<?php
/**
 * Created by PhpStorm.
 * User: Muhammad
 * Date: 05/07/2016
 * Time: 01:20 PM
 */


add_filter('get_user_metadata', 'decrypt_user_meta',10,4);
add_filter('add_user_metadata', 'encrypt_user_meta',10,5);
add_filter('update_user_metadata', 'encrypt_user_meta_in_update',10,5);


function get_meta_keys_to_encrypt(){
    return array('first_name', 'last_name', 'display_name' ); // meta_key s from wp_usermeta table that you want to encrypte
}


function decrypt_user_meta($value = null ,$object_id,$meta_key,$single){
    if(!in_array($meta_key, get_meta_keys_to_encrypt()))
        return null;

    $meta_cache = wp_cache_get($object_id, 'user' . '_meta');

    if ( !$meta_cache ) {
        $meta_cache = update_meta_cache( 'user', array( $object_id ) );
        $meta_cache = $meta_cache[$object_id];
    }

    if ( ! $meta_key ) {
        return decrypt($meta_cache);
    }

    if ( isset($meta_cache[$meta_key]) ) {
        if ( $single )
            return decrypt(maybe_unserialize( $meta_cache[$meta_key][0]));
        else
            return array_map('maybe_unserialize', decrypt($meta_cache[$meta_key]));
    }

    if ($single)
        return '';
    else
        return array();
}


function encrypt_user_meta($value = null ,$object_id,$meta_key, $meta_value, $unique){

    if(!in_array($meta_key, get_meta_keys_to_encrypt()))
        return null;

    global $wpdb;
    $table = _get_meta_table( 'user' );
    $column = sanitize_key('user' . '_id');


    if ( $unique && $wpdb->get_var( $wpdb->prepare(
            "SELECT COUNT(*) FROM $table WHERE meta_key = %s AND $column = %d",
            $meta_key, $object_id ) ) )
        return false;

    $_meta_value = $meta_value;
    $meta_value = encrypt(maybe_serialize( $meta_value ));

    /**
     * Fires immediately before meta of a specific type is added.
     *
     * The dynamic portion of the hook, `$meta_type`, refers to the meta
     * object type (comment, post, or user).
     *
     * @since 3.1.0
     *
     * @param int    $object_id  Object ID.
     * @param string $meta_key   Meta key.
     * @param mixed  $meta_value Meta value.
     */
    do_action( "add_user_meta", $object_id, $meta_key, $_meta_value );

    $result = $wpdb->insert( $table, array(
        $column => $object_id,
        'meta_key' => $meta_key,
        'meta_value' => $meta_value
    ) );

    if ( ! $result )
        return false;

    $mid = (int) $wpdb->insert_id;

    wp_cache_delete($object_id, 'user' . '_meta');

    /**
     * Fires immediately after meta of a specific type is added.
     *
     * The dynamic portion of the hook, `$meta_type`, refers to the meta
     * object type (comment, post, or user).
     *
     * @since 2.9.0
     *
     * @param int    $mid        The meta ID after successful update.
     * @param int    $object_id  Object ID.
     * @param string $meta_key   Meta key.
     * @param mixed  $meta_value Meta value.
     */
    do_action( "added_user_meta", $mid, $object_id, $meta_key, $_meta_value );

    return $mid;
}


function encrypt_user_meta_in_update($value = null ,$object_id,$meta_key, $meta_value, $prev_value){
    if(!in_array($meta_key, get_meta_keys_to_encrypt()))
        return null;

    global $wpdb;
    $meta_type = 'user';
    $table = _get_meta_table( 'user' );
    $column = sanitize_key('user' . '_id');
    $id_column = 'umeta_id';

    $raw_meta_key = $meta_key;
    $passed_value = $meta_value;


    // Compare existing value to new value if no prev value given and the key exists only once.
    if ( empty($prev_value) ) {
        $old_value = get_metadata('user', $object_id, $meta_key);
        if ( count($old_value) == 1 ) {
            if ( $old_value[0] === $meta_value )
                return false;
        }
    }

    $meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $id_column FROM $table WHERE meta_key = %s AND $column = %d", $meta_key, $object_id ) );
    if ( empty( $meta_ids ) ) {
        return add_metadata( $meta_type, $object_id, $raw_meta_key, $passed_value );
    }

    $_meta_value = $meta_value;
    $meta_value = maybe_serialize( encrypt($meta_value ));

    $data  = compact( 'meta_value' );
    $where = array( $column => $object_id, 'meta_key' => $meta_key );

    if ( !empty( $prev_value ) ) {
        $prev_value = maybe_serialize($prev_value);
        $where['meta_value'] = encrypt($prev_value);
    }

    foreach ( $meta_ids as $meta_id ) {
        /**
         * Fires immediately before updating metadata of a specific type.
         *
         * The dynamic portion of the hook, `$meta_type`, refers to the meta
         * object type (comment, post, or user).
         *
         * @since 2.9.0
         *
         * @param int    $meta_id    ID of the metadata entry to update.
         * @param int    $object_id  Object ID.
         * @param string $meta_key   Meta key.
         * @param mixed  $meta_value Meta value.
         */
        do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );

        if ( 'post' == $meta_type ) {
            /**
             * Fires immediately before updating a post's metadata.
             *
             * @since 2.9.0
             *
             * @param int    $meta_id    ID of metadata entry to update.
             * @param int    $object_id  Object ID.
             * @param string $meta_key   Meta key.
             * @param mixed  $meta_value Meta value.
             */
            do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
        }
    }

    $result = $wpdb->update( $table, $data, $where );
    if ( ! $result )
        return false;

    wp_cache_delete($object_id, $meta_type . '_meta');

    foreach ( $meta_ids as $meta_id ) {
        /**
         * Fires immediately after updating metadata of a specific type.
         *
         * The dynamic portion of the hook, `$meta_type`, refers to the meta
         * object type (comment, post, or user).
         *
         * @since 2.9.0
         *
         * @param int    $meta_id    ID of updated metadata entry.
         * @param int    $object_id  Object ID.
         * @param string $meta_key   Meta key.
         * @param mixed  $meta_value Meta value.
         */
        do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );

        if ( 'post' == $meta_type ) {
            /**
             * Fires immediately after updating a post's metadata.
             *
             * @since 2.9.0
             *
             * @param int    $meta_id    ID of updated metadata entry.
             * @param int    $object_id  Object ID.
             * @param string $meta_key   Meta key.
             * @param mixed  $meta_value Meta value.
             */
            do_action( 'updated_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
        }
    }

    return true;
}

function encrypt($src){
    if(is_array($src)){
        foreach ($src as $key => $val)
            $src[$key] = encrypt_value($val);

        return $src;
    }else
        return encrypt_value($src);
}

function encrypt_value($data){
    $password = "SuperSecretEncryptionKey";

    $salt = substr(md5(mt_rand(), true), 8);

    $key = md5($password . $salt, true);
    $iv  = md5($key . $password . $salt, true);

    $ct = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, $iv);

    return base64_encode('Salted__' . $salt . $ct);
}

function decrypt($src){
    if(is_array($src)){
        foreach ($src as $key => $val)
            $src[$key] = decrypt_value($val);
        return $src;
    }else
        return decrypt_value($src);

}

function decrypt_value($data){
    $password = "SuperSecretEncryptionKey";
    $data = base64_decode($data);
    $salt = substr($data, 8, 8);
    $ct   = substr($data, 16);

    $key = md5($password . $salt, true);
    $iv  = md5($key . $password . $salt, true);

    $pt = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $ct, MCRYPT_MODE_CBC, $iv);

    return trim($pt);
}