<?php
/**
 * Piwik - Open source web analytics
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 *
 * @category Piwik
 * @package Piwik
 */

/**
 * Simple class to handle the cookies:
 * - read a cookie values
 * - edit an existing cookie and save it
 * - create a new cookie, set values, expiration date, etc. and save it
 *
 * @package Piwik
 */
class Piwik_Cookie
{
    /**
     * Don't create a cookie bigger than 1k
     */
    const MAX_COOKIE_SIZE = 1024;

    /**
     * The name of the cookie
     * @var string
     */
    protected $name = null;

    /**
     * The expire time for the cookie (expressed in UNIX Timestamp)
     * @var int
     */
    protected $expire = null;

    /**
     * Restrict cookie path
     * @var string
     */
    protected $path = '';

    /**
     * Restrict cookie to a domain (or subdomains)
     * @var string
     */
    protected $domain = '';

    /**
     * If true, cookie should only be transmitted over secure HTTPS
     * @var bool
     */
    protected $secure = false;

    /**
     * If true, cookie will only be made available via the HTTP protocol.
     * Note: not well supported by browsers.
     * @var bool
     */
    protected $httponly = false;

    /**
     * The content of the cookie
     * @var array
     */
    protected $value = array();

    /**
     * The character used to separate the tuple name=value in the cookie
     */
    const VALUE_SEPARATOR = ':';

    /**
     * Instantiate a new Cookie object and tries to load the cookie content if the cookie
     * exists already.
     *
     * @param string $cookieName  cookie Name
     * @param int $expire      The timestamp after which the cookie will expire, eg time() + 86400;
     *                                  use 0 (int zero) to expire cookie at end of browser session
     * @param string $path        The path on the server in which the cookie will be available on.
     * @param bool|string $keyStore    Will be used to store several bits of data (eg. one array per website)
     */
    public function __construct($cookieName, $expire = null, $path = null, $keyStore = false)
    {
        $this->name = $cookieName;
        $this->path = $path;
        $this->expire = $expire;
        if (is_null($expire)
            || !is_numeric($expire)
            || $expire < 0
        ) {
            $this->expire = $this->getDefaultExpire();
        }

        $this->keyStore = $keyStore;
        if ($this->isCookieFound()) {
            $this->loadContentFromCookie();
        }
    }

    /**
     * Returns true if the visitor already has the cookie.
     *
     * @return bool
     */
    public function isCookieFound()
    {
        return isset($_COOKIE[$this->name]);
    }

    /**
     * Returns the default expiry time, 2 years
     *
     * @return int  Timestamp in 2 years
     */
    protected function getDefaultExpire()
    {
        return time() + 86400 * 365 * 2;
    }

    /**
     * setcookie() replacement -- we don't use the built-in function because
     * it is buggy for some PHP versions.
     *
     * @link http://php.net/setcookie
     *
     * @param string $Name      Name of cookie
     * @param string $Value     Value of cookie
     * @param int $Expires   Time the cookie expires
     * @param string $Path
     * @param string $Domain
     * @param bool $Secure
     * @param bool $HTTPOnly
     */
    protected function setCookie($Name, $Value, $Expires, $Path = '', $Domain = '', $Secure = false, $HTTPOnly = false)
    {
        if (!empty($Domain)) {
            // Fix the domain to accept domains with and without 'www.'.
            if (!strncasecmp($Domain, 'www.', 4)) {
                $Domain = substr($Domain, 4);
            }
            $Domain = '.' . $Domain;

            // Remove port information.
            $Port = strpos($Domain, ':');
            if ($Port !== false) $Domain = substr($Domain, 0, $Port);
        }

        $header = 'Set-Cookie: ' . rawurlencode($Name) . '=' . rawurlencode($Value)
            . (empty($Expires) ? '' : '; expires=' . gmdate('D, d-M-Y H:i:s', $Expires) . ' GMT')
            . (empty($Path) ? '' : '; path=' . $Path)
            . (empty($Domain) ? '' : '; domain=' . $Domain)
            . (!$Secure ? '' : '; secure')
            . (!$HTTPOnly ? '' : '; HttpOnly');

        Piwik_Common::sendHeader($header, false);
    }

    /**
     * We set the privacy policy header
     */
    protected function setP3PHeader()
    {
        Piwik_Common::sendHeader("P3P: CP='OTI DSP COR NID STP UNI OTPa OUR'");
    }

    /**
     * Delete the cookie
     */
    public function delete()
    {
        $this->setP3PHeader();
        $this->setCookie($this->name, 'deleted', time() - 31536001, $this->path, $this->domain);
    }

    /**
     * Saves the cookie (set the Cookie header).
     * You have to call this method before sending any text to the browser or you would get the
     * "Header already sent" error.
     */
    public function save()
    {
        $cookieString = $this->generateContentString();
        if (strlen($cookieString) > self::MAX_COOKIE_SIZE) {
            // If the cookie was going to be too large, instead, delete existing cookie and start afresh
            $this->delete();
            return;
        }

        $this->setP3PHeader();
        $this->setCookie($this->name, $cookieString, $this->expire, $this->path, $this->domain, $this->secure, $this->httponly);
    }

    /**
     * Extract signed content from string: content VALUE_SEPARATOR '_=' signature
     *
     * @param string $content
     * @return string|bool  Content or false if unsigned
     */
    private function extractSignedContent($content)
    {
        $signature = substr($content, -40);
        if (substr($content, -43, 3) == self::VALUE_SEPARATOR . '_=' &&
            $signature == sha1(substr($content, 0, -40) . Piwik_Common::getSalt())
        ) {
            // strip trailing: VALUE_SEPARATOR '_=' signature"
            return substr($content, 0, -43);
        }
        return false;
    }

    /**
     * Load the cookie content into a php array.
     * Parses the cookie string to extract the different variables.
     * Unserialize the array when necessary.
     * Decode the non numeric values that were base64 encoded.
     */
    protected function loadContentFromCookie()
    {
        $cookieStr = $this->extractSignedContent($_COOKIE[$this->name]);
        if ($cookieStr === false) {
            return;
        }

        $values = explode(self::VALUE_SEPARATOR, $cookieStr);
        foreach ($values as $nameValue) {
            $equalPos = strpos($nameValue, '=');
            $varName = substr($nameValue, 0, $equalPos);
            $varValue = substr($nameValue, $equalPos + 1);

            // no numeric value are base64 encoded so we need to decode them
            if (!is_numeric($varValue)) {
                $tmpValue = base64_decode($varValue);
                $varValue = safe_unserialize($tmpValue);

                // discard entire cookie
                // note: this assumes we never serialize a boolean
                if ($varValue === false && $tmpValue !== 'b:0;') {
                    $this->value = array();
                    unset($_COOKIE[$this->name]);
                    break;
                }
            }

            $this->value[$varName] = $varValue;
        }
    }

    /**
     * Returns the string to save in the cookie from the $this->value array of values.
     * It goes through the array and generates the cookie content string.
     *
     * @return string  Cookie content
     */
    protected function generateContentString()
    {
        $cookieStr = '';
        foreach ($this->value as $name => $value) {
            if (!is_numeric($value)) {
                $value = base64_encode(safe_serialize($value));
            }

            $cookieStr .= "$name=$value" . self::VALUE_SEPARATOR;
        }

        if (!empty($cookieStr)) {
            $cookieStr .= '_=';

            // sign cookie
            $signature = sha1($cookieStr . Piwik_Common::getSalt());
            return $cookieStr . $signature;
        }

        return '';
    }

    /**
     * Set cookie domain
     *
     * @param string $domain
     */
    public function setDomain($domain)
    {
        $this->domain = $domain;
    }

    /**
     * Set secure flag
     *
     * @param bool $secure
     */
    public function setSecure($secure)
    {
        $this->secure = $secure;
    }

    /**
     * Set HTTP only
     *
     * @param bool $httponly
     */
    public function setHttpOnly($httponly)
    {
        $this->httponly = $httponly;
    }

    /**
     * Registers a new name => value association in the cookie.
     *
     * Registering new values is optimal if the value is a numeric value.
     * If the value is a string, it will be saved as a base64 encoded string.
     * If the value is an array, it will be saved as a serialized and base64 encoded
     * string which is not very good in terms of bytes usage.
     * You should save arrays only when you are sure about their maximum data size.
     * A cookie has to stay small and its size shouldn't increase over time!
     *
     * @param string $name   Name of the value to save; the name will be used to retrieve this value
     * @param string|array|number $value  Value to save. If null, entry will be deleted from cookie.
     */
    public function set($name, $value)
    {
        $name = self::escapeValue($name);

        // Delete value if $value === null
        if (is_null($value)) {
            if ($this->keyStore === false) {
                unset($this->value[$name]);
                return;
            }
            unset($this->value[$this->keyStore][$name]);
            return;
        }

        if ($this->keyStore === false) {
            $this->value[$name] = $value;
            return;
        }
        $this->value[$this->keyStore][$name] = $value;
    }

    /**
     * Returns the value defined by $name from the cookie.
     *
     * @param string|integer Index name of the value to return
     * @return mixed  The value if found, false if the value is not found
     */
    public function get($name)
    {
        $name = self::escapeValue($name);
        if ($this->keyStore === false) {
            return isset($this->value[$name])
                ? self::escapeValue($this->value[$name])
                : false;
        }
        return isset($this->value[$this->keyStore][$name])
            ? self::escapeValue($this->value[$this->keyStore][$name])
            : false;
    }

    /**
     * Returns an easy to read cookie dump
     *
     * @return string  The cookie dump
     */
    public function __toString()
    {
        $str = 'COOKIE ' . $this->name . ', rows count: ' . count($this->value) . ', cookie size = ' . strlen($this->generateContentString()) . " bytes\n";
        $str .= var_export($this->value, $return = true);
        return $str;
    }

    /**
     * Escape values from the cookie before sending them back to the client
     * (when using the get() method).
     *
     * @param string $value  Value to be escaped
     * @return mixed  The value once cleaned.
     */
    protected static function escapeValue($value)
    {
        return Piwik_Common::sanitizeInputValues($value);
    }
}
