<?php
namespace TestProject;

/*
 * Quiz class
 */
class Quiz extends Item {
	private const tb_str      = 'quiz';
	private const resultTb_str = 'quiz_result';

	private $name_str;
	private $maxScore_int;
	private $questionID_arr;

	/**
	 * Load quiz
	 *
	 * @param int $id_int ID of quiz to load
	 */
	public function __construct( int $id_int ){
		$db = DB::getDB();

		$rows_arr = $db->select( self::tb_str, array(), array( 'id' => $id_int ) );
		if ( empty( $rows_arr ) ){
			throw new \RuntimeException( 'Invalid quiz ID' );
		}

		$this->id_int       = $rows_arr[0]['id'];
		$this->name_str     = $rows_arr[0]['name'];
		$this->maxScore_int = $rows_arr[0]['max_score'];

		$this->questionID_arr = Question::getList( $this->id_int );
	}

	/**
	 * Get a list of quiz IDs and names
	 *
	 * @return string[] Array of quiz names keyed by id
	 */
	public static function getList(){
		$db = DB::getDB();

		$quiz_arr = $db->select( self::tb_str, array( 'id', 'name' ) );

		return $quiz_arr;
	}

	/**
	 * Get name of Quiz
	 *
	 * @return string Name
	 */
	public function getName(){
		return $this->name_str;
	}

	/**
	 * Get Maximum possible Score of quiz
	 *
	 * @return int Max score
	 */
	public function getMaxScore(){
		return $this->maxScore_int;
	}

	/**
	 * Calculate and save the total score of a user
	 *
	 * @param int $userID_int $userID_int ID of user
	 *
	 * @return string Access key for results page
	 */
	public function saveResult( int $userID_int ){
		$db = DB::getDB();

		$total_int = 0;
		foreach( $this->questionID_arr as $questionID_int ){
			$question = new Question( $questionID_int );
			$total_int += $question->getScore( $userID_int );
		}

		$accessKey_str = hash( 'sha256', $this->id_int . $userID_int . microtime() );

		$db->insert(
			self::resultTb_str,
			array(
				'quiz'       => $this->id_int,
				'user'       => $userID_int,
				'score'      => $total_int,
				'access_key' => $accessKey_str
			)
		);

		return $accessKey_str;
	}

	/**
	 * Get result for user and calculate average score
	 *
	 * @param string $acessKey_str Access key for result
	 *
	 * @return mixed[] Array of result data
	 */
	public static function getResult( string $accessKey_str ){
		$db = DB::getDB();

		$rows_arr = $db->select( self::resultTb_str, array(), array( 'access_key' => $accessKey_str ) );

		if ( empty( $rows_arr ) ){
			throw new \RuntimeException( 'Invalid access key' );
		}

		$result_arr = $rows_arr[0];

		$rows_arr = $db->select( self::resultTb_str, array( 'score' ), array( 'quiz' => $result_arr['quiz'] ) );

		$total_int = 0;
		foreach ( $rows_arr as $row_arr ){
			$total_int += $row_arr['score'];
		}
		$result_arr['average'] = $total_int / count( $rows_arr );

		return $result_arr;
	}

}