<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 */

namespace Zend\Captcha;

use Zend\Math\Rand;
use Zend\Session\Container;

/**
 * AbstractWord-based captcha adapter
 *
 * Generates random word which user should recognise
 */
abstract class AbstractWord extends AbstractAdapter
{
    /**#@+
     * @var array Character sets
     */
    public static $V  = array("a", "e", "i", "o", "u", "y");
    public static $VN = array("a", "e", "i", "o", "u", "y","2","3","4","5","6","7","8","9");
    public static $C  = array("b","c","d","f","g","h","j","k","m","n","p","q","r","s","t","u","v","w","x","z");
    public static $CN = array("b","c","d","f","g","h","j","k","m","n","p","q","r","s","t","u","v","w","x","z","2","3","4","5","6","7","8","9");
    /**#@-*/

    /**
     * Random session ID
     *
     * @var string
     */
    protected $id;

    /**
     * Generated word
     *
     * @var string
     */
    protected $word;

    /**
     * Session
     *
     * @var Container
     */
    protected $session;

    /**
     * Class name for sessions
     *
     * @var string
     */
    protected $sessionClass = 'Zend\Session\Container';

    /**
     * Should the numbers be used or only letters
     *
     * @var bool
     */
    protected $useNumbers = true;

    /**
     * Should both cases be used or only lowercase
     *
     * @var bool
     */
    // protected $useCase = false;

    /**
     * Session lifetime for the captcha data
     *
     * @var int
     */
    protected $timeout = 300;

    /**
     * Should generate() keep session or create a new one?
     *
     * @var bool
     */
    protected $keepSession = false;

    /**#@+
     * Error codes
     */
    const MISSING_VALUE = 'missingValue';
    const MISSING_ID    = 'missingID';
    const BAD_CAPTCHA   = 'badCaptcha';
    /**#@-*/

    /**
     * Error messages
     * @var array
     */
    protected $messageTemplates = array(
        self::MISSING_VALUE => 'Empty captcha value',
        self::MISSING_ID    => 'Captcha ID field is missing',
        self::BAD_CAPTCHA   => 'Captcha value is wrong',
    );

    /**
     * Length of the word to generate
     *
     * @var int
     */
    protected $wordlen = 8;

    /**
     * Retrieve session class to utilize
     *
     * @return string
     */
    public function getSessionClass()
    {
        return $this->sessionClass;
    }

    /**
     * Set session class for persistence
     *
     * @param  string $sessionClass
     * @return AbstractWord
     */
    public function setSessionClass($sessionClass)
    {
        $this->sessionClass = $sessionClass;
        return $this;
    }

    /**
     * Retrieve word length to use when generating captcha
     *
     * @return int
     */
    public function getWordlen()
    {
        return $this->wordlen;
    }

    /**
     * Set word length of captcha
     *
     * @param int $wordlen
     * @return AbstractWord
     */
    public function setWordlen($wordlen)
    {
        $this->wordlen = $wordlen;
        return $this;
    }

    /**
     * Retrieve captcha ID
     *
     * @return string
     */
    public function getId()
    {
        if (null === $this->id) {
            $this->setId($this->generateRandomId());
        }
        return $this->id;
    }

    /**
     * Set captcha identifier
     *
     * @param string $id
     * @return AbstractWord
     */
    protected function setId($id)
    {
        $this->id = $id;
        return $this;
    }

    /**
     * Set timeout for session token
     *
     * @param  int $ttl
     * @return AbstractWord
     */
    public function setTimeout($ttl)
    {
        $this->timeout = (int) $ttl;
        return $this;
    }

    /**
     * Get session token timeout
     *
     * @return int
     */
    public function getTimeout()
    {
        return $this->timeout;
    }

    /**
     * Sets if session should be preserved on generate()
     *
     * @param bool $keepSession Should session be kept on generate()?
     * @return AbstractWord
     */
    public function setKeepSession($keepSession)
    {
        $this->keepSession = $keepSession;
        return $this;
    }

    /**
     * Numbers should be included in the pattern?
     *
     * @return bool
     */
    public function getUseNumbers()
    {
        return $this->useNumbers;
    }

    /**
     * Set if numbers should be included in the pattern
     *
     * @param  bool $useNumbers numbers should be included in the pattern?
     * @return AbstractWord
     */
    public function setUseNumbers($useNumbers)
    {
        $this->useNumbers = $useNumbers;
        return $this;
    }

    /**
     * Get session object
     *
     * @throws Exception\InvalidArgumentException
     * @return Container
     */
    public function getSession()
    {
        if (!isset($this->session) || (null === $this->session)) {
            $id = $this->getId();
            if (!class_exists($this->sessionClass)) {
                throw new Exception\InvalidArgumentException("Session class $this->sessionClass not found");
            }
            $this->session = new $this->sessionClass('Zend_Form_Captcha_' . $id);
            $this->session->setExpirationHops(1, null);
            $this->session->setExpirationSeconds($this->getTimeout());
        }
        return $this->session;
    }

    /**
     * Set session namespace object
     *
     * @param  Container $session
     * @return AbstractWord
     */
    public function setSession(Container $session)
    {
        $this->session = $session;
        if ($session) {
            $this->keepSession = true;
        }
        return $this;
    }

    /**
     * Get captcha word
     *
     * @return string
     */
    public function getWord()
    {
        if (empty($this->word)) {
            $session     = $this->getSession();
            $this->word  = $session->word;
        }
        return $this->word;
    }

    /**
     * Set captcha word
     *
     * @param  string $word
     * @return AbstractWord
     */
    protected function setWord($word)
    {
        $session       = $this->getSession();
        $session->word = $word;
        $this->word    = $word;
        return $this;
    }

    /**
     * Generate new random word
     *
     * @return string
     */
    protected function generateWord()
    {
        $word       = '';
        $wordLen    = $this->getWordLen();
        $vowels     = $this->useNumbers ? static::$VN : static::$V;
        $consonants = $this->useNumbers ? static::$CN : static::$C;

        for ($i=0; $i < $wordLen; $i = $i + 2) {
            // generate word with mix of vowels and consonants
            $consonant = $consonants[array_rand($consonants)];
            $vowel     = $vowels[array_rand($vowels)];
            $word     .= $consonant . $vowel;
        }

        if (strlen($word) > $wordLen) {
            $word = substr($word, 0, $wordLen);
        }

        return $word;
    }

    /**
     * Generate new session ID and new word
     *
     * @return string session ID
     */
    public function generate()
    {
        if (!$this->keepSession) {
            $this->session = null;
        }
        $id = $this->generateRandomId();
        $this->setId($id);
        $word = $this->generateWord();
        $this->setWord($word);
        return $id;
    }

    /**
     * Generate a random identifier
     *
     * @return string
     */
    protected function generateRandomId()
    {
        return md5(Rand::getBytes(32));
    }

    /**
     * Validate the word
     *
     * @see    Zend\Validator\ValidatorInterface::isValid()
     * @param  mixed $value
     * @param  mixed $context
     * @return bool
     */
    public function isValid($value, $context = null)
    {
        if (!is_array($value)) {
            if (!is_array($context)) {
                $this->error(self::MISSING_VALUE);
                return false;
            }
            $value = $context;
        }

        $name = $this->getName();

        if (isset($value[$name])) {
            $value = $value[$name];
        }

        if (!isset($value['input'])) {
            $this->error(self::MISSING_VALUE);
            return false;
        }
        $input = strtolower($value['input']);
        $this->setValue($input);

        if (!isset($value['id'])) {
            $this->error(self::MISSING_ID);
            return false;
        }

        $this->id = $value['id'];
        if ($input !== $this->getWord()) {
            $this->error(self::BAD_CAPTCHA);
            return false;
        }

        return true;
    }

    /**
     * Get helper name used to render captcha
     *
     * @return string
     */
    public function getHelperName()
    {
        return 'captcha/word';
    }
}
