Add mechanism at (un)install of an extension

Test if the install or uninstall has been successfully performed.
If these methods return true, all is ok but if a string is returned,
the string must explain the problem. This problem is stored in log file.

A feedback is given to explain to check log file.

This commit fix a problem in the english translation of
feedback.sub.feed.internal_problem.

app/Controllers/extensionController.php

@@ -88,15 +88,21 @@ class FreshRSS_extension_Controller extends Minz_ActionController {
 				                  $url_redirect);
 			}
 
-			$ext->install();
+			$res = $ext->install();
 
-			$ext_list = $conf->extensions_enabled;
-			array_push_unique($ext_list, $ext_name);
-			$conf->extensions_enabled = $ext_list;
-			$conf->save();
+			if ($res === true) {
+				$ext_list = $conf->extensions_enabled;
+				array_push_unique($ext_list, $ext_name);
+				$conf->extensions_enabled = $ext_list;
+				$conf->save();
 
-			Minz_Request::good(_t('feedback.extensions.enabled', $ext_name),
-			                  $url_redirect);
+				Minz_Request::good(_t('feedback.extensions.enable.ok', $ext_name),
+				                   $url_redirect);
+			} else {
+				Minz_Log::warning('Can not enable extension ' . $ext_name . ': ' . $res);
+				Minz_Request::bad(_t('feedback.extensions.enable.ko', $ext_name, _url('index', 'logs')),
+				                  $url_redirect);
+			}
 		}
 
 		Minz_Request::forward($url_redirect, true);
@@ -138,15 +144,21 @@ class FreshRSS_extension_Controller extends Minz_ActionController {
 				                  $url_redirect);
 			}
 
-			$ext->uninstall();
+			$res = $ext->uninstall();
 
-			$ext_list = $conf->extensions_enabled;
-			array_remove($ext_list, $ext_name);
-			$conf->extensions_enabled = $ext_list;
-			$conf->save();
+			if ($res === true) {
+				$ext_list = $conf->extensions_enabled;
+				array_remove($ext_list, $ext_name);
+				$conf->extensions_enabled = $ext_list;
+				$conf->save();
 
-			Minz_Request::good(_t('feedback.extensions.disabled', $ext_name),
-			                  $url_redirect);
+				Minz_Request::good(_t('feedback.extensions.disable.ok', $ext_name),
+				                   $url_redirect);
+			} else {
+				Minz_Log::warning('Can not unable extension ' . $ext_name . ': ' . $res);
+				Minz_Request::bad(_t('feedback.extensions.disable.ko', $ext_name, _url('index', 'logs')),
+				                  $url_redirect);
+			}
 		}
 
 		Minz_Request::forward($url_redirect, true);

app/i18n/en/feedback.php

@@ -31,8 +31,14 @@ return array(
 	),
 	'extensions' => array(
 		'already_enabled' => '%s is already enabled',
-		'disabled' => '%s is now disabled',
-		'enabled' => '%s is now enabled',
+		'disable' => array(
+			'ko' => '%s cannot be disabled. <a href="%s">Check FressRSS logs</a> for details.',
+			'ok' => '%s is now disabled',
+		),
+		'enable' => array(
+			'ko' => '%s cannot be enabled. <a href="%s">Check FressRSS logs</a> for details.',
+			'ok' => '%s is now enabled',
+		),
 		'no_access' => 'You have no access on %s',
 		'not_enabled' => '%s is not enabled yet',
 		'not_found' => '%s does not exist',
@@ -67,7 +73,7 @@ return array(
 			'already_subscribed' => 'You have already subscribed to <em>%s</em>',
 			'deleted' => 'Feed has been deleted',
 			'error' => 'Feed cannot be updated',
-			'internal_problem_feed' => 'The RSS feed could not be added. <a href="%s">Check FressRSS logs</a> for details.',
+			'internal_problem' => 'The RSS feed could not be added. <a href="%s">Check FressRSS logs</a> for details.',
 			'invalid_url' => 'URL <em>%s</em> is invalid',
 			'marked_read' => 'Feeds have been marked as read',
 			'n_actualized' => '%d feeds have been updated',

app/i18n/fr/feedback.php

@@ -31,8 +31,14 @@ return array(
 	),
 	'extensions' => array(
 		'already_enabled' => '%s est déjà activée',
-		'disabled' => '%s est désormais désactivée',
-		'enabled' => '%s est désormais activée',
+		'disable' => array(
+			'ko' => '%s ne peut pas être désactivée. <a href="%s">Consulter les logs de FreshRSS</a> pour plus de détails.',
+			'ok' => '%s est désormais désactivée',
+		),
+		'enable' => array(
+			'ko' => '%s ne peut pas être activée. <a href="%s">Consulter les logs de FreshRSS</a> pour plus de détails.',
+			'ok' => '%s est désormais activée',
+		),
 		'no_access' => 'Vous n’avez aucun accès sur %s',
 		'not_enabled' => '%s n’est pas encore activée',
 		'not_found' => '%s n’existe pas',

lib/Minz/Extension.php

@@ -51,16 +51,26 @@ class Minz_Extension {
 	 * Used when installing an extension (e.g. update the database scheme).
 	 *
 	 * It must be redefined by child classes.
+	 *
+	 * @return true if the extension has been installed or a string explaining
+	 *         the problem.
 	 */
-	public function install() {}
+	public function install() {
+		return true;
+	}
 
 	/**
 	 * Used when uninstalling an extension (e.g. revert the database scheme to
 	 * cancel changes from install).
 	 *
 	 * It must be redefined by child classes.
+	 *
+	 * @return true if the extension has been uninstalled or a string explaining
+	 *         the problem.
 	 */
-	public function uninstall() {}
+	public function uninstall() {
+		return true;
+	}
 
 	/**
 	 * Call at the initialization of the extension (i.e. when the extension is