<?php

/**
 *
 *
 * @author Sebastian Büttner <sebastian.buettner@powerserverplus.net>
 * @package void
 * @version 1.0.0
 * @copyright (c) 2013, powerserverplus.net
 */

class FileNotFoundException extends Exception {}

class Template
{
    /**
     * @var String Path to tempalte dir
     */
    const template_dir = 'templates';

    /**
     * @var String (sub)template filename
     */
    protected $template = '';

    /**
     * @var Array data to be used within the template
     */
    protected $data;

    /**
     * Template constructor
     *
     * @param String $templ name of the template
     */
    public function __construct($templ, $layout = 'index')
    {
        $this->load($layout);

        $this->data = array();
        $this->assign('subtemplate', $templ);
    }

    /**
     * Save a passed variable for later use in template
     *
     * @param String $name name of the varaible used to identify
     * @param Mixed $value value to be assigned to the variable
     */
    public function assign($name, $value)
    {
        /* Separate name by dot */
        $path = explode('.', $name);

        /* Take the last element of the array, as this is our final identifier */
        $lastKey = array_pop($path);

        /* Create / fill array structure, start with the template`s data base array */
        $parent = &$this->data;

        /* Iterate through the given name structure... */
        foreach ($path as $key)
        {
            /* ...And create substructres where needed */
            if (!isset($parent[$key]))
                $parent[$key] = array();

            /* Move the parent `pointer` deeper within the structure */
            $parent = &$parent[$key];
        }

        /* Finally assign the value to the deepest element in structure */
        $parent[$lastKey] = $value;
    }

    /**
     * Prepare and display the tempalte
     *
     */
    public function display()
    {
        /* We start with no code */
        $template_code = '';

        /* Merge template data with session-flash data */
        $data = $this->data;

        if (isset($_SESSION['appends']) && is_array($_SESSION['appends']) && !empty($_SESSION['appends']))
            $data = array_merge($data, $_SESSION['appends']);

        $_SESSION['appends'] = array();

        /* And iterate then over all passed variables, making them executable code again */
        foreach ($data as $key => $value)
        {
            /* Add a new line to the template code */
            $template_code .=
                /* Write varaible name */
                '$' . $key . ' = ' .
                /* Let php unserialize the variables content (which has been serialized above) at runtime of evaluation */
                'unserialize(\'' .
                /* Serialize the variables content, what is needed for arrays */
                serialize($value) .
                /* Close unserialize function and do a newline for more proper readable code */
                '\');' . "\n";

        }

        /* Put a php close tag, as we are continuing with out html-code-template */
        $template_code .= '?>';

        /* Append the template */
        $template_code .= file_get_contents($this->template);

        /* Execute the build string as PHP-Code */
        eval($template_code);
    }

    /**
     * Includes a given template by name
     *
     * @param String $templ the name of the tempalte file to be included
     */
    static function getInclude($templ)
    {
        /* Build the full path of the file to load */
        $filename = Template::template_dir . '/' . $templ . '.template.php';

        /* Check whether the requested file does exist, if not throw exception */
        if ( ! file_exists($filename) )
            throw new FileNotFoundException('Template file ' . $filename . ' not found.');

        /* return the filename to include */
        return $filename;
    }

    /**
     * Helper function, gives $default back when $var is unset
     *
     * @param Mixed $var
     * @param Mixed $default
     *
     */
    static function withDefault(&$var, $default)
    {
        if (!isset($var))
            return $default;

        return $var;
    }

    /**
     * Try to load template by name, can throw FileNotFoundException
     *
     * @param String $templ template name
     */
    private function load($templ)
    {
        /* Build the full path of the file to load */
        $filename = Template::template_dir . '/' . $templ . '.template.php';

        /* Check whether the requested file does exist, if not throw exception */
        if ( ! file_exists($filename) )
            throw new FileNotFoundException('Template file ' . $filename . ' not found.');

        /* Set the filename of the template */
        $this->template = $filename;
    }


}

?>