<?php
/**
 * Base class for consent storage handlers.
 *
 * @package SimpleSAMLphp
 * @author Olav Morken <olav.morken@uninett.no>
 * @author JAcob Christiansen <jach@wayf.dk>
 */
abstract class sspmod_consent_Store
{
    /**
     * Constructor for the base class.
     *
     * This constructor should always be called first in any class which implements
     * this class.
     *
     * @param array &$config The configuration for this storage handler.
     */
    protected function __construct(&$config)
    {
        assert('is_array($config)');
    }

    /**
     * Check for consent.
     *
     * This function checks whether a given user has authorized the release of
     * the attributes identified by $attributeSet from $source to $destination.
     *
     * @param string $userId        The hash identifying the user at an IdP.
     * @param string $destinationId A string which identifyes the destination.
     * @param string $attributeSet  A hash which identifies the attributes.
     *
     * @return bool True if the user has given consent earlier, false if not
     *              (or on error).
     */
    abstract public function hasConsent($userId, $destinationId, $attributeSet);

    /**
     * Save consent.
     *
     * Called when the user asks for the consent to be saved. If consent information
     * for the given user and destination already exists, it should be overwritten.
     *
     * @param string $userId        The hash identifying the user at an IdP.
     * @param string $destinationId A string which identifyes the destination.
     * @param string $attributeSet  A hash which identifies the attributes.
     *
     * @return bool True if consent is succesfully saved otherwise false 
     */
    abstract public function saveConsent($userId, $destinationId, $attributeSet);

    /**
     * Delete consent.
     *
     * Called when a user revokes consent for a given destination.
     *
     * @param string $userId        The hash identifying the user at an IdP.
     * @param string $destinationId A string which identifyes the destination.
     *
     * @return mixed Should be the number of consent deleted 
     */
    abstract public function deleteConsent($userId, $destinationId);

    /**
     * Delete all consents.
     *
     * Called when a user revokes all consents
     *
     * @param string $userId The hash identifying the user at an IdP.
     *
     * @return mixed Should be the number of consent removed
     */
    public function deleteAllConsents($userId)
    {
        throw new Exception('Not implemented: deleteAllConsents()');
    }

    /**
     * Get statistics for all consent given in the consent store
     *
     * @return mixed Statistics from the consent store
     */
    public function getStatistics()
    {
        throw new Exception('Not implemented: getStatistics()');
    }

    /**
     * Retrieve consents.
     *
     * This function should return a list of consents the user has saved.
     *
     * @param string $userId The hash identifying the user at an IdP.
     *
     * @return array Array of all destination ids the user has given consent for.
     */
    abstract public function getConsents($userId);

    /**
     * Parse consent storage configuration.
     *
     * This function parses the configuration for a consent storage method.
     * An exception will be thrown if configuration parsing fails.
     *
     * @param mixed $config The configuration.
     *
     * @return sspmod_consent_Store An object which implements the
     *                              sspmod_consent_Store class.
     */
    public static function parseStoreConfig($config)
    {
        if (is_string($config)) {
            $config = array($config);
        }

        if (!is_array($config)) {
            throw new Exception(
                'Invalid configuration for consent store option: ' . 
                var_export($config, true)
            );
        }

        if (!array_key_exists(0, $config)) {
            throw new Exception('Consent store without name given.');
        }

        $className = SimpleSAML_Module::resolveClass(
            $config[0],
            'Consent_Store',
            'sspmod_consent_Store'
        );

        unset($config[0]);
        return new $className($config);
    }
}
