<?php

namespace SMW\Tests\Utils\File;

use SMW\Exception\JSONFileParseException;

/**
 * @license GPL-2.0-or-later
 * @since 2.1
 *
 * @author mwjames
 */
class JsonFileReader {

	/**
	 * @var string|null
	 */
	private $file = null;

	/**
	 * @var array|null
	 */
	private $contents = null;

	/**
	 * @since 2.1
	 *
	 * @param string|null $file
	 */
	public function __construct( ?string $file = null ) {
		$this->setFile( $file ?? '' );
	}

	/**
	 * @since 2.1
	 *
	 * @param string $file
	 */
	public function setFile( string $file ) {
		$this->file = str_replace( [ '\\', '/' ], DIRECTORY_SEPARATOR, $file );
		$this->contents = null;
	}

	/**
	 * @since 2.1
	 *
	 * @return array
	 * @throws RuntimeException
	 */
	public function read() {
		if ( $this->contents === null && $this->isReadable() ) {
			$this->contents = $this->parse( $this->file );
		}

		if ( $this->contents !== null ) {
			return $this->contents;
		}

		throw new RuntimeException( "Expected a readable {$this->file} file" );
	}

	/**
	 * @since 2.1
	 *
	 * @return bool
	 */
	public function isReadable() {
		return is_file( $this->file ) && is_readable( $this->file );
	}

	/**
	 * @since 2.1
	 *
	 * @return int
	 * @throws RuntimeException
	 */
	public function getModificationTime() {
		if ( $this->isReadable() ) {
			return filemtime( $this->file );
		}

		throw new RuntimeException( "Expected a readable {$this->file} file" );
	}

	private function parse( $file ) {
		$json = file_get_contents( $file );

		$json = preg_replace(
			'~ ("(?:[^\\\"]+|\\\.)*") |' . // preserve strings
			'/\* (?:[^*]+|\*+(?!/))* \*/ |' . // strip multi-line comments
			'//\V* ~sx', // strip //-comments
			'$1', $json );

		$contents = json_decode( $json, true );

		if ( $contents !== null && json_last_error() === JSON_ERROR_NONE ) {
			return $contents;
		}

		throw new JSONFileParseException( $file );
	}

}