<?php
/**
 * Logger functionality for Agentorie Chat.
 *
 * @package    Agentorie_Chat
 * @subpackage Agentorie_Chat/includes
 * @since      1.0.0
 */

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

/**
 * Logger class.
 *
 * @since 1.0.0
 */
class Agentorie_Logger {

	/**
	 * Log level constants.
	 *
	 * @var array
	 */
	const LEVELS = array(
		'ERROR'   => 1,
		'WARNING' => 2,
		'INFO'    => 3,
		'DEBUG'   => 4,
	);

	/**
	 * Maximum log file size in bytes (5 MB).
	 *
	 * @var int
	 */
	const MAX_FILE_SIZE = 5242880;

	/**
	 * Maximum number of rotated log files.
	 *
	 * @var int
	 */
	const MAX_ROTATED_FILES = 3;

	/**
	 * Log directory path.
	 *
	 * @var string|null
	 */
	private static $log_dir = null;

	/**
	 * Log file path.
	 *
	 * @var string|null
	 */
	private static $log_file = null;

	/**
	 * Debug mode status.
	 *
	 * @var bool|null
	 */
	private static $debug_mode = null;

	/**
	 * Log an error message.
	 *
	 * @since 1.0.0
	 * @param string $message Log message.
	 * @param array  $context Optional context data.
	 * @return bool True on success.
	 */
	public static function error( $message, $context = array() ) {
		return self::log( 'ERROR', $message, $context );
	}

	/**
	 * Log a warning message.
	 *
	 * @since 1.0.0
	 * @param string $message Log message.
	 * @param array  $context Optional context data.
	 * @return bool True on success.
	 */
	public static function warning( $message, $context = array() ) {
		return self::log( 'WARNING', $message, $context );
	}

	/**
	 * Log an info message.
	 *
	 * Only logs to file when debug mode is enabled.
	 * Always sends to error_log for critical info (activation/deactivation).
	 *
	 * @since 1.0.0
	 * @param string $message Log message.
	 * @param array  $context Optional context data.
	 * @param bool   $force   Force logging even without debug mode (for critical events).
	 * @return bool True on success.
	 */
	public static function info( $message, $context = array(), $force = false ) {
		return self::log( 'INFO', $message, $context, $force );
	}

	/**
	 * Log a debug message (only if debug mode enabled).
	 *
	 * @since 1.0.0
	 * @param string $message Log message.
	 * @param array  $context Optional context data.
	 * @return bool True on success, false if debug mode disabled.
	 */
	public static function debug( $message, $context = array() ) {
		if ( ! self::is_debug_mode() ) {
			return false;
		}
		return self::log( 'DEBUG', $message, $context, true );
	}

	/**
	 * Write a log entry.
	 *
	 * Behavior depends on debug mode:
	 * - Debug OFF: ERROR/WARNING go to error_log() only (WP.org friendly)
	 * - Debug ON: All levels go to custom log file (support-friendly)
	 *
	 * @since 1.0.0
	 * @param string $level   Log level.
	 * @param string $message Log message.
	 * @param array  $context Optional context data.
	 * @param bool   $force   Force file logging even without debug mode.
	 * @return bool True on success.
	 */
	private static function log( $level, $message, $context = array(), $force = false ) {
		$timestamp   = current_time( 'Y-m-d H:i:s' );
		$log_message = sprintf( '[Agentorie Chat] [%s] [%s] %s', $timestamp, $level, $message );

		if ( ! empty( $context ) ) {
			$log_message .= ' | Context: ' . wp_json_encode( $context, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES );
		}

		// Always use error_log for ERROR and WARNING when debug mode is off.
		// This ensures critical issues are logged somewhere (WP.org friendly).
		if ( ! self::is_debug_mode() && ! $force ) {
			if ( in_array( $level, array( 'ERROR', 'WARNING' ), true ) ) {
				// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
				error_log( $log_message );
			}
			return true;
		}

		// Debug mode ON or forced: write to custom log file.
		if ( ! self::ensure_log_directory() ) {
			// Fallback to error_log if directory creation fails.
			// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
			error_log( $log_message );
			return false;
		}

		self::maybe_rotate_logs();

		$log_entry = sprintf( '[%s] [%s] %s', $timestamp, $level, $message );

		if ( ! empty( $context ) ) {
			$log_entry .= ' | Context: ' . wp_json_encode( $context, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES );
		}

		$log_entry .= PHP_EOL;

		$log_file = self::get_log_file_path();

		// WP_Filesystem does not support atomic append (FILE_APPEND | LOCK_EX).
		// Direct file operation required for concurrent-safe log writing.
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
		$result = file_put_contents( $log_file, $log_entry, FILE_APPEND | LOCK_EX );

		return false !== $result;
	}

	/**
	 * Get the log file path.
	 *
	 * Uses a hashed filename to prevent direct URL guessing.
	 *
	 * @since 1.0.0
	 * @return string Log file path.
	 */
	public static function get_log_file_path() {
		if ( null === self::$log_file ) {
			$hash           = self::get_log_hash();
			self::$log_file = self::get_log_directory() . 'error-' . $hash . '.log';
		}
		return self::$log_file;
	}

	/**
	 * Get the log directory path.
	 *
	 * Uses a dedicated directory within the uploads folder as recommended
	 * by WordPress plugin guidelines. The directory is protected with
	 * .htaccess and index files to prevent direct access.
	 *
	 * @since 1.0.0
	 * @return string Log directory path.
	 */
	public static function get_log_directory() {
		if ( null === self::$log_dir ) {
			$upload_dir    = wp_upload_dir();
			self::$log_dir = trailingslashit( $upload_dir['basedir'] ) . 'agentorie-chat/logs/';
		}
		return self::$log_dir;
	}

	/**
	 * Get a unique hash for this site's log files.
	 *
	 * This makes log filenames unpredictable to prevent direct access.
	 *
	 * @since 1.0.0
	 * @return string Unique hash for log filenames.
	 */
	private static function get_log_hash() {
		$hash = get_option( 'agentorie_chat_log_hash' );

		if ( empty( $hash ) ) {
			$hash = wp_generate_password( 16, false );
			update_option( 'agentorie_chat_log_hash', $hash, false );
		}

		return $hash;
	}

	/**
	 * Ensure the log directory exists.
	 *
	 * Creates the directory with restrictive permissions and protection files.
	 * Note: For Nginx servers, additional server configuration is recommended
	 * to block access to the agentorie-logs directory.
	 *
	 * @since 1.0.0
	 * @return bool True if directory is writable.
	 */
	private static function ensure_log_directory() {
		$log_dir = self::get_log_directory();

		if ( ! file_exists( $log_dir ) ) {
			if ( ! wp_mkdir_p( $log_dir ) ) {
				return false;
			}

			// Set restrictive permissions (owner read/write only).
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_chmod
			chmod( $log_dir, 0700 );

			// Protect directory from direct access.
			$filesystem = self::get_filesystem();

			if ( $filesystem ) {
				$filesystem->put_contents( $log_dir . '.htaccess', "Order deny,allow\nDeny from all", FS_CHMOD_FILE );
				$filesystem->put_contents( $log_dir . 'index.php', '<?php // Silence is golden.', FS_CHMOD_FILE );
				$filesystem->put_contents( $log_dir . 'index.html', '', FS_CHMOD_FILE );
			} else {
				// Fallback to direct file operations if WP_Filesystem is unavailable.
				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Fallback when WP_Filesystem unavailable (FTP credentials required).
				file_put_contents( $log_dir . '.htaccess', "Order deny,allow\nDeny from all" );
				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Fallback when WP_Filesystem unavailable.
				file_put_contents( $log_dir . 'index.php', '<?php // Silence is golden.' );
				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Fallback when WP_Filesystem unavailable.
				file_put_contents( $log_dir . 'index.html', '' );
			}
		}

		return wp_is_writable( $log_dir );
	}

	/**
	 * Check if rotation is needed.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	private static function maybe_rotate_logs() {
		$log_file = self::get_log_file_path();

		if ( ! file_exists( $log_file ) ) {
			return;
		}

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_filesize
		$file_size = filesize( $log_file );

		if ( $file_size < self::MAX_FILE_SIZE ) {
			return;
		}

		self::rotate_logs();
	}

	/**
	 * Rotate log files.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	private static function rotate_logs() {
		$log_file = self::get_log_file_path();
		$log_dir  = self::get_log_directory();
		$hash     = self::get_log_hash();

		$oldest_file = $log_dir . 'error-' . $hash . '.' . self::MAX_ROTATED_FILES . '.log';
		if ( file_exists( $oldest_file ) ) {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink
			unlink( $oldest_file );
		}

		for ( $i = self::MAX_ROTATED_FILES - 1; $i >= 1; $i-- ) {
			$old_file = $log_dir . 'error-' . $hash . '.' . $i . '.log';
			$new_file = $log_dir . 'error-' . $hash . '.' . ( $i + 1 ) . '.log';

			if ( file_exists( $old_file ) ) {
				// phpcs:ignore WordPress.WP.AlternativeFunctions.rename_rename
				rename( $old_file, $new_file );
			}
		}

		// phpcs:ignore WordPress.WP.AlternativeFunctions.rename_rename
		rename( $log_file, $log_dir . 'error-' . $hash . '.1.log' );
	}

	/**
	 * Get log file size.
	 *
	 * @since 1.0.0
	 * @return int File size in bytes.
	 */
	public static function get_log_file_size() {
		$log_file = self::get_log_file_path();

		if ( ! file_exists( $log_file ) ) {
			return 0;
		}

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_filesize
		return (int) filesize( $log_file );
	}

	/**
	 * Get formatted log file size.
	 *
	 * @since 1.0.0
	 * @return string Formatted file size.
	 */
	public static function get_formatted_log_file_size() {
		return size_format( self::get_log_file_size() );
	}

	/**
	 * Get last error timestamp.
	 *
	 * @since 1.0.0
	 * @return string|null Last error timestamp or null.
	 */
	public static function get_last_error_time() {
		$log_file = self::get_log_file_path();

		if ( ! file_exists( $log_file ) ) {
			return null;
		}

		$filesystem = self::get_filesystem();

		if ( $filesystem ) {
			$content = $filesystem->get_contents( $log_file );
		} else {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Fallback when WP_Filesystem unavailable.
			$content = file_get_contents( $log_file );
		}

		if ( empty( $content ) ) {
			return null;
		}

		preg_match_all( '/\[(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})\] \[(ERROR|WARNING)\]/', $content, $matches );

		if ( empty( $matches[1] ) ) {
			return null;
		}

		return end( $matches[1] );
	}

	/**
	 * Get log contents.
	 *
	 * @since 1.0.0
	 * @param int $lines Number of lines to return (0 for all).
	 * @return string Log contents.
	 */
	public static function get_log_contents( $lines = 0 ) {
		$log_file = self::get_log_file_path();

		if ( ! file_exists( $log_file ) ) {
			return '';
		}

		$filesystem = self::get_filesystem();

		if ( $filesystem ) {
			$content = $filesystem->get_contents( $log_file );
		} else {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Fallback when WP_Filesystem unavailable.
			$content = file_get_contents( $log_file );
		}

		if ( false === $content ) {
			return '';
		}

		if ( 0 === $lines ) {
			return $content;
		}

		$all_lines  = explode( PHP_EOL, $content );
		$last_lines = array_slice( $all_lines, -$lines );

		return implode( PHP_EOL, $last_lines );
	}

	/**
	 * Download logs.
	 *
	 * Outputs log file as a downloadable text file.
	 * This function should only be called after verifying user permissions
	 * (manage_options capability check in the calling code).
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public static function download_logs() {
		// Security: Verify user has permission (defense in depth).
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'You do not have permission to download logs.', 'agentorie-chat' ) );
		}

		$log_file = self::get_log_file_path();
		$filename = 'agentorie-chat-logs-' . gmdate( 'Y-m-d-His' ) . '.log';

		// Security: Verify file is within allowed directory.
		$log_dir   = self::get_log_directory();
		$real_path = realpath( $log_file );
		$real_dir  = realpath( $log_dir );

		if ( false === $real_path || false === $real_dir || 0 !== strpos( $real_path, $real_dir ) ) {
			wp_die( esc_html__( 'Invalid log file path.', 'agentorie-chat' ) );
		}

		// Set headers for file download.
		header( 'Content-Type: text/plain; charset=utf-8' );
		header( 'Content-Disposition: attachment; filename="' . esc_attr( $filename ) . '"' );
		header( 'Pragma: no-cache' );
		header( 'Expires: 0' );

		if ( file_exists( $log_file ) && is_readable( $log_file ) ) {
			// Use readfile() for better memory efficiency with large files.
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile
			readfile( $log_file );
		} else {
			echo esc_html__( 'No logs available.', 'agentorie-chat' );
		}

		exit;
	}

	/**
	 * Clear all logs.
	 *
	 * @since 1.0.0
	 * @return bool True on success.
	 */
	public static function clear_logs() {
		$log_dir = self::get_log_directory();

		if ( ! file_exists( $log_dir ) ) {
			return true;
		}

		$files = glob( $log_dir . 'error*.log' );

		if ( ! empty( $files ) ) {
			foreach ( $files as $file ) {
				// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink
				if ( ! unlink( $file ) ) {
					return false;
				}
			}
		}

		return true;
	}

	/**
	 * Check if debug mode enabled.
	 *
	 * @since 1.0.0
	 * @return bool True if debug mode is enabled.
	 */
	public static function is_debug_mode() {
		if ( null === self::$debug_mode ) {
			if ( function_exists( 'agentorie_chat_get_setting' ) ) {
				self::$debug_mode = (bool) agentorie_chat_get_setting( 'debug_mode', false );
			} else {
				self::$debug_mode = false;
			}
		}
		return self::$debug_mode;
	}

	/**
	 * Get WP_Filesystem instance.
	 *
	 * Returns the global WP_Filesystem object if available, or null if it
	 * cannot be initialized (e.g., FTP credentials required).
	 *
	 * @since 1.1.4
	 * @return WP_Filesystem_Base|null Filesystem instance or null.
	 */
	private static function get_filesystem() {
		global $wp_filesystem;

		if ( $wp_filesystem instanceof WP_Filesystem_Base ) {
			return $wp_filesystem;
		}

		if ( ! function_exists( 'WP_Filesystem' ) ) {
			require_once ABSPATH . 'wp-admin/includes/file.php';
		}

		// Pass false to avoid FTP credentials prompt.
		if ( WP_Filesystem( false ) && $wp_filesystem instanceof WP_Filesystem_Base ) {
			return $wp_filesystem;
		}

		return null;
	}

	/**
	 * Clear cache.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public static function clear_cache() {
		self::$debug_mode = null;
		self::$log_dir    = null;
		self::$log_file   = null;
	}

	/**
	 * PHP error handler.
	 *
	 * @since 1.0.0
	 * @param int    $errno   Error number.
	 * @param string $errstr  Error message.
	 * @param string $errfile File where error occurred.
	 * @param int    $errline Line number.
	 * @return bool False to continue with default error handler.
	 */
	public static function error_handler( $errno, $errstr, $errfile, $errline ) {
		if ( false === strpos( $errfile, 'agentorie-chat' ) ) {
			return false;
		}

		$level = 'ERROR';
		switch ( $errno ) {
			case E_WARNING:
			case E_USER_WARNING:
				$level = 'WARNING';
				break;
			case E_NOTICE:
			case E_USER_NOTICE:
				$level = 'INFO';
				break;
			case E_DEPRECATED:
			case E_USER_DEPRECATED:
				$level = 'DEBUG';
				break;
		}

		self::log(
			$level,
			$errstr,
			array(
				'file' => basename( $errfile ),
				'line' => $errline,
				'type' => $errno,
			)
		);

		return false;
	}

	/**
	 * PHP exception handler.
	 *
	 * @since 1.0.0
	 * @param Throwable $exception The exception.
	 * @return void
	 */
	public static function exception_handler( $exception ) {
		if ( false === strpos( $exception->getFile(), 'agentorie-chat' ) ) {
			return;
		}

		self::error(
			'Uncaught exception: ' . $exception->getMessage(),
			array(
				'file'  => basename( $exception->getFile() ),
				'line'  => $exception->getLine(),
				'trace' => self::format_trace( $exception->getTraceAsString() ),
			)
		);
	}

	/**
	 * Format trace.
	 *
	 * @since 1.0.0
	 * @param string $trace Stack trace string.
	 * @return string Formatted trace.
	 */
	private static function format_trace( $trace ) {
		$trace = substr( $trace, 0, 500 );
		$trace = preg_replace( '/[A-Za-z]:?[\\/][^\s:]+[\\/]/', '', $trace );
		return $trace;
	}

	/**
	 * Log activation.
	 *
	 * Always logs (forced) as this is a critical event for debugging.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public static function log_activation() {
		self::info(
			'Plugin activated',
			array(
				'version'    => defined( 'AGENTORIE_CHAT_VERSION' ) ? AGENTORIE_CHAT_VERSION : 'unknown',
				'wp_version' => get_bloginfo( 'version' ),
				'php'        => PHP_VERSION,
			),
			true // Force logging even without debug mode.
		);
	}

	/**
	 * Log deactivation.
	 *
	 * Always logs (forced) as this is a critical event for debugging.
	 *
	 * @since 1.0.0
	 * @return void
	 */
	public static function log_deactivation() {
		self::info(
			'Plugin deactivated',
			array(
				'version' => defined( 'AGENTORIE_CHAT_VERSION' ) ? AGENTORIE_CHAT_VERSION : 'unknown',
			),
			true // Force logging even without debug mode.
		);
	}
}