<?php

/**
 * Icinga Backend Abstract
 *
 * @package Icinga\Backend
 */
namespace Icinga\Backend;
use Icinga\Application\Config;

abstract class AbstractBackend
{
    protected $config;
    protected $extensions = array();

    /**
     * Backend constructor, should not be overwritten
     *
     * Makes sure that $this->config exists. Config is a Zend_Config
     * object right now, only the main Config is an Icinga one
     *
     * return void
     */
    final public function __construct(\Zend_Config $config = null)
    {
        if ($config == null)
            $config = new \Zend_Config(array());
        $this->config = $config;
        $this->init();
    }

    /**
     * Override this function for initialization tasks
     *
     * return void
     */
    protected function init() {}

    /**
     * Dummy function for fluent code
     *
     * return \Icinga\Backend\Ido
     */
    public function select()
    {
        return $this;
    }

    /**
     * Create a Query object instance for given virtual table and desired fields
     *
     * Leave fields empty to get all available properties
     *
     * @param string Virtual table name
     * @param array  Fields
     * return \Icinga\Backend\Ido\Query
     */
    public function from($virtual_table, $fields = array())
    {
        $classname = $this->tableToClassName($virtual_table);
        if (! class_exists($classname)) {
            throw new \Exception(sprintf('Asking for invalid virtual table %s', $classname));
        }
        $query = new $classname($this, $fields);
        return $query;
    }

    public function hasView($virtual_table)
    {
        return class_exists($this->tableToClassName($virtual_table));
    }

    protected function tableToClassName($virtual_table)
    {
        if (strpos($virtual_table,"/") !== false) {
            list($module, $classname) = explode("/",$virtual_table,2);
            $class = array_pop(explode("\\",get_class($this)));
            return 'Icinga\\'.ucfirst($module).'\\Backend\\'.$class.'\\'.ucfirst($classname).'Query';
        } else {
            return get_class($this) . '\\' . ucfirst($virtual_table . 'Query');
        }
    }

    public function getName()
    {
        return preg_replace('~^.+\\\(.+?)$~', '$1', get_class($this));
    }

    public function __toString()
    {
        return $this->getName();
    }

}