<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Condition class
 *
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 *
 * @package   availability_ipaddress
 * @copyright 2019-05-14 Mfreak.nl | LdesignMedia.nl - Luuk Verhoeven
 * @author    Luuk Verhoeven
 **/

namespace availability_ipaddress;

use core_availability\info;

defined('MOODLE_INTERNAL') || die;

/**
 * Class condition
 *
 * @package   availability_ipaddress
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @copyright 2019-05-14 Mfreak.nl | LdesignMedia.nl - Luuk Verhoeven
 */
class condition extends \core_availability\condition {

    /**
     * @var string
     */
    protected $ip_addresses = '';

    /**
     * condition constructor.
     *
     * @param $structure
     *
     * @throws \coding_exception
     */
    public function __construct($structure) {

        if (isset($structure->ip_addresses)) {
            // set a number
            $this->ip_addresses = $structure->ip_addresses;
        } else {
            throw new \coding_exception('Missing or invalid ->ip_addresses for ipaddress condition');
        }
    }

    /**
     * Determines whether a particular item is currently available
     * according to this availability condition.
     *
     * If implementations require a course or modinfo, they should use
     * the get methods in $info.
     *
     * The $not option is potentially confusing. This option always indicates
     * the 'real' value of NOT. For example, a condition inside a 'NOT AND'
     * group will get this called with $not = true, but if you put another
     * 'NOT OR' group inside the first group, then a condition inside that will
     * be called with $not = false. We need to use the real values, rather than
     * the more natural use of the current value at this point inside the tree,
     * so that the information displayed to users makes sense.
     *
     * @param bool $not        Set true if we are inverting the condition
     * @param info $info       Item we're checking
     * @param bool $grabthelot Performance hint: if true, caches information
     *                         required for all course-modules, to make the front page and similar
     *                         pages work more quickly (works only for current user)
     * @param int  $userid     User ID to check availability for
     *
     * @return bool True if available
     */
    public function is_available($not, info $info, $grabthelot, $userid) {

        if (empty($this->ip_addresses)) {
            return true;
        }

        // Check if ip-address matches
        if (address_in_subnet(getremoteaddr(), trim($this->ip_addresses))) {
            return true;
        }

        return false;
    }

    /**
     * Obtains a string describing this restriction (whether or not
     * it actually applies). Used to obtain information that is displayed to
     * students if the activity is not available to them, and for staff to see
     * what conditions are.
     *
     * The $full parameter can be used to distinguish between 'staff' cases
     * (when displaying all information about the activity) and 'student' cases
     * (when displaying only conditions they don't meet).
     *
     * If implementations require a course or modinfo, they should use
     * the get methods in $info.
     *
     * The special string <AVAILABILITY_CMNAME_123/> can be returned, where
     * 123 is any number. It will be replaced with the correctly-formatted
     * name for that activity.
     *
     * @param bool $full Set true if this is the 'full information' view
     * @param bool $not  Set true if we are inverting the condition
     * @param info $info Item we're checking
     *
     * @return string Information string (for admin) about all restrictions on
     *   this item
     * @throws \coding_exception
     */
    public function get_description($full, $not, info $info) {
        return get_string('require_condition', 'availability_ipaddress');
    }

    /**
     * Obtains a representation of the options of this condition as a string,
     * for debugging.
     *
     * @return string Text representation of parameters
     */
    protected function get_debug_string() {
        return !empty($this->ip_addresses) ? 'ip_addresses ON' : 'ip_addresses OFF';
    }

    /**
     * Returns a JSON object which corresponds to a condition of this type.
     *
     * Intended for unit testing, as normally the JSON values are constructed
     * by JavaScript code.
     *
     * @param string $ip_addresses
     *
     * @return \stdClass Object representing condition
     */
    public static function get_json($ip_addresses) {
        return (object)[
            'type' => 'ipaddress',
            'ip_addresses' => $ip_addresses,
        ];
    }

    /**
     * Check if ip-address is valid
     *
     * @param $ip_addresses
     *
     * @return bool
     */
    public static function is_valid_ip_addresses($ip_addresses) {
        $ip_addresses = implode(',', $ip_addresses);
        foreach ($ip_addresses as $ip_address) {
            if (!filter_var($ip_address, FILTER_VALIDATE_IP)) {
                return false;
            }
        }

        return true;

    }

    /**
     * Saves tree data back to a structure object.
     *
     * @return \stdClass Structure object (ready to be made into JSON format)
     */
    public function save() {


        return (object)[
            'type' => 'ipaddress',
            'ip_addresses' => $this->ip_addresses,
        ];
    }
}