<?php
/* Icinga Web 2 | (c) 2013-2015 Icinga Development Team | GPLv2+ */

namespace Icinga\File\Ini;

use Zend_Config;
use Zend_Config_Ini;
use Zend_Config_Exception;
use Zend_Config_Writer_FileAbstract;
use Icinga\Application\Config;

/**
 * A INI file adapter that respects the file structure and the comments of already existing ini files
 */
class IniWriter extends Zend_Config_Writer_FileAbstract
{
    /**
     * Stores the options
     *
     * @var array
     */
    protected $options;

    /**
     * The mode to set on new files
     *
     * @var int
     */
    public static $fileMode = 0660;

    /**
     * Create a new INI writer
     *
     * @param array $options   Supports all options of Zend_Config_Writer and additional options:
     *                          * filemode:             The mode to set on new files
     *                          * valueIndentation:     The indentation level of the values
     *                          * commentIndentation:   The indentation level of the comments
     *                          * sectionSeparators:    The amount of newlines between sections
     *
     * @link http://framework.zend.com/apidoc/1.12/files/Config.Writer.html#\Zend_Config_Writer
     */
    public function __construct(array $options = null)
    {
        if (isset($options['config']) && $options['config'] instanceof Config) {
            // As this class inherits from Zend_Config_Writer_FileAbstract we must
            // not pass the config directly as it needs to be of type Zend_Config
            $options['config'] = new Zend_Config($options['config']->toArray(), true);
        }

        $this->options = $options;
        parent::__construct($options);
    }

    /**
     * Render the Zend_Config into a config file string
     *
     * @return  string
     */
    public function render()
    {
        if (file_exists($this->_filename)) {
            $oldconfig = new Zend_Config_Ini($this->_filename);
            $content = trim(file_get_contents($this->_filename));
        } else {
            $oldconfig = new Zend_Config(array());
            $content = '';
        }

        $newconfig = $this->_config;
        $editor = new IniEditor($content, $this->options);
        $this->diffConfigs($oldconfig, $newconfig, $editor);
        $this->updateSectionOrder($newconfig, $editor);
        return $editor->getText();
    }

    /**
     * Write configuration to file and set file mode in case it does not exist yet
     *
     * @param string $filename
     * @param Zend_Config $config
     * @param bool $exclusiveLock
     */
    public function write($filename = null, Zend_Config $config = null, $exclusiveLock = null)
    {
        $filePath = $filename !== null ? $filename : $this->_filename;
        $setMode = false === file_exists($filePath);

        parent::write($filename, $config, $exclusiveLock);

        if ($setMode) {
            $mode = isset($this->options['filemode']) ? $this->options['filemode'] : static::$fileMode;
            if (is_int($mode) && false === @chmod($filePath, $mode)) {
                throw new Zend_Config_Exception(sprintf('Failed to set file mode "%o" on file "%s"', $mode, $filePath));
            }
        }
    }

    /**
     * Create a property diff and apply the changes to the editor
     *
     * @param   Zend_Config     $oldconfig      The config representing the state before the change
     * @param   Zend_Config     $newconfig      The config representing the state after the change
     * @param   IniEditor       $editor         The editor that should be used to edit the old config file
     * @param   array           $parents        The parent keys that should be respected when editing the config
     */
    protected function diffConfigs(
        Zend_Config $oldconfig,
        Zend_Config $newconfig,
        IniEditor $editor,
        array $parents = array()
    ) {
        $this->diffPropertyUpdates($oldconfig, $newconfig, $editor, $parents);
        $this->diffPropertyDeletions($oldconfig, $newconfig, $editor, $parents);
    }

    /**
     * Update the order of the sections in the ini file to match the order of the new config
     */
    protected function updateSectionOrder(Zend_Config $newconfig, IniEditor $editor)
    {
        $order = array();
        foreach ($newconfig as $key => $value) {
            if ($value instanceof Zend_Config) {
                array_push($order, $key);
            }
        }
        $editor->refreshSectionOrder($order);
    }

    /**
     * Search for created and updated properties and use the editor to create or update these entries
     *
     * @param Zend_Config   $oldconfig  The config representing the state before the change
     * @param Zend_Config   $newconfig  The config representing the state after the change
     * @param IniEditor     $editor     The editor that should be used to edit the old config file
     * @param array         $parents    The parent keys that should be respected when editing the config
     */
    protected function diffPropertyUpdates(
        Zend_Config $oldconfig,
        Zend_Config $newconfig,
        IniEditor $editor,
        array $parents = array()
    ) {
        // The current section. This value is null when processing the section-less root element
        $section = empty($parents) ? null : $parents[0];
        // Iterate over all properties in the new configuration file and search for changes
        foreach ($newconfig as $key => $value) {
            $oldvalue = $oldconfig->get($key);
            $nextParents = array_merge($parents, array($key));
            $keyIdentifier = empty($parents) ? array($key) : array_slice($nextParents, 1, null, true);
            if ($value instanceof Zend_Config) {
                // The value is a nested Zend_Config, handle it recursively
                if ($section === null) {
                    // Update the section declaration
                    $extends = $newconfig->getExtends();
                    $extend = array_key_exists($key, $extends) ? $extends[$key] : null;
                    $editor->setSection($key, $extend);
                }
                if ($oldvalue === null) {
                    $oldvalue = new Zend_Config(array());
                }
                $this->diffConfigs($oldvalue, $value, $editor, $nextParents);
            } else {
                // The value is a plain value, use the editor to set it
                if (is_numeric($key)) {
                    $editor->setArrayElement($keyIdentifier, $value, $section);
                } else {
                    $editor->set($keyIdentifier, $value, $section);
                }
            }
        }
    }

    /**
     * Search for deleted properties and use the editor to delete these entries
     *
     * @param Zend_Config   $oldconfig  The config representing the state before the change
     * @param Zend_Config   $newconfig  The config representing the state after the change
     * @param IniEditor     $editor     The editor that should be used to edit the old config file
     * @param array         $parents    The parent keys that should be respected when editing the config
     */
    protected function diffPropertyDeletions(
        Zend_Config $oldconfig,
        Zend_Config $newconfig,
        IniEditor $editor,
        array $parents = array()
    ) {
        // The current section. This value is null when processing the section-less root element
        $section = empty($parents) ? null : $parents[0];

        // Iterate over all properties in the old configuration file and search for deleted properties
        foreach ($oldconfig as $key => $value) {
            if ($newconfig->get($key) === null) {
                $nextParents = array_merge($parents, array($key));
                $keyIdentifier = empty($parents) ? array($key) : array_slice($nextParents, 1, null, true);
                foreach ($this->getPropertyIdentifiers($value, $keyIdentifier) as $propertyIdentifier) {
                    $editor->reset($propertyIdentifier, $section);
                }
            }
        }
    }

    /**
     * Return all possible combinations of property identifiers for the given value
     *
     * @param   mixed   $value  The value to return all combinations for
     * @param   array   $key    The root property identifier, if any
     *
     * @return  array           All property combinations that are possible
     *
     * @todo                    Cannot handle array properties yet (e.g. a.b[]='c')
     */
    protected function getPropertyIdentifiers($value, array $key = null)
    {
        $combinations = array();
        $rootProperty = $key !== null ? $key : array();

        if ($value instanceof Zend_Config) {
            foreach ($value as $subProperty => $subValue) {
                $combinations = array_merge(
                    $combinations,
                    $this->getPropertyIdentifiers($subValue, array_merge($rootProperty, array($subProperty)))
                );
            }
        } elseif (is_string($value)) {
            $combinations[] = $rootProperty;
        }

        return $combinations;
    }

    /**
     * Getter for filename
     *
     * @return string
     */
    public function getFilename()
    {
        return $this->_filename;
    }
}