<?php

namespace Icinga\Web;
use Icinga\Application\Logger as Log;
use Icinga\Exception\ProgrammingError;

class Hook
{
    protected static $hooks = array();
    protected static $instances = array();
    public static $BASE_NS = 'Icinga\\Web\\Hook\\';

    public static function clean()
    {
        self::$hooks = array();
        self::$instances = array();
        self::$BASE_NS = 'Icinga\\Web\\Hook\\';
    }

    public static function has($name,$key=null)
    {
        if ($key !== null) {
            return isset(self::$hooks[$name][$key]);
        } else {
            return isset(self::$hooks[$name]);
        }
    }

    public static function createInstance($name,$key)
    {
        if (!self::has($name,$key)) {
            return null;
        }
        if (isset(self::$instances[$name][$key])) {
            return self::$instances[$name][$key];
        }
        $class = self::$hooks[$name][$key];
        try {
            $instance = new $class();
        } catch (\Exception $e) {
            Log::debug(
                'Hook "%s" (%s) (%s) failed, will be unloaded: %s',
                $name,
                $key,
                $class,
                $e->getMessage()
            );
            unset(self::$hooks[$name][$key]);
            return null;
        }
        self::assertValidHook($instance,$name);
        self::$instances[$name][$key] = $instance;
        return $instance;
    }

    private static function assertValidHook(&$instance, $name)
    {
        $base_class =  self::$BASE_NS.ucfirst($name);
        if (! $instance instanceof $base_class) {
            throw new ProgrammingError(sprintf(
                '%s is not an instance of %s',
                get_class($instance),
                $base_class
            ));
        }
    }

    public static function all($name)
    {
        if (!self::has($name)) {
            return array();
        }
        foreach (self::$hooks[$name] as $key=>$hook) {
            if(self::createInstance($name,$key) === null)
                return array();
        }
        return self::$instances[$name];
    }

    public static function first($name)
    {
        return self::createInstance($name,key(self::$hooks[$name]));
    }

    public static function register($name, $key, $class)
    {
        self::$hooks[$name][$key] = $class;
    }
}