first commit

payment/classes/account.php

@@ -0,0 +1,156 @@
+<?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/>.
+
+/**
+ * Class account
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment;
+
+use core\persistent;
+
+/**
+ * Class account
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account extends persistent {
+    /**
+     * Database table.
+     */
+    const TABLE = 'payment_accounts';
+
+    /** @var array */
+    protected $gateways;
+
+    /**
+     * Return the definition of the properties of this model.
+     *
+     * @return array
+     */
+    protected static function define_properties(): array {
+        return array(
+            'name' => [
+                'type' => PARAM_TEXT,
+            ],
+            'idnumber' => [
+                'type' => PARAM_RAW_TRIMMED,
+            ],
+            'contextid' => [
+                'type' => PARAM_INT,
+                'default' => function() {
+                    return \context_system::instance()->id;
+                }
+            ],
+            'enabled' => [
+                'type' => PARAM_BOOL,
+                'default' => true
+            ],
+            'archived' => [
+                'type' => PARAM_BOOL,
+                'default' => false
+            ],
+        );
+    }
+
+    /**
+     * Account context
+     *
+     * @return \context
+     * @throws \coding_exception
+     */
+    public function get_context(): \context {
+        return \context::instance_by_id($this->get('contextid'));
+    }
+
+    /**
+     * Account name ready for display
+     *
+     * @return string
+     * @throws \coding_exception
+     */
+    public function get_formatted_name(): string {
+        return format_string($this->get('name'), true, ['context' => $this->get_context(), 'escape' => false]);
+    }
+
+    /**
+     * Manage account url
+     *
+     * @param array $extraparams
+     * @return \moodle_url
+     * @throws \coding_exception
+     * @throws \moodle_exception
+     */
+    public function get_edit_url(array $extraparams = []): \moodle_url {
+        return new \moodle_url('/payment/manage_account.php',
+            ($this->get('id') ? ['id' => $this->get('id')] : []) + $extraparams);
+    }
+
+    /**
+     * List of gateways configured (or possible) for this account
+     *
+     * @param bool $enabledpluginsonly only return payment plugins that are enabled
+     * @return account_gateway[]
+     * @throws \coding_exception
+     */
+    public function get_gateways(bool $enabledpluginsonly = true): array {
+        $id = $this->get('id');
+        if (!$id) {
+            return [];
+        }
+        if ($this->gateways === null) {
+            \core_component::get_plugin_list('paygw');
+            $this->gateways = [];
+            foreach (\core_component::get_plugin_list('paygw') as $gatewayname => $unused) {
+                $gateway = account_gateway::get_record(['accountid' => $id, 'gateway' => $gatewayname]);
+                if (!$gateway) {
+                    $gateway = new account_gateway(0, (object)['accountid' => $id, 'gateway' => $gatewayname,
+                        'enabled' => false, 'config' => null]);
+                }
+                $this->gateways[$gatewayname] = $gateway;
+            }
+        }
+        if ($enabledpluginsonly) {
+            $enabledplugins = \core\plugininfo\paygw::get_enabled_plugins();
+            return array_intersect_key($this->gateways, $enabledplugins);
+        }
+        return $this->gateways;
+    }
+
+    /**
+     * Is this account available (used in management interface)
+     *
+     * @return bool
+     * @throws \coding_exception
+     */
+    public function is_available(): bool {
+        if (!$this->get('id') || !$this->get('enabled')) {
+            return false;
+        }
+        foreach ($this->get_gateways() as $gateway) {
+            if ($gateway->get('id') && $gateway->get('enabled')) {
+                return true;
+            }
+        }
+        return false;
+    }
+}

payment/classes/account_gateway.php

@@ -0,0 +1,106 @@
+<?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/>.
+
+/**
+ * Class account_gateway
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment;
+
+use core\persistent;
+
+/**
+ * Class account_gateway
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account_gateway extends persistent {
+    /**
+     * Database table.
+     */
+    const TABLE = 'payment_gateways';
+
+    /**
+     * Return the definition of the properties of this model.
+     *
+     * @return array
+     */
+    protected static function define_properties(): array {
+        return array(
+            'accountid' => [
+                'type' => PARAM_INT,
+            ],
+            'gateway' => [
+                'type' => PARAM_COMPONENT,
+            ],
+            'enabled' => [
+                'type' => PARAM_BOOL,
+                'default' => true
+            ],
+            'config' => [
+                'type' => PARAM_RAW,
+                'optional' => true,
+                'null' => NULL_ALLOWED,
+                'default' => null
+            ],
+        );
+    }
+
+    /**
+     * Return the gateway name ready for display
+     *
+     * @return string
+     */
+    public function get_display_name(): string {
+        return get_string('pluginname', 'paygw_' . $this->get('gateway'));
+    }
+
+    /**
+     * Gateway management url
+     *
+     * @return \moodle_url
+     */
+    public function get_edit_url(): \moodle_url {
+        $params = $this->get('id') ? ['id' => $this->get('id')] :
+            ['accountid' => $this->get('accountid'), 'gateway' => $this->get('gateway')];
+        return new \moodle_url('/payment/manage_gateway.php', $params);
+    }
+
+    /**
+     * Get corresponding account
+     *
+     * @return account
+     */
+    public function get_account(): account {
+        return new account($this->get('accountid'));
+    }
+
+    /**
+     * Parse configuration from the json-encoded stored value
+     *
+     * @return array
+     */
+    public function get_configuration(): array {
+        $config = @json_decode($this->get('config'), true);
+        return ($config && is_array($config)) ? $config : [];
+    }
+}

payment/classes/event/account_created.php

@@ -0,0 +1,94 @@
+<?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/>.
+
+namespace core_payment\event;
+
+use core\event\base;
+use core_payment\account;
+
+/**
+ * Class account_created
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+
+/**
+ * Class account_created
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account_created extends base {
+
+    /**
+     * Initialise event parameters.
+     */
+    protected function init() {
+        $this->data['objecttable'] = 'payment_accounts';
+        $this->data['crud'] = 'c';
+        $this->data['edulevel'] = self::LEVEL_OTHER;
+    }
+
+    /**
+     * Create an instance of the event and add a record snapshot
+     *
+     * @param account $account
+     * @return base
+     * @throws \coding_exception
+     */
+    public static function create_from_account(account $account) {
+        $eventparams = [
+            'objectid' => $account->get('id'),
+            'context'  => $account->get_context(),
+            'other'    => ['name' => $account->get('name')]
+        ];
+        $event = self::create($eventparams);
+        $event->add_record_snapshot($event->objecttable, $account->to_record());
+        return $event;
+    }
+
+    /**
+     * Returns localised event name.
+     *
+     * @return string
+     */
+    public static function get_name() {
+        return get_string('eventaccountcreated', 'payment');
+    }
+
+    /**
+     * Returns non-localised event description with id's for admin use only.
+     *
+     * @return string
+     */
+    public function get_description() {
+        $name = s($this->other['name']);
+        return "The user with id '$this->userid' created payment account with id '$this->objectid' and the name '{$name}'.";
+    }
+
+    /**
+     * Returns relevant URL.
+     *
+     * @return \moodle_url
+     */
+    public function get_url() {
+        return new \moodle_url('/payment/accounts.php');
+    }
+}

payment/classes/event/account_deleted.php

@@ -0,0 +1,94 @@
+<?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/>.
+
+namespace core_payment\event;
+
+use core\event\base;
+use core_payment\account;
+
+/**
+ * Class account_deleted
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+
+/**
+ * Class account_deleted
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account_deleted extends base {
+
+    /**
+     * Initialise event parameters.
+     */
+    protected function init() {
+        $this->data['objecttable'] = 'payment_accounts';
+        $this->data['crud'] = 'd';
+        $this->data['edulevel'] = self::LEVEL_OTHER;
+    }
+
+    /**
+     * Create an instance of the event and add a record snapshot
+     *
+     * @param account $account
+     * @return base
+     * @throws \coding_exception
+     */
+    public static function create_from_account(account $account) {
+        $eventparams = [
+            'objectid' => $account->get('id'),
+            'context'  => $account->get_context(),
+            'other'    => ['name' => $account->get('name')]
+        ];
+        $event = self::create($eventparams);
+        $event->add_record_snapshot($event->objecttable, $account->to_record());
+        return $event;
+    }
+
+    /**
+     * Returns localised event name.
+     *
+     * @return string
+     */
+    public static function get_name() {
+        return get_string('eventaccountdeleted', 'payment');
+    }
+
+    /**
+     * Returns non-localised event description with id's for admin use only.
+     *
+     * @return string
+     */
+    public function get_description() {
+        $name = s($this->other['name']);
+        return "The user with id '$this->userid' deleted payment account with id '$this->objectid' and the name '{$name}'.";
+    }
+
+    /**
+     * Returns relevant URL.
+     *
+     * @return \moodle_url
+     */
+    public function get_url() {
+        return new \moodle_url('/payment/accounts.php');
+    }
+}

payment/classes/event/account_updated.php

@@ -0,0 +1,101 @@
+<?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/>.
+
+namespace core_payment\event;
+
+use core\event\base;
+use core_payment\account;
+
+/**
+ * Class account_updated
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+
+/**
+ * Class account_updated
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account_updated extends base {
+
+    /**
+     * Initialise event parameters.
+     */
+    protected function init() {
+        $this->data['objecttable'] = 'payment_accounts';
+        $this->data['crud'] = 'u';
+        $this->data['edulevel'] = self::LEVEL_OTHER;
+    }
+
+    /**
+     * Create an instance of the event and add a record snapshot
+     *
+     * @param account $account
+     * @param array $other
+     * @return base
+     */
+    public static function create_from_account(account $account, array $other = []) {
+        $eventparams = [
+            'objectid' => $account->get('id'),
+            'context'  => $account->get_context(),
+            'other'    => ['name' => $account->get('name')] + $other
+        ];
+        $event = self::create($eventparams);
+        $event->add_record_snapshot($event->objecttable, $account->to_record());
+        return $event;
+    }
+
+    /**
+     * Returns localised event name.
+     *
+     * @return string
+     */
+    public static function get_name() {
+        return get_string('eventaccountupdated', 'payment');
+    }
+
+    /**
+     * Returns non-localised event description with id's for admin use only.
+     *
+     * @return string
+     */
+    public function get_description() {
+        $name = s($this->other['name']);
+        if (!empty($this->other['archived'])) {
+            $verb = 'archived';
+        } else if (!empty($this->other['restored'])) {
+            $verb = 'restored';
+        } else {
+            $verb = 'updated';
+        }
+        return "The user with id '$this->userid' $verb payment account with id '$this->objectid' and the name '{$name}'.";
+    }
+
+    /**
+     * Returns relevant URL.
+     *
+     * @return \moodle_url
+     */
+    public function get_url() {
+        return new \moodle_url('/payment/accounts.php');
+    }
+}

payment/classes/external/get_available_gateways.php

@@ -0,0 +1,102 @@
+<?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/>.
+
+/**
+ * This is the external API for this component.
+ *
+ * @package    core_payment
+ * @copyright  2019 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\external;
+
+use core_payment\helper;
+use core_external\external_api;
+use core_external\external_value;
+use core_external\external_single_structure;
+use core_external\external_multiple_structure;
+use core_external\external_function_parameters;
+
+class get_available_gateways extends external_api {
+
+    /**
+     * Returns description of method parameters.
+     *
+     * @return external_function_parameters
+     */
+    public static function execute_parameters(): external_function_parameters {
+        return new external_function_parameters([
+            'component' => new external_value(PARAM_COMPONENT, 'Component'),
+            'paymentarea' => new external_value(PARAM_AREA, 'Payment area in the component'),
+            'itemid' => new external_value(PARAM_INT, 'An identifier for payment area in the component')
+        ]);
+    }
+
+    /**
+     * Returns the list of gateways that can process payments in the given currency.
+     *
+     * @param string $component
+     * @param string $paymentarea
+     * @param int $itemid
+     * @return \stdClass[]
+     */
+    public static function execute(string $component, string $paymentarea, int $itemid): array {
+
+        $params = external_api::validate_parameters(self::execute_parameters(), [
+            'component' => $component,
+            'paymentarea' => $paymentarea,
+            'itemid' => $itemid,
+        ]);
+
+        $list = [];
+        $gateways = helper::get_available_gateways($params['component'], $params['paymentarea'], $params['itemid']);
+        $payable = helper::get_payable($params['component'], $params['paymentarea'], $params['itemid']);
+        $amount = $payable->get_amount();
+        $currency = $payable->get_currency();
+
+        foreach ($gateways as $gateway) {
+            $surcharge = helper::get_gateway_surcharge($gateway);
+            $list[] = (object)[
+                'shortname' => $gateway,
+                'name' => get_string('gatewayname', 'paygw_' . $gateway),
+                'description' => get_string('gatewaydescription', 'paygw_' . $gateway),
+                'surcharge' => $surcharge,
+                'cost' => helper::get_cost_as_string($amount, $currency, $surcharge),
+            ];
+        }
+
+        return $list;
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return external_multiple_structure
+     */
+    public static function execute_returns(): external_multiple_structure {
+        return new external_multiple_structure(
+                new external_single_structure([
+                    'shortname' => new external_value(PARAM_PLUGIN, 'Name of the plugin'),
+                    'name' => new external_value(PARAM_TEXT, 'Human readable name of the gateway'),
+                    'description' => new external_value(PARAM_RAW, 'description of the gateway'),
+                    'surcharge' => new external_value(PARAM_INT, 'percentage of surcharge when using the gateway'),
+                    'cost' => new external_value(PARAM_TEXT,
+                        'Cost in human-readable form (amount plus surcharge with currency sign)'),
+                ])
+        );
+    }
+}

payment/classes/form/account.php

@@ -0,0 +1,66 @@
+<?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/>.
+
+/**
+ * Class account
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\form;
+
+use core\form\persistent;
+
+/**
+ * Class account
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account extends persistent {
+
+    /** @var string The persistent class. */
+    protected static $persistentclass = 'core_payment\account';
+
+    /**
+     * Define the form - called by parent constructor
+     */
+    public function definition() {
+        $mform = $this->_form;
+
+        $mform->addElement('hidden', 'id');
+        $mform->addElement('hidden', 'contextid');
+
+        $mform->addElement('text', 'name', get_string('accountname', 'payment'), 'maxlength="255"');
+        $mform->addHelpButton('name', 'accountname', 'payment');
+        $mform->setType('name', PARAM_TEXT);
+        $mform->addRule('name', get_string('required'), 'required', null, 'client');
+        $mform->addRule('name', get_string('maximumchars', '', 255), 'maxlength', 255, 'server');
+
+        $mform->addElement('text', 'idnumber', get_string('accountidnumber', 'payment'), 'maxlength="100"');
+        $mform->addHelpButton('idnumber', 'accountidnumber', 'payment');
+        $mform->setType('idnumber', PARAM_RAW_TRIMMED);
+        $mform->addRule('idnumber', get_string('maximumchars', '', 100), 'maxlength', 100, 'server');
+
+        $mform->addElement('static', 'staticinfo', '', get_string('accountconfignote', 'payment'));
+
+        $mform->addElement('advcheckbox', 'enabled', get_string('enable'));
+        $this->add_action_buttons();
+    }
+}

payment/classes/form/account_gateway.php

@@ -0,0 +1,147 @@
+<?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/>.
+
+/**
+ * Class account_gateway
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\form;
+
+use core\form\persistent;
+
+/**
+ * Class account_gateway
+ *
+ * @package     core_payment
+ * @copyright   2020 Marina Glancy
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class account_gateway extends persistent {
+
+    /** @var string The persistent class. */
+    protected static $persistentclass = \core_payment\account_gateway::class;
+
+    protected static $fieldstoremove = ['accountname', 'gatewayname', 'submitbutton'];
+
+    /**
+     * Define the form - called by parent constructor
+     */
+    public function definition() {
+        $mform = $this->_form;
+
+        $mform->addElement('hidden', 'id');
+        $mform->addElement('hidden', 'accountid');
+        $mform->addElement('hidden', 'gateway');
+
+        $mform->addElement('static', 'accountname', get_string('accountname', 'payment'),
+            $this->get_gateway_persistent()->get_account()->get_formatted_name());
+
+        $mform->addElement('static', 'gatewayname', get_string('type_paygw', 'plugin'),
+            $this->get_gateway_persistent()->get_display_name());
+
+        $mform->addElement('advcheckbox', 'enabled', get_string('enable'));
+
+        /** @var \core_payment\gateway $classname */
+        $classname = '\paygw_' . $this->get_gateway_persistent()->get('gateway') . '\gateway';
+        if (class_exists($classname)) {
+            $classname::add_configuration_to_gateway_form($this);
+        }
+
+        $this->add_action_buttons();
+    }
+
+    /**
+     * Form validation
+     *
+     * @param \stdClass $data
+     * @param array $files
+     * @param array $errors
+     */
+    protected function extra_validation($data, $files, array &$errors) {
+        /** @var \core_payment\gateway $classname */
+        $classname = '\paygw_' . $this->get_gateway_persistent()->get('gateway') . '\gateway';
+        if (class_exists($classname)) {
+            $classname::validate_gateway_form($this, $data, $files, $errors);
+        }
+    }
+
+    /**
+     * Exposes the protected attribute to be accessed by the \core_payment\gateway callback
+     *
+     * @return \MoodleQuickForm
+     */
+    public function get_mform(): \MoodleQuickForm {
+        return $this->_form;
+    }
+
+    /**
+     * Exposes the protected attribute to be accessed by the \core_payment\gateway callback
+     *
+     * @return \core_payment\account_gateway
+     */
+    public function get_gateway_persistent(): \core_payment\account_gateway {
+        return $this->get_persistent();
+    }
+
+    /**
+     * Filter out the foreign fields of the persistent.
+     *
+     * This can be overridden to filter out more complex fields.
+     *
+     * @param \stdClass $data The data to filter the fields out of.
+     * @return \stdClass.
+     */
+    protected function filter_data_for_persistent($data) {
+        $data = parent::filter_data_for_persistent($data);
+        return (object) array_intersect_key((array)$data, \core_payment\account_gateway::properties_definition());
+    }
+
+    /**
+     * Overwrite parent method to json encode config
+     *
+     * @return object|\stdClass|null
+     * @throws \coding_exception
+     */
+    public function get_data() {
+        if (!$data = parent::get_data()) {
+            return $data;
+        }
+        // Everything that is not a property of the account_gateway class is a gateway config.
+        $data = (array)$data;
+        $properties = \core_payment\account_gateway::properties_definition() + ['id' => 1];
+        $config = array_diff_key($data, $properties, ['timemodified' => 1, 'timecreated' => 1]);
+        $data = array_intersect_key($data, $properties);
+        $data['config'] = json_encode($config);
+        return (object)$data;
+    }
+
+    /**
+     * Overwrite parent method to json decode config
+     *
+     * @param array|\stdClass $values
+     */
+    public function set_data($values) {
+        if (($config = isset($values->config) ? @json_decode($values->config, true) : null) && is_array($config)) {
+            $values = (object)((array)$values + $config);
+        }
+        unset($values->config);
+        parent::set_data($values);
+    }
+}

payment/classes/gateway.php

@@ -0,0 +1,66 @@
+<?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/>.
+
+/**
+ * Contains base class for payment gateways.
+ *
+ * @package    core_payment
+ * @copyright  2019 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment;
+
+/**
+ * Base class for payment gateways.
+ *
+ * @copyright  2019 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class gateway {
+    /**
+     * Returns the list of currencies that the payment gateway supports.
+     *
+     * @return string[] An array of the currency codes in the three-character ISO-4217 format
+     */
+    abstract public static function get_supported_currencies(): array;
+
+    /**
+     * Configuration form for the gateway instance
+     *
+     * Use $form->get_mform() to access the \MoodleQuickForm instance
+     *
+     * @param \core_payment\form\account_gateway $form
+     */
+    abstract public static function add_configuration_to_gateway_form(\core_payment\form\account_gateway $form): void;
+
+    /**
+     * Validates the gateway configuration form.
+     *
+     * Needs to be overridden to make sure the incomplete configuration can not be enabled.
+     *
+     * @param \core_payment\form\account_gateway $form
+     * @param \stdClass $data
+     * @param array $files
+     * @param array $errors form errors (passed by reference)
+     */
+    public static function validate_gateway_form(\core_payment\form\account_gateway $form,
+                                                 \stdClass $data, array $files, array &$errors): void {
+        if ($data->enabled) {
+            $errors['enabled'] = get_string('gatewaycannotbeenabled', 'payment');
+        }
+    }
+}

payment/classes/helper.php

@@ -0,0 +1,416 @@
+<?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/>.
+
+/**
+ * Contains helper class for the payment subsystem.
+ *
+ * @package    core_payment
+ * @copyright  2019 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment;
+
+use core_payment\event\account_created;
+use core_payment\event\account_deleted;
+use core_payment\event\account_updated;
+
+/**
+ * Helper class for the payment subsystem.
+ *
+ * @copyright  2019 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class helper {
+
+    /**
+     * Returns an accumulated list of supported currencies by all payment gateways.
+     *
+     * @return string[] An array of the currency codes in the three-character ISO-4217 format
+     */
+    public static function get_supported_currencies(): array {
+        $currencies = [];
+
+        $plugins = \core_plugin_manager::instance()->get_enabled_plugins('paygw');
+        foreach ($plugins as $plugin) {
+            /** @var \paygw_paypal\gateway $classname */
+            $classname = '\paygw_' . $plugin . '\gateway';
+
+            $currencies = array_merge($currencies, component_class_callback($classname, 'get_supported_currencies', [], []));
+        }
+
+        $currencies = array_unique($currencies);
+
+        return $currencies;
+    }
+
+    /**
+     * Returns the list of gateways that can process payments in the given currency.
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the component
+     * @return string[]
+     */
+    public static function get_available_gateways(string $component, string $paymentarea, int $itemid): array {
+        $gateways = [];
+
+        $payable = static::get_payable($component, $paymentarea, $itemid);
+        $account = new account($payable->get_account_id());
+
+        if (!$account->get('id') || !$account->get('enabled')) {
+            return $gateways;
+        }
+
+        $currency = $payable->get_currency();
+        foreach ($account->get_gateways() as $plugin => $gateway) {
+            if (!$gateway->get('enabled')) {
+                continue;
+            }
+            /** @var gateway $classname */
+            $classname = '\paygw_' . $plugin . '\gateway';
+
+            $currencies = component_class_callback($classname, 'get_supported_currencies', [], []);
+            if (in_array($currency, $currencies)) {
+                $gateways[] = $plugin;
+            }
+        }
+
+        return $gateways;
+    }
+
+    /**
+     * Rounds the cost based on the currency fractional digits, can also apply surcharge
+     *
+     * @param float $amount amount in the currency units
+     * @param string $currency currency, used for calculating the number of fractional digits
+     * @param float $surcharge surcharge in percents
+     * @return float
+     */
+    public static function get_rounded_cost(float $amount, string $currency, float $surcharge = 0): float {
+        $amount = $amount * (100 + $surcharge) / 100;
+
+        $locale = get_string('localecldr', 'langconfig');
+        $fmt = \NumberFormatter::create($locale, \NumberFormatter::CURRENCY);
+        $localisedcost = numfmt_format_currency($fmt, $amount, $currency);
+
+        return numfmt_parse_currency($fmt, $localisedcost, $currency);
+    }
+
+    /**
+     * Returns human-readable amount with correct number of fractional digits and currency indicator, can also apply surcharge
+     *
+     * @param float $amount amount in the currency units
+     * @param string $currency The currency
+     * @param float $surcharge surcharge in percents
+     * @return string
+     */
+    public static function get_cost_as_string(float $amount, string $currency, float $surcharge = 0): string {
+        $amount = $amount * (100 + $surcharge) / 100;
+
+        $locale = get_string('localecldr', 'langconfig');
+        $fmt = \NumberFormatter::create($locale, \NumberFormatter::CURRENCY);
+        $localisedcost = numfmt_format_currency($fmt, $amount, $currency);
+
+        return $localisedcost;
+    }
+
+    /**
+     * Returns the percentage of surcharge that is applied when using a gateway
+     *
+     * @param string $gateway Name of the gateway
+     * @return float
+     */
+    public static function get_gateway_surcharge(string $gateway): float {
+        return (float)get_config('paygw_' . $gateway, 'surcharge');
+    }
+
+    /**
+     * Returns the attributes to place on a pay button.
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An internal identifier that is used by the component
+     * @param string $description Description of the payment
+     * @return array
+     */
+    public static function gateways_modal_link_params(string $component, string $paymentarea, int $itemid,
+            string $description): array {
+
+        $payable = static::get_payable($component, $paymentarea, $itemid);
+        $successurl = static::get_success_url($component, $paymentarea, $itemid);
+
+        return [
+            'id' => 'gateways-modal-trigger',
+            'role' => 'button',
+            'data-action' => 'core_payment/triggerPayment',
+            'data-component' => $component,
+            'data-paymentarea' => $paymentarea,
+            'data-itemid' => $itemid,
+            'data-cost' => static::get_cost_as_string($payable->get_amount(), $payable->get_currency()),
+            'data-description' => $description,
+            'data-successurl' => $successurl->out(false),
+        ];
+    }
+
+    /**
+     * Get the name of the service provider class
+     *
+     * @param string $component The component
+     * @return string
+     * @throws \coding_exception
+     */
+    private static function get_service_provider_classname(string $component) {
+        $providerclass = "$component\\payment\\service_provider";
+
+        if (class_exists($providerclass)) {
+            $rc = new \ReflectionClass($providerclass);
+            if ($rc->implementsInterface(local\callback\service_provider::class)) {
+                return $providerclass;
+            }
+        }
+
+        throw new \coding_exception("$component does not have an eligible implementation of payment service_provider.");
+    }
+
+    /**
+     * Asks the payable from the related component.
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An internal identifier that is used by the component
+     * @return local\entities\payable
+     */
+    public static function get_payable(string $component, string $paymentarea, int $itemid): local\entities\payable {
+        $providerclass = static::get_service_provider_classname($component);
+
+        return component_class_callback($providerclass, 'get_payable', [$paymentarea, $itemid]);
+    }
+
+    /**
+     * Fetches the URL of the page the user should be redirected to from the related component
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the component
+     * @return \moodle_url
+     */
+    public static function get_success_url(string $component, string $paymentarea, int $itemid): \moodle_url {
+        $providerclass = static::get_service_provider_classname($component);
+        return component_class_callback($providerclass, 'get_success_url', [$paymentarea, $itemid]);
+    }
+
+    /**
+     * Returns the gateway configuration for given component and gateway
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the component
+     * @param string $gatewayname The gateway name
+     * @return array
+     * @throws \moodle_exception
+     */
+    public static function get_gateway_configuration(string $component, string $paymentarea, int $itemid,
+            string $gatewayname): array {
+        $payable = self::get_payable($component, $paymentarea, $itemid);
+        $gateway = null;
+        $account = new account($payable->get_account_id());
+        if ($account && $account->get('enabled')) {
+            $gateway = $account->get_gateways()[$gatewayname] ?? null;
+        }
+        if (!$gateway) {
+            throw new \moodle_exception('gatewaynotfound', 'payment');
+        }
+        return $gateway->get_configuration();
+    }
+
+    /**
+     * Delivers what the user paid for.
+     *
+     * @uses \core_payment\local\callback\service_provider::deliver_order()
+     *
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An internal identifier that is used by the component
+     * @param int $paymentid payment id as inserted into the 'payments' table, if needed for reference
+     * @param int $userid The userid the order is going to deliver to
+     * @return bool Whether successful or not
+     */
+    public static function deliver_order(string $component, string $paymentarea, int $itemid, int $paymentid, int $userid): bool {
+        $providerclass = static::get_service_provider_classname($component);
+        $result = component_class_callback($providerclass, 'deliver_order', [$paymentarea, $itemid, $paymentid, $userid]);
+
+        return $result;
+    }
+
+    /**
+     * Stores essential information about the payment and returns the "id" field of the payment record in DB.
+     * Each payment gateway may then store the additional information their way.
+     *
+     * @param int $accountid Account id
+     * @param string $component Name of the component that the paymentarea and itemid belong to
+     * @param string $paymentarea Payment area
+     * @param int $itemid An internal identifier that is used by the component
+     * @param int $userid Id of the user who is paying
+     * @param float $amount Amount of payment
+     * @param string $currency Currency of payment
+     * @param string $gateway The gateway that is used for the payment
+     * @return int
+     */
+    public static function save_payment(int $accountid, string $component, string $paymentarea, int $itemid, int $userid,
+            float $amount, string $currency, string $gateway): int {
+        global $DB;
+
+        $record = new \stdClass();
+        $record->component = $component;
+        $record->paymentarea = $paymentarea;
+        $record->itemid = $itemid;
+        $record->userid = $userid;
+        $record->amount = $amount;
+        $record->currency = $currency;
+        $record->gateway = $gateway;
+        $record->accountid = $accountid;
+        $record->timecreated = $record->timemodified = time();
+
+        $id = $DB->insert_record('payments', $record);
+
+        return $id;
+    }
+
+    /**
+     * This functions adds the settings that are common for all payment gateways.
+     *
+     * @param \admin_settingpage $settings The settings object
+     * @param string $gateway The gateway name prefixed with paygw_
+     */
+    public static function add_common_gateway_settings(\admin_settingpage $settings, string $gateway): void {
+        $settings->add(new \admin_setting_configtext($gateway . '/surcharge', get_string('surcharge', 'core_payment'),
+                get_string('surcharge_desc', 'core_payment'), 0, PARAM_INT));
+
+    }
+
+    /**
+     * Save a new or edited payment account (used in management interface)
+     *
+     * @param \stdClass $data
+     * @return account
+     */
+    public static function save_payment_account(\stdClass $data): account {
+
+        if (empty($data->id)) {
+            $account = new account(0, $data);
+            $account->save();
+            account_created::create_from_account($account)->trigger();
+        } else {
+            $account = new account($data->id);
+            $account->from_record($data);
+            $account->save();
+            account_updated::create_from_account($account)->trigger();
+        }
+
+        return $account;
+    }
+
+    /**
+     * Delete a payment account (used in management interface)
+     *
+     * @param account $account
+     */
+    public static function delete_payment_account(account $account): void {
+        global $DB;
+        if ($DB->record_exists('payments', ['accountid' => $account->get('id')])) {
+            $account->set('archived', 1);
+            $account->save();
+            account_updated::create_from_account($account, ['archived' => 1])->trigger();
+            return;
+        }
+
+        foreach ($account->get_gateways(false) as $gateway) {
+            if ($gateway->get('id')) {
+                $gateway->delete();
+            }
+        }
+        $event = account_deleted::create_from_account($account);
+        $account->delete();
+        $event->trigger();
+    }
+
+    /**
+     * Restore archived payment account (used in management interface)
+     *
+     * @param account $account
+     */
+    public static function restore_payment_account(account $account): void {
+        $account->set('archived', 0);
+        $account->save();
+        account_updated::create_from_account($account, ['restored' => 1])->trigger();
+    }
+
+    /**
+     * Save a payment gateway linked to an existing account (used in management interface)
+     *
+     * @param \stdClass $data
+     * @return account_gateway
+     */
+    public static function save_payment_gateway(\stdClass $data): account_gateway {
+        if (empty($data->id)) {
+            $records = account_gateway::get_records(['accountid' => $data->accountid, 'gateway' => $data->gateway]);
+            if ($records) {
+                $gateway = reset($records);
+            } else {
+                $gateway = new account_gateway(0, $data);
+            }
+        } else {
+            $gateway = new account_gateway($data->id);
+        }
+        unset($data->accountid, $data->gateway, $data->id);
+        $gateway->from_record($data);
+
+        $account = $gateway->get_account();
+        $gateway->save();
+        account_updated::create_from_account($account)->trigger();
+        return $gateway;
+    }
+
+    /**
+     * Returns the list of payment accounts in the given context (used in management interface)
+     *
+     * @param \context $context
+     * @return account[]
+     */
+    public static function get_payment_accounts_to_manage(\context $context, bool $showarchived = false): array {
+        $records = account::get_records(['contextid' => $context->id] + ($showarchived ? [] : ['archived' => 0]));
+        \core_collator::asort_objects_by_method($records, 'get_formatted_name');
+        return $records;
+    }
+
+    /**
+     * Get list of accounts available in the given context
+     *
+     * @param \context $context
+     * @return array
+     */
+    public static function get_payment_accounts_menu(\context $context): array {
+        global $DB;
+        [$sql, $params] = $DB->get_in_or_equal($context->get_parent_context_ids(true));
+        $accounts = array_filter(account::get_records_select('contextid '.$sql, $params), function($account) {
+            return $account->is_available() && !$account->get('archived');
+        });
+        return array_map(function($account) {
+            return $account->get_formatted_name();
+        }, $accounts);
+    }
+}

payment/classes/local/callback/service_provider.php

@@ -0,0 +1,67 @@
+<?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/>.
+
+/**
+ * This file contains the \core_payment\local\local\callback\service_provider interface.
+ *
+ * Plugins should implement this if they use payment subsystem.
+ *
+ * @package core_payment
+ * @copyright 2020 Shamim Rezaie <shamim@moodle.com>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\local\callback;
+
+/**
+ * The service_provider interface for plugins to provide callbacks which are needed by the payment subsystem.
+ *
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+interface service_provider {
+
+    /**
+     * Callback function that returns the cost of the given item in the specified payment area,
+     * along with the accountid that payments are paid to.
+     *
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the plugin
+     * @return \core_payment\local\entities\payable
+     */
+    public static function get_payable(string $paymentarea, int $itemid): \core_payment\local\entities\payable;
+
+    /**
+     * Callback function that returns the URL of the page the user should be redirected to in the case of a successful payment.
+     *
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the plugin
+     * @return \moodle_url
+     */
+    public static function get_success_url(string $paymentarea, int $itemid): \moodle_url;
+
+    /**
+     * Callback function that delivers what the user paid for to them.
+     *
+     * @param string $paymentarea Payment area
+     * @param int $itemid An identifier that is known to the plugin
+     * @param int $paymentid payment id as inserted into the 'payments' table, if needed for reference
+     * @param int $userid The userid the order is going to deliver to
+     *
+     * @return bool Whether successful or not
+     */
+    public static function deliver_order(string $paymentarea, int $itemid, int $paymentid, int $userid): bool;
+}

payment/classes/local/entities/payable.php

@@ -0,0 +1,70 @@
+<?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/>.
+
+/**
+ * The payable class.
+ *
+ * @package    core_payment
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\local\entities;
+
+/**
+ * The payable class.
+ *
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class payable {
+    private $amount;
+    private $currency;
+    private $accountid;
+
+    public function __construct(float $amount, string $currency, int $accountid) {
+        $this->amount = $amount;
+        $this->currency = $currency;
+        $this->accountid = $accountid;
+    }
+
+    /**
+     * Get the amount of the payable cost.
+     *
+     * @return float
+     */
+    public function get_amount(): float {
+        return $this->amount;
+    }
+
+    /**
+     * Get the currency of the payable cost.
+     *
+     * @return string
+     */
+    public function get_currency(): string {
+        return $this->currency;
+    }
+
+    /**
+     * Get the id of the payment account the cost is payable to.
+     *
+     * @return int
+     */
+    public function get_account_id(): int {
+        return $this->accountid;
+    }
+}

payment/classes/privacy/consumer_provider.php

@@ -0,0 +1,69 @@
+<?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/>.
+
+namespace core_payment\privacy;
+
+use core_privacy\local\request\approved_contextlist;
+use core_privacy\local\request\approved_userlist;
+use core_privacy\local\request\userlist;
+use context;
+
+interface consumer_provider {
+
+    /**
+     * Return contextid for the provided payment data
+     *
+     * @param string $paymentarea Payment area
+     * @param int $itemid The item id
+     * @return int|null
+     */
+    public static function get_contextid_for_payment(string $paymentarea, int $itemid): ?int;
+
+    /**
+     * Get the list of users who have data within a context.
+     *
+     * @param userlist $userlist The userlist containing the list of users who have data in this context/plugin combination.
+     */
+    public static function get_users_in_context(userlist $userlist);
+
+    /**
+     * Export all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts to export information for.
+     */
+    public static function export_user_data(approved_contextlist $contextlist);
+
+    /**
+     * Delete all data for all users in the specified context.
+     *
+     * @param context $context The specific context to delete data for.
+     */
+    public static function delete_data_for_all_users_in_context(context $context);
+
+    /**
+     * Delete all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts and user information to delete information for.
+     */
+    public static function delete_data_for_user(approved_contextlist $contextlist);
+
+    /**
+     * Delete multiple users within a single context.
+     *
+     * @param approved_userlist $userlist The approved context and user information to delete information for.
+     */
+    public static function delete_data_for_users(approved_userlist $userlist);
+}

payment/classes/privacy/paygw_provider.php

@@ -0,0 +1,37 @@
+<?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/>.
+
+namespace core_payment\privacy;
+
+interface paygw_provider {
+
+    /**
+     * Export all user data for the specified payment record, and the given context.
+     *
+     * @param \context $context Context
+     * @param array $subcontext The location within the current context that the payment data belongs
+     * @param \stdClass $payment The payment record
+     */
+    public static function export_payment_data(\context $context, array $subcontext, \stdClass $payment);
+
+    /**
+     * Delete all user data related to the given payments.
+     *
+     * @param string $paymentsql SQL query that selects payment.id field for the payments
+     * @param array $paymentparams Array of parameters for $paymentsql
+     */
+    public static function delete_data_for_payment_sql(string $paymentsql, array $paymentparams);
+}

payment/classes/privacy/provider.php

@@ -0,0 +1,338 @@
+<?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/>.
+
+/**
+ * Privacy Subsystem implementation for core_payment.
+ *
+ * @package    core_payment
+ * @category   privacy
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\privacy;
+
+use core_privacy\local\metadata\collection;
+use core_privacy\local\request\approved_contextlist;
+use core_privacy\local\request\approved_userlist;
+use core_privacy\local\request\contextlist;
+use core_privacy\local\request\transform;
+use core_privacy\local\request\userlist;
+use core_privacy\local\request\writer;
+use core_payment\helper as payment_helper;
+
+/**
+ * Privacy Subsystem implementation for core_payment.
+ *
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class provider implements
+    // This component has data.
+    // We need to return all payment information where the user is
+    // listed in the payment.userid field.
+    // We may also need to fetch this informtion from individual plugins in some cases.
+    // e.g. to fetch the full and other gateway-specific meta-data.
+    \core_privacy\local\metadata\provider,
+
+    // This is a subsysytem which provides information to core.
+    \core_privacy\local\request\subsystem\provider,
+
+    // This is a subsysytem which provides information to plugins.
+    \core_privacy\local\request\subsystem\plugin_provider,
+
+    // This plugin is capable of determining which users have data within it.
+    \core_privacy\local\request\core_userlist_provider,
+
+    // This plugin is capable of determining which users have data within it for the plugins it provides data to.
+    \core_privacy\local\request\shared_userlist_provider
+{
+
+    /**
+     * Returns meta data about this system.
+     *
+     * @param   collection $collection The initialised collection to add items to.
+     * @return  collection A listing of user data stored through this system.
+     */
+    public static function get_metadata(collection $collection): collection {
+        // The 'payments' table contains data about payments.
+        $collection->add_database_table('payments', [
+            'userid'       => 'privacy:metadata:database:payments:userid',
+            'amount'       => 'privacy:metadata:database:payments:amount',
+            'currency'     => 'privacy:metadata:database:payments:currency',
+            'gateway'      => 'privacy:metadata:database:payments:gateway',
+            'timecreated'  => 'privacy:metadata:database:payments:timecreated',
+            'timemodified' => 'privacy:metadata:database:payments:timemodified',
+        ], 'privacy:metadata:database:payments');
+
+        return $collection;
+    }
+
+    /**
+     * Get the list of users who have data within a context.
+     *
+     * @param   int $userid The user to search.
+     * @return  contextlist The contextlist containing the list of contexts used in this plugin.
+     */
+    public static function get_contexts_for_userid(int $userid): contextlist {
+        global $DB;
+
+        $contextids = [];
+        $payments = $DB->get_recordset('payments', ['userid' => $userid]);
+        foreach ($payments as $payment) {
+            $contextids[] = \core_privacy\manager::component_class_callback(
+                $payment->component,
+                consumer_provider::class,
+                'get_contextid_for_payment',
+                [$payment->paymentarea, $payment->itemid]
+            ) ?: SYSCONTEXTID;
+        }
+        $payments->close();
+
+        $contextlist = new contextlist();
+
+        if (!empty($contextids)) {
+            [$insql, $inparams] = $DB->get_in_or_equal(array_unique($contextids), SQL_PARAMS_NAMED);
+            $contextlist->add_from_sql("SELECT id FROM {context} WHERE id {$insql}", $inparams);
+        }
+
+        return $contextlist;
+    }
+
+    /**
+     * Get the list of users who have data within a context.
+     *
+     * @param   userlist    $userlist   The userlist containing the list of users who have data in this context/plugin combination.
+     */
+    public static function get_users_in_context(userlist $userlist) {
+        global $DB;
+
+        $providers = static::get_consumer_providers();
+
+        foreach ($providers as $provider) {
+            $provider::get_users_in_context($userlist);
+        }
+
+        // Orphaned payments.
+        $context = $userlist->get_context();
+        if ($context instanceof \context_system) {
+            [$notinsql, $notinparams] = $DB->get_in_or_equal($providers, SQL_PARAMS_NAMED, 'param', false);
+            $sql = "SELECT p.userid
+                      FROM {payments} p
+                     WHERE component $notinsql";
+
+            $userlist->add_from_sql('userid', $sql, $notinparams);
+        }
+    }
+
+    /**
+     * Export all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts to export information for.
+     */
+    public static function export_user_data(approved_contextlist $contextlist) {
+        global $DB;
+
+        $providers = static::get_consumer_providers();
+
+        foreach ($providers as $provider) {
+            $provider::export_user_data($contextlist);
+        }
+
+        // Orphaned payments.
+        if (in_array(SYSCONTEXTID, $contextlist->get_contextids())) {
+            [$notinsql, $notinparams] = $DB->get_in_or_equal($providers, SQL_PARAMS_NAMED, 'param', false);
+            $params = ['userid' => $contextlist->get_user()->id] + $notinparams;
+            $orphanedpayments = $DB->get_records_sql(
+                "SELECT *
+                   FROM {payments}
+                  WHERE userid = :userid AND component $notinsql",
+                $params
+            );
+
+            foreach ($orphanedpayments as $payment) {
+                static::export_payment_data_for_user_in_context(
+                    \context_system::instance(),
+                    [''],
+                    $payment->userid,
+                    $payment->component,
+                    $payment->paymentarea,
+                    $payment->itemid
+                );
+            }
+        }
+    }
+
+    /**
+     * Delete all data for all users in the specified context.
+     *
+     * @param context $context The specific context to delete data for.
+     */
+    public static function delete_data_for_all_users_in_context(\context $context) {
+        global $DB;
+
+        $providers = static::get_consumer_providers();
+
+        foreach ($providers as $provider) {
+            $provider::delete_data_for_all_users_in_context($context);
+        }
+
+        // Orphaned payments.
+        if ($context instanceof \context_system) {
+            [$notinsql, $params] = $DB->get_in_or_equal($providers, SQL_PARAMS_NAMED, 'param', false);
+            $paymentsql = "SELECT id FROM {payments} WHERE component $notinsql";
+
+            static::delete_data_for_payment_sql($paymentsql, $params);
+        }
+    }
+
+    /**
+     * Delete all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts and user information to delete information for.
+     */
+    public static function delete_data_for_user(approved_contextlist $contextlist) {
+        global $DB;
+
+        $providers = static::get_consumer_providers();
+
+        foreach ($providers as $provider) {
+            $provider::delete_data_for_user($contextlist);
+        }
+
+        // Orphaned payments.
+        if (in_array(SYSCONTEXTID, $contextlist->get_contextids())) {
+            [$notinsql, $notinparams] = $DB->get_in_or_equal($providers, SQL_PARAMS_NAMED, 'param', false);
+            $paymentsql = "SELECT id
+                             FROM {payments}
+                            WHERE userid = :userid AND component $notinsql";
+            $paymentparams = ['userid' => $contextlist->get_user()->id] + $notinparams;
+
+            static::delete_data_for_payment_sql($paymentsql, $paymentparams);
+        }
+    }
+
+    /**
+     * Delete multiple users within a single context.
+     *
+     * @param   approved_userlist   $userlist   The approved context and user information to delete information for.
+     */
+    public static function delete_data_for_users(approved_userlist $userlist) {
+        global $DB;
+
+        $providers = static::get_consumer_providers();
+
+        foreach ($providers as $provider) {
+            $provider::delete_data_for_users($userlist);
+        }
+
+        // Orphaned payments.
+        if ($userlist->get_context() instanceof \context_system) {
+            [$notinsql, $notinparams] = $DB->get_in_or_equal($providers, SQL_PARAMS_NAMED, 'param', false);
+            [$usersql, $userparams] = $DB->get_in_or_equal($userlist->get_userids(), SQL_PARAMS_NAMED);
+
+            $paymentsql = "SELECT id
+                             FROM {payments}
+                            WHERE component $notinsql AND userid $usersql";
+            $paymentparams = $notinparams + $userparams;
+
+            static::delete_data_for_payment_sql($paymentsql, $paymentparams);
+        }
+    }
+
+    /**
+     * Returns the list of plugins that use the payment subsystem and implement the consumer_provider interface.
+     *
+     * @return string[] provider class names
+     */
+    private static function get_consumer_providers(): array {
+        $providers = [];
+        foreach (array_keys(\core_component::get_plugin_types()) as $plugintype) {
+            $potentialproviders = \core_component::get_plugin_list_with_class($plugintype, 'privacy\provider');
+            foreach ($potentialproviders as $potentialprovider) {
+                if (is_a($potentialprovider, consumer_provider::class, true)) {
+                    $providers[] = $potentialprovider;
+                }
+            }
+        }
+        return $providers;
+    }
+
+    /**
+     * Export all user data for the specified user, in the specified context.
+     *
+     * @param \context $context The context that the payment belongs to
+     * @param string[] $subpath Sub-path to be used during export
+     * @param int $userid User id
+     * @param string $component Component name
+     * @param string $paymentarea Payment area
+     * @param int $itemid An internal identifier that is used by the component
+     */
+    public static function export_payment_data_for_user_in_context(\context $context, array $subpath, int $userid,
+            string $component, string $paymentarea, int $itemid) {
+        global $DB;
+
+        $payments = $DB->get_records('payments', [
+            'component' => $component,
+            'paymentarea' => $paymentarea,
+            'itemid' => $itemid,
+            'userid' => $userid,
+        ]);
+
+        foreach ($payments as $payment) {
+            $data = (object) [
+                'userid'       => transform::user($payment->userid),
+                'amount'       => payment_helper::get_cost_as_string($payment->amount, $payment->currency),
+                'timecreated'  => transform::datetime($payment->timecreated),
+                'timemodified' => transform::datetime($payment->timemodified),
+            ];
+            $subcontext = array_merge(
+                [get_string('payments', 'payment')],
+                $subpath,
+                ['payment-' . $payment->id]
+            );
+            writer::with_context($context)->export_data(
+                $subcontext,
+                $data
+            );
+            \core_privacy\manager::component_class_callback(
+                'paygw_' . $payment->gateway,
+                paygw_provider::class,
+                'export_payment_data',
+                [$context, $subcontext, $payment]
+            );
+        }
+    }
+
+    /**
+     * Delete all user data related to the given payments.
+     *
+     * @param string $paymentsql SQL query that selects payment.id field for the payments
+     * @param array $paymentparams Array of parameters for $paymentsql
+     */
+    public static function delete_data_for_payment_sql(string $paymentsql, array $paymentparams) {
+        global $DB;
+
+        \core_privacy\manager::plugintype_class_callback(
+            'paygw',
+            paygw_provider::class,
+            'delete_data_for_payment_sql',
+            [$paymentsql, $paymentparams]
+        );
+
+        $DB->delete_records_subquery('payments', 'id', 'id', $paymentsql, $paymentparams);
+    }
+}