<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Form;

/**
 * Adapter for rendering form templates with a specific templating engine.
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
interface FormRendererEngineInterface
{
    /**
     * Sets the theme(s) to be used for rendering a view and its children.
     *
     * @param FormViewInterface $view   The view to assign the theme(s) to.
     * @param mixed             $themes The theme(s). The type of these themes
     *                                  is open to the implementation.
     */
    public function setTheme(FormViewInterface $view, $themes);

    /**
     * Returns the resource for a block name.
     *
     * The resource is first searched in the themes attached to $view, then
     * in the themes of its parent view and so on, until a resource was found.
     *
     * The type of the resource is decided by the implementation. The resource
     * is later passed to {@link renderBlock()} by the rendering algorithm.
     *
     * @param FormViewInterface $view  The view for determining the used themes.
     *                                 First the themes attached directly to the
     *                                 view with {@link setTheme()} are considered,
     *                                 then the ones of its parent etc.
     * @param string            $block The name of the block to render.
     *
     * @return mixed The renderer resource or false, if none was found.
     */
    public function getResourceForBlock(FormViewInterface $view, $block);

    /**
     * Returns the resource for a block hierarchy.
     *
     * A block hierarchy is an array which starts with the root of the hierarchy
     * and continues with the child of that root, the child of that child etc.
     * The following is an example for a block hierarchy:
     *
     * <code>
     * form_widget
     * text_widget
     * url_widget
     * </code>
     *
     * In this example, "url_widget" is the most specific block, while the other
     * blocks are its ancestors in the hierarchy.
     *
     * The second parameter $hierarchyLevel determines the level of the hierarchy
     * that should be rendered. For example, if $hierarchyLevel is 2 for the
     * above hierarchy, the engine will first look for the block "url_widget",
     * then, if that does not exist, for the block "text_widget" etc.
     *
     * The type of the resource is decided by the implementation. The resource
     * is later passed to {@link renderBlock()} by the rendering algorithm.
     *
     * @param FormViewInterface $view           The view for determining the used
     *                                          themes. First the themes attached
     *                                          directly to the view with
     *                                          {@link setTheme()} are considered,
     *                                          then the ones of its parent etc.
     * @param array             $blockHierarchy The block name hierarchy, with
     *                                          the root block at the beginning.
     * @param integer           $hierarchyLevel The level in the hierarchy at
     *                                          which to start looking. Level 0
     *                                          indicates the root block, i.e.
     *                                          the first element of $blockHierarchy.
     *
     * @return mixed The renderer resource or false, if none was found.
     */
    public function getResourceForBlockHierarchy(FormViewInterface $view, array $blockHierarchy, $hierarchyLevel);

    /**
     * Returns the hierarchy level at which a resource can be found.
     *
     * A block hierarchy is an array which starts with the root of the hierarchy
     * and continues with the child of that root, the child of that child etc.
     * The following is an example for a block hierarchy:
     *
     * <code>
     * form_widget
     * text_widget
     * url_widget
     * </code>
     *
     * The second parameter $hierarchyLevel determines the level of the hierarchy
     * that should be rendered.
     *
     * If we call this method with the hierarchy level 2, the engine will first
     * look for a resource for block "url_widget". If such a resource exists,
     * the method returns 2. Otherwise it tries to find a resource for block
     * "text_widget" (at level 1) and, again, returns 1 if a resource was found.
     * The method continues to look for resources until the root level was
     * reached and nothing was found. In this case false is returned.
     *
     * The type of the resource is decided by the implementation. The resource
     * is later passed to {@link renderBlock()} by the rendering algorithm.
     *
     * @param FormViewInterface $view           The view for determining the used
     *                                          themes. First the themes attached
     *                                          directly to the view with
     *                                          {@link setTheme()} are considered,
     *                                          then the ones of its parent etc.
     * @param array             $blockHierarchy The block name hierarchy, with
     *                                          the root block at the beginning.
     * @param integer           $hierarchyLevel The level in the hierarchy at
     *                                          which to start looking. Level 0
     *                                          indicates the root block, i.e.
     *                                          the first element of $blockHierarchy.
     *
     * @return integer|Boolean The hierarchy level or false, if no resource was found.
     */
    public function getResourceHierarchyLevel(FormViewInterface $view, array $blockHierarchy, $hierarchyLevel);

    /**
     * Renders a block in the given renderer resource.
     *
     * The resource can be obtained by calling {@link getResourceForBlock()}
     * or {@link getResourceForBlockHierarchy()}. The type of the resource is
     * decided by the implementation.
     *
     * @param FormViewInterface $view      The view to render.
     * @param mixed             $resource  The renderer resource.
     * @param string            $block     The name of the block to render.
     * @param array             $variables The variables to pass to the template.
     *
     * @return string The HTML markup.
     */
    public function renderBlock(FormViewInterface $view, $resource, $block, array $variables = array());
}