<?php

namespace SilverStripe\View;

/**
 * Interface that is implemented by any classes that want to expose a method that can be called in any
 * scope in a template that returns values dependent on the state of the iterator of the current scope.
 *
 * SSViewer_BasicIteratorSupport is an example of this. See also @TemplateGlobalProvider
 */
interface TemplateIteratorProvider
{

    /**
     * Called by SSViewer to get a list of iterator variables to expose to the template, the instance method to call
     * on an instance of this class to get the value for those variables, and the class to use for casting the returned
     * value for use in a template
     *
     * If the method to call is not included for a particular template variable, a method named the same as the
     * template variable will be called
     *
     * If the casting class is not specified for a particular template variable, ViewableData::$default_cast is used
     *
     * The first letter of the template variable is case-insensitive. However the method name is always case sensitive.
     *
     * @abstract
     * @return array Returns an array of items. Each key => value pair is one of three forms:
     *  - template name (no key)
     *  - template name => method name
     *  - template name => array(), where the array can contain these key => value pairs
     *     - "method" => method name
     *     - "casting" => casting class to use (i.e., Varchar, HTMLFragment, etc)
     */
    public static function get_template_iterator_variables();

    /**
     * Set the current iterator properties - where we are on the iterator.
     *
     * This is called by SSViewer prior to calling any of the variables exposed to the template (that is, as returned
     * from a call to get_template_iterator_variables)
     *
     * @abstract
     * @param int $pos position in iterator
     * @param int $totalItems total number of items
     */
    public function iteratorProperties($pos, $totalItems);
}