<?php

namespace TwoFAS\TwoFAS\Readme;

use RuntimeException;
use TwoFAS\TwoFAS\Update\Plugin_Version;

class Upgrade_Notice {

	/**
	 * @var Plugin_Version
	 */
	private $plugin_version;

	/**
	 * @var Readme
	 */
	private $readme;

	/**
	 * @param Plugin_Version $plugin_version
	 * @param Readme         $readme
	 */
	public function __construct( Plugin_Version $plugin_version, Readme $readme ) {
		$this->plugin_version = $plugin_version;
		$this->readme         = $readme;
	}

	/**
	 * @return array
	 *
	 * @throws RuntimeException
	 */
	public function get_paragraphs() {
		$section         = $this->get_upgrade_notice_section();
		$current_version = $this->plugin_version->get_source_code_version();
		$result          = array();

		array_walk( $section, function ( $paragraphs, $version ) use ( &$result, $current_version ) {
			if ( version_compare( $current_version, $version, '<' ) ) {
				$result = array_merge( $result, $paragraphs );
			}
		} );

		return $result;
	}

	/**
	 * @return array
	 *
	 * @throws RuntimeException
	 */
	private function get_upgrade_notice_section() {
		$section = $this->readme->get_section( Readme::SECTION_UPGRADE_NOTICE );

		if ( is_null( $section ) ) {
			return array();
		}

		return $this->parse( $section );
	}

	/**
	 * @param string $content
	 *
	 * @return array
	 *
	 * @throws RuntimeException
	 */
	private function parse( $content ) {
		$pattern = '/= (\d+\.\d+\.\d+) =/';

		preg_match_all( $pattern, $content, $matches );

		$versions = preg_filter( $pattern, '${1}', $matches[0] );
		$messages = preg_split( $pattern, $content, null, PREG_SPLIT_NO_EMPTY );
		$messages = $this->split( $messages );

		if ( count( $versions ) === count( $messages ) ) {
			return array_combine( $versions, $messages );
		}

		throw new RuntimeException( 'Upgrade Notice section has invalid format.' );
	}

	/**
	 * @param array $messages
	 *
	 * @return array
	 */
	private function split( array $messages ) {
		return array_map( function ( $message ) {
			$message = htmlspecialchars( $message, ENT_QUOTES );
			return preg_split( '/\r|\n|\r\n/', $message, null, PREG_SPLIT_NO_EMPTY );
		}, $messages );
	}
}