<?php
defined( 'ABSPATH' ) || exit;
/**
 * Opt-in local debug log.
 *
 * There is no remote telemetry in this plugin and there never will be. This
 * logger writes to the site's own PHP error log and to a small bounded ring
 * buffer in the database so an administrator can read the last few entries in
 * wp-admin. Both are off unless the administrator switches debug logging on.
 *
 * @package AdvisorPPC
 */

/**
 * Class AdvisorPPC_Logger.
 */
class AdvisorPPC_Logger {

	/**
	 * Non-autoloaded option holding the ring buffer.
	 */
	const BUFFER_KEY = 'advisorppc_log';

	/**
	 * How many entries the ring buffer keeps.
	 */
	const BUFFER_SIZE = 100;

	/**
	 * Whether logging is switched on.
	 *
	 * @return bool
	 */
	public static function is_enabled() {
		/**
		 * Filter whether the debug log is active.
		 *
		 * @param bool $enabled Whether logging is on.
		 */
		return (bool) apply_filters( 'advisorppc_debug_log_enabled', (bool) AdvisorPPC_Options::get( 'debug_log', false ) );
	}

	/**
	 * Record a line.
	 *
	 * @param string $message Message. Never include a secret; anything that
	 *                        matches the stored site secret is redacted anyway.
	 * @param array  $context Extra data, JSON encoded into the line.
	 * @param string $level   debug|info|warning|error.
	 * @return void
	 */
	public static function log( $message, $context = array(), $level = 'info' ) {
		if ( ! self::is_enabled() ) {
			return;
		}

		$level   = in_array( $level, array( 'debug', 'info', 'warning', 'error' ), true ) ? $level : 'info';
		$message = self::redact( (string) $message );

		$line = '[advisorppc][' . $level . '] ' . $message;

		if ( ! empty( $context ) ) {
			$encoded = wp_json_encode( self::redact_deep( $context ) );
			if ( is_string( $encoded ) ) {
				$line .= ' ' . self::truncate( $encoded, 1000 );
			}
		}

		// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log -- Opt-in debug logging to the site's own error log.
		error_log( $line );

		self::push_buffer(
			array(
				'time'    => time(),
				'level'   => $level,
				'message' => self::truncate( $message, 500 ),
			)
		);
	}

	/**
	 * Debug-level line.
	 *
	 * @param string $message Message.
	 * @param array  $context Context.
	 * @return void
	 */
	public static function debug( $message, $context = array() ) {
		self::log( $message, $context, 'debug' );
	}

	/**
	 * Info-level line.
	 *
	 * @param string $message Message.
	 * @param array  $context Context.
	 * @return void
	 */
	public static function info( $message, $context = array() ) {
		self::log( $message, $context, 'info' );
	}

	/**
	 * Warning-level line.
	 *
	 * @param string $message Message.
	 * @param array  $context Context.
	 * @return void
	 */
	public static function warning( $message, $context = array() ) {
		self::log( $message, $context, 'warning' );
	}

	/**
	 * Error-level line.
	 *
	 * @param string $message Message.
	 * @param array  $context Context.
	 * @return void
	 */
	public static function error( $message, $context = array() ) {
		self::log( $message, $context, 'error' );
	}

	/**
	 * The stored ring buffer, newest first.
	 *
	 * @return array
	 */
	public static function entries() {
		$buffer = get_option( self::BUFFER_KEY, array() );

		if ( ! is_array( $buffer ) ) {
			return array();
		}

		return array_reverse( $buffer );
	}

	/**
	 * Empty the ring buffer.
	 *
	 * @return void
	 */
	public static function clear() {
		delete_option( self::BUFFER_KEY );
	}

	/**
	 * Append to the ring buffer.
	 *
	 * @param array $entry Entry.
	 * @return void
	 */
	protected static function push_buffer( $entry ) {
		$buffer = get_option( self::BUFFER_KEY, array() );

		if ( ! is_array( $buffer ) ) {
			$buffer = array();
		}

		$buffer[] = $entry;

		if ( count( $buffer ) > self::BUFFER_SIZE ) {
			$buffer = array_slice( $buffer, -self::BUFFER_SIZE );
		}

		if ( false === get_option( self::BUFFER_KEY, false ) ) {
			add_option( self::BUFFER_KEY, $buffer, '', false );
			return;
		}

		update_option( self::BUFFER_KEY, $buffer, false );
	}

	/**
	 * Replace the site secret with a marker wherever it appears.
	 *
	 * @param string $text Text.
	 * @return string
	 */
	protected static function redact( $text ) {
		$secret = AdvisorPPC_Options::get_secret();

		if ( '' !== $secret ) {
			$text = str_replace( $secret, '[redacted]', $text );
		}

		return $text;
	}

	/**
	 * Redact recursively through an array of context values.
	 *
	 * @param mixed $value Value.
	 * @return mixed
	 */
	protected static function redact_deep( $value ) {
		if ( is_array( $value ) ) {
			$out = array();
			foreach ( $value as $key => $item ) {
				if ( in_array( $key, array( 'site_secret', 'secret', 'authorization', 'password' ), true ) ) {
					$out[ $key ] = '[redacted]';
					continue;
				}
				$out[ $key ] = self::redact_deep( $item );
			}
			return $out;
		}

		if ( is_string( $value ) ) {
			return self::redact( $value );
		}

		return $value;
	}

	/**
	 * Hard-limit a string length.
	 *
	 * @param string $text  Text.
	 * @param int    $limit Maximum characters.
	 * @return string
	 */
	protected static function truncate( $text, $limit ) {
		if ( strlen( $text ) <= $limit ) {
			return $text;
		}

		return substr( $text, 0, $limit ) . '...';
	}
}