Merge branch 'develop'

16 files changed, 1907 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7b1fb72
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,39 @@
+# This file specifies intentionally untracked files that all Moodle git
+# repositories should ignore. It is recommended not to modify this file in your
+# local clone. Instead, use .git/info/exclude and add new records there as
+# needed.
+#
+# Example: if you deploy a contributed plugin mod/foobar into your site, put
+# the following line into .git/info/exclude file in your Moodle clone:
+# /mod/foobar/
+#
+# See gitignore(5) man page for more details
+#
+/config.php
+/lib/editor/tinymce/extra/tools/temp/
+*~
+*.swp
+/tags
+/TAGS
+/cscope.*
+/.patches/
+/.idea/
+/nbproject/
+CVS
+.DS_Store
+/.settings/
+/.project
+/.buildpath
+/.cache
+phpunit.xml
+# Composer support. Do not ignore composer.json, or composer.lock. These should be shipped by us.
+composer.phar
+/vendor/
+/behat.yml
+*/yui/build/*/*-coverage.js
+/lib/yuilib/*/build/*/*-coverage.js
+# lib/yuilib/version/module/module-coverage.js
+/lib/yuilib/*/*/*-coverage.js
+atlassian-ide-plugin.xml
+/node_modules/
+/build/
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..6270ce6
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,76 @@
+language: php
+sudo: true
+
+addons:
+  firefox: "latest-esr"
+  postgresql: "9.6"
+  apt:
+    packages:
+      - "oracle-java8-installer"
+      - "oracle-java8-set-default"
+
+cache:
+  directories:
+    - "$HOME/.composer/cache"
+    - "$HOME/.npm"
+
+php:
+  - 7.0
+  - 7.1
+  - 7.2
+
+env:
+  global:
+    - MOODLE_BRANCH=MOODLE_35_STABLE
+  matrix:
+    - DB=mysqli
+    - DB=pgsql
+
+before_install:
+  - phpenv config-rm xdebug.ini
+  - nvm install 8.9
+  - nvm use 8.9
+  - cd ../..
+  - composer selfupdate
+  - composer create-project -n --no-dev --prefer-dist moodlerooms/moodle-plugin-ci ci ^2
+  - export PATH="$(cd ci/bin; pwd):$(cd ci/vendor/bin; pwd):$PATH"
+
+install:
+  - moodle-plugin-ci install
+
+script:
+  - moodle-plugin-ci phplint
+  - moodle-plugin-ci phpcpd
+  - moodle-plugin-ci phpmd
+  - moodle-plugin-ci codechecker
+  - moodle-plugin-ci validate
+  - moodle-plugin-ci savepoints
+  - moodle-plugin-ci mustache
+  - moodle-plugin-ci grunt
+  - moodle-plugin-ci phpunit
+  - moodle-plugin-ci behat
+
+jobs:
+  include:
+    - stage: test old
+      env: DB=mysqli MOODLE_BRANCH=MOODLE_33_STABLE
+      php: 5.6
+
+    - stage: deploy
+      php: 7.2
+
+      before_deploy:
+        - cd "$TRAVIS_REPO_SLUG"
+        - git stash --all
+        - /bin/sh build.sh
+
+      deploy:
+        api_key: $GITHUB_PROJECT_TOKEN
+        email: "info@valentineus.link"
+        file: "../build/*.zip"
+        file_glob: true
+        provider: releases
+        skip_cleanup: true
+
+        on:
+          tags: true
diff --git a/LICENSE.txt b/LICENSE.txt
index e69de29..48bdb12 100644
--- a/LICENSE.txt
+++ b/LICENSE.txt
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
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+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
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+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
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+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    tool_apisiteadmins. Extends the standard administrator management API.
+    Copyright (C) 2018  "Valentin Popov" <info@valentineus.link>
+
+    This program 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.
+
+    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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    tool_apisiteadmins  Copyright (C) 2018  "Valentin Popov"
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
\ No newline at end of file
diff --git a/README.md b/README.md
index e69de29..1b7c2d8 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,124 @@
+# Advanced API administration management
+
+[![GitHub Release](https://img.shields.io/github/release/valentineus/moodle-tool_apisiteadmins.svg)](https://github.com/valentineus/moodle-tool_apisiteadmins/releases)
+[![Build Status](https://travis-ci.org/valentineus/moodle-tool_apisiteadmins.svg?branch=master)](https://travis-ci.org/valentineus/moodle-tool_apisiteadmins)
+[![Codacy Badge](https://api.codacy.com/project/badge/Grade/eea97c9ae1f54cc0ac7cb6f53966b98c)](https://www.codacy.com/app/valentineus/moodle-tool_apisiteadmins)
+
+The plug-in extends and complements the system API for managing administrators.
+Main library is well documented and tested.
+Can be used by third-party developers for development.
+
+In addition, the plugin adds functions for
+[Web services](https://docs.moodle.org/dev/Web_services)
+that interact with the list of administrators.
+For documentation on Web services, see Moodle:
+`https://example.domain/admin/webservice/documentation.php`
+
+## Installation
+
+Get the installation package in any of the available methods:
+
+* [GitHub Releases](https://github.com/valentineus/moodle-tool_apisiteadmins/releases).
+* [Compilation from the source code](#build).
+
+In Moodle in the administration panel go to the "Plugins" section and make a
+standard installation of the plug-in.
+
+## Testing
+
+* Perform the installation of `PHPUnit` and configure the test environment.
+Use the
+[official guide](https://docs.moodle.org/dev/PHPUnit#Installation_of_PHPUnit_via_Composer)
+for detailed information.
+
+* To run the plugin test, use the following commands:
+
+```bash
+# Run all tests
+php vendor/bin/phpunit --testdox --group tool_apisiteadmins
+
+# Or running individual tests
+php vendor/bin/phpunit --testdox tool_apisiteadmins_api_testcase admin/tool/apisiteadmins/tests/api_test.php
+php vendor/bin/phpunit --testdox tool_apisiteadmins_external_testcase admin/tool/apisiteadmins/tests/external_test.php
+```
+
+## Build
+
+Self-assembly package is as follows:
+
+* Clone the repository:
+
+```bash
+git clone https://github.com/valentineus/moodle-tool_apisiteadmins.git apisiteadmins
+```
+
+* Run the build script:
+
+```bash
+cd ./apisiteadmins
+/bin/sh build.sh
+```
+
+## API
+
+### tool_apisiteadmins::add_user( $userid ) ⇒`Boolean`
+
+Adds a user to the list of administrators.
+
+| Param | Type | Description |
+| ------- | -------- | -------------- |
+| $userid | `Number` | System user ID |
+
+Example:
+
+```php
+require_once($CFG->dirroot . "/admin/tool/apisiteadmins/lib.php");
+
+$userid = 2;
+tool_apisiteadmins::add_user($userid);
+// result: true
+```
+
+### tool_apisiteadmins::remove_user( $userid ) ⇒`Boolean`
+
+Removes a user from the list of administrators.
+
+| Param | Type | Description |
+| ------- | -------- | -------------- |
+| $userid | `Number` | System user ID |
+
+Example:
+
+```php
+require_once($CFG->dirroot . "/admin/tool/apisiteadmins/lib.php");
+
+$userid = 2;
+tool_apisiteadmins::remove_user($userid);
+// result: true
+```
+
+### tool_apisiteadmins::set_main( $userid ) ⇒`Boolean`
+
+Registers the user as the primary administrator.
+
+| Param | Type | Description |
+| ------- | -------- | -------------- |
+| $userid | `Number` | System user ID |
+
+Example:
+
+```php
+require_once($CFG->dirroot . "/admin/tool/apisiteadmins/lib.php");
+
+$userid = 2;
+tool_apisiteadmins::set_main($userid);
+// result: true
+```
+
+## License
+
+<img height="256px" alt="GNU Banner" src="https://www.gnu.org/graphics/runfreegnu.png" />
+
+[GNU GPLv3](LICENSE.txt).
+Copyright (c)
+[Valentin Popov](mailto:info@valentineus.link).
diff --git a/build.sh b/build.sh
new file mode 100755
index 0000000..fcd294f
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+# Author:       Valentin Popov
+# Email:        info@valentineus.link
+# Date:         2018-06-11
+# Usage:        /bin/sh ./build.sh
+# Description:  Build the final package for installation in Moodle.
+
+# Updating the Environment
+PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+export PATH="$PATH:/usr/local/scripts"
+
+# Current project
+PROJECT="tool_apisiteadmins"
+
+# Defining directories
+DIRECTORY="$(pwd)"
+NAMEDIR="$(basename $DIRECTORY)"
+TMPDIR="$(mktemp --directory)"
+
+# Creating a Temporary Directory
+cp --recursive --verbose "../$NAMEDIR" "$TMPDIR/$PROJECT"
+mkdir --parents --verbose "$DIRECTORY/build"
+cd "$TMPDIR"
+
+# Creating an archive
+zip -9 -r "$DIRECTORY/build/$PROJECT.zip" "$PROJECT" \
+    -x "$PROJECT/.git*" \
+    -x "$PROJECT/.travis.yml" \
+    -x "$PROJECT/build*"
+
+# End of work
+exit 0
diff --git a/classes/event/administrator_added.php b/classes/event/administrator_added.php
new file mode 100644
index 0000000..dd1aab2
--- /dev/null
+++ b/classes/event/administrator_added.php
@@ -0,0 +1,59 @@
+<?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/>.
+
+/**
+ * Registration of the system of events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+namespace tool_apisiteadmins\event;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Defines how to work with events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class administrator_added extends \core\event\base {
+    /**
+     * Init method.
+     */
+    protected function init() {
+        $this->data["crud"] = "c";
+        $this->data["edulevel"] = self::LEVEL_OTHER;
+        $this->context = \context_system::instance();
+    }
+
+    /**
+     * Return localised event name.
+     */
+    public static function get_name() {
+        return new \lang_string("sitelogs", "moodle");
+    }
+
+    /**
+     * Returns description of what happened.
+     */
+    public function get_description() {
+        return "The user '$this->relateduserid' was added to the list of administrators.";
+    }
+}
diff --git a/classes/event/administrator_changed.php b/classes/event/administrator_changed.php
new file mode 100644
index 0000000..4280d1d
--- /dev/null
+++ b/classes/event/administrator_changed.php
@@ -0,0 +1,59 @@
+<?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/>.
+
+/**
+ * Registration of the system of events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+namespace tool_apisiteadmins\event;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Defines how to work with events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class administrator_changed extends \core\event\base {
+    /**
+     * Init method.
+     */
+    protected function init() {
+        $this->data["crud"] = "u";
+        $this->data["edulevel"] = self::LEVEL_OTHER;
+        $this->context = \context_system::instance();
+    }
+
+    /**
+     * Return localised event name.
+     */
+    public static function get_name() {
+        return new \lang_string("sitelogs", "moodle");
+    }
+
+    /**
+     * Returns description of what happened.
+     */
+    public function get_description() {
+        return "The user '$this->relateduserid' was appointed the main administrator of the site.";
+    }
+}
diff --git a/classes/event/administrator_deleted.php b/classes/event/administrator_deleted.php
new file mode 100644
index 0000000..81b89b9
--- /dev/null
+++ b/classes/event/administrator_deleted.php
@@ -0,0 +1,59 @@
+<?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/>.
+
+/**
+ * Registration of the system of events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+namespace tool_apisiteadmins\event;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Defines how to work with events.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class administrator_deleted extends \core\event\base {
+    /**
+     * Init method.
+     */
+    protected function init() {
+        $this->data["crud"] = "d";
+        $this->data["edulevel"] = self::LEVEL_OTHER;
+        $this->context = \context_system::instance();
+    }
+
+    /**
+     * Return localised event name.
+     */
+    public static function get_name() {
+        return new \lang_string("sitelogs", "moodle");
+    }
+
+    /**
+     * Returns description of what happened.
+     */
+    public function get_description() {
+        return "The user '$this->relateduserid' was removed from the list of administrators.";
+    }
+}
diff --git a/db/services.php b/db/services.php
new file mode 100644
index 0000000..7212a72
--- /dev/null
+++ b/db/services.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/>.
+
+/**
+ * Registers external functions.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$functions = array(
+    "tool_apisiteadmins_add_to_administrators" => array(
+        "classname"     => "tool_apisiteadmins_external",
+        "classpath"     => "admin/tool/apisiteadmins/externallib.php",
+        "description"   => "Adds a user to the list of administrators.",
+        "methodname"    => "add_to_administrators",
+        "type"          => "write"
+    ),
+
+    "tool_apisiteadmins_remove_from_administrators" => array(
+        "classname"     => "tool_apisiteadmins_external",
+        "classpath"     => "admin/tool/apisiteadmins/externallib.php",
+        "description"   => "Removes a user from the list of administrators.",
+        "methodname"    => "remove_from_administrators",
+        "type"          => "write"
+    ),
+
+    "tool_apisiteadmins_change_main_administrator" => array(
+        "classname"     => "tool_apisiteadmins_external",
+        "classpath"     => "admin/tool/apisiteadmins/externallib.php",
+        "description"   => "Registers the user as the primary administrator.",
+        "methodname"    => "change_main_administrator",
+        "type"          => "write"
+    ),
+
+    "tool_apisiteadmins_get_list_administrators" => array(
+        "classname"     => "tool_apisiteadmins_external",
+        "classpath"     => "admin/tool/apisiteadmins/externallib.php",
+        "description"   => "Gets the list of administrators in the system.",
+        "methodname"    => "get_list_administrators",
+        "type"          => "read"
+    ),
+
+    "tool_apisiteadmins_get_main_administrator" => array(
+        "classname"     => "tool_apisiteadmins_external",
+        "classpath"     => "admin/tool/apisiteadmins/externallib.php",
+        "description"   => "Gets information about the main administrator.",
+        "methodname"    => "get_main_administrator",
+        "type"          => "read"
+    )
+);
diff --git a/externallib.php b/externallib.php
new file mode 100644
index 0000000..3f83eca
--- /dev/null
+++ b/externallib.php
@@ -0,0 +1,237 @@
+<?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/>.
+
+/**
+ * External API.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+require_once(__DIR__ . "/lib.php");
+
+require_once($CFG->dirroot . "/lib/external/externallib.php");
+require_once($CFG->dirroot . "/user/externallib.php");
+require_once($CFG->dirroot . "/user/lib.php");
+
+/**
+ * External functions.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class tool_apisiteadmins_external extends external_api {
+    /**
+     * Returns description of method parameters.
+     *
+     * @return  external_function_parameters
+     * @since   Moodle 2.2
+     */
+    public static function add_to_administrators_parameters() {
+        return new external_function_parameters(
+            array(
+                "userid" => new external_value(PARAM_INT, "ID of the user")
+            )
+        );
+    }
+
+    /**
+     * Adds a user to the list of administrators.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     * @since   Moodle 2.2
+     * @throws  moodle_exception
+     */
+    public static function add_to_administrators($userid) {
+        $parameters = self::validate_parameters(self::add_to_administrators_parameters(), array("userid" => $userid));
+
+        $context = context_system::instance();
+        self::validate_context($context);
+
+        return tool_apisiteadmins::add_user($parameters["userid"]);
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return  external_description
+     * @since   Moodle 2.2
+     */
+    public static function add_to_administrators_returns() {
+        return new external_value(PARAM_BOOL, "Result of execution");
+    }
+
+    /**
+     * Returns description of method parameters.
+     *
+     * @return  external_function_parameters
+     * @since   Moodle 2.2
+     */
+    public static function remove_from_administrators_parameters() {
+        return new external_function_parameters(
+            array(
+                "userid" => new external_value(PARAM_INT, "ID of the user")
+            )
+        );
+    }
+
+    /**
+     * Removes a user from the list of administrators.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     * @since   Moodle 2.2
+     * @throws  moodle_exception
+     */
+    public static function remove_from_administrators($userid) {
+        $parameters = self::validate_parameters(self::remove_from_administrators_parameters(), array("userid" => $userid));
+
+        $context = context_system::instance();
+        self::validate_context($context);
+
+        return tool_apisiteadmins::remove_user($parameters["userid"]);
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return  external_description
+     * @since   Moodle 2.2
+     */
+    public static function remove_from_administrators_returns() {
+        return new external_value(PARAM_BOOL, "Result of execution");
+    }
+
+    /**
+     * Returns description of method parameters.
+     *
+     * @return  external_function_parameters
+     * @since   Moodle 2.2
+     */
+    public static function change_main_administrator_parameters() {
+        return new external_function_parameters(
+            array(
+                "userid" => new external_value(PARAM_INT, "ID of the user")
+            )
+        );
+    }
+
+    /**
+     * Registers the user as the primary administrator.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     * @since   Moodle 2.2
+     * @throws  moodle_exception
+     */
+    public static function change_main_administrator($userid) {
+        $parameters = self::validate_parameters(self::change_main_administrator_parameters(), array("userid" => $userid));
+
+        $context = context_system::instance();
+        self::validate_context($context);
+
+        return tool_apisiteadmins::set_main($parameters["userid"]);
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return  external_description
+     * @since   Moodle 2.2
+     */
+    public static function change_main_administrator_returns() {
+        return new external_value(PARAM_BOOL, "Result of execution");
+    }
+
+    /**
+     * Returns description of method parameters.
+     *
+     * @return  external_function_parameters
+     * @since   Moodle 2.2
+     */
+    public static function get_main_administrator_parameters() {
+        return new external_function_parameters(array());
+    }
+
+    /**
+     * Gets information about the main administrator.
+     *
+     * @return  array           An array of arrays containg user profiles
+     * @since   Moodle 2.2
+     */
+    public static function get_main_administrator() {
+        $context = context_system::instance();
+        self::validate_context($context);
+
+        $result = array();
+        $result[] = user_get_user_details(get_admin());
+
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return  external_description
+     * @since   Moodle 2.2
+     */
+    public static function get_main_administrator_returns() {
+        return new external_multiple_structure(core_user_external::user_description());
+    }
+
+    /**
+     * Returns description of method parameters.
+     *
+     * @return  external_function_parameters
+     * @since   Moodle 2.2
+     */
+    public static function get_list_administrators_parameters() {
+        return new external_function_parameters(array());
+    }
+
+    /**
+     * Gets the list of administrators in the system.
+     *
+     * @return  array           An array of arrays containg user profiles
+     * @since   Moodle 2.2
+     */
+    public static function get_list_administrators() {
+        $context = context_system::instance();
+        self::validate_context($context);
+
+        $result = array();
+        foreach (get_admins() as $user) {
+            $result[] = user_get_user_details($user);
+        }
+
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value.
+     *
+     * @return  external_description
+     * @since   Moodle 2.2
+     */
+    public static function get_list_administrators_returns() {
+        return new external_multiple_structure(core_user_external::user_description());
+    }
+}
diff --git a/lang/en/tool_apisiteadmins.php b/lang/en/tool_apisiteadmins.php
new file mode 100644
index 0000000..0c0ea4b
--- /dev/null
+++ b/lang/en/tool_apisiteadmins.php
@@ -0,0 +1,25 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Strings for component 'tool_apisiteadmins', language 'en'.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+$string["pluginname"] = "Advanced API administration management";
diff --git a/lang/ru/tool_apisiteadmins.php b/lang/ru/tool_apisiteadmins.php
new file mode 100644
index 0000000..830058a
--- /dev/null
+++ b/lang/ru/tool_apisiteadmins.php
@@ -0,0 +1,25 @@
+<?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/>.
+
+/**
+ * Strings for component 'tool_apisiteadmins', language 'ru'.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+$string["pluginname"] = "Расширенный API управления администраторами";
diff --git a/lib.php b/lib.php
new file mode 100644
index 0000000..d41597b
--- /dev/null
+++ b/lib.php
@@ -0,0 +1,137 @@
+<?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/>.
+
+/**
+ * Main functions of the plugin.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Functions for working with the list of administrators.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class tool_apisiteadmins {
+    /**
+     * Adds a user to the list of administrators.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     */
+    public static function add_user($userid) {
+        if (!core_user::is_real_user($userid, true)) {
+            print_error("invaliduser", "error", null);
+        }
+
+        $userid = (int)$userid;
+        $admins = self::get_list();
+        $admins[$userid] = $userid;
+
+        self::create_event("administrator_added", $userid);
+        return self::save_changes($admins);
+    }
+
+    /**
+     * Removes a user from the list of administrators.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     */
+    public static function remove_user($userid) {
+        if (!core_user::is_real_user($userid, true)) {
+            print_error("invaliduser", "error", null);
+        }
+
+        $userid = (int)$userid;
+        $admins = self::get_list();
+        unset($admins[$userid]);
+
+        self::create_event("administrator_deleted", $userid);
+        return self::save_changes($admins);
+    }
+
+    /**
+     * Registers the user as the primary administrator.
+     *
+     * @param   number  $userid System user ID
+     * @return  boolean         Result of execution
+     */
+    public static function set_main($userid) {
+        if (!core_user::is_real_user($userid, true)) {
+            print_error("invaliduser", "error", null);
+        }
+
+        $userid = (int)$userid;
+        $admins = self::get_list();
+        if (isset($admins[$userid])) {
+            unset($admins[$userid]);
+            array_unshift($admins, $userid);
+        }
+
+        self::create_event("administrator_changed", $userid);
+        return self::save_changes($admins);
+    }
+
+    /**
+     * Creates an entry in the system log.
+     *
+     * @param   string  $name   Event name
+     * @param   number  $userid System user ID
+     */
+    private static function create_event($name, $userid) {
+        $function = "tool_apisiteadmins\\event\\$name";
+        $function::create(array("relateduserid" => $userid))->trigger();
+    }
+
+    /**
+     * Applies the changes on the site.
+     *
+     * @return  array           List of administrators
+     */
+    private static function get_list() {
+        $config = get_config("core", "siteadmins");
+
+        $result = array();
+        foreach (explode(",", $config) as $id) {
+            $id = (int)$id;
+            if (!empty($id)) {
+                $result[$id] = $id;
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Applies the changes on the site.
+     *
+     * @param   array   $admins List of administrators
+     */
+    private static function save_changes($admins) {
+        if (empty($admins)) {
+            $admins = self::get_list();
+        }
+
+        return set_config("siteadmins", implode(",", $admins));
+    }
+}
diff --git a/tests/api_test.php b/tests/api_test.php
new file mode 100644
index 0000000..8155545
--- /dev/null
+++ b/tests/api_test.php
@@ -0,0 +1,132 @@
+<?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/>.
+
+/**
+ * Test 'tool_apisiteadmins' class.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+
+require_once(__DIR__ . "/../lib.php");
+
+/**
+ * Test 'tool_apisiteadmins' class.
+ *
+ * @category    phpunit
+ * @group       tool_apisiteadmins
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class tool_apisiteadmins_api_testcase extends advanced_testcase {
+    public function test_adding_and_deleting_administrator() {
+        $this->resetAfterTest(true);
+
+        $user = $this->getDataGenerator()->create_user();
+
+        /* Adds a user to the list */
+        tool_apisiteadmins::add_user($user->id);
+        $this->assertArrayHasKey($user->id, get_admins());
+        $this->assertCount(2, get_admins());
+
+        /* Re-adds the user to the list */
+        tool_apisiteadmins::add_user($user->id);
+        $this->assertArrayHasKey($user->id, get_admins());
+        $this->assertCount(2, get_admins());
+
+        /* Removes the user from the list */
+        tool_apisiteadmins::remove_user($user->id);
+        $this->assertArrayNotHasKey($user->id, get_admins());
+        $this->assertCount(1, get_admins());
+
+        /* Removes a remote user from the list */
+        tool_apisiteadmins::remove_user($user->id);
+        $this->assertArrayNotHasKey($user->id, get_admins());
+        $this->assertCount(1, get_admins());
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     */
+    public function test_changing_main_administrator() {
+        $this->resetAfterTest(true);
+
+        $user1 = $this->getDataGenerator()->create_user();
+        $user2 = $this->getDataGenerator()->create_user();
+
+        /* Adds users to the list */
+        tool_apisiteadmins::add_user($user1->id);
+        tool_apisiteadmins::add_user($user2->id);
+        $this->assertArrayHasKey($user1->id, get_admins());
+        $this->assertArrayHasKey($user2->id, get_admins());
+        $this->assertCount(3, get_admins());
+
+        /* Sets first user main */
+        tool_apisiteadmins::set_main($user1->id);
+        $this->assertEquals($user1, get_admin());
+
+        /* Sets second user main */
+        tool_apisiteadmins::set_main($user2->id);
+        $this->assertEquals($user2, get_admin());
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     */
+    public function test_deleting_all_administrators() {
+        $this->resetAfterTest(true);
+
+        $this->assertCount(1, get_admins());
+        $user = get_admin();
+
+        /* Removes a single administrator */
+        tool_apisiteadmins::remove_user($user->id);
+        $this->assertCount(1, get_admins());
+        $this->assertEquals($user, get_admin());
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     */
+    public function test_exception_adding_check() {
+        $this->expectException(moodle_exception::class);
+        $this->resetAfterTest(true);
+
+        $userid = mt_rand(99, 999);
+
+        /* Adds a non-existent user */
+        tool_apisiteadmins::add_user($userid);
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     */
+    public function test_exception_removal_check() {
+        $this->expectException(moodle_exception::class);
+        $this->resetAfterTest(true);
+
+        $userid = mt_rand(99, 999);
+
+        /* Removes a non-existent user */
+        tool_apisiteadmins::remove_user($userid);
+    }
+}
diff --git a/tests/external_test.php b/tests/external_test.php
new file mode 100644
index 0000000..83c58c5
--- /dev/null
+++ b/tests/external_test.php
@@ -0,0 +1,131 @@
+<?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/>.
+
+/**
+ * Test 'tool_apisiteadmins_external' class.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+
+require_once(__DIR__ . "/../externallib.php");
+
+/**
+ * Test tool_apisiteadmins_external class.
+ *
+ * @category    phpunit
+ * @group       tool_apisiteadmins
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+class tool_apisiteadmins_external_testcase extends advanced_testcase {
+    public function test_adding_and_deleting_administrator() {
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        $user = $this->getDataGenerator()->create_user();
+
+        /* Adds a user to the list */
+        $result = tool_apisiteadmins_external::add_to_administrators($user->id);
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::add_to_administrators_returns(), $result);
+        $this->assertArrayHasKey($user->id, get_admins());
+        $this->assertCount(2, get_admins());
+        $this->assertTrue($result);
+
+        /* Removes the user from the list */
+        $result = tool_apisiteadmins_external::remove_from_administrators($user->id);
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::remove_from_administrators_returns(), $result);
+        $this->assertArrayNotHasKey($user->id, get_admins());
+        $this->assertCount(1, get_admins());
+        $this->assertTrue($result);
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     */
+    public function test_changing_main_administrator() {
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        $user1 = $this->getDataGenerator()->create_user();
+        $user2 = $this->getDataGenerator()->create_user();
+
+        /* Adds users to the list */
+        tool_apisiteadmins_external::add_to_administrators($user1->id);
+        tool_apisiteadmins_external::add_to_administrators($user2->id);
+        $this->assertArrayHasKey($user1->id, get_admins());
+        $this->assertArrayHasKey($user2->id, get_admins());
+        $this->assertCount(3, get_admins());
+
+        /* Changes the primary administrator */
+        $result = tool_apisiteadmins_external::change_main_administrator($user1->id);
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::change_main_administrator_returns(), $result);
+        $this->assertEquals($user1, get_admin());
+        $this->assertTrue($result);
+
+        /* Changes the primary administrator */
+        $result = tool_apisiteadmins_external::change_main_administrator($user2->id);
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::change_main_administrator_returns(), $result);
+        $this->assertEquals($user2, get_admin());
+        $this->assertTrue($result);
+    }
+
+    /**
+     * @depends test_adding_and_deleting_administrator
+     * @depends test_changing_main_administrator
+     */
+    public function test_getting_list_administrators() {
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        $user1 = $this->getDataGenerator()->create_user();
+        $user2 = $this->getDataGenerator()->create_user();
+
+        /* Adds users to the list */
+        tool_apisiteadmins_external::add_to_administrators($user1->id);
+        tool_apisiteadmins_external::add_to_administrators($user2->id);
+        $this->assertArrayHasKey($user1->id, get_admins());
+        $this->assertArrayHasKey($user2->id, get_admins());
+        $this->assertCount(3, get_admins());
+
+        /* Gets the list of administrators */
+        $result = tool_apisiteadmins_external::get_list_administrators();
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::get_list_administrators_returns(), $result);
+        $this->assertArraySubset(array("id" => $user1->id), $result[1]);
+        $this->assertArraySubset(array("id" => $user2->id), $result[2]);
+        $this->assertCount(3, $result);
+
+        /* Changes the primary administrator */
+        tool_apisiteadmins_external::change_main_administrator($user1->id);
+        $result = tool_apisiteadmins_external::get_main_administrator();
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::get_main_administrator_returns(), $result);
+        $this->assertArraySubset(array("id" => $user1->id), $result[0]);
+        $this->assertCount(1, $result);
+
+        /* Changes the primary administrator */
+        tool_apisiteadmins_external::change_main_administrator($user2->id);
+        $result = tool_apisiteadmins_external::get_main_administrator();
+        $result = external_api::clean_returnvalue(tool_apisiteadmins_external::get_main_administrator_returns(), $result);
+        $this->assertArraySubset(array("id" => $user2->id), $result[0]);
+        $this->assertCount(1, $result);
+    }
+}
diff --git a/version.php b/version.php
new file mode 100644
index 0000000..460c521
--- /dev/null
+++ b/version.php
@@ -0,0 +1,31 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Information about the version of the plugin.
+ *
+ * @copyright   2018 "Valentin Popov" <info@valentineus.link>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package     tool_apisiteadmins
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$plugin->component = "tool_apisiteadmins";
+$plugin->maturity  = MATURITY_STABLE;
+$plugin->release   = "1.0.0 (Build: 2018061100)";
+$plugin->requires  = 2015050500;
+$plugin->version   = 2018061100;