--- /dev/null
+Plugin Development
+=======================
+
+SamplePlugin.php
+-----------------------
+
+Each plugin requires a main class to interact with the GNU social system.
+
+The main class usually extends the Plugin class that comes with GNU social.
+
+The class has standard-named methods that will be called when certain events
+happen in the code base. These methods have names like 'onX' where X is an
+event name (see EVENTS.txt for the list of available events). Event handlers
+have pre-defined arguments, based on which event they're handling. A typical
+event handler:
+
+```php
+function onSomeEvent($paramA, &$paramB)
+{
+ if ($paramA == 'jed') {
+ throw new Exception(sprintf(_m("Invalid parameter %s"), $paramA));
+ }
+ $paramB = 'spock';
+ return true;
+}
+```
+
+Event Handlers
+-----------------------
+
+Event handlers must return a Boolean value.
+
+If they return false, all other event handlers for this event (in other plug-in)
+will be skipped, and in some cases the default processing for that event would
+be skipped. This is great for replacing the default action of an event.
+
+If the handler returns true, processing of other event handlers and the default
+processing will continue. This is great for extending existing functionality.
+
+If the handler throws an exception, processing will stop, and the exception's
+error will be shown to the user.
+
+Installation
+------------------
+
+To install a plugin (like this one), site admins add the following code to their
+config.php file:
+
+```php
+addPlugin('Sample');
+```
+
+Plugins must be installed in one of the following directories:
+
+* local/plugins/{$pluginclass}.php
+* local/plugins/{$name}/{$pluginclass}.php
+* local/{$pluginclass}.php
+* local/{$name}/{$pluginclass}.php
+* plugins/{$pluginclass}.php
+* plugins/{$name}/{$pluginclass}.php
+
+Here, `{$name}` is the name of the plugin, like 'Sample', and `{$pluginclass}`
+is the name of the main class, like 'SamplePlugin'. Plugins that are part of
+the main GNU social distribution go in 'plugins' and third-party or local ones
+go in 'local'.
+
+Simple plugins can be implemented as a single module. Others are more complex
+and require additional modules; these should use their own directory, like
+'local/plugins/{$name}/'. All files related to the plugin, including images,
+JavaScript, CSS, external libraries or PHP modules should go in the plugin
+directory.
+
+Plugin Configuration
+------------------
+
+Plugins are configured using public instance attributes. To set their values,
+site administrators use this syntax:
+
+```php
+addPlugin('Sample', array('attr1' => 'foo', 'attr2' => 'bar'));
+```
+
+The same plugin class can be initialized multiple times with different arguments:
+
+```php
+addPlugin('EmailNotify', array('sendTo' => 'evan@status.net'));
+addPlugin('EmailNotify', array('sendTo' => 'brionv@status.net'));
+```
+
+```php
+class SamplePlugin extends Plugin
+{
+ public $attr1 = null;
+ public $attr2 = null;
+}
+```
+
+Initialization
+------------------
+
+Plugins overload this method to do any initialization they need, like connecting
+to remote servers or creating paths or so on. @return boolean hook value; true
+means continue processing, false means stop.
+
+```php
+function initialize()
+{
+ return true;
+}
+```
+
+Clean Up
+------------------
+
+Plugins overload this method to do any cleanup they need, like disconnecting from
+remote servers or deleting temp files or so on.
+
+```php
+function cleanup()
+{
+ return true;
+}
+```
+
+Database schema setup
+------------------
+
+Plugins can add their own tables to the GNU social database. Plugins should use
+GNU social's schema interface to add or delete tables. The ensureTable() method
+provides an easy way to ensure a table's structure and availability.
+
+By default, the schema is checked every time GNU social is run (say, when a Web
+page is hit). Admins can configure their systems to only check the schema when
+the checkschema.php script is run, greatly improving performance. However, they
+need to remember to run that script after installing or upgrading a plugin!
+
+```php
+function onCheckSchema()
+{
+ $schema = Schema::get();
+
+ // '''For storing user-submitted flags on profiles'''
+
+ $schema->ensureTable('user_greeting_count',
+ array(new ColumnDef('user_id', 'integer', null,
+ true, 'PRI'),
+ new ColumnDef('greeting_count', 'integer')));
+
+ return true;
+}
+```
+
+Load related modules when needed
+------------------
+
+Most non-trivial plugins will require extra modules to do their work. Typically
+these include data classes, action classes, widget classes, or external libraries.
+
+This method receives a class name and loads the PHP file related to that class.
+By tradition, action classes typically have files named for the action, all
+lower-case. Data classes are in files with the data class name, initial letter
+capitalized.
+
+Note that this method will be called for *all* overloaded classes, not just ones
+in this plugin! So, make sure to return true by default to let other plugins,
+and the core code, get a chance.
+
+```php
+function onAutoload($cls)
+{
+ $dir = dirname(__FILE__);
+
+ switch ($cls)
+ {
+ case 'HelloAction':
+ include_once $dir . '/' . strtolower(mb_substr($cls, 0, -6)) . '.php';
+ return false;
+ case 'User_greeting_count':
+ include_once $dir . '/'.$cls.'.php';
+ return false;
+ default:
+ return true;
+ }
+}
+```
+
+Map URLs to actions
+------------------
+
+This event handler lets the plugin map URLs on the site to actions (and thus an
+action handler class). Note that the action handler class for an action will be
+named 'FoobarAction', where action = 'foobar'. The class must be loaded in the
+onAutoload() method.
+
+```php
+function onRouterInitialized($m)
+{
+ $m->connect('main/hello',
+ array('action' => 'hello'));
+ return true;
+}
+```
+
+Modify the default menu to link to our custom action
+------------------
+
+Using event handlers, it's possible to modify the default UI for pages almost
+without limit. In this method, we add a menu item to the default primary menu
+for the interface to link to our action.
+
+Action Class
+------------------
+
+The Action class provides a rich set of events to hook, as well as output methods.
+
+```php
+function onEndPrimaryNav($action)
+{
+ // '''common_local_url()''' gets the correct URL for the action name we provide
+
+ $action->menuItem(common_local_url('hello'),
+ _m('Hello'), _m('A warm greeting'), false, 'nav_hello');
+ return true;
+}
+
+function onPluginVersion(&$versions)
+{
+ $versions[] = array('name' => 'Sample',
+ 'version' => STATUSNET_VERSION,
+ 'author' => 'Brion Vibber, Evan Prodromou',
+ 'homepage' => 'http://example.org/plugin',
+ 'rawdescription' =>
+ _m('A sample plugin to show basics of development for new hackers.'));
+ return true;
+}
+```
+
+hello.php
+------------------
+
+This section is taken directly from the 'hello.php'. ( plugins/Sample/hello.php )
+
+Give a warm greeting to our friendly user.
+
+This sample action shows some basic ways of doing output in an action class.
+
+Action classes have several output methods that they override from the parent class.
+
+```php
+class HelloAction extends Action
+{
+ var $user = null;
+ var $gc = null;
+}
+```
+
+Take arguments for running
+------------------
+
+This method is called first, and it lets the action class get all its arguments
+and validate them. It's also the time to fetch any relevant data from the database.
+
+Action classes should run parent::prepare($args) as the first line of this
+method to make sure the default argument-processing happens.
+
+```php
+function prepare($args)
+{
+ parent::prepare($args);
+
+ $this->user = common_current_user();
+
+ if (!empty($this->user)) {
+ $this->gc = User_greeting_count::inc($this->user->id);
+ }
+
+ return true;
+}
+```
+
+Handle request
+------------------
+
+This is the main method for handling a request. Note that most preparation
+should be done in the prepare() method; by the time handle() is called the
+action should be more or less ready to go.
+
+```php
+function handle($args)
+{
+ parent::handle($args);
+
+ $this->showPage();
+}
+```
+
+Title of this page
+------------------
+
+Override this method to show a custom title.
+
+```php
+function title()
+{
+ if (empty($this->user)) {
+ return _m('Hello');
+ } else {
+ return sprintf(_m('Hello, %s'), $this->user->nickname);
+ }
+}
+```
+
+Show content in the content area
+------------------
+
+The default GNU social page has a lot of decorations: menus, logos, tabs, all
+that jazz. This method is used to show content in the content area of the
+page; it's the main thing you want to overload. This method also demonstrates
+use of a plural localized string.
+
+```php
+function showContent()
+{
+ if (empty($this->user)) {
+ $this->element('p', array('class' => 'greeting'),
+ _m('Hello, stranger!'));
+ } else {
+ $this->element('p', array('class' => 'greeting'),
+ sprintf(_m('Hello, %s'), $this->user->nickname));
+ $this->element('p', array('class' => 'greeting_count'),
+ sprintf(_m('I have greeted you %d time.',
+ 'I have greeted you %d times.',
+ $this->gc->greeting_count),
+ $this->gc->greeting_count));
+ }
+}
+```
+
+Return true if read only.
+------------------
+
+Some actions only read from the database; others read and write. The simple
+database load-balancer built into GNU social will direct read-only actions to
+database mirrors (if they are configured) and read-write actions to the master database.
+
+This defaults to false to avoid data integrity issues, but you should make sure
+to overload it for performance gains.
+
+```php
+function isReadOnly($args)
+{
+ return false;
+}
+```
+
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