Refs #1986 #2170 #2225. Added semantic manifest.xml support and unit tests. Also added plugin dependencies system. See engine/tests/test_files/plugin_18/manifest.xml for examples. Not closing tickets pending discussion.

git-svn-id: http://code.elgg.org/elgg/trunk@7512 36083f99-b078-4883-b0ff-0f9b5a30f544

12 files changed, 1466 insertions, 204 deletions

diff --git a/engine/classes/ElggPluginManifest.php b/engine/classes/ElggPluginManifest.php
index 395208c95..ccd0d984a 100644
--- a/engine/classes/ElggPluginManifest.php
+++ b/engine/classes/ElggPluginManifest.php
@@ -2,11 +2,18 @@
 /**
  * Parses Elgg manifest.xml files.
  *
+ * Normalizes the values from the ElggManifestParser object.
+ *
  * This requires an ElggPluginManifestParser class implementation
  * as $this->parser.
  *
+ * To add new parser versions, name them ElggPluginManifestParserXX
+ * where XX is the version specified in the top-level <plugin-manifest>
+ * tag.
+ *
  * @package    Elgg.Core
  * @subpackage Plugins
+ * @since      1.8
  */
 class ElggPluginManifest {
 
@@ -16,6 +23,72 @@ class ElggPluginManifest {
 	protected $parser;
 
 	/**
+	 * The expected structure of a requires element
+	 */
+	private $_depsRequiresStructPlugin = array(
+		'type' => '',
+		'name' => '',
+		'version' => '',
+		'comparison' => 'ge'
+	);
+
+	/*
+	 * The expected structure of elgg and elgg_release requires element
+	 */
+	private $_depsRequiresStructElgg = array(
+		'type' => '',
+		'version' => '',
+		'comparison' => 'ge'
+	);
+
+	/**
+	 * The expected structure of a requires php_ini dependency element
+	 */
+	private $_depsRequiresStructPhpIni = array(
+		'type' => '',
+		'name' => '',
+		'value' => '',
+		'comparison' => '='
+	);
+
+	/**
+	 * The expected structure of a requires php_extension dependency element
+	 */
+	private $_depsRequiresStructPhpExtension = array(
+		'type' => '',
+		'name' => '',
+		'version' => '',
+		'comparison' => '='
+	);
+
+	/**
+	 * The expected structure of a conflicts depedency element
+	 */
+	private $_depsConflictsStruct = array(
+		'type' => '',
+		'name' => '',
+		'version' => '',
+		'comparison' => '='
+	);
+
+	/**
+	 * The expected structure of a provides dependency element.
+	 */
+	private $_depsProvidesStruct = array(
+		'type' => '',
+		'name' => '',
+		'version' => ''
+	);
+
+	/**
+	 * The expected structure of a screenshot element
+	 */
+	private $_screenshotStruct = array(
+		'description' => '',
+		'path' => ''
+	);
+
+	/**
 	 * The API version of the manifest.
 	 *
 	 * @var int
@@ -48,7 +121,7 @@ class ElggPluginManifest {
 			if (substr(trim($manifest), 0, 1) == '<') {
 				// this is a string
 				$raw_xml = $manifest;
-			} elseif (is_readable($manifest)) {
+			} elseif (is_file($manifest)) {
 				// this is a file
 				$raw_xml = file_get_contents($manifest);
 			}
@@ -57,7 +130,8 @@ class ElggPluginManifest {
 		}
 
 		if (!$manifest_obj) {
-			throw new PluginException(elgg_echo('PluginException:InvalidManifest', array($this->getPluginID())));
+			throw new PluginException(elgg_echo('PluginException:InvalidManifest',
+						array($this->getPluginID())));
 		}
 
 		// set manifest api version
@@ -67,19 +141,20 @@ class ElggPluginManifest {
 			$this->apiVersion = 1.7;
 		}
 
-		switch ($this->apiVersion) {
-			case 1.8:
-				$this->parser = new ElggPluginManifestParser18($manifest_obj, $this);
-				break;
+		$parser_class_name = 'ElggPluginManifestParser' . str_replace('.', '', $this->apiVersion);
 
-			case 1.7:
-				$this->parser = new ElggPluginManifestParser17($manifest_obj, $this);
-				break;
+		// @todo currently the autoloader freaks out if a class doesn't exist.
+		try {
+			$class_exists = class_exists($parser_class_name);
+		} catch (Exception $e) {
+			$class_exists = false;
+		}
 
-			default:
-				throw new PluginException(elgg_echo('PluginException:NoAvailableParser',
+		if ($class_exists) {
+			$this->parser = new $parser_class_name($manifest_obj, $this);
+		} else {
+			throw new PluginException(elgg_echo('PluginException:NoAvailableParser',
 							array($this->apiVersion, $this->getPluginID())));
-				break;
 		}
 
 		if (!$this->parser->parse()) {
@@ -124,35 +199,9 @@ class ElggPluginManifest {
 		return $this->parser->getManifest();
 	}
 
-	/**
-	 * Returns the dependencies listed.
-	 *
-	 * @return array
-	 */
-	public function getDepends() {
-		$deps = $this->parser->getAttribute('depends');
-
-		if (!is_array($deps)) {
-			$deps = array();
-		}
-
-		return $deps;
-	}
-
-	/**
-	 * Returns the conflicts listed
-	 *
-	 * @return array
-	 */
-	public function getConflicts() {
-		$conflicts = $this->parser->getAttribute('conflicts');
-
-		if (!is_array($conflicts)) {
-			$conflicts = array();
-		}
-
-		return $conflicts;
-	}
+	/***************************************
+	 * Parsed and Normalized Manifest Data *
+	 ***************************************/
 
 	/**
 	 * Returns the plugin name
@@ -163,19 +212,20 @@ class ElggPluginManifest {
 		$name = $this->parser->getAttribute('name');
 
 		if (!$name && $this->pluginID) {
-			$name = ucwords(str_replace('_', ' ', $pluginID));
+			$name = ucwords(str_replace('_', ' ', $this->pluginID));
 		}
 
 		return $name;
 	}
 
+
 	/**
 	 * Return the description
 	 *
 	 * @return string
 	 */
 	public function getDescription() {
-		return $this->parser->getAttribute('description');
+		return elgg_echo($this->parser->getAttribute('description'));
 	}
 
 	/**
@@ -184,9 +234,7 @@ class ElggPluginManifest {
 	 * @return string
 	 */
 	public function getBlurb() {
-		$blurb = $this->parser->getAttribute('blurb');
-
-		if (!$blurb) {
+		if (!$blurb = elgg_echo($this->parser->getAttribute('blurb'))) {
 			$blurb = elgg_get_excerpt($this->getDescription());
 		}
 
@@ -245,9 +293,7 @@ class ElggPluginManifest {
 	 * @return array
 	 */
 	public function getCategories() {
-		$cats = $this->parser->getAttribute('categories');
-
-		if (!is_array($cats)) {
+		if (!$cats = $this->parser->getAttribute('category')) {
 			$cats = array();
 		}
 
@@ -260,13 +306,16 @@ class ElggPluginManifest {
 	 * @return array
 	 */
 	public function getScreenshots() {
-		$ss = $this->parser->getAttribute('screenshots');
-
-		if (!is_array($ss)) {
+		if (!$ss = $this->parser->getAttribute('screenshot')) {
 			$ss = array();
 		}
 
-		return $ss;
+		$normalized = array();
+		foreach ($ss as $s) {
+			$normalized[] = $this->buildStruct($this->_screenshotStruct, $s);
+		}
+
+		return $normalized;
 	}
 
 	/**
@@ -275,13 +324,151 @@ class ElggPluginManifest {
 	 * @return array
 	 */
 	public function getProvides() {
-		$provides = $this->parser->getAttribute('provides');
+		if (!$provides = $this->parser->getAttribute('provides')) {
+			$provides = array();
+		}
 
 		// always provide ourself if we can
 		if ($this->pluginID) {
-			$provides[] = array('name' => $this->getPluginID(), 'version' => $this->getVersion);
+			$provides[] = array(
+				'type' => 'plugin',
+				'name' => $this->getPluginID(),
+				'version' => $this->getVersion()
+			);
+		}
+
+		$normalized = array();
+		foreach ($provides as $provide) {
+			$normalized[] = $this->buildStruct($this->_depsProvidesStruct, $provide);
+		}
+
+		return $normalized;
+	}
+
+	/**
+	 * Returns the dependencies listed.
+	 *
+	 * @return array
+	 */
+	public function getRequires() {
+		if (!$reqs = $this->parser->getAttribute('requires')) {
+			$reqs = array();
+		}
+
+		$normalized = array();
+		foreach ($reqs as $req) {
+
+			switch ($req['type']) {
+				case 'elgg':
+				case 'elgg_release':
+					$struct = $this->_depsRequiresStructElgg;
+					break;
+
+				case 'plugin':
+					$struct = $this->_depsRequiresStructPlugin;
+					break;
+
+				case 'php_extension':
+					$struct = $this->_depsRequiresStructPhpExtension;
+					break;
+
+				case 'php_ini':
+					$struct = $this->_depsRequiresStructPhpIni;
+
+					// also normalize boolean values
+					if (isset($req['value'])) {
+						switch (strtolower($normalized_req['value'])) {
+							case 'yes':
+							case 'true':
+							case 'on':
+							case 1:
+								$normalized_req['value'] = 1;
+								break;
+
+							case 'no':
+							case 'false':
+							case 'off':
+							case 0:
+							case '':
+								$normalized_req['value'] = 0;
+								break;
+						}
+					}
+
+					break;
+			}
+
+			$normalized_req = $this->buildStruct($struct, $req);
+
+			// normalize comparison operators
+			switch ($normalized_req['comparison']) {
+				case '<':
+					$normalized_req['comparison'] = 'lt';
+					break;
+
+				case '<=':
+					$normalized_req['comparison'] = 'le';
+					break;
+
+				case '>':
+					$normalized_req['comparison'] = 'gt';
+					break;
+
+				case '>=':
+					$normalized_req['comparison'] = 'ge';
+					break;
+
+				case '==':
+				case 'eq':
+					$normalized_req['comparison'] = '=';
+					break;
+
+				case '<>':
+				case 'ne':
+					$normalized_req['comparison'] = '!=';
+					break;
+			}
+
+			$normalized[] = $normalized_req;
+		}
+
+		return $normalized;
+	}
+
+	/**
+	 * Returns the conflicts listed
+	 *
+	 * @return array
+	 */
+	public function getConflicts() {
+		if (!$conflicts = $this->parser->getAttribute('conflicts')) {
+			$conflicts = array();
+		}
+
+		$normalized = array();
+
+		foreach ($conflicts as $conflict) {
+			$normalized[] = $this->buildStruct($this->_depsConflictsStruct, $conflict);
+		}
+
+		return $normalized;
+	}
+
+	/**
+	 * Normalizes an array into the structure specified
+	 *
+	 * @param array $struct The struct to normalize $element to.
+	 * @param array $array  The array
+	 *
+	 * @return array
+	 */
+	protected function buildStruct(array $struct, array $array) {
+		$return = array();
+
+		foreach ($struct as $index => $default) {
+			$return[$index] = elgg_get_array_value($index, $array, $default);
 		}
 
-		return $provides;
+		return $return;
 	}
 }
\ No newline at end of file
diff --git a/engine/classes/ElggPluginManifestParser.php b/engine/classes/ElggPluginManifestParser.php
index 0ce3e3024..dce46cbb4 100644
--- a/engine/classes/ElggPluginManifestParser.php
+++ b/engine/classes/ElggPluginManifestParser.php
@@ -2,9 +2,24 @@
 /**
  * Parent class for manifest parsers.
  *
+ * Converts manifest.xml files or strings to an array.
+ *
+ * This should be extended by a class that does the actual work
+ * to convert based on the manifest.xml version.
+ *
+ * This class only parses XML to an XmlEntity object and
+ * an array.  The array should be used primarily to extract
+ * information since it is quicker to parse once and store
+ * values from the XmlElement object than to parse the object
+ * each time.
+ *
+ * The array should be an exact representation of the manifest.xml
+ * file or string.  Any normalization needs to be done in the
+ * calling class / function.
+ *
  * @package    Elgg.Core
  * @subpackage Plugins
- *
+ * @since      1.8
  */
 abstract class ElggPluginManifestParser {
 	/**
@@ -38,7 +53,7 @@ abstract class ElggPluginManifestParser {
 	/**
 	 * Loads the manifest XML to be parsed.
 	 *
-	 * @param XmlElement $xml    The Manifest XML to be parsed
+	 * @param XmlElement $xml    The Manifest XML object to be parsed
 	 * @param object     $caller The object calling this parser.
 	 */
 	public function __construct(XmlElement $xml, $caller) {
@@ -71,12 +86,8 @@ abstract class ElggPluginManifestParser {
 	 * @return mixed
 	 */
 	public function getAttribute($name) {
-		if (array_key_exists($name, $this->validAttributes)) {
-			if (isset($this->manifest[$name])) {
-				return $this->manifest[$name];
-			} else {
-				return $this->validAttributes[$name];
-			}
+		if (in_array($name, $this->validAttributes) && isset($this->manifest[$name])) {
+			return $this->manifest[$name];
 		}
 
 		return false;
diff --git a/engine/classes/ElggPluginManifestParser17.php b/engine/classes/ElggPluginManifestParser17.php
index 49b91ef52..f439b5af0 100644
--- a/engine/classes/ElggPluginManifestParser17.php
+++ b/engine/classes/ElggPluginManifestParser17.php
@@ -4,24 +4,18 @@
  *
  * @package    Elgg.Core
  * @subpackage Plugins
+ * @since      1.8
  */
 class ElggPluginManifestParser17 extends ElggPluginManifestParser {
 	/**
 	 * The valid top level attributes and defaults for a 1.7 manifest
 	 */
 	protected $validAttributes = array(
-		'author' => null,
-		'version' => null,
-		'description' => null,
-		'website' => null,
-		'copyright' => null,
-		'license' => 'GNU Public License version 2',
-		'elgg_version' => null,
+		'author', 'version', 'description', 'website',
+		'copyright', 'license', 'elgg_version',
 
 		// were never really used and not enforced in code.
-		'requires' => null,
-		'recommends' => null,
-		'conflicts' => null
+		'requires', 'recommends', 'conflicts'
 	);
 
 	/**
@@ -30,6 +24,10 @@ class ElggPluginManifestParser17 extends ElggPluginManifestParser {
 	 * @return void
 	 */
 	public function parse() {
+		if (!isset($this->manifestObject->children)) {
+			return false;
+		}
+
 		foreach ($this->manifestObject->children as $element) {
 			$key = $element->attributes['key'];
 			$value = $element->attributes['value'];
@@ -47,8 +45,27 @@ class ElggPluginManifestParser17 extends ElggPluginManifestParser {
 			}
 		}
 
-		$this->manifest = $elements;
+		if (!$this->manifest = $elements) {
+			return false;
+		}
 
 		return true;
 	}
+
+	/**
+	 * Return an attribute in the manifest.
+	 *
+	 * Overrides ElggPluginManifestParser::getAttribute() because before 1.8
+	 * there were no rules...weeeeeeeee!
+	 *
+	 * @param string $name Attribute name
+	 * @return mixed
+	 */
+	public function getAttribute($name) {
+		if (isset($this->manifest[$name])) {
+			return $this->manifest[$name];
+		}
+
+		return false;
+	}
 }
\ No newline at end of file
diff --git a/engine/classes/ElggPluginManifestParser18.php b/engine/classes/ElggPluginManifestParser18.php
index 1d4e9daed..54aa9603f 100644
--- a/engine/classes/ElggPluginManifestParser18.php
+++ b/engine/classes/ElggPluginManifestParser18.php
@@ -4,6 +4,7 @@
  *
  * @package    Elgg.Core
  * @subpackage Plugins
+ * @since      1.8
  */
 class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 	/**
@@ -12,23 +13,9 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 	 * @var array
 	 */
 	protected $validAttributes = array(
-		'name' => null,
-		'author' => null,
-		'version' => null,
-		'blurb' => null,
-		'description' => null,
-		'website' => null,
-		'copyright' => null,
-		'license' => 'GNU Public License version 2',
-		'depends' => array(),
-		'screenshots' => array(),
-		'conflicts' => array(),
-		'provides' => array(),
-		'admin' => array(
-			'on_enable' => null,
-			'on_disable' => null,
-			'interface_type' => 'advanced'
-		)
+		'name', 'author', 'version', 'blurb', 'description',
+		'website', 'copyright', 'license', 'requires', 'screenshot',
+		'category', 'conflicts', 'provides', 'admin'
 	);
 
 	/**
@@ -37,7 +24,7 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 	 * @var array
 	 */
 	protected $requiredAttributes = array(
-		'name', 'author', 'version', 'description', 'depends'
+		'name', 'author', 'version', 'description', 'requires'
 	);
 
 	/**
@@ -50,11 +37,8 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 		foreach ($this->manifestObject->children as $element) {
 			switch ($element->name) {
 				// single elements
-				// translatable
 				case 'blurb':
 				case 'description':
-					$element->content = elgg_echo($element->content);
-
 				case 'name':
 				case 'author':
 				case 'version':
@@ -65,14 +49,8 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 					break;
 
 				// arrays
-				case 'screenshot':
-					if (isset($element->attributes['description'])) {
-						$description = elgg_echo($element->attributes['description']);
-					}
-					$parsed['screenshots'][] = array(
-						'description' => $description,
-						'path' => $element->content
-					);
+				case 'category':
+					$parsed['category'][] = $element->content;
 					break;
 
 				case 'admin':
@@ -87,9 +65,10 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 
 					break;
 
+				case 'screenshot':
 				case 'provides':
 				case 'conflicts':
-				case 'depends':
+				case 'requires':
 					if (!isset($element->children)) {
 						return false;
 					}
@@ -112,7 +91,9 @@ class ElggPluginManifestParser18 extends ElggPluginManifestParser {
 			}
 		}
 
-		$this->manifest = $parsed;
+		if (!$this->manifest = $parsed) {
+			return false;
+		}
 
 		return true;
 	}
diff --git a/engine/classes/ElggPluginPackage.php b/engine/classes/ElggPluginPackage.php
new file mode 100644
index 000000000..c00df7f8d
--- /dev/null
+++ b/engine/classes/ElggPluginPackage.php
@@ -0,0 +1,763 @@
+<?php
+/**
+ * Manages plugin packages under mod.
+ *
+ * @todo This should eventually be merged into ElggPlugin.
+ * Currently ElggPlugin objects are only used to get and save
+ * plugin settings and user settings, so not every plugin
+ * has an ElggPlugin object.  It's not implemented in ElggPlugin
+ * right now because of conflicts with at least the constructor,
+ * enable(), disable(), and private settings.
+ *
+ * Around 1.9 or so we should each plugin over to using
+ * ElggPlugin and merge ElggPluginPackage and ElggPlugin.
+ *
+ * @package    Elgg.Core
+ * @subpackage Plugins
+ * @since      1.8
+ */
+class ElggPluginPackage {
+
+	/**
+	 * The required files in the package
+	 *
+	 * @var array
+	 */
+	private $_requiredFiles = array(
+		'start.php', 'manifest.xml'
+	);
+
+	/**
+	 * Valid types for provides.
+	 *
+	 * @var array
+	 */
+	private $_providesSupportedTypes = array(
+		'plugin', 'php_extension'
+	);
+
+	/**
+	 * The type of requires/conflicts supported
+	 *
+	 * @var array
+	 */
+	private $_depsSupportedTypes = array(
+		'elgg', 'elgg_release', 'php_extension', 'php_ini', 'plugin'
+	);
+
+	/**
+	 * An invalid plugin error.
+	 */
+	private $_invalidPluginError = '';
+
+	/**
+	 * Any dependencies messages
+	 */
+	private $_depsMsgs = array();
+
+	/**
+	 * The plugin's manifest object
+	 *
+	 * @var ElggPluginManifest
+	 */
+	protected $manifest;
+
+	/**
+	 * The plugin's full path
+	 *
+	 * @var string
+	 */
+	protected $path;
+
+	/**
+	 * Is the plugin valid?
+	 *
+	 * @var mixed Bool after validation check, null before.
+	 */
+	protected $valid = null;
+
+	/**
+	 * The plugin ID (dir name)
+	 *
+	 * @var string
+	 */
+	protected $id;
+
+	/**
+	 * Load a plugin package from mod/$id or by full path.
+	 *
+	 * @param string $plugin   The ID (directory name) or full path of the plugin.
+	 * @param bool   $validate Automatically run isValid()?
+	 *
+	 * @return true
+	 * @throws PluginException
+	 */
+	public function __construct($plugin, $validate = true) {
+		if (substr($plugin, 0, 1) == '/') {
+			// this is a path
+			$plugin = sanitise_filepath($plugin);
+
+			if (!is_dir($plugin)) {
+				throw new PluginException(elgg_echo('PluginException:InvalidPath', array($plugin)));
+			}
+
+			// the id is the last element of the array
+			$path_array = explode('/', trim($plugin, '/'));
+			$this->id = array_pop($path_array);
+			$this->path = $plugin;
+		} else {
+			// this is a plugin name
+
+			// strict plugin names
+			if (preg_match('/[^a-z0-9\.\-_]/i', $id)) {
+				throw new PluginException(elgg_echo('PluginException:InvalidID', array($plugin)));
+			}
+
+			$this->id = $plugin;
+			$this->path = get_config('pluginspath') . "$plugin/";
+		}
+
+		if ($validate && !$this->isValid()) {
+			if ($this->_invalidPluginError) {
+				throw new PluginException(elgg_echo('PluginException:InvalidPlugin:Details',
+							array($plugin, $this->_invalidPluginError)));
+			} else {
+				throw new PluginException(elgg_echo('PluginException:InvalidPlugin', array($plugin)));
+			}
+		}
+
+		return true;
+	}
+
+	/********************************
+	 * Validation and sanity checks *
+	 ********************************/
+
+	/**
+	 * Checks if this is a valid Elgg plugin.
+	 *
+	 * Checks for requires files as defined at the start of this
+	 * class.  Will check require manifest fields via ElggPluginManifest
+	 * for Elgg 1.8 plugins.
+	 *
+	 * @note This doesn't check dependencies or conflicts.
+	 * Use {@link ElggPluginPackage::canActivate()} or
+	 * {@link ElggPluginPackage::checkDependencies()} for that.
+	 *
+	 * @return bool
+	 */
+	public function isValid() {
+		if (isset($this->valid)) {
+			return $this->valid;
+		}
+
+		$valid = true;
+
+		// check required files.
+		$have_req_files = true;
+		foreach ($this->_requiredFiles as $file) {
+			if (!is_readable($this->path . $file)) {
+				$have_req_files = false;
+				$this->_invalidPluginError =
+					elgg_echo('ElggPluginPackage:InvalidPlugin:MissingFile', array($file));
+				break;
+			}
+		}
+
+		// check required files
+		if (!$have_req_files) {
+			$valid = false;
+		}
+
+		// check for valid manifest.
+		if (!$this->_loadManifest()) {
+			$valid = false;
+		}
+
+		// can't require or conflict with yourself or something you provide.
+		// make sure provides are all valid.
+		if (!$this->_isSaneDeps()) {
+			$valid = false;
+		}
+
+		$this->valid = $valid;
+
+		return $valid;
+	}
+
+	/**
+	 * Check the plugin doesn't require or conflict with itself
+	 * or something provides.  Also check that it only list
+	 * valid provides.  Deps are checked in checkDependencies()
+	 *
+	 * @note Plugins always provide themselves.
+	 *
+	 * @todo Don't let them require and conflict the same thing
+	 *
+	 * @return bool
+	 */
+	private function _isSaneDeps() {
+		$conflicts = $this->getManifest()->getConflicts();
+		$requires = $this->getManifest()->getRequires();
+		$provides = $this->getManifest()->getProvides();
+
+		foreach ($provides as $provide) {
+			// only valid provide types
+			if (!in_array($provide['type'], $this->_providesSupportedTypes)) {
+				$this->_invalidPluginError =
+					elgg_echo('ElggPluginPackage:InvalidPlugin:InvalidProvides', array($provide['type']));
+				return false;
+			}
+
+			// doesn't conflict or require any of its provides
+			$name = $provide['name'];
+			foreach (array('conflicts', 'requires') as $dep_type) {
+				foreach (${$dep_type} as $dep) {
+					if (!in_array($dep['type'], $this->_depsSupportedTypes)) {
+						$this->_invalidPluginError =
+							elgg_echo('ElggPluginPackage:InvalidPlugin:InvalidDependency', array($dep['type']));
+						return false;
+					}
+
+					// make sure nothing is providing something it conflicts or requires.
+					if ($dep['name'] == $name) {
+						$version_compare = version_compare($provide['version'], $dep['version'], $dep['comparison']);
+
+						if ($version_compare) {
+							$this->_invalidPluginError =
+								elgg_echo('ElggPluginPackage:InvalidPlugin:CircularDep',
+									array($dep['type'], $dep['name'], $this->id));
+
+							return false;
+						}
+					}
+				}
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Checks if this plugin can be activated on the current
+	 * Elgg installation.
+	 *
+	 * @return bool
+	 */
+	public function canActivate() {
+		return $this->checkDependencies();
+	}
+
+
+	/************
+	 * Manifest *
+	 ************/
+
+	/**
+	 * Returns a parsed manifest file.
+	 *
+	 * @return ElggPluginManifest
+	 */
+	public function getManifest() {
+		if (!$this->manifest) {
+			$this->_loadManifest();
+		}
+
+		return $this->manifest;
+	}
+
+	/**
+	 * Loads the manifest into this->manifest as an
+	 * ElggPluginManifest object.
+	 *
+	 * @return bool
+	 */
+	private function _loadManifest() {
+		$file = $this->path . 'manifest.xml';
+		if ($this->manifest = new ElggPluginManifest($file, $this->id)) {
+			return true;
+		}
+
+		return false;
+	}
+
+
+	/***********************
+	 * Dependencies system *
+	 ***********************/
+
+	/**
+	 * Returns if the Elgg system meets the plugin's dependency
+	 * requirements.  This includes both requires and conflicts.
+	 *
+	 * Full reports can be requested.  The results are returned
+	 * as an array of arrays in the form array(
+	 * 	'type' => requires|conflicts,
+	 * 	'dep' => array( dependency array ),
+	 * 	'status' => bool if depedency is met,
+	 * 	'comment' => optional comment to display to the user.
+	 * )
+	 *
+	 * @param bool $full_report Return a full report.
+	 * @return bool|array
+	 */
+	public function checkDependencies($full_report = false) {
+		$requires = $this->getManifest()->getRequires();
+		$conflicts = $this->getManifest()->getConflicts();
+		$enabled_plugins = get_installed_plugins('enabled');
+		$report = array();
+
+		foreach (array('requires', 'conflicts') as $dep_type) {
+			$inverse = ($dep_type == 'conflicts') ? true : false;
+
+			foreach (${$dep_type} as $dep) {
+				switch ($dep['type']) {
+					case 'elgg':
+						$result = $this->_checkDepElgg($dep, get_version());
+						break;
+
+					case 'elgg_release':
+						$result = $this->_checkDepElgg($dep, get_version(true));
+						break;
+
+					case 'plugin':
+						$result = $this->_checkDepPlugin($dep, $enabled_plugins, $inverse);
+						break;
+
+					case 'php_extension':
+						$result = $this->_checkDepPhpExtension($dep);
+						break;
+
+					case 'php_ini':
+						$result = $this->_checkDepPhpIni($dep);
+						break;
+				}
+
+				// unless we're doing a full report, break as soon as we fail.
+				if (!$full_report && !$result) {
+					return $result;
+				} else {
+					// build report element and comment
+					if ($dep_type == 'requires') {
+						$comment = '';
+					} elseif ($dep_type == 'conflicts') {
+						$comment = '';
+					}
+
+					$report[] = array(
+						'type' => $dep_type,
+						'dep' => $dep,
+						'status' => $result,
+						'comment' => $comment
+					);
+				}
+			}
+		}
+
+		if ($full_report) {
+			return $report;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Checks if $plugins meets the requirement by $dep.
+	 *
+	 * @param array $dep     An Elgg manifest.xml deps array
+	 * @param array $plugins A list of plugins as returned by get_installed_plugins();
+	 * @param bool  $inverse Inverse the results to use as a conflicts.
+	 * @return bool
+	 */
+	private function _checkDepPlugin(array $dep, array $plugins, $inverse = false) {
+		$r = elgg_check_plugins_provides('plugin', $dep['name'], $dep['version'], $dep['comparison']);
+
+		if ($inverse) {
+			$r = !$r;
+		}
+
+		return $r;
+	}
+
+	/**
+	 * Checks if $elgg_version meets the requirement by $dep.
+	 *
+	 * @param array $dep          An Elgg manifest.xml deps array
+	 * @param array $elgg_version An Elgg version (either YYYYMMDDXX or X.Y.Z)
+	 * @param bool  $inverse      Inverse the result to use as a conflicts.
+	 * @return bool
+	 */
+	private function _checkDepElgg(array $dep, $elgg_version, $inverse = false) {
+		$r = version_compare($elgg_version, $dep['version'], $dep['comparison']);
+
+		if ($inverse) {
+			$r = !$r;
+		}
+
+		return $r;
+	}
+
+	/**
+	 * Checks if the PHP extension in $dep is loaded.
+	 *
+	 * @todo Can this be merged with the plugin checker?
+	 *
+	 * @param array $dep An Elgg manifest.xml deps array
+	 * @return bool
+	 */
+	private function _checkDepPhpExtension(array $dep) {
+		$name = $dep['name'];
+		$version = $dep['version'];
+		$comparison = $dep['comparison'];
+
+		// not enabled.
+		$r = extension_loaded($name);
+
+		// enabled. check version.
+		$ext_version = phpversion($name);
+
+		if ($version && !version_compare($ext_version, $version, $comparison)) {
+			$r = false;
+		}
+
+		// some php extensions can be emulated, so check provides.
+		if ($r == false) {
+			$r = elgg_check_plugins_provides('php_extension', $name, $version, $comparison);
+		}
+
+		return $r;
+	}
+
+	/**
+	 * Check if the PHP ini setting satisfies $dep.
+	 *
+	 * @param array $dep An Elgg manifest.xml deps array
+	 * @return bool
+	 */
+	private function _checkDepPhpIni($dep) {
+		$name = $dep['name'];
+		$value = $dep['value'];
+		$comparison = $dep['comparison'];
+
+		// ini_get() normalizes truthy values to 1 but falsey values to 0 or ''.
+		// version_compare() considers '' < 0, so normalize '' to 0.
+		// ElggPluginManifest normalizes all bool values and '' to 1 or 0.
+		$setting = ini_get($name);
+
+		if ($setting === '') {
+			$setting = 0;
+		}
+
+		$r = version_compare($setting, $value, $comparison);
+
+		return $r;
+	}
+
+
+	/**************************************
+	 * Detailed reports for requirements. *
+	 **************************************/
+
+
+	/**
+	 * Returns a report of the dependencies with human
+	 * readable statuses.
+	 *
+	 * @return array
+	 */
+	public function getDependenciesReport() {
+		$requires = $this->getManifest()->getRequires();
+		$conflicts = $this->getManifest()->getConflicts();
+		$enabled_plugins = get_installed_plugins('enabled');
+
+		$status = true;
+		$messages = array();
+
+		$return = array(
+			array(
+				'type' => 'requires',
+				'dep' => $dep,
+				'status' => 'bool',
+				'comment' => ''
+			)
+		);
+
+		foreach ($requires as $require) {
+			switch ($require['type']) {
+				case 'elgg':
+					$result = $this->_checkRequiresElgg($require, get_version());
+					break;
+
+				case 'elgg_release':
+					$result = $this->_checkRequiresElgg($require, get_version(true));
+					break;
+
+				case 'plugin':
+					$result = $this->_checkDepsPlugin($require, $enabled_plugins);
+					break;
+
+				case 'php_extension':
+					$result = $this->_checkRequiresPhpExtension($require);
+					break;
+
+				case 'php_ini':
+					$result = $this->_checkRequiresPhpIni($require);
+					break;
+
+				default:
+					$result = array(
+						'status' => false,
+						'message' => elgg_echo('ElggPluginPackage:UnknownDep',
+										array($require['type'], $this->getManifest()->getPluginID()))
+					);
+					break;
+			}
+
+			if (!$result['status']) {
+				$status = false;
+				$messages[] = $result['message'];
+			}
+		}
+
+		foreach ($conflicts as $conflict) {
+
+		}
+
+		$return = array(
+			'status' => $status,
+			'messages' => $messages
+		);
+
+		return $return;
+	}
+
+	/**
+	 * Checks if $plugins meets the requirement by $require.
+	 *
+	 * Returns an array in the form array('status' => bool, 'message' => 'Any messages')
+	 *
+	 * @param array $require An Elgg manifest.xml requires array
+	 * @param array $plugins A list of plugins as returned by get_installed_plugins();
+	 * @return array
+	 */
+	private function _checkRequiresPlugin(array $require, array $plugins = array()) {
+		$status = true;
+		$message = '';
+
+		$name = $require['name'];
+		$version = $require['version'];
+		$comparison = $require['comparison'];
+
+		// not enabled.
+		if (!array_key_exists($name, $plugins)) {
+			$status = false;
+
+			if ($version) {
+				$message = elgg_echo("ElggPluginPackage:Requires:Plugin:NotEnabled:$comparison",
+							array($this->getManifest()->getPluginID(), $name, $version));
+			} else {
+				$message = elgg_echo('ElggPluginPackage:Requires:Plugin:NotEnabled:NoVersion',
+							array($this->getManifest()->getPluginID(), $name));
+			}
+		}
+
+		// enabled. check version.
+		if ($status != false) {
+			$requires_plugin_info = $plugins[$name];
+
+			//@todo boot strapping until we can migrate everything over to ElggPluginPackage.
+			$plugin_package = new ElggPluginPackage($name);
+			$plugin_version = $plugin_package->getManifest()->getVersion();
+
+			if ($version && !version_compare($plugin_version, $version, $comparison)) {
+				$status = false;
+
+				$message = elgg_echo("ElggPluginPackage:Requires:Plugin:$comparison",
+								array($this->getManifest()->getPluginID(), $name, $version, $plugin_version));
+			}
+		}
+
+		// if all else fails check with the provides
+		if ($status == false) {
+			if (elgg_check_plugins_provides('plugin', $name)) {
+				// it's provided. check version if asked.
+				$status = true;
+				$message = '';
+
+				if ($version && !elgg_check_plugins_provides('plugin', $name, $version, $comparison)) {
+						// change the message to something more meaningful
+						$provide = elgg_get_plugins_provides('plugin', $name);
+						$plugin_version = "{$provide['provided_by']}:$name={$provide['version']}";
+
+						$status = false;
+						$message = elgg_echo("ElggPluginPackage:Requires:Plugin:$comparison",
+								array($this->getManifest()->getPluginID(), $name, $version, $plugin_version));
+				}
+			}
+		}
+
+		return array(
+			'status' => $status,
+			'message' => $message
+		);
+	}
+
+	/**
+	 * Checks if $elgg_version meets the requirement by $require.
+	 *
+	 * Returns an array in the form array('status' => bool, 'message' => 'Any messages')
+	 *
+	 * @param array $require      An Elgg manifest.xml requires array
+	 * @param array $elgg_version An Elgg version (either YYYYMMDDXX or X.Y.Z)
+	 * @return array
+	 */
+	private function _checkRequiresElgg(array $require, $elgg_version) {
+		$status = true;
+		$message = '';
+		$version = $require['version'];
+		$comparison = $require['comparison'];
+
+		if (!version_compare($elgg_version, $version, $comparison)) {
+			$status = false;
+			$message = elgg_echo("ElggPluginPackage:Requires:Elgg:$comparison",
+							array($this->getManifest()->getPluginID(), $version));
+		}
+
+		return array(
+			'status' => $status,
+			'message' => $message
+		);
+	}
+
+	/**
+	 * Checks if the PHP extension in $require is loaded.
+	 *
+	 * @todo Can this be merged with the plugin checker?
+	 *
+	 * @param array $require An Elgg manifest.xml deps array
+	 * @return array
+	 */
+	private function _checkRequiresPhpExtension($require) {
+		$status = true;
+		$message = '';
+
+		$name = $require['name'];
+		$version = $require['version'];
+		$comparison = $require['comparison'];
+
+		// not enabled.
+		if (!extension_loaded($name)) {
+			$status = false;
+			if ($version) {
+				$message = elgg_echo("ElggPluginPackage:Requires:PhpExtension:NotInstalled:$comparison",
+							array($this->getManifest()->getPluginID(), $name, $version));
+			} else {
+				$message = elgg_echo('ElggPluginPackage:Requires:PhpExtension:NotInstalled:NoVersion',
+							array($this->getManifest()->getPluginID(), $name));
+			}
+		}
+
+		// enabled. check version.
+		if ($status != false) {
+			$ext_version = phpversion($name);
+
+			if ($version && !version_compare($ext_version, $version, $comparison)) {
+				$status = false;
+				$message = elgg_echo("ElggPluginPackage:Requires:PhpExtension:$comparison",
+								array($this->getManifest()->getPluginID(), $name, $version));
+			}
+		}
+
+		// some php extensions can be emulated, so check provides.
+		if ($status == false) {
+			if (elgg_check_plugins_provides('php_extension', $name)) {
+				// it's provided. check version if asked.
+				$status = true;
+				$message = '';
+
+				if ($version && !elgg_check_plugins_provides('php_extension', $name, $version, $comparison)) {
+						// change the message to something more meaningful
+						$provide = elgg_get_plugins_provides('php_extension', $name);
+						$plugin_version = "{$provide['provided_by']}:$name={$provide['version']}";
+
+						$status = false;
+						$message = elgg_echo("ElggPluginPackage:Requires:PhpExtension:$comparison",
+								array($this->getManifest()->getPluginID(), $name, $version, $plugin_version));
+				}
+			}
+		}
+
+		return array(
+			'status' => $status,
+			'message' => $message
+		);
+	}
+
+
+	/**
+	 * Check if the PHP ini setting satisfies $require.
+	 *
+	 * @param array $require An Elgg manifest.xml requires array
+	 * @return array
+	 */
+	private function _checkRequiresPhpIni($require) {
+		$status = true;
+		$message = '';
+
+		$name = $require['name'];
+		$value = $require['value'];
+		$comparison = $require['comparison'];
+
+		// ini_get() normalizes truthy values to 1 but falsey values to 0 or ''.
+		// version_compare() considers '' < 0, so normalize '' to 0.
+		// ElggPluginManifest normalizes all bool values and '' to 1 or 0.
+		$setting = ini_get($name);
+
+		if ($setting === '') {
+			$setting = 0;
+		}
+
+		if (!version_compare($setting, $value, $comparison)) {
+			$status = false;
+			$message = elgg_echo("ElggPluginPackage:Requires:PhpIni:$comparison",
+					array($this->getManifest()->getPluginID(), $name, $value, $setting));
+		}
+
+		return array(
+			'status' => $status,
+			'message' => $message
+		);
+	}
+
+	/**
+	 * Activate the plugin.
+	 *
+	 * @note This method is activate() to avoid clashing with ElggEntity::enable()
+	 *
+	 * @return bool
+	 */
+	public function activate() {
+		return enable_plugin($this->getID());
+	}
+
+	/**
+	 * Deactivate the plugin.
+	 *
+	 * @note This method is deactivate() to avoid clashing with ElggEntity::disable()
+	 *
+	 * @return bool
+	 */
+	public function deactivate() {
+		return disable_plugin($this->getID());
+	}
+
+	/**
+	 * Returns the Plugin ID
+	 *
+	 * @return string
+	 */
+	public function getID() {
+		return $this->id;
+	}
+
+}
\ No newline at end of file
diff --git a/engine/lib/plugins.php b/engine/lib/plugins.php
index 7624b1768..1c91a7776 100644
--- a/engine/lib/plugins.php
+++ b/engine/lib/plugins.php
@@ -306,6 +306,87 @@ function check_plugin_compatibility($manifest_elgg_version_string) {
 }
 
 /**
+ * Returns an array of all provides from all active plugins.
+ *
+ * Array in the form array(
+ * 	'provide_type' => array(
+ * 		'provided_name' => array(
+ * 			'version' => '1.8',
+ * 			'provided_by' => 'provider_plugin_id'
+ *  	)
+ *  )
+ * )
+ *
+ * @param string $type The type of provides to return
+ * @param string $name A specific provided name to return. Requires $provide_type.
+ *
+ * @return array
+ */
+function elgg_get_plugins_provides($type = null, $name = null) {
+	static $provides = null;
+	$active_plugins = get_installed_plugins('enabled');
+
+	if (!isset($provides)) {
+		$provides = array();
+
+		foreach ($active_plugins as $plugin_id => $plugin_info) {
+			// @todo remove this when fully converted to ElggPluginPackage.
+			$package = new ElggPluginPackage($plugin_id);
+
+			if ($plugin_provides = $package->getManifest()->getProvides()) {
+				foreach ($plugin_provides as $provided) {
+					$provides[$provided['type']][$provided['name']] = array(
+						'version' => $provided['version'],
+						'provided_by' => $plugin_id
+					);
+				}
+			}
+		}
+	}
+
+	if ($type && $name) {
+		if (isset($provides[$type][$name])) {
+			return $provides[$type][$name];
+		} else {
+			return false;
+		}
+	} elseif ($type) {
+		if (isset($provides[$type])) {
+			return $provides[$type];
+		} else {
+			return false;
+		}
+	}
+
+	return $provides;
+}
+
+/**
+ * Checks if a plugin is currently providing $type and $name, and optionally
+ * checking a version.
+ *
+ * @param string $type       The type of the provide
+ * @param string $name       The name of the provide
+ * @param string $version    A version to check against
+ * @param string $comparison The comparison operator to use in version_compare()
+ *
+ * @return bool
+ */
+function elgg_check_plugins_provides($type, $name, $version = null, $comparison = 'ge') {
+	if (!$provided = elgg_get_plugins_provides($type, $name)) {
+		return false;
+	}
+
+	if ($provided) {
+		if ($version) {
+			return version_compare($provided['version'], $version, $comparison);
+		} else {
+			return true;
+		}
+	}
+}
+
+/**
  * Shorthand function for finding the plugin settings.
  *
  * @param string $plugin_name Optional plugin name, if not specified
diff --git a/engine/tests/api/plugins.php b/engine/tests/api/plugins.php
index 66e87c91e..61e2cdde6 100644
--- a/engine/tests/api/plugins.php
+++ b/engine/tests/api/plugins.php
@@ -2,83 +2,30 @@
 /**
  * Elgg Plugins Test
  *
- * @package Elgg
- * @subpackage Test
+ * @package Elgg.Core
+ * @subpackage Plugins.Test
  */
 class ElggCorePluginsAPITest extends ElggCoreUnitTest {
-	var $manifest_file_18 = <<<___END
-<?xml version="1.0" encoding="UTF-8"?>
-<plugin_manifest version="1.8">
-	<name>Test Manifest</name>
-	<author>Anyone</author>
-	<version>1.0</version>
-	<blurb>A concise description.</blurb>
-	<description>A longer, more interesting description.</description>
-	<website>http://www.elgg.org/</website>
-	<copyright>(C) Elgg 2010</copyright>
-	<license>GNU Public License version 2</license>
-	<depends>
-		<type>elgg</type>
-		<value>2009030802</value>
-	</depends>
-
-	<screenshot description="Fun things to do 1">graphics/plugin_ss1.png</screenshot>
-	<screenshot description="Fun things to do 2">graphics/plugin_ss2.png</screenshot>
-
-	<admin>
-	<on_enable>setup_function</on_enable>
-		<on_disable>teardown_function</on_disable>
-		<interface_type>simple</interface_type>
-	</admin>
-
-	<depends>
-		<type>php_extension</type>
-		<value>gd</value>
-	</depends>
-
-	<depends>
-		<type>php_ini</type>
-		<name>safe_mode</name>
-		<value>off</value>
-	</depends>
-
-	<conflicts>
-		<type>plugin</type>
-		<value>profile</value>
-	</conflicts>
-
-	<provides>
-		<name>profile_api</name>
-		<version>1.3</version>
-	</provides>
-
-</plugin_manifest>
-___END;
-
 	// 1.8 manifest object
 	var $manifest18;
 
-	var $manifest_file_17 = <<<___END
-<?xml version="1.0" encoding="UTF-8"?>
-<plugin_manifest>
-	<field key="author" value="Anyone" />
-	<field key="version" value="1.0" />
-	<field key="description" value="A 1.7-style manifest" />
-	<field key="website" value="http://www.elgg.org/" />
-	<field key="copyright" value="(C) Elgg2008-2009" />
-	<field key="license" value="GNU Public License version 2" />
-	<field key="elgg_version" value="2009030702" />
-</plugin_manifest>
-___END;
+	// 1.8 package at test_files/plugin_18/
+	var $package18;
 
 	// 1.7 manifest object
 	var $manifest17;
 
+	// 1.7 package at test_files/plugin_17/
+	var $package17;
+
 	public function __construct() {
 		parent::__construct();
 
-		$this->manifest18 = new ElggPluginManifest($this->manifest_file_18, 'unit_test');
-		$this->manifest17 = new ElggPluginManifest($this->manifest_file_17);
+		$this->manifest18 = new ElggPluginManifest(get_config('path') . 'engine/tests/test_files/plugin_18/manifest.xml', 'plugin_test_18');
+		$this->manifest17 = new ElggPluginManifest(get_config('path') . 'engine/tests/test_files/plugin_17/manifest.xml', 'plugin_test_17');
+
+		$this->package18 = new ElggPluginPackage(get_config('path') . 'engine/tests/test_files/plugin_18');
+		$this->package17 = new ElggPluginPackage(get_config('path') . 'engine/tests/test_files/plugin_17');
 	}
 
 	/**
@@ -89,38 +36,30 @@ ___END;
 		$this->swallowErrors();
 	}
 
-
 	// generic tests
 	public function testElggPluginManifestFromString() {
-		$manifest = new ElggPluginManifest($this->manifest_file_17);
+		$manifest_file = file_get_contents(get_config('path') . 'engine/tests/test_files/plugin_17/manifest.xml');
+		$manifest = new ElggPluginManifest($manifest_file);
 
 		$this->assertIsA($manifest, 'ElggPluginManifest');
 	}
 
 	public function testElggPluginManifestFromFile() {
-		$file = get_config('dataroot') . '/manifest_test.xml';
-		$fp = fopen($file, 'wb');
-		fputs($fp, $this->manifest_file_17);
-		fclose($fp);
-
+		$file = get_config('path') . 'engine/tests/test_files/plugin_17/manifest.xml';
 		$manifest = new ElggPluginManifest($file);
 
 		$this->assertIsA($manifest, 'ElggPluginManifest');
-
-		unlink($file);
 	}
 
-	public function testElggPluginManifestFromXML() {
-		$xml = xml_to_object($this->manifest_file_17);
+	public function testElggPluginManifestFromXMLEntity() {
+		$xml = xml_to_object($manifest_file = file_get_contents(get_config('path') . 'engine/tests/test_files/plugin_17/manifest.xml'));
 		$manifest = new ElggPluginManifest($xml);
 
 		$this->assertIsA($manifest, 'ElggPluginManifest');
 	}
 
-
-
+	// exact manifest values
 	// 1.8 interface
-
 	public function testElggPluginManifest18() {
 		$manifest_array = array(
 			'name' => 'Test Manifest',
@@ -132,23 +71,33 @@ ___END;
 			'copyright' => '(C) Elgg 2010',
 			'license' => 'GNU Public License version 2',
 
-			'depends' => array(
-				array('type' => 'elgg', 'value' => '2009030802'),
-				array('type' => 'php_extension', 'value' => 'gd'),
-				array('type' => 'php_ini', 'name' => 'safe_mode', 'value' => 'off'),
+			'requires' => array(
+				array('type' => 'elgg', 'version' => '3009030802', 'comparison' => 'lt'),
+				array('type' => 'elgg_release', 'version' => '1.8-svn'),
+				array('type' => 'php_extension', 'name' => 'gd'),
+				array('type' => 'php_ini', 'name' => 'short_open_tag', 'value' => 'off'),
+				array('type' => 'php_extension', 'name' => 'made_up', 'version' => '1.0'),
+				array('type' => 'plugin', 'name' => 'fake_plugin', 'version' => '1.0'),
+				array('type' => 'plugin', 'name' => 'profile', 'version' => '1.0'),
+				array('type' => 'plugin', 'name' => 'profile_api', 'version' => '1.3', 'comparison' => 'lt'),
 			),
 
-			'screenshots' => array(
+			'screenshot' => array(
 				array('description' => 'Fun things to do 1', 'path' => 'graphics/plugin_ss1.png'),
 				array('description' => 'Fun things to do 2', 'path' => 'graphics/plugin_ss2.png'),
 			),
 
+			'category' => array(
+				'Admin', 'ServiceAPI'
+			),
+
 			'conflicts' => array(
-				array('type' => 'plugin', 'value' => 'profile')
+				array('type' => 'plugin', 'name' => 'profile_api', 'version' => 1.0)
 			),
 
 			'provides' => array(
-				array('name' => 'profile_api', 'version' => 1.3)
+				array('type' => 'plugin', 'name' => 'profile_api', 'version' => 1.3),
+				array('type' => 'php_extension', 'name' => 'big_math', 'version' => 1.0)
 			),
 
 			'admin' => array(
@@ -161,53 +110,160 @@ ___END;
 		$this->assertEqual($this->manifest18->getManifest(), $manifest_array);
 	}
 
+	public function testElggPluginManifest17() {
+		$manifest_array = array(
+			'author' => 'Anyone',
+			'version' => '1.0',
+			'description' => 'A 1.7-style manifest.',
+			'website' => 'http://www.elgg.org/',
+			'copyright' => '(C) Elgg 2010',
+			'license' => 'GNU Public License version 2',
+			'elgg_version' => '2009030702'
+		);
+
+		$this->assertEqual($this->manifest17->getManifest(), $manifest_array);
+	}
+
+
 	public function testElggPluginManifestGetApiVersion() {
 		$this->assertEqual($this->manifest18->getApiVersion(), 1.8);
+		$this->assertEqual($this->manifest17->getApiVersion(), 1.7);
 	}
 
+	public function testElggPluginManifestGetPluginID() {
+		$this->assertEqual($this->manifest18->getPluginID(), 'plugin_test_18');
+		$this->assertEqual($this->manifest17->getPluginID(), 'plugin_test_17');
+	}
+
+
+	// normalized attributes
 	public function testElggPluginManifestGetName() {
 		$this->assertEqual($this->manifest18->getName(), 'Test Manifest');
+		$this->assertEqual($this->manifest17->getName(), 'Plugin Test 17');
 	}
 
 	public function testElggPluginManifestGetAuthor() {
 		$this->assertEqual($this->manifest18->getAuthor(), 'Anyone');
+		$this->assertEqual($this->manifest17->getAuthor(), 'Anyone');
 	}
 
 	public function testElggPluginManifestGetVersion() {
 		$this->assertEqual($this->manifest18->getVersion(), 1.0);
+		$this->assertEqual($this->manifest17->getVersion(), 1.0);
 	}
 
 	public function testElggPluginManifestGetBlurb() {
 		$this->assertEqual($this->manifest18->getBlurb(), 'A concise description.');
+		$this->assertEqual($this->manifest17->getBlurb(), 'A 1.7-style manifest.');
 	}
 
 	public function testElggPluginManifestGetWebsite() {
 		$this->assertEqual($this->manifest18->getWebsite(), 'http://www.elgg.org/');
+		$this->assertEqual($this->manifest17->getWebsite(), 'http://www.elgg.org/');
 	}
 
 	public function testElggPluginManifestGetCopyright() {
 		$this->assertEqual($this->manifest18->getCopyright(), '(C) Elgg 2010');
+		$this->assertEqual($this->manifest18->getCopyright(), '(C) Elgg 2010');
 	}
 
 	public function testElggPluginManifestGetLicense() {
 		$this->assertEqual($this->manifest18->getLicense(), 'GNU Public License version 2');
+		$this->assertEqual($this->manifest17->getLicense(), 'GNU Public License version 2');
 	}
 
 
-	// 1.7 interface
+	public function testElggPluginManifestGetRequires() {
+		$requires = array(
+			array('type' => 'elgg', 'version' => '3009030802', 'comparison' => 'lt'),
+			array('type' => 'elgg_release', 'version' => '1.8-svn', 'comparison' => 'ge'),
+			array('type' => 'php_extension', 'name' => 'gd', 'version' => '', 'comparison' => '='),
+			array('type' => 'php_ini', 'name' => 'short_open_tag', 'value' => 'off', 'comparison' => '='),
+			array('type' => 'php_extension', 'name' => 'made_up', 'version' => '1.0', 'comparison' => '='),
+			array('type' => 'plugin', 'name' => 'fake_plugin', 'version' => '1.0', 'comparison' => 'ge'),
+			array('type' => 'plugin', 'name' => 'profile', 'version' => '1.0', 'comparison' => 'ge'),
+			array('type' => 'plugin', 'name' => 'profile_api', 'version' => '1.3', 'comparison' => 'lt'),
+		);
 
-	public function testElggPluginManifest17() {
-		$manifest_array = array(
-			'author' => 'Anyone',
-			'version' => '1.0',
-			'description' => 'A 1.7-style manifest',
-			'website' => 'http://www.elgg.org/',
-			'copyright' => '(C) Elgg2008-2009',
-			'license' => 'GNU Public License version 2',
-			'elgg_version' => '2009030702'
+		$this->assertEqual($this->package18->getManifest()->getRequires(), $requires);
+
+		$this->assertEqual($this->package17->getManifest()->getRequires(), array());
+	}
+
+	public function testElggPluginManifestGetDescription() {
+		$this->assertEqual($this->package18->getManifest()->getDescription(), 'A longer, more interesting description.');
+		$this->assertEqual($this->package17->getManifest()->getDescription(), 'A 1.7-style manifest.');
+	}
+
+	public function testElggPluginManifestGetDescriptionTranslated() {
+		$en = array(
+			$this->package18->getManifest()->getDescription() => 'A translated 1.8 description!',
+			$this->package17->getManifest()->getDescription() => 'A translated 1.7 description!',
 		);
 
-		$this->assertEqual($this->manifest17->getManifest(), $manifest_array);
+		add_translation('en', $en);
+
+		$this->assertEqual($this->package18->getManifest()->getDescription(), 'A translated 1.8 description!');
+		$this->assertEqual($this->package17->getManifest()->getDescription(), 'A translated 1.7 description!');
+	}
+
+	public function testElggPluginManifestGetCategories() {
+		$categories = array(
+			'Admin', 'ServiceAPI'
+		);
+
+		$this->assertEqual($this->package18->getManifest()->getCategories(), $categories);
+		$this->assertEqual($this->package17->getManifest()->getCategories(), array());
+	}
+
+	public function testElggPluginManifestGetScreenshots() {
+		$screenshots = array(
+			array('description' => 'Fun things to do 1', 'path' => 'graphics/plugin_ss1.png'),
+			array('description' => 'Fun things to do 2', 'path' => 'graphics/plugin_ss2.png'),
+		);
+
+		$this->assertEqual($this->package18->getManifest()->getScreenshots(), $screenshots);
+		$this->assertEqual($this->package17->getManifest()->getScreenshots(), array());
+	}
+
+	public function testElggPluginManifestGetProvides() {
+		$provides = array(
+			array('type' => 'plugin', 'name' => 'profile_api', 'version' => 1.3),
+			array('type' => 'php_extension', 'name' => 'big_math', 'version' => 1.0),
+			array('type' => 'plugin', 'name' => 'plugin_18', 'version' => 1.0)
+		);
+
+		$this->assertEqual($this->package18->getManifest()->getProvides(), $provides);
+
+
+		$provides = array(
+			array('type' => 'plugin', 'name' => 'plugin_17', 'version' => '1.0')
+		);
+
+		$this->assertEqual($this->package17->getManifest()->getProvides(), $provides);
 	}
 
+	public function testElggPluginManifestGetConflicts() {
+		$conflicts = array(
+			array(
+				'type' => 'plugin',
+				'name' => 'profile_api',
+				'version' => '1.0',
+				'comparison' => '='
+			)
+		);
+
+		$this->assertEqual($this->manifest18->getConflicts(), $conflicts);
+		$this->assertEqual($this->manifest17->getConflicts(), array());
+	}
+
+	// ElggPluginPackage
+	public function testElggPluginPackageDetectIDFromPath() {
+		$this->assertEqual($this->package18->getID(), 'plugin_18');
+	}
+
+	public function testElggPluginPackageDetectIDFromPluginID() {
+		$package = new ElggPluginPackage('profile');
+		$this->assertEqual($package->getID(), 'profile');
+	}
 }
diff --git a/engine/tests/test_files/plugin_17/manifest.xml b/engine/tests/test_files/plugin_17/manifest.xml
new file mode 100644
index 000000000..bb178ab93
--- /dev/null
+++ b/engine/tests/test_files/plugin_17/manifest.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<plugin_manifest>
+	<field key="author" value="Anyone" />
+	<field key="version" value="1.0" />
+	<field key="description" value="A 1.7-style manifest." />
+	<field key="website" value="http://www.elgg.org/" />
+	<field key="copyright" value="(C) Elgg 2010" />
+	<field key="license" value="GNU Public License version 2" />
+	<field key="elgg_version" value="2009030702" />
+</plugin_manifest>
\ No newline at end of file
diff --git a/engine/tests/test_files/plugin_17/start.php b/engine/tests/test_files/plugin_17/start.php
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/engine/tests/test_files/plugin_17/start.php
diff --git a/engine/tests/test_files/plugin_18/manifest.xml b/engine/tests/test_files/plugin_18/manifest.xml
new file mode 100644
index 000000000..182117a50
--- /dev/null
+++ b/engine/tests/test_files/plugin_18/manifest.xml
@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<plugin_manifest version="1.8">
+	<name>Test Manifest</name>
+	<author>Anyone</author>
+	<version>1.0</version>
+	<blurb>A concise description.</blurb>
+	<description>A longer, more interesting description.</description>
+	<website>http://www.elgg.org/</website>
+	<copyright>(C) Elgg 2010</copyright>
+	<license>GNU Public License version 2</license>
+
+	<requires>
+		<type>elgg</type>
+		<version>3009030802</version>
+		<comparison>lt</comparison>
+	</requires>
+
+	<requires>
+		<type>elgg_release</type>
+		<version>1.8-svn</version>
+	</requires>
+
+	<screenshot>
+		<description>Fun things to do 1</description>
+		<path>graphics/plugin_ss1.png</path>
+	</screenshot>
+
+	<screenshot>
+		<description>Fun things to do 2</description>
+		<path>graphics/plugin_ss2.png</path>
+	</screenshot>
+
+	<category>Admin</category>
+
+	<category>ServiceAPI</category>
+
+	<admin>
+		<on_enable>setup_function</on_enable>
+		<on_disable>teardown_function</on_disable>
+		<interface_type>simple</interface_type>
+	</admin>
+
+	<requires>
+		<type>php_extension</type>
+		<name>gd</name>
+	</requires>
+
+	<requires>
+		<type>php_ini</type>
+		<name>short_open_tag</name>
+		<value>off</value>
+	</requires>
+
+	<requires>
+		<type>php_extension</type>
+		<name>made_up</name>
+		<version>1.0</version>
+	</requires>
+
+	<requires>
+		<type>plugin</type>
+		<name>fake_plugin</name>
+		<version>1.0</version>
+	</requires>
+
+	<requires>
+		<type>plugin</type>
+		<name>profile</name>
+		<version>1.0</version>
+	</requires>
+
+	<requires>
+		<type>plugin</type>
+		<name>profile_api</name>
+		<version>1.3</version>
+		<comparison>lt</comparison>
+	</requires>
+
+	<conflicts>
+		<type>plugin</type>
+		<name>profile_api</name>
+		<version>1.0</version>
+	</conflicts>
+
+	<provides>
+		<type>plugin</type>
+		<name>profile_api</name>
+		<version>1.3</version>
+	</provides>
+
+	<provides>
+		<type>php_extension</type>
+		<name>big_math</name>
+		<version>1.0</version>
+	</provides>
+
+</plugin_manifest>
\ No newline at end of file
diff --git a/engine/tests/test_files/plugin_18/start.php b/engine/tests/test_files/plugin_18/start.php
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/engine/tests/test_files/plugin_18/start.php
diff --git a/languages/en.php b/languages/en.php
index 7155cf223..b1796f51f 100644
--- a/languages/en.php
+++ b/languages/en.php
@@ -63,6 +63,65 @@ $english = array(
 	'InvalidClassException:NotValidElggStar' => "GUID:%d is not a valid %s",
 
 	'PluginException:MisconfiguredPlugin' => "%s is a misconfigured plugin. It has been disabled. Please search the Elgg wiki for possible causes (http://docs.elgg.org/wiki/).",
+	'PluginException:InvalidID' => "%s is an invalid plugin ID.",
+	'PluginException:InvalidPath' => "%s is an invalid plugin path.",
+	'PluginException:InvalidManifest' => 'Invalid manifest file for plugin %s',
+	'PluginException:InvalidPlugin' => '%s is not a valid plugin.',
+	'PluginException:InvalidPlugin:Details' => '%s is not a valid plugin: %s',
+	'ElggPluginPackage:InvalidPlugin:MissingFile' => 'Missing file %s in package',
+	'ElggPluginPackage:InvalidPlugin:InvalidDependency' => 'Invalid dependency type "%s"',
+	'ElggPluginPackage:InvalidPlugin:InvalidProvides' => 'Invalid provides type "%s"',
+	'ElggPluginPackage:InvalidPlugin:CircularDep' => 'Invalid %s dependency "%s" in plugin %s.  Plugins cannot conflict with or require something they provide!',
+
+	'PluginException:ParserError' => 'Error parsing manifest with API version %s in plugin %s.',
+	'PluginException:NoAvailableParser' => 'Cannot find a parser for manifest API version %s in plugin %s.',
+	'PluginException:ParserErrorMissingRequiredAttribute' => "Missing required '%s' attribute in manifest for plugin %s.",
+
+	'ElggPluginPackage:UnknownDep' => 'Unknown dependency %s in plugin %s',
+
+	'ElggPluginPackage:Requires:Plugin:lt' => '%s requires the %s plugin below version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:Plugin:le' => '%s requires the %s plugin version %s or below.  Version %s is installed.',
+	'ElggPluginPackage:Requires:Plugin:=' => '%s requires the %s plugin version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:Plugin:!=' => '%s requires the %s plugin not equal to version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:Plugin:ge' => '%s requires the %s plugin version %s or higher.  Version %s is installed.',
+	'ElggPluginPackage:Requires:Plugin:gt' => '%s requires the %s plugin higher than version %s.  Version %s is installed.',
+
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:lt' => '%s requires the %s plugin below version %s.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:le' => '%s requires the %s plugin version %s or below.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:=' => '%s requires the %s plugin version %s.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:!=' => '%s requires the %s plugin not equal to version %s.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:ge' => '%s requires the %s plugin version %s or higher.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:gt' => '%s requires the %s plugin higher than version %s.',
+	'ElggPluginPackage:Requires:Plugin:NotEnabled:NoVersion' => '%s requires the %s plugin.',
+
+	'ElggPluginPackage:Requires:Elgg:lt' => '%s requires Elgg below version %s.',
+	'ElggPluginPackage:Requires:Elgg:le' => '%s requires Elgg %s or below.',
+	'ElggPluginPackage:Requires:Elgg:=' => '%s requires Elgg version %s.',
+	'ElggPluginPackage:Requires:Elgg:!=' => '%s requires Elgg not equal to version %s.',
+	'ElggPluginPackage:Requires:Elgg:ge' => '%s requires Elgg version %s or higher.',
+	'ElggPluginPackage:Requires:Elgg:gt' => '%s requires Elgg higher than version %s.',
+
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:lt' => '%s requires the %s PHP extension below version %s.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:le' => '%s requires the %s PHP extension version %s or below.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:=' => '%s requires the %s PHP extension version %s.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:!=' => '%s requires the %s PHP extension not equal to version %s.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:ge' => '%s requires the %s PHP extension version %s or higher.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:gt' => '%s requires the %s PHP extension higher than version %s.',
+	'ElggPluginPackage:Requires:PhpExtension:NotInstalled:NoVersion' => '%s requires the %s PHP extension.',
+
+	'ElggPluginPackage:Requires:PhpExtension:lt' => '%s requires the %s PHP extension below version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:PhpExtension:le' => '%s requires the %s PHP extension version %s or below.  Version %s is installed.',
+	'ElggPluginPackage:Requires:PhpExtension:=' => '%s requires the %s PHP extension version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:PhpExtension:!=' => '%s requires the %s PHP extension not equal to version %s.  Version %s is installed.',
+	'ElggPluginPackage:Requires:PhpExtension:ge' => '%s requires the %s PHP extension version %s or higher.  Version %s is installed.',
+	'ElggPluginPackage:Requires:PhpExtension:gt' => '%s requires the %s PHP extension higher than version %s.  Version %s is installed.',
+
+	'ElggPluginPackage:Requires:PhpIni:lt' => '%s requires the %s php.ini option set less than %s.  Currently set to %s.',
+	'ElggPluginPackage:Requires:PhpIni:le' => '%s requires the %s php.ini option set less than or equal to %s.  Currently set to %s.',
+	'ElggPluginPackage:Requires:PhpIni:=' => '%s requires the %s php.ini option set to %s.  Currently set to %s.',
+	'ElggPluginPackage:Requires:PhpIni:!=' => '%s requires the %s php.ini option not set to %s.  Currently set to %s.',
+	'ElggPluginPackage:Requires:PhpIni:ge' => '%s requires the %s php.ini option set greater than or equal to %s.  Currently set to %s.',
+	'ElggPluginPackage:Requires:PhpIni:gt' => '%s requires the %s php.ini option set greater than %s.  Currently set to %s.',
 
 	'InvalidParameterException:NonElggUser' => "Passing a non-ElggUser to an ElggUser constructor!",
 
@@ -770,7 +829,7 @@ Once you have logged in, we highly recommend that you change your password.
 	'upgrading' => 'Upgrading...',
 	'upgrade:db' => 'Your database was upgraded.',
 	'upgrade:core' => 'Your elgg installation was upgraded.',
-		
+
 	'deprecated:function' => '%s() was deprecated by %s()',
 
 /**