<?php

/**
 * Backend class for a custom address book
 *
 * This part of the Roundcube+Kolab integration and connects the
 * rcube_addressbook interface with the kolab_storage wrapper from libkolab
 *
 * @author Thomas Bruederli <bruederli@kolabsys.com>
 * @author Aleksander Machniak <machniak@kolabsys.com>
 *
 * Copyright (C) 2011, Kolab Systems AG <contact@kolabsys.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 * @see rcube_addressbook
 */
class rcube_kolab_contacts extends rcube_addressbook
{
    public $primary_key = 'ID';
    public $readonly = true;
    public $editable = false;
    public $undelete = true;
    public $groups = true;
    public $coltypes = array(
      'name'         => array('limit' => 1),
      'firstname'    => array('limit' => 1),
      'surname'      => array('limit' => 1),
      'middlename'   => array('limit' => 1),
      'prefix'       => array('limit' => 1),
      'suffix'       => array('limit' => 1),
      'nickname'     => array('limit' => 1),
      'jobtitle'     => array('limit' => 1),
      'organization' => array('limit' => 1),
      'department'   => array('limit' => 1),
      'email'        => array('subtypes' => null),
      'phone'        => array(),
      'address'      => array('subtypes' => array('home','work','office')),
      'website'      => array('subtypes' => array('homepage','blog')),
      'im'           => array('subtypes' => null),
      'gender'       => array('limit' => 1),
      'birthday'     => array('limit' => 1),
      'anniversary'  => array('limit' => 1),
      'profession'   => array('type' => 'text', 'size' => 40, 'maxlength' => 80, 'limit' => 1,
                                'label' => 'kolab_addressbook.profession', 'category' => 'personal'),
      'manager'      => array('limit' => null),
      'assistant'    => array('limit' => null),
      'spouse'       => array('limit' => 1),
      'children'     => array('type' => 'text', 'size' => 40, 'maxlength' => 80, 'limit' => null,
                                'label' => 'kolab_addressbook.children', 'category' => 'personal'),
      'freebusyurl'  => array('type' => 'text', 'size' => 40, 'limit' => 1,
                                'label' => 'kolab_addressbook.freebusyurl'),
      'pgppublickey' => array('type' => 'textarea', 'size' => 70, 'rows' => 10, 'limit' => 1,
                                'label' => 'kolab_addressbook.pgppublickey'),
      'pkcs7publickey' => array('type' => 'textarea', 'size' => 70, 'rows' => 10, 'limit' => 1,
                                'label' => 'kolab_addressbook.pkcs7publickey'),
      'notes'        => array(),
      'photo'        => array(),
      // TODO: define more Kolab-specific fields such as: language, latitude, longitude, crypto settings
    );

    /**
     * vCard additional fields mapping
     */
    public $vcard_map = array(
      'profession'     => 'X-PROFESSION',
      'officelocation' => 'X-OFFICE-LOCATION',
      'initials'       => 'X-INITIALS',
      'children'       => 'X-CHILDREN',
      'freebusyurl'    => 'X-FREEBUSY-URL',
      'pgppublickey'   => 'KEY',
    );

    private $gid;
    private $storagefolder;
    private $contacts;
    private $distlists;
    private $groupmembers;
    private $filter;
    private $result;
    private $namespace;
    private $imap_folder = 'INBOX/Contacts';
    private $action;


    public function __construct($imap_folder = null)
    {
        if ($imap_folder) {
            $this->imap_folder = $imap_folder;
        }

        // extend coltypes configuration 
        $format = kolab_format::factory('contact');
        $this->coltypes['phone']['subtypes'] = array_keys($format->phonetypes);
        $this->coltypes['address']['subtypes'] = array_keys($format->addresstypes);

        // set localized labels for proprietary cols
        foreach ($this->coltypes as $col => $prop) {
            if (is_string($prop['label']))
                $this->coltypes[$col]['label'] = rcube_label($prop['label']);
        }

        // fetch objects from the given IMAP folder
        $this->storagefolder = kolab_storage::get_folder($this->imap_folder);
        $this->ready = $this->storagefolder && !PEAR::isError($this->storagefolder);

        // Set readonly and editable flags according to folder permissions
        if ($this->ready) {
            if ($this->storagefolder->get_owner() == $_SESSION['username']) {
                $this->editable = true;
                $this->readonly = false;
            }
            else {
                $rights = $this->storagefolder->get_myrights();
                if (!PEAR::isError($rights)) {
                    if (strpos($rights, 'i') !== false)
                        $this->readonly = false;
                    if (strpos($rights, 'a') !== false || strpos($rights, 'x') !== false)
                        $this->editable = true;
                }
            }
        }

        $this->action = rcube::get_instance()->action;
    }


    /**
     * Getter for the address book name to be displayed
     *
     * @return string Name of this address book
     */
    public function get_name()
    {
        $folder = kolab_storage::object_name($this->imap_folder, $this->namespace);
        return $folder;
    }


    /**
     * Getter for the IMAP folder name
     *
     * @return string Name of the IMAP folder
     */
    public function get_realname()
    {
        return $this->imap_folder;
    }


    /**
     * Getter for the name of the namespace to which the IMAP folder belongs
     *
     * @return string Name of the namespace (personal, other, shared)
     */
    public function get_namespace()
    {
        if ($this->namespace === null && $this->ready) {
            $this->namespace = $this->storagefolder->get_namespace();
        }

        return $this->namespace;
    }


    /**
     * Setter for the current group
     */
    public function set_group($gid)
    {
        $this->gid = $gid;
    }


    /**
     * Save a search string for future listings
     *
     * @param mixed Search params to use in listing method, obtained by get_search_set()
     */
    public function set_search_set($filter)
    {
        $this->filter = $filter;
    }


    /**
     * Getter for saved search properties
     *
     * @return mixed Search properties used by this class
     */
    public function get_search_set()
    {
        return $this->filter;
    }


    /**
     * Reset saved results and search parameters
     */
    public function reset()
    {
        $this->result = null;
        $this->filter = null;
    }


    /**
     * List all active contact groups of this source
     *
     * @param string  Optional search string to match group name
     * @return array  Indexed list of contact groups, each a hash array
     */
    function list_groups($search = null)
    {
        $this->_fetch_groups();
        $groups = array();
        foreach ((array)$this->distlists as $group) {
            if (!$search || strstr(strtolower($group['name']), strtolower($search)))
                $groups[$group['name']] = array('ID' => $group['ID'], 'name' => $group['name']);
        }

        // sort groups
        ksort($groups, SORT_LOCALE_STRING);

        return array_values($groups);
    }


    /**
     * List the current set of contact records
     *
     * @param  array  List of cols to show
     * @param  int    Only return this number of records, use negative values for tail
     * @return array  Indexed list of contact records, each a hash array
     */
    public function list_records($cols=null, $subset=0)
    {
        $this->result = new rcube_result_set(0, ($this->list_page-1) * $this->page_size);;

        // list member of the selected group
        if ($this->gid) {
            $this->_fetch_groups();
            $seen = array();
            foreach ((array)$this->distlists[$this->gid]['member'] as $member) {
                // skip member that don't match the search filter
                if (is_array($this->filter['ids']) && array_search($member['ID'], $this->filter['ids']) === false)
                    continue;

                if ($member['uid'] && ($contact = $this->storagefolder->get_object($member['uid'])) && !$seen[$member['ID']]++) {
                    $this->contacts[$member['ID']] = $this->_to_rcube_contact($contact);
                    $this->result->count++;
                }
                else if ($member['email'] && !$seen[$member['ID']]++) {
                    $this->contacts[$member['ID']] = $member;
                    $this->result->count++;
                }
            }
            $ids = array_keys($seen);
        }
        else if (is_array($this->filter['ids'])) {
            $ids = $this->filter['ids'];
            if ($this->result->count = count($ids))
                $this->_fetch_contacts(array(array('uid', '=', $ids)));
        }
        else {
            $this->_fetch_contacts();
            $ids = array_keys($this->contacts);
            $this->result->count = count($ids);
        }

        // sort data arrays according to desired list sorting
        if ($count = count($ids)) {
            uasort($this->contacts, array($this, '_sort_contacts_comp'));
            // get sorted IDs
            if ($count != count($this->contacts))
                $ids = array_values(array_intersect(array_keys($this->contacts), $ids));
            else
                $ids = array_keys($this->contacts);
        }

        // fill contact data into the current result set
        $start_row = $subset < 0 ? $this->result->first + $this->page_size + $subset : $this->result->first;
        $last_row = min($subset != 0 ? $start_row + abs($subset) : $this->result->first + $this->page_size, $count);

        for ($i = $start_row; $i < $last_row; $i++) {
            if ($id = $ids[$i])
                $this->result->add($this->contacts[$id]);
        }

        return $this->result;
    }


    /**
     * Search records
     *
     * @param mixed   $fields   The field name of array of field names to search in
     * @param mixed   $value    Search value (or array of values when $fields is array)
     * @param int     $mode     Matching mode:
     *                          0 - partial (*abc*),
     *                          1 - strict (=),
     *                          2 - prefix (abc*)
     * @param boolean $select   True if results are requested, False if count only
     * @param boolean $nocount  True to skip the count query (select only)
     * @param array   $required List of fields that cannot be empty
     *
     * @return object rcube_result_set List of contact records and 'count' value
     */
    public function search($fields, $value, $mode=0, $select=true, $nocount=false, $required=array())
    {
        // search by ID
        if ($fields == $this->primary_key) {
            $ids    = !is_array($value) ? explode(',', $value) : $value;
            $result = new rcube_result_set();

            foreach ($ids as $id) {
                if ($rec = $this->get_record($id, true)) {
                    $result->add($rec);
                    $result->count++;
                }
            }
            return $result;
        }
        else if ($fields == '*') {
          $fields = array_keys($this->coltypes);
        }

        if (!is_array($fields))
            $fields = array($fields);
        if (!is_array($required) && !empty($required))
            $required = array($required);

        // advanced search
        if (is_array($value)) {
            $advanced = true;
            $value = array_map('mb_strtolower', $value);
        }
        else
            $value = mb_strtolower($value);

        $scount = count($fields);
        // build key name regexp
        $regexp = '/^(' . implode($fields, '|') . ')(?:.*)$/';

        // pass query to storage if only indexed cols are involved
        // NOTE: this is only some rough pre-filtering but probably includes false positives
        $squery = array();
        if (count(array_intersect(kolab_format_contact::$fulltext_cols, $fields)) == $scount) {
            switch ($mode) {
                case 1:  $prefix = '^'; $suffix = '$'; break;  // strict
                case 2:  $prefix = '^'; $suffix = '';  break;  // prefix
                default: $prefix = '';  $suffix = '';  break;  // substring
            }

            $search_string = is_array($value) ? join(' ', $value) : $value;
            foreach (rcube_utils::normalize_string($search_string, true) as $word) {
                $squery[] = array('words', 'LIKE', $prefix . $word . $suffix);
            }
        }

        // get all/matching records
        $this->_fetch_contacts($squery);

        // save searching conditions
        $this->filter = array('fields' => $fields, 'value' => $value, 'mode' => $mode, 'ids' => array());

        // search be iterating over all records in memory
        foreach ($this->contacts as $id => $contact) {
            // check if current contact has required values, otherwise skip it
            if ($required) {
                foreach ($required as $f)
                    if (empty($contact[$f]))
                        continue 2;
            }

            $found = array();
            foreach (preg_grep($regexp, array_keys($contact)) as $col) {
                if ($advanced) {
                    $pos     = strpos($col, ':');
                    $colname = $pos ? substr($col, 0, $pos) : $col;
                    $search  = $value[array_search($colname, $fields)];
                }
                else {
                    $search = $value;
                }

                foreach ((array)$contact[$col] as $val) {
                    foreach ((array)$val as $str) {
                        $str = mb_strtolower($str);
                        switch ($mode) {
                        case 1:
                            $got = ($str == $search);
                            break;
                        case 2:
                            $got = ($search == substr($str, 0, strlen($search)));
                            break;
                        default:
                            $got = (strpos($str, $search) !== false);
                            break;
                        }
                    }

                    if ($got) {
                        if (!$advanced) {
                            $this->filter['ids'][] = $id;
                            break 2;
                        }
                        else {
                            $found[$colname] = true;
                        }
                    }
                }
            }

            if (count($found) >= $scount) // && $advanced
                $this->filter['ids'][] = $id;
        }

        // list records (now limited by $this->filter)
        return $this->list_records();
    }


    /**
     * Refresh saved search results after data has changed
     */
    public function refresh_search()
    {
        if ($this->filter)
            $this->search($this->filter['fields'], $this->filter['value'], $this->filter['mode']);

        return $this->get_search_set();
    }


    /**
     * Count number of available contacts in database
     *
     * @return rcube_result_set Result set with values for 'count' and 'first'
     */
    public function count()
    {
        if ($this->gid) {
            $this->_fetch_groups();
            $count = count($this->distlists[$this->gid]['member']);
        }
        else if (is_array($this->filter['ids'])) {
            $count = count($this->filter['ids']);
        }
        else {
            $count = $this->storagefolder->count();
        }

        return new rcube_result_set($count, ($this->list_page-1) * $this->page_size);
    }


    /**
     * Return the last result set
     *
     * @return rcube_result_set Current result set or NULL if nothing selected yet
     */
    public function get_result()
    {
        return $this->result;
    }


    /**
     * Get a specific contact record
     *
     * @param mixed record identifier(s)
     * @param boolean True to return record as associative array, otherwise a result set is returned
     * @return mixed Result object with all record fields or False if not found
     */
    public function get_record($id, $assoc=false)
    {
        $rec = null;
        $uid = $this->_id2uid($id);
        if (strpos($uid, 'mailto:') === 0) {
            $this->_fetch_groups(true);
            $rec = $this->contacts[$id];
            $this->readonly = true;  // set source to read-only
        }
        else if ($object = $this->storagefolder->get_object($uid)) {
            $rec = $this->_to_rcube_contact($object);
        }

        if ($rec) {
            $this->result = new rcube_result_set(1);
            $this->result->add($rec);
            return $assoc ? $rec : $this->result;
        }

        return false;
    }


    /**
     * Get group assignments of a specific contact record
     *
     * @param mixed Record identifier
     * @return array List of assigned groups as ID=>Name pairs
     */
    public function get_record_groups($id)
    {
        $out = array();
        $this->_fetch_groups();

        foreach ((array)$this->groupmembers[$id] as $gid) {
            if ($group = $this->distlists[$gid])
                $out[$gid] = $group['name'];
        }

        return $out;
    }


    /**
     * Create a new contact record
     *
     * @param array Assoziative array with save data
     *  Keys:   Field name with optional section in the form FIELD:SECTION
     *  Values: Field value. Can be either a string or an array of strings for multiple values
     * @param boolean True to check for duplicates first
     * @return mixed The created record ID on success, False on error
     */
    public function insert($save_data, $check=false)
    {
        if (!is_array($save_data))
            return false;

        $insert_id = $existing = false;

        // check for existing records by e-mail comparison
        if ($check) {
            foreach ($this->get_col_values('email', $save_data, true) as $email) {
                if (($res = $this->search('email', $email, true, false)) && $res->count) {
                    $existing = true;
                    break;
                }
            }
        }

        if (!$existing) {
            // remove existing id attributes (#1101)
            unset($save_data['ID'], $save_data['uid']);

            // generate new Kolab contact item
            $object = $this->_from_rcube_contact($save_data);
            $saved  = $this->storagefolder->save($object, 'contact');

            if (!$saved) {
                rcube::raise_error(array(
                  'code' => 600, 'type' => 'php',
                  'file' => __FILE__, 'line' => __LINE__,
                  'message' => "Error saving contact object to Kolab server"),
                true, false);
            }
            else {
                $contact = $this->_to_rcube_contact($object);
                $id = $contact['ID'];
                $this->contacts[$id] = $contact;
                $insert_id = $id;
            }
        }

        return $insert_id;
    }


    /**
     * Update a specific contact record
     *
     * @param mixed Record identifier
     * @param array Assoziative array with save data
     *  Keys:   Field name with optional section in the form FIELD:SECTION
     *  Values: Field value. Can be either a string or an array of strings for multiple values
     * @return boolean True on success, False on error
     */
    public function update($id, $save_data)
    {
        $updated = false;
        if ($old = $this->storagefolder->get_object($this->_id2uid($id))) {
            $object = $this->_from_rcube_contact($save_data, $old);

            if (!$this->storagefolder->save($object, 'contact', $old['uid'])) {
                rcube::raise_error(array(
                  'code' => 600, 'type' => 'php',
                  'file' => __FILE__, 'line' => __LINE__,
                  'message' => "Error saving contact object to Kolab server"),
                true, false);
            }
            else {
                $this->contacts[$id] = $this->_to_rcube_contact($object);
                $updated = true;

                // TODO: update data in groups this contact is member of
            }
        }

        return $updated;
    }


    /**
     * Mark one or more contact records as deleted
     *
     * @param array   Record identifiers
     * @param boolean Remove record(s) irreversible (mark as deleted otherwise)
     *
     * @return int Number of records deleted
     */
    public function delete($ids, $force=true)
    {
        $this->_fetch_groups();

        if (!is_array($ids))
            $ids = explode(',', $ids);

        $count = 0;
        foreach ($ids as $id) {
            if ($uid = $this->_id2uid($id)) {
                $is_mailto = strpos($uid, 'mailto:') === 0;
                $deleted = $is_mailto || $this->storagefolder->delete($uid, $force);

                if (!$deleted) {
                    rcube::raise_error(array(
                      'code' => 600, 'type' => 'php',
                      'file' => __FILE__, 'line' => __LINE__,
                      'message' => "Error deleting a contact object $uid from the Kolab server"),
                    true, false);
                }
                else {
                    // remove from distribution lists
                    foreach ((array)$this->groupmembers[$id] as $gid) {
                        if (!$is_mailto || $gid == $this->gid)
                            $this->remove_from_group($gid, $id);
                    }

                    // clear internal cache
                    unset($this->contacts[$id], $this->groupmembers[$id]);
                    $count++;
                }
            }
        }

        return $count;
    }


    /**
     * Undelete one or more contact records.
     * Only possible just after delete (see 2nd argument of delete() method).
     *
     * @param array  Record identifiers
     *
     * @return int Number of records restored
     */
    public function undelete($ids)
    {
        if (!is_array($ids))
            $ids = explode(',', $ids);

        $count = 0;
        foreach ($ids as $id) {
            $uid = $this->_id2uid($id);
            if ($this->storagefolder->undelete($uid)) {
                $count++;
            }
            else {
                rcube::raise_error(array(
                  'code' => 600, 'type' => 'php',
                  'file' => __FILE__, 'line' => __LINE__,
                  'message' => "Error undeleting a contact object $uid from the Kolab server"),
                true, false);
            }
        }

        return $count;
    }


    /**
     * Remove all records from the database
     */
    public function delete_all()
    {
        if ($this->storagefolder->delete_all()) {
            $this->contacts = array();
            $this->result = null;
        }
    }


    /**
     * Close connection to source
     * Called on script shutdown
     */
    public function close()
    {
    }


    /**
     * Create a contact group with the given name
     *
     * @param string The group name
     * @return mixed False on error, array with record props in success
     */
    function create_group($name)
    {
        $this->_fetch_groups();
        $result = false;

        $list = array(
            'name' => $name,
            'member' => array(),
        );
        $saved = $this->storagefolder->save($list, 'distribution-list');

        if (!$saved) {
            rcube::raise_error(array(
                'code' => 600, 'type' => 'php',
                'file' => __FILE__, 'line' => __LINE__,
                'message' => "Error saving distribution-list object to Kolab server"),
            true, false);
            return false;
        }
        else {
            $id = $this->_uid2id($list['uid']);
            $this->distlists[$id] = $list;
            $result = array('id' => $id, 'name' => $name);
        }

        return $result;
    }

    /**
     * Delete the given group and all linked group members
     *
     * @param string Group identifier
     * @return boolean True on success, false if no data was changed
     */
    function delete_group($gid)
    {
        $this->_fetch_groups();
        $result = false;

        if ($list = $this->distlists[$gid]) {
            $deleted = $this->storagefolder->delete($list['uid']);
        }

        if (!$deleted) {
            rcube::raise_error(array(
                'code' => 600, 'type' => 'php',
                'file' => __FILE__, 'line' => __LINE__,
                'message' => "Error deleting distribution-list object from the Kolab server"),
            true, false);
        }
        else {
            $result = true;
        }

        return $result;
    }

    /**
     * Rename a specific contact group
     *
     * @param string Group identifier
     * @param string New name to set for this group
     * @return boolean New name on success, false if no data was changed
     */
    function rename_group($gid, $newname)
    {
        $this->_fetch_groups();
        $list = $this->distlists[$gid];

        if ($newname != $list['name']) {
            $list['name'] = $newname;
            $saved = $this->storagefolder->save($list, 'distribution-list', $list['uid']);
        }

        if (!$saved) {
            rcube::raise_error(array(
                'code' => 600, 'type' => 'php',
                'file' => __FILE__, 'line' => __LINE__,
                'message' => "Error saving distribution-list object to Kolab server"),
            true, false);
            return false;
        }

        return $newname;
    }

    /**
     * Add the given contact records the a certain group
     *
     * @param string  Group identifier
     * @param array   List of contact identifiers to be added
     * @return int    Number of contacts added
     */
    function add_to_group($gid, $ids)
    {
        if (!is_array($ids))
            $ids = explode(',', $ids);

        $added = 0;
        $exists = array();

        $this->_fetch_groups(true);
        $list = $this->distlists[$gid];

        foreach ((array)$list['member'] as $i => $member)
            $exists[] = $member['ID'];

        // substract existing assignments from list
        $ids = array_diff($ids, $exists);

        foreach ($ids as $contact_id) {
            $uid = $this->_id2uid($contact_id);
            if ($contact = $this->storagefolder->get_object($uid)) {
                foreach ($this->get_col_values('email', $contact, true) as $email)
                    break;

                $list['member'][] = array(
                    'uid' => $uid,
                    'email' => $email,
                    'name' => self::compose_display_name($contact),
                );
                $this->groupmembers[$contact_id][] = $gid;
                $added++;
            }
            else if (strpos($uid, 'mailto:') === 0 && ($contact = $this->contacts[$contact_id])) {
                $list['member'][] = array(
                    'email' => $contact['email'],
                    'name' => $contact['name'],
                );
                $this->groupmembers[$contact_id][] = $gid;
                $added++;
            }
        }

        if ($added)
            $saved = $this->storagefolder->save($list, 'distribution-list', $list['uid']);
        else
            $saved = true;

        if (!$saved) {
            rcube::raise_error(array(
                'code' => 600, 'type' => 'php',
                'file' => __FILE__, 'line' => __LINE__,
                'message' => "Error saving distribution-list to Kolab server"),
            true, false);
            $added = false;
            $this->set_error(self::ERROR_SAVING, 'errorsaving');
        }
        else {
            $this->distlists[$gid] = $list;
        }

        return $added;
    }

    /**
     * Remove the given contact records from a certain group
     *
     * @param string  Group identifier
     * @param array   List of contact identifiers to be removed
     * @return int    Number of deleted group members
     */
    function remove_from_group($gid, $ids)
    {
        if (!is_array($ids))
            $ids = explode(',', $ids);

        $this->_fetch_groups();
        if (!($list = $this->distlists[$gid]))
            return false;

        $new_member = array();
        foreach ((array)$list['member'] as $member) {
            if (!in_array($member['ID'], $ids))
                $new_member[] = $member;
        }

        // write distribution list back to server
        $list['member'] = $new_member;
        $saved = $this->storagefolder->save($list, 'distribution-list', $list['uid']);

        if (!$saved) {
            rcube::raise_error(array(
                'code' => 600, 'type' => 'php',
                'file' => __FILE__, 'line' => __LINE__,
                'message' => "Error saving distribution-list object to Kolab server"),
            true, false);
        }
        else {
            // remove group assigments in local cache
            foreach ($ids as $id) {
                $j = array_search($gid, $this->groupmembers[$id]);
                unset($this->groupmembers[$id][$j]);
            }
            $this->distlists[$gid] = $list;
            return true;
        }

        return false;
    }

    /**
     * Check the given data before saving.
     * If input not valid, the message to display can be fetched using get_error()
     *
     * @param array Associative array with contact data to save
     *
     * @return boolean True if input is valid, False if not.
     */
    public function validate($save_data)
    {
        // validate e-mail addresses
        $valid = parent::validate($save_data);

        // require at least one e-mail address (syntax check is already done)
        if ($valid) {
            if (!strlen($save_data['name'])
                && !array_filter($this->get_col_values('email', $save_data, true))
            ) {
                $this->set_error('warning', 'kolab_addressbook.noemailnamewarning');
                $valid = false;
            }
        }

        return $valid;
    }

    /**
     * Query storage layer and store records in private member var
     */
    private function _fetch_contacts($query = array())
    {
        if (!isset($this->contacts)) {
            $this->contacts = array();
            foreach ((array)$this->storagefolder->select($query) as $record) {
                $contact = $this->_to_rcube_contact($record);
                $id = $contact['ID'];
                $this->contacts[$id] = $contact;
            }
        }
    }

    /**
     * Callback function for sorting contacts
     */
    private function _sort_contacts_comp($a, $b)
    {
        $a_value = $b_value = '';

        switch ($this->sort_col) {
        case 'name':
            $a_value = $a['name'] . $a['prefix'];
            $b_value = $b['name'] . $b['prefix'];
        case 'firstname':
            $a_value .= $a['firstname'] . $a['middlename'] . $a['surname'];
            $b_value .= $b['firstname'] . $b['middlename'] . $b['surname'];
            break;

        case 'surname':
            $a_value = $a['surname'] . $a['firstname'] . $a['middlename'];
            $b_value = $b['surname'] . $b['firstname'] . $b['middlename'];
            break;

        default:
            $a_value = $a[$this->sort_col];
            $b_value = $b[$this->sort_col];
            break;
        }

        $a_value .= is_array($a['email']) ? $a['email'][0] : $a['email'];
        $b_value .= is_array($b['email']) ? $b['email'][0] : $b['email'];

        $a_value = mb_strtolower($a_value);
        $b_value = mb_strtolower($b_value);

        // return strcasecmp($a_value, $b_value);
        // make sorting unicode-safe and locale-dependent
        if ($a_value == $b_value)
            return 0;

        $arr = array($a_value, $b_value);
        sort($arr, SORT_LOCALE_STRING);
        return $a_value == $arr[0] ? -1 : 1;
    }

    /**
     * Read distribution-lists AKA groups from server
     */
    private function _fetch_groups($with_contacts = false)
    {
        if (!isset($this->distlists)) {
            $this->distlists = $this->groupmembers = array();
            foreach ((array)$this->storagefolder->get_objects('distribution-list') as $record) {
                $record['ID'] = $this->_uid2id($record['uid']);
                foreach ((array)$record['member'] as $i => $member) {
                    $mid = $this->_uid2id($member['uid'] ? $member['uid'] : 'mailto:' . $member['email']);
                    $record['member'][$i]['ID'] = $mid;
                    $record['member'][$i]['readonly'] = empty($member['uid']);
                    $this->groupmembers[$mid][] = $record['ID'];

                    if ($with_contacts && empty($member['uid']))
                        $this->contacts[$mid] = $record['member'][$i];
                }
                $this->distlists[$record['ID']] = $record;
            }
        }
    }

    /**
     * Encode object UID into a safe identifier
     */
    private function _uid2id($uid)
    {
        return rtrim(strtr(base64_encode($uid), '+/', '-_'), '=');
    }

    /**
     * Convert Roundcube object identifier back into the original UID
     */
    private function _id2uid($id)
    {
        return base64_decode(str_pad(strtr($id, '-_', '+/'), strlen($id) % 4, '=', STR_PAD_RIGHT));
    }

    /**
     * Map fields from internal Kolab_Format to Roundcube contact format
     */
    private function _to_rcube_contact($record)
    {
        $record['ID'] = $this->_uid2id($record['uid']);

        if (is_array($record['phone'])) {
            $phones = $record['phone'];
            unset($record['phone']);
            foreach ((array)$phones as $i => $phone) {
                $key = 'phone' . ($phone['type'] ? ':' . $phone['type'] : '');
                $record[$key][] = $phone['number'];
            }
        }

        if (is_array($record['website'])) {
            $urls = $record['website'];
            unset($record['website']);
            foreach ((array)$urls as $i => $url) {
                $key = 'website' . ($url['type'] ? ':' . $url['type'] : '');
                $record[$key][] = $url['url'];
            }
        }

        if (is_array($record['address'])) {
            $addresses = $record['address'];
            unset($record['address']);
            foreach ($addresses as $i => $adr) {
                $key = 'address' . ($adr['type'] ? ':' . $adr['type'] : '');
                $record[$key][] = array(
                    'street'   => $adr['street'],
                    'locality' => $adr['locality'],
                    'zipcode'  => $adr['code'],
                    'region'   => $adr['region'],
                    'country'  => $adr['country'],
                );
            }
        }

        // photo is stored as separate attachment
        if ($record['photo'] && strlen($record['photo']) < 255 && ($att = $record['_attachments'][$record['photo']])) {
            // only fetch photo content if requested
            if ($this->action == 'photo')
                $record['photo'] = $att['content'] ? $att['content'] : $this->storagefolder->get_attachment($record['uid'], $att['id']);
        }

        // truncate publickey value for display
        if ($record['pgppublickey'] && $this->action == 'show')
            $record['pgppublickey'] = substr($record['pgppublickey'], 0, 140) . '...';

        // remove empty fields
        return array_filter($record);
    }

    /**
     * Map fields from Roundcube format to internal kolab_format_contact properties
     */
    private function _from_rcube_contact($contact, $old = array())
    {
        if (!$contact['uid'] && $contact['ID'])
            $contact['uid'] = $this->_id2uid($contact['ID']);
        else if (!$contact['uid'] && $old['uid'])
            $contact['uid'] = $old['uid'];

        $contact['email'] = array_filter($this->get_col_values('email', $contact, true));
        $contact['im']    = array_filter($this->get_col_values('im', $contact, true));

        $websites  = array();
        $phones    = array();
        $addresses = array();

        foreach ($this->get_col_values('website', $contact) as $type => $values) {
            foreach ((array)$values as $url) {
                if (!empty($url)) {
                    $websites[] = array('url' => $url, 'type' => $type);
                }
            }
            unset($contact['website:'.$type]);
        }

        foreach ($this->get_col_values('phone', $contact) as $type => $values) {
            foreach ((array)$values as $phone) {
                if (!empty($phone)) {
                    $phones[] = array('number' => $phone, 'type' => $type);
                }
            }
            unset($contact['phone:'.$type]);
        }

        foreach ($this->get_col_values('address', $contact) as $type => $values) {
            foreach ((array)$values as $adr) {
                // skip empty address
                $adr = array_filter($adr);
                if (empty($adr))
                    continue;

                $addresses[] = array(
                    'type' => $type,
                    'street' => $adr['street'],
                    'locality' => $adr['locality'],
                    'code' => $adr['zipcode'],
                    'region' => $adr['region'],
                    'country' => $adr['country'],
                );
            }

            unset($contact['address:'.$type]);
        }

        $contact['website'] = $websites;
        $contact['phone']   = $phones;
        $contact['address'] = $addresses;

        // copy meta data (starting with _) from old object
        foreach ((array)$old as $key => $val) {
            if (!isset($contact[$key]) && $key[0] == '_')
                $contact[$key] = $val;
        }

        // convert one-item-array elements into string element
        // this is needed e.g. to properly import birthday field
        foreach ($this->coltypes as $type => $col_def) {
            if ($col_def['limit'] == 1 && is_array($contact[$type])) {
                $contact[$type] = array_shift(array_filter($contact[$type]));
            }
        }

        // add empty values for some fields which can be removed in the UI
        return array_filter($contact) + array('nickname' => '', 'birthday' => '', 'anniversary' => '', 'freebusyurl' => '', 'photo' => $contact['photo']);
    }

}