = wp_get_current_user();

		WC_EDM_DB::insert_audit_entry(
			array(
				'user_id'    => $user ? (int) $user->ID : 0,
				'user_login' => $user && $user->user_login ? $user->user_login : '',
				'ip'         => self::get_client_ip(),
				'method'     => strtoupper( substr( (string) $method, 0, 10 ) ),
				'route'      => substr( (string) $route, 0, 191 ),
				'status'     => (int) $status,
				'outcome'    => $outcome,
				'details'    => ! empty( $details ) ? wp_json_encode( $details ) : null,
			)
		);
	}

	/**
	 * Delete entries older than the retention period.
	 *
	 * @return void
	 */
	public static function prune() {
		WC_EDM_DB::prune_audit_log( self::retention_days() );
	}
}