<?php
// write class Event that implements interface ParticipableInterface
// Event represents real life event like - concert, meetup, or some other gathering of people
// for storing participants - use array,
// consider edge cases scenarios
// It is allowed to use google for searching documentation.

interface ParticipableInterface
{
    public function getStartDate(); // Trivial - Do not implement

    public function getParticipants(); // Trivial - Do not implement

    public function setStartDate(DateTime $date);

    public function getDuration(); // Trivial -- Do not implement

    /**
     * $duration -- integer, amount of minutes
     */
    public function setDuration($duration);

    // should return instance of DateTime or rise exception if duration has not been set yet
    public function getEndDate();

    // when user joins event
    public function join(ParticipantInterface $participant);

    // when user leaves
    public function part(ParticipantInterface $participant);
}

// FOR YOUR INFORMATION -- Do not implement this interface
interface ParticipantInterface
{
    public function getId();

    public function getName();

    public function getEmail();
}

class User implements ParticipantInterface
{
    public $id;
    public $name;
    public $email;

    public function getId()
    {
        return $this->id;
    }

    public function getName()
    {
        return $this->name;
    }

    public function getEmail()
    {
        return $this->email;
    }

    /**
     * Constructor.
     */
    public function __construct($id, $name, $email)
    {
        $this->id = $id;
        $this->email = $email;
        $this->name = $name;
    }
}

class Event implements ParticipableInterface
{
    /** @var  $nameEvent string */
    public $nameEvent;

    /**
     * @var array
     */
    public $participants = [];

    /** @var $startDate DateTime */
    public $startDate;

    /** @var  integer */
    public $duration;

    /** @var $endDate DateTime */
    public $endDate;

    public function getStartDate() {
        return $this->startDate;
    }

    public function getParticipants() {
        return $this->participants;
    }

    public function setStartDate(DateTime $date) {
        $this->startDate = $date;
        return $this;
    }

    public function getDuration() {
        return $this->duration;
    }

    /**
     * $duration integer
     */
    public function setDuration($duration) {
        $this->duration = $duration;
        return $this;
    }

    // should return instance of DateTime or rise exception if duration has not been set yet
    public function getEndDate() {
        if ($this->startDate->modify('+'.$this->duration.' minutes') >= new DateTime('now')) {
            return new Exception('has not been set yet');
        }
        return $this->startDate->modify('+'.$this->duration.' minutes')->format('Y-m-d H:i:s');
    }

    // when user joins event
    public function join(ParticipantInterface $participant) {
        $this->addParticipant($participant);
    }

    /**
     * @param array $participant
     * @return $this
     */
    public function setParticipant(array $participant)
    {
        $this->participants = $participant;
        return $this;
    }

    public function addParticipant(ParticipantInterface $participant)
    {
        $participant = strtoupper($participant->getEmail());
        if (!in_array($participant, $this->participants, true)) {
            $this->participants[] = $participant;
        }

        return $this;
    }

    public function unsetParticipant(ParticipantInterface $participant)
    {
        $usersArrayEmail = $this->getParticipants();
        $key = array_search((strtoupper($participant->getEmail())), $usersArrayEmail);
        if ($key !== false) {
            unset($usersArrayEmail[$key]);
            $this->setParticipant($usersArrayEmail);
        }

        return $this;
    }

    // when user leaves
    public function part(ParticipantInterface $participant) {
        $this->unsetParticipant($participant);
    }

    /**
     * Constructor.
     */
    public function __construct($nameEvent)
    {
        $this->nameEvent = $nameEvent;
    }
}

    $event = new Event('concert');
    $event
        ->setStartDate(new DateTime('now'))
        ->setDuration(10)
        ;

    $user = new User(1, 'Ivan', '[email protected]');

    $event->join($user);
    var_dump($event);
    $event->part($user);
    var_dump($event);


// YOUR CODE HERE


// Palindrome is word that can be read backwards and it is the same word as read forwards example: kayak, dad
// write function that will check if given word is palindrome
// Simplest solution is most desired

/**
 * @param string $word
 * @return bool
 */
function is_palindrome($word) {
    return strrev((string) $word) === $word ? true : false;
}