<?php
/**
 * Singleton Static Proxy
 *
 * @author    Andy Fragen
 * @license   MIT
 * @link      https://github.com/afragen/singleton
 * @package   singleton
 */

namespace Fragen;

/*
 * Exit if called directly.
 */
if ( ! defined( 'WPINC' ) ) {
	return;
}

if ( ! class_exists( 'Fragen\\Singleton' ) ) {
	/**
	 * Class Singleton
	 *
	 * A static proxy for creating Singletons from passed class names.
	 */
	final class Singleton {
		/**
		 * Get instance of class.
		 *
		 * @param string            $class_name Class name.
		 * @param object            $caller     Originating object.
		 * @param null|array|object $options    Options for class constructor. Optional.
		 *
		 * @return object $instance[ $class ]
		 */
		public static function get_instance( $class_name, $caller, $options = null ) {
			static $instance = null;

			$class = get_class( $caller );
			$class = self::get_class( $class_name, $class );

			if ( null === $instance || ! isset( $instance[ $class ] ) ) {
				$instance[ $class ] = new $class( $options );
			}

			return $instance[ $class ];
		}

		/**
		 * Determine correct class name with namespace and return.
		 *
		 * @param string $class_name Class name.
		 * @param string $class      Calling class name.
		 *
		 * @throws \Exception Undefinded class name.
		 *
		 * @return string Namespaced class name.
		 */
		private static function get_class( $class_name, $class ) {
			$reflection      = self::get_reflection( $class );
			$namespace       = $reflection->getNamespaceName();
			$namespace_parts = explode( '\\', $namespace );
			$count           = count( $namespace_parts );
			$classes[-1]     = null;

			for ( $i = 0; $i < $count; $i++ ) {
				$classes[ $i ] = ltrim( $classes[ $i - 1 ] . '\\' . $namespace_parts[ $i ], '\\' );
			}

			$classes = array_reverse( $classes );
			foreach ( $classes as $namespace ) {
				$namespaced_class = $namespace . '\\' . $class_name;
				if ( class_exists( $namespaced_class ) ) {
					return ltrim( $namespaced_class, '\\' );
				}
			}

			try {
				throw new \Exception( "Undefined class '{$class_name}'" );
			} catch ( \Exception $e ) {
				$message = "PHP Fatal error: {$e->getMessage()}\nPHP Stack trace:\n";
				$trace   = $e->getTraceAsString();
				error_log( $message . $trace );
				// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
				die( "<pre><strong>{$message}</strong>{$trace}</pre>" );
			}
		}

		/**
		 * Get ReflectionClass of passed class name.
		 *
		 * @param string $class Class name.
		 *
		 * @return \ReflectionClass $reflection
		 */
		private static function get_reflection( $class ) {
			try {
				$reflection = new \ReflectionClass( $class );
			} catch ( \ReflectionException $Exception ) {
				// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
				die( '<table>' . $Exception->xdebug_message . '</table>' );
			}

			return $reflection;
		}
	}
}