Add an IniWriter that preserves the comments in already existing files

Add a function to create diffs between two object, add a
FileEditor to edit files line-by-line and add the class PropertyDiff to
describe a single property change.

refs #4352

library/Icinga/Config/Config.php

@@ -28,7 +28,6 @@
 
 namespace Icinga\Application;
 
-use Icinga\Protocol\Ldap\Exception;
 use Zend_Config_Ini;
 
 /**
@@ -71,7 +70,7 @@ class Config extends Zend_Config_Ini
     public function __construct($filename)
     {
         if (!@is_readable($filename)) {
-            throw new Exception('Cannot read config file: ' . $filename);
+            throw new \Exception('Cannot read config file: ' . $filename);
         };
         $this->configFile = $filename;
         $section = null;

library/Icinga/Config/PreservingIniWriter.php

@@ -0,0 +1,311 @@
+<?php
+
+// {{{ICINGA_LICENSE_HEADER}}}
+/**
+ * This file is part of Icinga 2 Web.
+ *
+ * Icinga 2 Web - Head for multiple monitoring backends.
+ * Copyright (C) 2013 Icinga Development Team
+ *
+ * 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 Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * @copyright 2013 Icinga Development Team <info@icinga.org>
+ * @license   http://www.gnu.org/licenses/gpl-2.0.txt GPL, version 2
+ * @author    Icinga Development Team <info@icinga.org>
+ */
+// {{{ICINGA_LICENSE_HEADER}}}
+
+namespace Icinga\Config;
+
+/**
+ * A ini file adapter that preserves comments in the existing ini file, when writing changes to it
+ */
+class PreservingIniWriter extends \Zend_Config_Writer
+{
+    /**
+     * The file that is written to
+     *
+     * @var string
+     */
+    private $filename;
+
+    public function setFilename($filename)
+    {
+        $this->filename = $filename;
+    }
+
+    function __construct(array $options)
+    {
+        parent::__construct($options);
+    }
+
+    /**
+     * Write the config to the file
+     */
+    public function write()
+    {
+        if (empty($this->filename)) {
+            throw new Exception('No filename for configuration provided');
+        }
+        $oldConfig = parse_ini_file($this->filename);
+        $newConfig = $this->_config;
+        $diff = $this->createPropertyDiff($oldConfig,$newConfig);
+    }
+
+    /**
+     * Create a diff between the properties of two Zend_Config objects
+     *
+     * @param \Zend_Config $oldConfig
+     * @param \Zend_Config $newConfig
+     */
+    private function createConfigDiff(\Zend_Config $oldConfig, \Zend_Config $newConfig)
+    {
+        // TODO: Find deleted sections in old
+    }
+
+    private function updateIniWithDiff($fileDiff)
+    {
+        $iniReader = new IniKeyPositionReader();
+        $editor = new FileEditor($this->filename);
+        foreach ($fileDiff as $key => $diff) {
+
+        }
+    }
+
+    private function unwrapKeys($parents,$diffs)
+    {
+
+    }
+}
+
+/**
+ * Can read information about the position of ini-file keys and values
+ * from
+ */
+class IniKeyPositionReader
+{
+    public function getKeyStart(array $parents,String $key)
+    {
+        // return line
+    }
+
+    public function getKeyContainerFirstEmpty(String $section)
+    {
+        // return line
+    }
+
+    public function getKeyLine(String $section,String $key)
+    {
+        // return line
+    }
+}
+
+/**
+ * Edit a file line by line
+ *
+ * The functions delete, insert and update can be applied to certain lines
+ * of the file and are written to it, once applyChanges is called. Line inserts and deletes
+ * are handled automatically and the changes in line numbers don't need to be respected when
+ * calling the edit functions.
+ */
+class FileEditor
+{
+    /**
+     * @var String
+     */
+    private $filename;
+
+    /**
+     * The symbol that delimits a comment.
+     *
+     * @var string
+     */
+    private $commentDelimiter = '';
+
+    /**
+     * Set a new comment delimiter
+     */
+    public function setCommentDelimiter(String $delimiter)
+    {
+        $this->commentDelimiter = $delimiter;
+        return $this;
+    }
+
+    /**
+     * Get the current comment delimiter
+     *
+     * @return string The comment delimiter
+     */
+    public function getCommentDelimiter()
+    {
+        return $this->commentDelimiter;
+    }
+
+    /**
+     * Create a new FileEditor
+     *
+     * @param $filename The file that should be edited.
+     */
+    public function __constructor($filename)
+    {
+        $this->filename = $filename;
+    }
+
+    /**
+     * Delete a line
+     *
+     * @param $line The line
+     */
+    public function delete($line)
+    {
+
+    }
+
+    /**
+     * Insert a text into the file
+     *
+     * @param $line The line where the text should be inserted
+     * @param $text The text
+     */
+    public function insert($line,$text)
+    {
+
+    }
+
+    /**
+     * Update the given line and insert $text
+     *
+     * Update the line but ignore text separated by a comment delimiter.
+     *
+     * @param $line The line number
+     * @param $text The text that will be inserted
+     */
+    public function update($line,$text)
+    {
+
+    }
+
+    /**
+     * Write changes to the file
+     */
+    public function applyChanges()
+    {
+
+    }
+}
+
+/**
+ * A diff that describes the change of an object property
+ */
+class PropertyDiff {
+
+    /**
+     * Create the property diff between two objects
+     *
+     * @param stdClass $oldObject The object representing the state before the change
+     * @param stdClass $newObject The object representing the state after the change
+     *
+     * @return array An associative array mapping all changed properties to a property diff
+     * describing the change
+     */
+    public static function createObjectDiff(stdClass $oldObject,stdClass $newObject)
+    {
+        $diffs = array();
+        /*
+         * Search inserted or updated properties
+         */
+        foreach ($newObject as $key => $value) {
+            $newProperty = $value;
+            $oldProperty = $oldObject->{$key};
+            if (is_array($newProperty)) {
+                if (empty($oldProperty)) {
+                    $diffs[$key] = new PropertyDiff(
+                        PropertyDiff::ACTION_INSERT,
+                        PropertyDiff::createObjectDiff(new \stdClass(),$newObject));
+                } else {
+                    $diffs[$key] = new PropertyDiff(
+                        PropertyDiff::ACTION_NONE,
+                        PropertyDiff::createObjectDiff($oldObject,$newObject)
+                    );
+                }
+            } else {
+                if (empty($oldProperty)) {
+                    $diffs[$key] =
+                        new PropertyDiff(PropertyDiff::ACTION_INSERT,$newProperty);
+                } elseif (strcasecmp($newProperty,$oldProperty) != 0) {
+                    $diffs[$key] =
+                        new PropertyDiff(PropertyDiff::ACTION_UPDATE,$newProperty);
+                }
+            }
+        }
+        /*
+         * Search deleted properties
+         */
+        foreach ($oldObject as $key => $value) {
+            if (empty($newObject->{$key})) {
+                $oldProperty = $value;
+                if (is_array($oldProperty)){
+                    $diffs[key] = new PropertyDiff(
+                        PropertyDiff::ACTION_DELETE,
+                        PropertyDiff::createObjectDiff($oldObject,new \stdClass())
+                    );
+                } else {
+                    $diffs[$key] =
+                        new PropertyDiff(PropertyDiff::ACTION_DELETE,null);
+                }
+            }
+        }
+    }
+
+    /**
+     * The available action types
+     */
+    const ACTION_INSERT = 0;
+    const ACTION_UPDATE = 1;
+    const ACTION_DELETE = 2;
+    const ACTION_NONE = 3;
+
+    /**
+     * The action described by this diff
+     *
+     * @var String
+     */
+    public $action;
+
+    /**
+     * The value after the change
+     *
+     * @var StdClass
+     */
+    public $value;
+
+    /**
+     * Create a new PropertyDiff
+     *
+     * @param int $action The action described by this diff
+     * @param string $value The value after the change
+     */
+    public function Diff($action, $value)
+    {
+        if (action != ACTION_CREATE &&
+            action != ACTION_UPDATE &&
+            action != ACTION_DELETE) {
+            throw new \Exception('Invalid action code: '.$action);
+        }
+        $this->action = $action;
+        $this->value = $value;
+    }
+}
+