diff --git a/.editorconfig b/.editorconfig
index 79207a40cb9326b8c6b8c958fa864b5345f94e68..0fcdf7fd4fc5705384ea40f93be21e0fc85ac557 100755
--- a/.editorconfig
+++ b/.editorconfig
@@ -17,6 +17,3 @@ indent_size = 4
 [{.jshintrc,*.json,*.yml}]
 indent_style = space
 indent_size = 2
-
-[{*.txt,wp-config-sample.php}]
-end_of_line = crlf
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 40c53b76bbfcdb3b614b4ff21a13d2a52de56d50..a4d480111b33701c1f5cd7785d3f506e883a7b21 100755
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -2,6 +2,7 @@ variables:
   # Configure mysql service (https://hub.docker.com/_/mysql/)
   MYSQL_DATABASE: wordpress_tests
   MYSQL_ROOT_PASSWORD: mysql
+  WP_VERSION: latest
 
 cache:
   paths:
@@ -10,7 +11,7 @@ cache:
 
 before_script:
   # Set up WordPress tests
-  - bash bin/install-wp-tests.sh $MYSQL_DATABASE root $MYSQL_ROOT_PASSWORD mysql latest true
+  - bash bin/install-wp-tests.sh $MYSQL_DATABASE root $MYSQL_ROOT_PASSWORD mysql $WP_VERSION true
 
   # PHPUnit
   - |
@@ -20,10 +21,43 @@ before_script:
       composer global require "phpunit/phpunit=4.8.*"
     fi
 
-  # Install PHPCS and WPCS
-  - composer global require automattic/vipwpcs
-  - composer global require phpcompatibility/phpcompatibility-wp
-  - phpcs --config-set installed_paths $HOME/.composer/vendor/wp-coding-standards/wpcs,$HOME/.composer/vendor/automattic/vipwpcs,$HOME/.composer/vendor/phpcompatibility/php-compatibility,$HOME/.composer/vendor/phpcompatibility/phpcompatibility-paragonie,$HOME/.composer/vendor/phpcompatibility/phpcompatibility-wp
+PHPunit:PHP5.3:MySQL:
+  stage: test
+  variables:
+    WP_VERSION: 5.1.1
+  image: containers.ethitter.com:443/docker/images/php:5.3
+  services:
+    - mysql:5.6
+  script:
+    - find . -type "f" -iname "*.php" | xargs -L "1" php -l
+    - phpunit
+
+PHPunit:PHP5.6:MySQL:
+  stage: test
+  image: containers.ethitter.com:443/docker/images/php:5.6
+  services:
+    - mysql:5.6
+  script:
+    - find . -type "f" -iname "*.php" | xargs -L "1" php -l
+    - phpunit
+
+PHPunit:PHP7.0:MySQL:
+  stage: test
+  image: containers.ethitter.com:443/docker/images/php:7.0
+  services:
+    - mysql:5.6
+  script:
+    - find . -type "f" -iname "*.php" | xargs -L "1" php -l
+    - phpunit
+
+PHPunit:PHP7.1:MySQL:
+  stage: test
+  image: containers.ethitter.com:443/docker/images/php:7.1
+  services:
+    - mysql:5.6
+  script:
+    - find . -type "f" -iname "*.php" | xargs -L "1" php -l
+    - phpunit
 
 PHPunit:PHP7.2:MySQL:
   stage: test
@@ -32,9 +66,7 @@ PHPunit:PHP7.2:MySQL:
     - mysql:5.6
   script:
     - find . -type "f" -iname "*.php" | xargs -L "1" php -l
-    - phpcs -n
     - phpunit
-  allow_failure: true
 
 PHPunit:PHP7.3:MySQL:
   stage: test
@@ -43,13 +75,21 @@ PHPunit:PHP7.3:MySQL:
     - mysql:5.6
   script:
     - find . -type "f" -iname "*.php" | xargs -L "1" php -l
-    - phpcs -n
     - phpunit
-  allow_failure: true
+
+PHPCS:
+  stage: test
+  image: containers.ethitter.com:443/docker/images/php:7.3
+  before_script:
+    - composer global require automattic/vipwpcs
+    - composer global require phpcompatibility/phpcompatibility-wp
+    - phpcs --config-set installed_paths $HOME/.composer/vendor/wp-coding-standards/wpcs,$HOME/.composer/vendor/automattic/vipwpcs,$HOME/.composer/vendor/phpcompatibility/php-compatibility,$HOME/.composer/vendor/phpcompatibility/phpcompatibility-paragonie,$HOME/.composer/vendor/phpcompatibility/phpcompatibility-wp
+  script:
+    - phpcs -n
 
 PluginSVN:
   stage: deploy
-  image: containers.ethitter.com:443/docker/images/php:7.3
+  image: containers.ethitter.com:443/docker/wp-org-plugin-deploy:latest
   before_script:
     - curl -o ./bin/deploy.sh https://git-cdn.e15r.co/open-source/wp-org-plugin-deploy/raw/master/scripts/deploy.sh
     - chmod +x ./bin/deploy.sh
diff --git a/.phpcs.xml.dist b/.phpcs.xml.dist
index 0c031ac22c1fc4ce8e1529485409ecb9a643dca7..0717712f19a0fcd0a4dd366ba27a86737f0dccdd 100644
--- a/.phpcs.xml.dist
+++ b/.phpcs.xml.dist
@@ -19,7 +19,7 @@
 
 	<!-- Rules: Check PHP version compatibility -->
 	<!-- https://github.com/PHPCompatibility/PHPCompatibility#sniffing-your-code-for-compatibility-with-specific-php-versions -->
-	<config name="testVersion" value="7.2-"/>
+	<config name="testVersion" value="5.3-"/>
 	<!-- https://github.com/PHPCompatibility/PHPCompatibilityWP -->
 	<rule ref="PHPCompatibilityWP"/>
 
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..6c5b18cf143be14531cdd46247bfbd4cfe08bf04
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,280 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc., <http://fsf.org/>
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+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
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the 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 a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, 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.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE 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.
+
+                     END OF TERMS AND CONDITIONS
diff --git a/README.md b/README.md
index 38832a9c3aedd0d6076e4832f044c8fd23d55178..090e14d5620d72726e36d31dde61ffe03accdb18 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 **Tags:** revision, revisions, admin  
 **Requires at least:** 3.6  
 **Tested up to:** 5.2  
-**Stable tag:** 1.2.1  
+**Stable tag:** 1.3  
 **License:** GPLv2 or later  
 **License URI:** http://www.gnu.org/licenses/gpl-2.0.html  
 
@@ -35,6 +35,10 @@ Navigate to **Settings > Writing** in your WordPress Dashboard, and look for the
 
 ## Changelog ##
 
+### 1.3 ###
+* Introduce unit tests.
+* Conform to coding standards.
+
 ### 1.2.1 ###
 * Introduce Spanish translation thanks to Maria Ramos at [WebHostingHub](http://www.webhostinghub.com/).
 
diff --git a/inc/class-wp-revisions-control.php b/inc/class-wp-revisions-control.php
new file mode 100644
index 0000000000000000000000000000000000000000..87c8967ae384c693ab18bff7492fe53e0882e29a
--- /dev/null
+++ b/inc/class-wp-revisions-control.php
@@ -0,0 +1,548 @@
+<?php
+/**
+ * Main plugin functionality.
+ *
+ * @package WP_Revisions_Control
+ */
+
+/**
+ * Class WP_Revisions_Control.
+ */
+class WP_Revisions_Control {
+	/**
+	 * Singleton.
+	 *
+	 * @var static
+	 */
+	private static $__instance;
+
+	/**
+	 * Filter priority.
+	 *
+	 * @see $this->filter_priority()
+	 *
+	 * @var int
+	 */
+	private static $priority = null;
+
+	/**
+	 * Default filter priority.
+	 *
+	 * @var int
+	 */
+	private $priority_default = 50;
+
+	/**
+	 * Supported post types.
+	 *
+	 * @see $this->get_post_types()
+	 *
+	 * @var array
+	 */
+	private static $post_types = array();
+
+	/**
+	 * Plugin settings.
+	 *
+	 * @see $this->get_settings()
+	 *
+	 * @var array
+	 */
+	private static $settings = array();
+
+	/**
+	 * WordPress options page to display settings on.
+	 *
+	 * @var string
+	 */
+	private $settings_page = 'writing';
+
+	/**
+	 * Name of custom settings sections.
+	 *
+	 * @var string
+	 */
+	private $settings_section = 'wp_revisions_control';
+
+	/**
+	 * Meta key holding post's revisions limit.
+	 *
+	 * @var string
+	 */
+	private $meta_key_limit = '_wp_rev_ctl_limit';
+
+	/**
+	 * Silence is golden!
+	 */
+	private function __construct() {}
+
+	/**
+	 * Singleton implementation.
+	 *
+	 * @return static
+	 */
+	public static function get_instance() {
+		if ( ! is_a( static::$__instance, __CLASS__ ) ) {
+			static::$__instance = new self();
+
+			static::$__instance->setup();
+		}
+
+		return static::$__instance;
+	}
+
+	/**
+	 * Register actions and filters at `init` so others can interact, if desired.
+	 */
+	private function setup() {
+		add_action( 'plugins_loaded', array( $this, 'action_plugins_loaded' ) );
+		add_action( 'init', array( $this, 'action_init' ) );
+	}
+
+	/**
+	 * Load plugin translations.
+	 */
+	public function action_plugins_loaded() {
+		load_plugin_textdomain( 'wp_revisions_control', false, dirname( plugin_basename( __FILE__ ) ) . '/languages/' );
+	}
+
+	/**
+	 * Register actions and filters.
+	 */
+	public function action_init() {
+		add_action( 'admin_init', array( $this, 'action_admin_init' ) );
+
+		add_filter( 'wp_revisions_to_keep', array( $this, 'filter_wp_revisions_to_keep' ), $this->plugin_priority(), 2 );
+	}
+
+	/**
+	 * Register plugin's admin-specific elements.
+	 *
+	 * Plugin title is intentionally not translatable.
+	 */
+	public function action_admin_init() {
+		// Plugin setting section.
+		register_setting( $this->settings_page, $this->settings_section, array( $this, 'sanitize_options' ) );
+
+		add_settings_section( $this->settings_section, 'WP Revisions Control', array( $this, 'settings_section_intro' ), $this->settings_page );
+
+		foreach ( $this->get_post_types() as $post_type => $name ) {
+			add_settings_field( $this->settings_section . '-' . $post_type, $name, array( $this, 'field_post_type' ), $this->settings_page, $this->settings_section, array( 'post_type' => $post_type ) );
+		}
+
+		// Post-level functionality.
+		add_action( 'add_meta_boxes', array( $this, 'action_add_meta_boxes' ), 10, 2 );
+		add_action( 'wp_ajax_' . $this->settings_section . '_purge', array( $this, 'ajax_purge' ) );
+		add_action( 'save_post', array( $this, 'action_save_post' ) );
+	}
+
+	/**
+	 * PLUGIN SETTINGS SECTION
+	 * FOUND UNDER SETTINGS > WRITING
+	 */
+
+	/**
+	 * Display assistive text in settings section.
+	 */
+	public function settings_section_intro() {
+		?>
+		<p><?php esc_html_e( 'Set the number of revisions to save for each post type listed. To retain all revisions for a given post type, leave the field empty.', 'wp_revisions_control' ); ?></p>
+		<p><?php esc_html_e( 'If a post type isn\'t listed, revisions are not enabled for that post type.', 'wp_revisions_control' ); ?></p>
+		<?php
+
+		// Display a note if the plugin priority is other than the default.
+		// Will be useful when debugging issues later.
+		if ( $this->plugin_priority() !== $this->priority_default ) :
+			?>
+			<p>
+				<?php
+				printf(
+					/* translators: 1. Filter tag. */
+					esc_html__(
+						'A local change is causing this plugin\'s functionality to run at a priority other than the default. If you experience difficulties with the plugin, please unhook any functions from the %1$s filter.',
+						'wp_revisions_control'
+					),
+					'<code>wp_revisions_control_priority</code>'
+				);
+				?>
+			</p>
+			<?php
+		endif;
+	}
+
+	/**
+	 * Render field for each post type.
+	 *
+	 * @param array $args Field arguments.
+	 */
+	public function field_post_type( $args ) {
+		$revisions_to_keep = $this->get_revisions_to_keep( $args['post_type'], true );
+		?>
+		<input type="text" name="<?php echo esc_attr( $this->settings_section . '[' . $args['post_type'] . ']' ); ?>" value="<?php echo esc_attr( $revisions_to_keep ); ?>" class="small-text" />
+		<?php
+	}
+
+	/**
+	 * Sanitize plugin settings.
+	 *
+	 * @param array $options Unsanitized settings.
+	 * @return array
+	 */
+	public function sanitize_options( $options ) {
+		$options_sanitized = array();
+
+		if ( is_array( $options ) ) {
+			foreach ( $options as $post_type => $to_keep ) {
+				$type_length = strlen( $to_keep );
+
+				if ( 0 === $type_length ) {
+					$to_keep = -1;
+				} else {
+					$to_keep = (int) $to_keep;
+				}
+
+				// Lowest possible value is -1, used to indicate infinite revisions are stored.
+				if ( -1 > $to_keep ) {
+					$to_keep = -1;
+				}
+
+				$options_sanitized[ $post_type ] = $to_keep;
+			}
+		}
+
+		return $options_sanitized;
+	}
+
+	/**
+	 * REVISIONS QUANTITY OVERRIDES.
+	 */
+
+	/**
+	 * Allow others to change the priority this plugin's functionality runs at
+	 *
+	 * @uses apply_filters
+	 * @return int
+	 */
+	private function plugin_priority() {
+		if ( is_null( self::$priority ) ) {
+			$plugin_priority = apply_filters( 'wp_revisions_control_priority', $this->priority_default );
+
+			self::$priority = is_numeric( $plugin_priority ) ? (int) $plugin_priority : $this->priority_default;
+		}
+
+		return self::$priority;
+	}
+
+	/**
+	 * Override number of revisions to keep using plugin's settings.
+	 *
+	 * Can either be post-specific or universal.
+	 *
+	 * @param int     $qty  Number of revisions to keep.
+	 * @param WP_Post $post Post object.
+	 * @return int
+	 */
+	public function filter_wp_revisions_to_keep( $qty, $post ) {
+		$post_limit = get_post_meta( $post->ID, $this->meta_key_limit, true );
+
+		if ( 0 < strlen( $post_limit ) ) {
+			$qty = $post_limit;
+		} else {
+			$post_type = get_post_type( $post ) ? get_post_type( $post ) : $post->post_type;
+			$settings  = $this->get_settings();
+
+			if ( array_key_exists( $post_type, $settings ) ) {
+				$qty = $settings[ $post_type ];
+			}
+		}
+
+		return $qty;
+	}
+
+	/**
+	 * POST-LEVEL FUNCTIONALITY.
+	 */
+
+	/**
+	 * Override Core's revisions metabox.
+	 *
+	 * @param string $post_type Post type.
+	 * @param object $post      Post object.
+	 */
+	public function action_add_meta_boxes( $post_type, $post ) {
+		if ( post_type_supports( $post_type, 'revisions' ) && 'auto-draft' !== get_post_status() && count( wp_get_post_revisions( $post ) ) > 1 ) {
+			// Replace the metabox.
+			remove_meta_box( 'revisionsdiv', null, 'normal' );
+			add_meta_box(
+				'revisionsdiv-wp-rev-ctl',
+				__(
+					'Revisions',
+					'wp_revisions_control'
+				),
+				array(
+					$this,
+					'revisions_meta_box',
+				),
+				null,
+				'normal',
+				'core'
+			);
+
+			// A bit of JS for us.
+			$handle = 'wp-revisions-control-post';
+			wp_enqueue_script( $handle, plugins_url( 'js/post.js', __DIR__ ), array( 'jquery' ), '20131205', true );
+			wp_localize_script(
+				$handle,
+				$this->settings_section,
+				array(
+					'namespace'       => $this->settings_section,
+					'action_base'     => $this->settings_section,
+					'processing_text' => __( 'Processing&hellip;', 'wp_revisions_control' ),
+					'ays'             => __( 'Are you sure you want to remove revisions from this post?', 'wp_revisions_control' ),
+					'autosave'        => __( 'Autosave', 'wp_revisions_control' ),
+					'nothing_text'    => wpautop( __( 'There are no revisions to remove.', 'wp_revisions_control' ) ),
+					'error'           => __( 'An error occurred. Please refresh the page and try again.', 'wp_revisions_control' ),
+				)
+			);
+
+			// Add some styling to our metabox additions.
+			add_action( 'admin_head', array( $this, 'action_admin_head' ), 999 );
+		}
+	}
+
+	/**
+	 * Render Revisions metabox with plugin's additions
+	 *
+	 * @param WP_Post $post Post object.
+	 */
+	public function revisions_meta_box( $post ) {
+		post_revisions_meta_box( $post );
+
+		?>
+		<div id="<?php echo esc_attr( $this->settings_section ); ?>">
+			<h4>WP Revisions Control</h4>
+
+			<p class="button purge" data-postid="<?php the_ID(); ?>" data-nonce="<?php echo esc_attr( wp_create_nonce( $this->settings_section . '_purge' ) ); ?>"><?php _e( 'Purge these revisions', 'wp_revisions_control' ); ?></p>
+
+			<p>
+				<?php
+				printf(
+					/* translators: 1. Text input field. */
+					esc_html__(
+						'Limit this post to %1$s revisions. Leave this field blank for default behavior.',
+						'wp_revisions_control'
+					),
+					'<input type="text" name="' . esc_attr( $this->settings_section ) . '_qty" value="' . (int) $this->get_post_revisions_to_keep( $post->ID ) . '" id="' . esc_attr( $this->settings_section ) . '_qty" size="2" />'
+				);
+				?>
+
+				<?php wp_nonce_field( $this->settings_section . '_limit', $this->settings_section . '_limit_nonce', false ); ?>
+			</p>
+		</div><!-- #<?php echo esc_attr( $this->settings_section ); ?> -->
+		<?php
+	}
+
+	/**
+	 * Process a post-specific request to purge revisions.
+	 */
+	public function ajax_purge() {
+		$post_id = isset( $_REQUEST['post_id'] ) ? (int) $_REQUEST['post_id'] : false;
+
+		// Hold the current state of this Ajax request.
+		$response = array();
+
+		// Check for necessary data and capabilities.
+		if ( ! $post_id ) {
+			$response['error'] = __( 'No post ID was provided. Please refresh the page and try again.', 'wp_revisions_control' );
+		} elseif ( ! check_ajax_referer( $this->settings_section . '_purge', 'nonce', false ) ) {
+			$response['error'] = __( 'Invalid request. Please refresh the page and try again.', 'wp_revisions_control' );
+		} elseif ( ! current_user_can( 'edit_post', $post_id ) ) {
+			$response['error'] = __( 'You are not allowed to edit this post.', 'wp_revisions_control' );
+		}
+
+		// Request is valid if $response is still empty, as no errors arose above.
+		if ( empty( $response ) ) {
+			$response = $this->do_purge_all( $post_id );
+		}
+
+		// Pass the response back to JS.
+		echo json_encode( $response );
+		exit;
+	}
+
+	/**
+	 * Remove all revisions from a given post ID.
+	 *
+	 * @param int $post_id Post ID to purge of revisions.
+	 * @return array
+	 */
+	public function do_purge_all( $post_id ) {
+		$response = array();
+
+		$revisions = wp_get_post_revisions( $post_id );
+
+		$count = count( $revisions );
+
+		foreach ( $revisions as $revision ) {
+			wp_delete_post_revision( $revision->ID );
+		}
+
+		$response['success'] = sprintf(
+			/* translators: 1. Number of removed revisions, already formatted for locale. */
+			esc_html__(
+				'Removed %1$s revisions associated with this post.',
+				'wp_revisions_control'
+			),
+			number_format_i18n( $count, 0 )
+		);
+
+		$response['count'] = $count;
+
+		return $response;
+	}
+
+	/**
+	 * Sanitize and store post-specifiy revisions quantity.
+	 *
+	 * @param int $post_id Post ID.
+	 */
+	public function action_save_post( $post_id ) {
+		$nonce = $this->settings_section . '_limit_nonce';
+		$qty   = $this->settings_section . '_qty';
+
+		if ( isset( $_POST[ $nonce ], $_POST[ $qty ] ) && wp_verify_nonce( sanitize_text_field( $_POST[ $nonce ] ), $this->settings_section . '_limit' ) ) {
+			$limit = (int) $_POST[ $qty ];
+
+			if ( -1 === $limit || empty( $limit ) ) {
+				delete_post_meta( $post_id, $this->meta_key_limit );
+			} else {
+				update_post_meta( $post_id, $this->meta_key_limit, absint( $limit ) );
+			}
+		}
+	}
+
+	/**
+	 * Add a border between the regular revisions list and this plugin's additions.
+	 */
+	public function action_admin_head() {
+		?>
+		<style type="text/css">
+			#revisionsdiv-wp-rev-ctl #<?php echo esc_attr( $this->settings_section ); ?> {
+				border-top: 1px solid #dfdfdf;
+				padding-top: 0;
+				margin-top: 20px;
+			}
+
+			#revisionsdiv-wp-rev-ctl #<?php echo esc_attr( $this->settings_section ); ?> h4 {
+				border-top: 1px solid #fff;
+				padding-top: 1.33em;
+				margin-top: 0;
+			}
+		</style>
+		<?php
+	}
+
+	/**
+	 * PLUGIN UTILITIES.
+	 */
+
+	/**
+	 * Retrieve plugin settings.
+	 *
+	 * @return array
+	 */
+	private function get_settings() {
+		if ( empty( self::$settings ) ) {
+			$post_types = $this->get_post_types();
+
+			$settings = get_option( $this->settings_section, array() );
+
+			if ( ! is_array( $settings ) ) {
+				$settings = array();
+			}
+
+			$merged_settings = array();
+
+			foreach ( $post_types as $post_type => $name ) {
+				if ( array_key_exists( $post_type, $settings ) ) {
+					$merged_settings[ $post_type ] = (int) $settings[ $post_type ];
+				} else {
+					$merged_settings[ $post_type ] = - 1;
+				}
+			}
+
+			self::$settings = $merged_settings;
+		}
+
+		return self::$settings;
+	}
+
+	/**
+	 * Retrieve array of supported post types and their labels.
+	 *
+	 * @return array
+	 */
+	private function get_post_types() {
+		if ( empty( self::$post_types ) ) {
+			foreach ( get_post_types() as $type ) {
+				if ( post_type_supports( $type, 'revisions' ) ) {
+					$object = get_post_type_object( $type );
+
+					if ( null === $object ) {
+						continue;
+					}
+
+					if ( property_exists( $object, 'labels' ) && property_exists( $object->labels, 'name' ) ) {
+						$name = $object->labels->name;
+					} else {
+						$name = $object->name;
+					}
+
+					self::$post_types[ $type ] = $name;
+				}
+			}
+		}
+
+		return self::$post_types;
+	}
+
+	/**
+	 * Retrieve number of revisions to keep for a given post type.
+	 *
+	 * @param string $post_type     Post type.
+	 * @param bool   $blank_for_all Should blank value be used to indicate all are kept.
+	 * @return int|string
+	 */
+	private function get_revisions_to_keep( $post_type, $blank_for_all = false ) {
+		// wp_revisions_to_keep() accepts a post object, not just the post type.
+		// We construct a new WP_Post object to ensure anything hooked to the wp_revisions_to_keep filter has the same basic data WP provides.
+		$_post   = new WP_Post( (object) array( 'post_type' => $post_type ) );
+		$to_keep = wp_revisions_to_keep( $_post );
+
+		if ( $blank_for_all && -1 === $to_keep ) {
+			return '';
+		} else {
+			return (int) $to_keep;
+		}
+	}
+
+	/**
+	 * Retrieve number of revisions to keep for a give post.
+	 *
+	 * @param int $post_id Post ID.
+	 * @return int|string
+	 */
+	private function get_post_revisions_to_keep( $post_id ) {
+		$to_keep = get_post_meta( $post_id, $this->meta_key_limit, true );
+
+		if ( -1 === $to_keep || empty( $to_keep ) ) {
+			$to_keep = '';
+		} else {
+			$to_keep = (int) $to_keep;
+		}
+
+		return $to_keep;
+	}
+}
+
+WP_Revisions_Control::get_instance();
diff --git a/languages/wp-revisions-control.pot b/languages/wp-revisions-control.pot
index d271808ce3c82bb36a18c491bd1d7efd6c923eb7..f865ce422da4bd3827d768da24b48b20af8a5a9e 100644
--- a/languages/wp-revisions-control.pot
+++ b/languages/wp-revisions-control.pot
@@ -2,10 +2,10 @@
 # This file is distributed under the same license as the WP Revisions Control package.
 msgid ""
 msgstr ""
-"Project-Id-Version: WP Revisions Control 1.2.1\n"
+"Project-Id-Version: WP Revisions Control 1.3\n"
 "Report-Msgid-Bugs-To: "
 "https://wordpress.org/support/plugin/wp-revisions-control\n"
-"POT-Creation-Date: 2019-04-14 04:52:10+00:00\n"
+"POT-Creation-Date: 2019-05-26 17:40:54+00:00\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=utf-8\n"
 "Content-Transfer-Encoding: 8bit\n"
@@ -25,71 +25,74 @@ msgstr ""
 "X-Poedit-Bookmarks: \n"
 "X-Textdomain-Support: yes\n"
 
-#: wp-revisions-control.php:148
+#: inc/class-wp-revisions-control.php:149
 msgid ""
 "Set the number of revisions to save for each post type listed. To retain "
 "all revisions for a given post type, leave the field empty."
 msgstr ""
 
-#: wp-revisions-control.php:149
+#: inc/class-wp-revisions-control.php:150
 msgid "If a post type isn't listed, revisions are not enabled for that post type."
 msgstr ""
 
-#: wp-revisions-control.php:155
+#: inc/class-wp-revisions-control.php:161
+#. translators: 1. Filter tag.
 msgid ""
 "A local change is causing this plugin's functionality to run at a priority "
 "other than the default. If you experience difficulties with the plugin, "
-"please unhook any functions from the %s filter."
+"please unhook any functions from the %1$s filter."
 msgstr ""
 
-#: wp-revisions-control.php:274
+#: inc/class-wp-revisions-control.php:278
 msgid "Revisions"
 msgstr ""
 
-#: wp-revisions-control.php:282
+#: inc/class-wp-revisions-control.php:300
 msgid "Processing&hellip;"
 msgstr ""
 
-#: wp-revisions-control.php:283
+#: inc/class-wp-revisions-control.php:301
 msgid "Are you sure you want to remove revisions from this post?"
 msgstr ""
 
-#: wp-revisions-control.php:284
+#: inc/class-wp-revisions-control.php:302
 msgid "Autosave"
 msgstr ""
 
-#: wp-revisions-control.php:285
+#: inc/class-wp-revisions-control.php:303
 msgid "There are no revisions to remove."
 msgstr ""
 
-#: wp-revisions-control.php:286
+#: inc/class-wp-revisions-control.php:304
 msgid "An error occurred. Please refresh the page and try again."
 msgstr ""
 
-#: wp-revisions-control.php:312
+#: inc/class-wp-revisions-control.php:325
 msgid "Purge these revisions"
 msgstr ""
 
-#: wp-revisions-control.php:315
+#: inc/class-wp-revisions-control.php:331
+#. translators: 1. Text input field.
 msgid ""
-"Limit this post to %s revisions. Leave this field blank for default "
+"Limit this post to %1$s revisions. Leave this field blank for default "
 "behavior."
 msgstr ""
 
-#: wp-revisions-control.php:341
+#: inc/class-wp-revisions-control.php:356
 msgid "No post ID was provided. Please refresh the page and try again."
 msgstr ""
 
-#: wp-revisions-control.php:343
+#: inc/class-wp-revisions-control.php:358
 msgid "Invalid request. Please refresh the page and try again."
 msgstr ""
 
-#: wp-revisions-control.php:345
+#: inc/class-wp-revisions-control.php:360
 msgid "You are not allowed to edit this post."
 msgstr ""
 
-#: wp-revisions-control.php:357
-msgid "Removed %s revisions associated with this post."
+#: inc/class-wp-revisions-control.php:392
+#. translators: 1. Number of removed revisions, already formatted for locale.
+msgid "Removed %1$s revisions associated with this post."
 msgstr ""
 
 #. Plugin Name of the plugin/theme
diff --git a/readme.txt b/readme.txt
index df46245421b2ddad74ec4a7f90dc5d11d0770de7..d1cd518e69ff10dbc0da8a16812968bc21976734 100644
--- a/readme.txt
+++ b/readme.txt
@@ -4,7 +4,7 @@ Donate link: https://ethitter.com/donate/
 Tags: revision, revisions, admin
 Requires at least: 3.6
 Tested up to: 5.2
-Stable tag: 1.2.1
+Stable tag: 1.3
 License: GPLv2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
 
@@ -35,6 +35,10 @@ Navigate to **Settings > Writing** in your WordPress Dashboard, and look for the
 
 == Changelog ==
 
+= 1.3 =
+* Introduce unit tests.
+* Conform to coding standards.
+
 = 1.2.1 =
 * Introduce Spanish translation thanks to Maria Ramos at [WebHostingHub](http://www.webhostinghub.com/).
 
diff --git a/tests/test-hooks.php b/tests/test-hooks.php
new file mode 100755
index 0000000000000000000000000000000000000000..7b6cdae66cf6b8978f1de696b705883cfdc2b2d2
--- /dev/null
+++ b/tests/test-hooks.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ * Test WP hooks.
+ *
+ * @package WP_Revisions_Control
+ */
+
+/**
+ * Class TestHooks.
+ */
+class TestHooks extends WP_UnitTestCase {
+	/**
+	 * Plugin slug used in many settings etc.
+	 *
+	 * @var string
+	 */
+	protected static $settings_section = 'wp_revisions_control';
+
+	/**
+	 * Plugin's limit meta key.
+	 *
+	 * @var string
+	 */
+	protected static $meta_key = '_wp_rev_ctl_limit';
+
+	/**
+	 * Test saving post's revisions limit.
+	 */
+	public function test_save_post() {
+		$post_id  = $this->factory->post->create();
+		$expected = 92;
+
+		$_POST[ static::$settings_section . '_limit_nonce' ] = wp_create_nonce( static::$settings_section . '_limit' );
+		$_POST[ static::$settings_section . '_qty' ]         = $expected;
+
+		WP_Revisions_Control::get_instance()->action_save_post( $post_id );
+
+		$to_keep          = (int) get_post_meta( $post_id, static::$meta_key, true );
+		$to_keep_filtered = wp_revisions_to_keep( get_post( $post_id ) );
+
+		$this->assertEquals( $expected, $to_keep );
+		$this->assertEquals( $expected, $to_keep_filtered );
+	}
+
+	/**
+	 * Test limits, ensuring no leakage.
+	 */
+	public function test_limits() {
+		$post_id_limited   = $this->factory->post->create();
+		$post_id_unlimited = $this->factory->post->create();
+		$expected          = 47;
+
+		update_post_meta( $post_id_limited, static::$meta_key, $expected );
+
+		$this->assertEquals(
+			$expected,
+			wp_revisions_to_keep( get_post( $post_id_limited ) )
+		);
+
+		$this->assertEquals(
+			-1,
+			wp_revisions_to_keep( get_post( $post_id_unlimited ) )
+		);
+	}
+
+	/**
+	 * Test revision purging.
+	 */
+	public function test_purge_all() {
+		$post_id    = $this->factory->post->create();
+		$iterations = 10;
+
+		for ( $i = 0; $i < $iterations; $i++ ) {
+			wp_update_post(
+				array(
+					'ID'           => $post_id,
+					'post_content' => wp_rand(),
+				)
+			);
+		}
+
+		$revisions_to_purge = count( wp_get_post_revisions( $post_id ) );
+		$this->assertEquals(
+			$iterations,
+			$revisions_to_purge,
+			'Failed to assert that there are revisions to purge.'
+		);
+
+		$purge = WP_Revisions_Control::get_instance()->do_purge_all( $post_id );
+		$revisions_remaining = count( wp_get_post_revisions( $post_id ) );
+
+		$this->assertEquals(
+			0,
+			$revisions_remaining,
+			'Failed to assert that all revisions were purged.'
+		);
+
+		$this->assertEquals(
+			10,
+			$purge['count'],
+			'Failed to assert that response includes expected count of purged revisions.'
+		);
+
+		$this->assertEquals(
+			'Removed 10 revisions associated with this post.',
+			$purge['success'],
+			'Failed to assert that response includes expected success message.'
+		);
+	}
+}
diff --git a/tests/test-sample.php b/tests/test-sample.php
deleted file mode 100755
index 6c88ac8560879088d217111b2b4bab2227b6331f..0000000000000000000000000000000000000000
--- a/tests/test-sample.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-/**
- * Class SampleTest
- *
- * @package WP_Revisions_Control
- */
-
-/**
- * Sample test case.
- */
-class SampleTest extends WP_UnitTestCase {
-
-	/**
-	 * A single example test.
-	 */
-	public function test_sample() {
-		// Replace this with some actual testing code.
-		$this->assertTrue( true );
-	}
-}
diff --git a/wp-revisions-control.php b/wp-revisions-control.php
index 4049892213802e5fd3a4cffa0c2958a2aa53080e..1b09aca69b2c8dcfd30a41d5711e2e2f5a7e3dc3 100644
--- a/wp-revisions-control.php
+++ b/wp-revisions-control.php
@@ -1,508 +1,33 @@
 <?php
-/*
-Plugin Name: WP Revisions Control
-Plugin URI: https://ethitter.com/plugins/wp-revisions-control/
-Description: Control how many revisions are stored for each post type
-Author: Erick Hitter
-Version: 1.2.1
-Author URI: https://ethitter.com/
-Text Domain: wp_revisions_control
-Domain Path: /languages/
-
-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 2 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, write to the Free Software
-Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-
-class WP_Revisions_Control {
-	/**
-	 * Singleton
-	 */
-	private static $__instance = null;
-
-	/**
-	 * Class variables
-	 */
-	private static $priority = null; // use $this->plugin_priority()
-	private $priority_default = 50;
-
-	private static $post_types = array(); // use $this->get_post_types()
-	private static $settings = array(); // use $this->get_settings()
-
-	private $settings_page = 'writing';
-	private $settings_section = 'wp_revisions_control';
-
-	private $meta_key_limit = '_wp_rev_ctl_limit';
-
-	/**
-	 * Silence is golden!
-	 */
-	private function __construct() {}
-
-	/**
-	 * Singleton implementation
-	 *
-	 * @uses self::setup
-	 * @return object
-	 */
-	public static function get_instance() {
-		if ( ! is_a( self::$__instance, __CLASS__ ) ) {
-			self::$__instance = new self;
-
-			self::$__instance->setup();
-		}
-
-		return self::$__instance;
-	}
-
-	/**
-	 * Register actions and filters at `init` so others can interact, if desired.
-	 *
-	 * @uses add_action
-	 * @return null
-	 */
-	private function setup() {
-		add_action( 'plugins_loaded', array( $this, 'action_plugins_loaded' ) );
-		add_action( 'init', array( $this, 'action_init' ) );
-	}
-
-	/**
-	 * Load plugin translations
-	 *
-	 * @uses load_plugin_textdomain
-	 * @uses plugin_basename
-	 * @action plugins_loaded
-	 * @return null
-	 */
-	public function action_plugins_loaded() {
-		load_plugin_textdomain( 'wp_revisions_control', false, dirname( plugin_basename( __FILE__ ) ) . '/languages/' );
-	}
-
-	/**
-	 * Register actions and filters
-	 *
-	 * @uses add_action
-	 * @uses add_filter
-	 * @uses this::plugin_priority
-	 * @return null
-	 */
-	public function action_init() {
-		add_action( 'admin_init', array( $this, 'action_admin_init' ) );
-
-		add_filter( 'wp_revisions_to_keep', array( $this, 'filter_wp_revisions_to_keep' ), $this->plugin_priority(), 2 );
-	}
-
-	/**
-	 * Register plugin's admin-specific elements
-	 *
-	 * Plugin title is intentionally not translatable.
-	 *
-	 * @uses register_setting
-	 * @uses add_settings_section
-	 * @uses __
-	 * @uses this::get_post_types
-	 * @uses add_settings_field
-	 * @action admin_init
-	 * @return null
-	 */
-	public function action_admin_init() {
-		// Plugin setting section
-		register_setting( $this->settings_page, $this->settings_section, array( $this, 'sanitize_options' ) );
-
-		add_settings_section( $this->settings_section, 'WP Revisions Control', array( $this, 'settings_section_intro' ), $this->settings_page );
-
-		foreach ( $this->get_post_types() as $post_type => $name ) {
-			add_settings_field( $this->settings_section . '-' . $post_type, $name, array( $this, 'field_post_type' ), $this->settings_page, $this->settings_section, array( 'post_type' => $post_type ) );
-		}
-
-		// Post-level functionality
-		add_action( 'add_meta_boxes', array( $this, 'action_add_meta_boxes' ), 10, 2 );
-		add_action( 'wp_ajax_' . $this->settings_section . '_purge', array( $this, 'ajax_purge' ) );
-		add_action( 'save_post', array( $this, 'action_save_post' ) );
-	}
-
-	/**
-	 ** PLUGIN SETTINGS SECTION
-	 ** FOUND UNDER SETTINGS > WRITING
-	 **/
-
-	/**
-	 * Display assistive text in settings section
-	 *
-	 * @uses _e
-	 * @uses this::plugin_priority
-	 * @return string
-	 */
-	public function settings_section_intro() {
-		?>
-		<p><?php _e( 'Set the number of revisions to save for each post type listed. To retain all revisions for a given post type, leave the field empty.', 'wp_revisions_control' ); ?></p>
-		<p><?php _e( "If a post type isn't listed, revisions are not enabled for that post type.", 'wp_revisions_control' ); ?></p>
-		<?php
-
-		// Display a note if the plugin priority is other than the default.
-		// Will be useful when debugging issues later.
-		if ( $this->plugin_priority() !== $this->priority_default ) : ?>
-			<p><?php printf( __( "A local change is causing this plugin's functionality to run at a priority other than the default. If you experience difficulties with the plugin, please unhook any functions from the %s filter.", 'wp_revisions_control' ), '<code>wp_revisions_control_priority</code>' ); ?></p>
-		<?php endif;
-	}
-
-	/**
-	 * Render field for each post type
-	 *
-	 * @param array $args
-	 * @uses this::get_revisions_to_keep
-	 * @uses esc_attr
-	 * @return string
-	 */
-	public function field_post_type( $args ) {
-		$revisions_to_keep = $this->get_revisions_to_keep( $args['post_type'], true );
-		?>
-		<input type="text" name="<?php echo esc_attr( $this->settings_section . '[' . $args['post_type'] . ']' ); ?>" value="<?php echo esc_attr( $revisions_to_keep ); ?>" class="small-text" />
-		<?php
-	}
-
-	/**
-	 * Sanitize plugin settings
-	 *
-	 * @param array $options
-	 * @return array
-	 */
-	public function sanitize_options( $options ) {
-		$options_sanitized = array();
-
-		if ( is_array( $options ) ) {
-			foreach ( $options as $post_type => $to_keep ) {
-				if ( 0 === strlen( $to_keep ) )
-					$to_keep = -1;
-				else
-					$to_keep = intval( $to_keep );
-
-				// Lowest possible value is -1, used to indicate infinite revisions are stored
-				if ( -1 > $to_keep )
-					$to_keep = -1;
-
-				$options_sanitized[ $post_type ] = $to_keep;
-			}
-		}
-
-		return $options_sanitized;
-	}
-
-	/**
-	 ** REVISIONS QUANTITY OVERRIDES
-	 **/
-
-	/**
-	 * Allow others to change the priority this plugin's functionality runs at
-	 *
-	 * @uses apply_filters
-	 * @return int
-	 */
-	private function plugin_priority() {
-		if ( is_null( self::$priority ) ) {
-			$plugin_priority = apply_filters( 'wp_revisions_control_priority', $this->priority_default );
-
-			self::$priority = is_numeric( $plugin_priority ) ? (int) $plugin_priority : $this->priority_default;
-		}
-
-		return self::$priority;
-	}
-
-	/**
-	 * Override number of revisions to keep using plugin's settings
-	 *
-	 * Can either be post-specific or universal
-	 *
-	 * @uses get_post_meta
-	 * @uses get_post_type
-	 * @uses this::get_settings
-	 * @filter wp_revisions_to_keep
-	 * @return mixed
-	 */
-	public function filter_wp_revisions_to_keep( $qty, $post ) {
-		$post_limit = get_post_meta( $post->ID, $this->meta_key_limit, true );
-
-		if ( 0 < strlen( $post_limit ) ) {
-			$qty = $post_limit;
-		} else {
-			$post_type = get_post_type( $post ) ? get_post_type( $post ) : $post->post_type;
-			$settings = $this->get_settings();
-
-			if ( array_key_exists( $post_type, $settings ) )
-				$qty = $settings[ $post_type ];
-		}
-
-		return $qty;
-	}
-
-	/**
-	 ** POST-LEVEL FUNCTIONALITY
-	 **/
-
-	/**
-	 * Override Core's revisions metabox
-	 *
-	 * @param string $post_type
-	 * @param object $post
-	 * @uses post_type_supports
-	 * @uses get_post_status
-	 * @uses wp_get_post_revisions
-	 * @uses remove_meta_box
-	 * @uses add_meta_box
-	 * @uses wp_enqueue_script
-	 * @uses plugins_url
-	 * @uses wp_localize_script
-	 * @uses wpautop
-	 * @uses add_action
-	 * @action add_meta_boxes
-	 * @return null
-	 */
-	public function action_add_meta_boxes( $post_type, $post ) {
-		if ( post_type_supports( $post_type, 'revisions' ) && 'auto-draft' != get_post_status() && count( wp_get_post_revisions( $post ) ) > 1 ) {
-			// Replace the metabox
-			remove_meta_box( 'revisionsdiv', null, 'normal' );
-			add_meta_box( 'revisionsdiv-wp-rev-ctl', __('Revisions', 'wp_revisions_control'), array( $this, 'revisions_meta_box' ), null, 'normal', 'core' );
-
-			// A bit of JS for us
-			$handle = 'wp-revisions-control-post';
-			wp_enqueue_script( $handle, plugins_url( 'js/post.js', __FILE__ ), array( 'jquery' ), '20131205', true );
-			wp_localize_script( $handle, $this->settings_section, array(
-				'namespace'       => $this->settings_section,
-				'action_base'     => $this->settings_section,
-				'processing_text' => __( 'Processing&hellip;', 'wp_revisions_control' ),
-				'ays'             => __( 'Are you sure you want to remove revisions from this post?', 'wp_revisions_control' ),
-				'autosave'        => __( 'Autosave', 'wp_revisions_control' ),
-				'nothing_text'    => wpautop( __( 'There are no revisions to remove.', 'wp_revisions_control' ) ),
-				'error'           => __( 'An error occurred. Please refresh the page and try again.', 'wp_revisions_control' )
-			) );
-
-			// Add some styling to our metabox additions
-			add_action( 'admin_head', array( $this, 'action_admin_head' ), 999 );
-		}
-	}
-
-	/**
-	 * Render Revisions metabox with plugin's additions
-	 *
-	 * @uses post_revisions_meta_box
-	 * @uses the_ID
-	 * @uses esc_attr
-	 * @uses wp_create_nonce
-	 * @uses this::get_post_revisions_to_keep
-	 * @uses wp_nonce_field
-	 * @return string
-	 */
-	public function revisions_meta_box( $post ) {
-		post_revisions_meta_box( $post );
-
-		?>
-		<div id="<?php echo esc_attr( $this->settings_section ); ?>">
-			<h4>WP Revisions Control</h4>
-
-			<p class="button purge" data-postid="<?php the_ID(); ?>" data-nonce="<?php echo esc_attr( wp_create_nonce( $this->settings_section . '_purge' ) ); ?>"><?php _e( 'Purge these revisions', 'wp_revisions_control' ); ?></p>
-
-			<p>
-				<?php printf( __( 'Limit this post to %s revisions. Leave this field blank for default behavior.', 'wp_revisions_control' ), '<input type="text" name="' . $this->settings_section . '_qty" value="' . $this->get_post_revisions_to_keep( $post->ID ) . '" id="' . $this->settings_section . '_qty" size="2" />' ); ?>
-
-				<?php wp_nonce_field( $this->settings_section . '_limit', $this->settings_section . '_limit_nonce', false ); ?>
-			</p>
-		</div><!-- #<?php echo esc_attr( $this->settings_section ); ?> -->
-		<?php
-	}
-
-	/**
-	 * Process a post-specific request to purge revisions
-	 *
-	 * @uses __
-	 * @uses check_ajax_referer
-	 * @uses current_user_can
-	 * @uses wp_get_post_revisions
-	 * @uses number_format_i18n
-	 * @return string
-	 */
-	public function ajax_purge() {
-		$post_id = isset( $_REQUEST['post_id'] ) ? (int) $_REQUEST['post_id'] : false;
-
-		// Hold the current state of this Ajax request
-		$response = array();
-
-		// Check for necessary data and capabilities
-		if ( ! $post_id )
-			$response['error'] = __( 'No post ID was provided. Please refresh the page and try again.', 'wp_revisions_control' );
-		elseif ( ! check_ajax_referer( $this->settings_section . '_purge', 'nonce', false ) )
-			$response['error'] = __( 'Invalid request. Please refresh the page and try again.', 'wp_revisions_control' );
-		elseif ( ! current_user_can( 'edit_post', $post_id ) )
-			$response['error'] = __( 'You are not allowed to edit this post.', 'wp_revisions_control' );
-
-		// Request is valid if $response is still empty, as no errors arose above
-		if ( empty( $response ) ) {
-			$revisions = wp_get_post_revisions( $post_id );
-
-			$count = count( $revisions );
-
-			foreach ( $revisions as $revision ) {
-				wp_delete_post_revision( $revision->ID );
-			}
-
-			$response['success'] = sprintf( __( 'Removed %s revisions associated with this post.', 'wp_revisions_control' ), number_format_i18n( $count, 0 ) );
-			$response['count'] = $count;
-		}
-
-		// Pass the response back to JS
-		echo json_encode( $response );
-		exit;
-	}
-
-	/**
-	 * Sanitize and store post-specifiy revisions quantity
-	 *
-	 * @uses wp_verify_nonce
-	 * @uses update_post_meta
-	 * @action save_post
-	 * @return null
-	 */
-	public function action_save_post( $post_id ) {
-		if ( isset( $_POST[ $this->settings_section . '_limit_nonce' ] ) && wp_verify_nonce( $_POST[ $this->settings_section . '_limit_nonce' ], $this->settings_section . '_limit' ) && isset( $_POST[ $this->settings_section . '_qty' ] ) ) {
-			$limit = $_POST[ $this->settings_section . '_qty' ];
-
-			if ( -1 == $limit || empty( $limit ) )
-				delete_post_meta( $post_id, $this->meta_key_limit );
-			else
-				update_post_meta( $post_id, $this->meta_key_limit, absint( $limit ) );
-		}
-	}
-
-	/**
-	 * Add a border between the regular revisions list and this plugin's additions
-	 *
-	 * @uses esc_attr
-	 * @action admin_head
-	 * @return string
-	 */
-	public function action_admin_head() {
-	?>
-		<style type="text/css">
-			#revisionsdiv-wp-rev-ctl #<?php echo esc_attr( $this->settings_section ); ?> {
-				 border-top: 1px solid #dfdfdf;
-				 padding-top: 0;
-				 margin-top: 20px;
-			}
-
-			#revisionsdiv-wp-rev-ctl #<?php echo esc_attr( $this->settings_section ); ?> h4 {
-				border-top: 1px solid #fff;
-				padding-top: 1.33em;
-				margin-top: 0;
-			}
-		</style>
-	<?php
-	}
-
-	/**
-	 ** PLUGIN UTILITIES
-	 **/
-
-	/**
-	 * Retrieve plugin settings
-	 *
-	 * @uses this::get_post_types
-	 * @uses get_option
-	 * @return array
-	 */
-	private function get_settings() {
-		if ( empty( self::$settings ) ) {
-			$post_types = $this->get_post_types();
-
-			$settings = get_option( $this->settings_section, array() );
-
-			$merged_settings = array();
-
-			foreach ( $post_types as $post_type => $name ) {
-				if ( array_key_exists( $post_type, $settings ) )
-					$merged_settings[ $post_type ] = (int) $settings[ $post_type ];
-				else
-					$merged_settings[ $post_type ] = -1;
-			}
-
-			self::$settings = $merged_settings;
-		}
-
-		return self::$settings;
-	}
-
-	/**
-	 * Retrieve array of supported post types and their labels
-	 *
-	 * @uses get_post_types
-	 * @uses post_type_supports
-	 * @uses get_post_type_object
-	 * @return array
-	 */
-	private function get_post_types() {
-		if ( empty( self::$post_types ) ) {
-			$types = get_post_types();
-
-			foreach ( $types as $type ) {
-				if ( post_type_supports( $type, 'revisions' ) ) {
-					$object = get_post_type_object( $type );
-
-					if ( property_exists( $object, 'labels' ) && property_exists( $object->labels, 'name' ) )
-						$name = $object->labels->name;
-					else
-						$name = $object->name;
-
-					self::$post_types[ $type ] = $name;
-				}
-			}
-		}
-
-		return self::$post_types;
-	}
-
-	/**
-	 * Retrieve number of revisions to keep for a given post type
-	 *
-	 * @uses WP_Post
-	 * @uses wp_revisions_to_keep
-	 * @return mixed
-	 */
-	private function get_revisions_to_keep( $post_type, $blank_for_all = false ) {
-		// wp_revisions_to_keep() accepts a post object, not just the post type
-		// We construct a new WP_Post object to ensure anything hooked to the wp_revisions_to_keep filter has the same basic data WP provides.
-		$_post = new WP_Post( (object) array( 'post_type' => $post_type ) );
-		$to_keep = wp_revisions_to_keep( $_post );
-
-		if ( $blank_for_all && -1 == $to_keep )
-			return '';
-		else
-			return (int) $to_keep;
-	}
-
-	/**
-	 * Retrieve number of revisions to keep for a give post
-	 *
-	 * @param int $post_id
-	 * @uses get_post_meta
-	 * @return mixed
-	 */
-	private function get_post_revisions_to_keep( $post_id ) {
-		$to_keep = get_post_meta( $post_id, $this->meta_key_limit, true );
-
-		if ( -1 == $to_keep || empty( $to_keep ) )
-			$to_keep = '';
-		else
-			$to_keep = (int) $to_keep;
-
-		return $to_keep;
-	}
-}
-WP_Revisions_Control::get_instance();
+/**
+ * Load plugin.
+ *
+ * @package WP_Revisions_Control
+ */
+
+/**
+ * Plugin Name: WP Revisions Control
+ * Plugin URI: https://ethitter.com/plugins/wp-revisions-control/
+ * Description: Control how many revisions are stored for each post type
+ * Author: Erick Hitter
+ * Version: 1.3
+ * Author URI: https://ethitter.com/
+ * Text Domain: wp_revisions_control
+ * Domain Path: /languages/
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+require_once __DIR__ . '/inc/class-wp-revisions-control.php';