<?php

declare(strict_types=1);

namespace MPBC;

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

class Autoloader {
	/**
	 * Relative path to the source directory (without trailing slash).
	 */
	protected const BASE_DIR = 'src';

	protected const AUTOLOAD_EXCEPTIONS = array(
		// Class name with namespace => The relative path to the file
	);

	protected const FUNCTION_FILES = array(
		// Relative path to the file in the source directory
		'functions.php',
		'template-functions.php',
	);

	protected string $namespace = '';

	/**
	 * Absolute path to the plugin directory (with trailing slash).
	 */
	protected string $plugin_dir = '';

	/**
	 * @param string $plugin_dir Absolute path to the plugin directory (with
	 *     trailing slash).
	 */
	public function __construct( string $namespace, string $plugin_dir ) {
		$this->namespace = $namespace;
		$this->plugin_dir = $plugin_dir;

		spl_autoload_register( array( $this, 'load_class' ) );

		$this->load_functions();
	}

	/**
	 * @access protected
	 */
	public function load_class( string $class_name ): void {
		if ( strpos( $class_name, $this->namespace ) !== 0 ) {
			return; // Skip
		}

		if ( isset( static::AUTOLOAD_EXCEPTIONS[ $class_name ] ) ) {
			$plugin_file = static::AUTOLOAD_EXCEPTIONS[ $class_name ];
		} else {
			// 'MPBC\Sub_Package\Class_X' → 'src/sub-package/class-x.php'
			$plugin_file = str_replace( $this->namespace, static::BASE_DIR, $class_name );
			$plugin_file = str_replace( array( '\\', '/' ), DIRECTORY_SEPARATOR, $plugin_file );
			$plugin_file = str_replace( '_', '-', $plugin_file );
			$plugin_file = strtolower( $plugin_file );
			$plugin_file .= '.php';
		}

		require $this->plugin_dir . $plugin_file;
	}

	protected function load_functions(): void {
		$base_dir = $this->plugin_dir . static::BASE_DIR . DIRECTORY_SEPARATOR;

		foreach ( static::FUNCTION_FILES as $function_file ) {
			require $base_dir . $function_file;
		}
	}
}