<?php
/**
 * PSR-4 autoloader used at runtime, so releases ship without Composer's vendor directory.
 *
 * @package WPInterface\ProductReviews
 */

declare( strict_types=1 );

namespace WPInterface\ProductReviews;

defined( 'ABSPATH' ) || exit;

/**
 * Maps a namespace prefix to a base directory.
 */
final class Autoloader {

	/**
	 * Registered prefixes and their base directories.
	 *
	 * @var array<string, string>
	 */
	private static array $prefixes = array();

	/**
	 * Register a namespace prefix.
	 *
	 * @param string $prefix   Namespace prefix with a trailing backslash.
	 * @param string $base_dir Base directory with a trailing slash.
	 */
	public static function register( string $prefix, string $base_dir ): void {
		if ( array() === self::$prefixes ) {
			spl_autoload_register( array( self::class, 'load' ) );
		}
		self::$prefixes[ $prefix ] = rtrim( $base_dir, '/\\' ) . '/';
		// Longest prefix first, so nested namespaces (e.g. WPInterface\ProductReviews\Dev\) win.
		uksort( self::$prefixes, static fn( string $a, string $b ): int => strlen( $b ) <=> strlen( $a ) );
	}

	/**
	 * Load a class file if it belongs to a registered prefix.
	 *
	 * @param string $class_name Fully qualified class name.
	 */
	public static function load( string $class_name ): void {
		foreach ( self::$prefixes as $prefix => $base_dir ) {
			if ( 0 !== strpos( $class_name, $prefix ) ) {
				continue;
			}
			$relative = substr( $class_name, strlen( $prefix ) );
			$file     = $base_dir . str_replace( '\\', '/', $relative ) . '.php';
			if ( is_readable( $file ) ) {
				require_once $file;
				return;
			}
		}
	}
}