<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\widgets;

use Yii;
use yii\base\Widget;
use yii\base\InvalidConfigException;
use yii\helpers\Html;

/**
 * Breadcrumbs displays a list of links indicating the position of the current page in the whole site hierarchy.
 *
 * For example, breadcrumbs like "Home / Sample Post / Edit" means the user is viewing an edit page
 * for the "Sample Post". He can click on "Sample Post" to view that page, or he can click on "Home"
 * to return to the homepage.
 *
 * To use Breadcrumbs, you need to configure its [[links]] property, which specifies the links to be displayed. For example,
 *
 * ~~~
 * // $this is the view object currently being used
 * echo Breadcrumbs::widget([
 *     'links' => [
 *         ['label' => 'Sample Post', 'url' => ['post/edit', 'id' => 1]],
 *         'Edit',
 *     ],
 * ]);
 * ~~~
 *
 * Because breadcrumbs usually appears in nearly every page of a website, you may consider placing it in a layout view.
 * You can use a view parameter (e.g. `$this->params['breadcrumbs']`) to configure the links in different
 * views. In the layout view, you assign this view parameter to the [[links]] property like the following:
 *
 * ~~~
 * // $this is the view object currently being used
 * echo Breadcrumbs::widget([
 *     'links' => isset($this->params['breadcrumbs']) ? $this->params['breadcrumbs'] : [],
 * ]);
 * ~~~
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Breadcrumbs extends Widget
{
	/**
	 * @var string the name of the breadcrumb container tag.
	 */
	public $tag = 'ul';
	/**
	 * @var array the HTML attributes for the breadcrumb container tag.
	 * @see \yii\helpers\Html::renderTagAttributes() for details on how attributes are being rendered.
	 */
	public $options = ['class' => 'breadcrumb'];
	/**
	 * @var boolean whether to HTML-encode the link labels.
	 */
	public $encodeLabels = true;
	/**
	 * @var array the first hyperlink in the breadcrumbs (called home link).
	 * Please refer to [[links]] on the format of the link.
	 * If this property is not set, it will default to a link pointing to [[\yii\web\Application::homeUrl]]
	 * with the label 'Home'. If this property is false, the home link will not be rendered.
	 */
	public $homeLink;
	/**
	 * @var array list of links to appear in the breadcrumbs. If this property is empty,
	 * the widget will not render anything. Each array element represents a single link in the breadcrumbs
	 * with the following structure:
	 *
	 * ~~~
	 * [
	 *     'label' => 'label of the link',  // required
	 *     'url' => 'url of the link',      // optional, will be processed by Url::to()
	 * ]
	 * ~~~
	 *
	 * If a link is active, you only need to specify its "label", and instead of writing `['label' => $label]`,
	 * you should simply use `$label`.
	 */
	public $links = [];
	/**
	 * @var string the template used to render each inactive item in the breadcrumbs. The token `{link}`
	 * will be replaced with the actual HTML link for each inactive item.
	 */
	public $itemTemplate = "<li>{link}</li>\n";
	/**
	 * @var string the template used to render each active item in the breadcrumbs. The token `{link}`
	 * will be replaced with the actual HTML link for each active item.
	 */
	public $activeItemTemplate = "<li class=\"active\">{link}</li>\n";

	/**
	 * Renders the widget.
	 */
	public function run()
	{
		if (empty($this->links)) {
			return;
		}
		$links = [];
		if ($this->homeLink === null) {
			$links[] = $this->renderItem([
				'label' => Yii::t('yii', 'Home'),
				'url' => Yii::$app->homeUrl,
			], $this->itemTemplate);
		} elseif ($this->homeLink !== false) {
			$links[] = $this->renderItem($this->homeLink, $this->itemTemplate);
		}
		foreach ($this->links as $link) {
			if (!is_array($link)) {
				$link = ['label' => $link];
			}
			$links[] = $this->renderItem($link, isset($link['url']) ? $this->itemTemplate : $this->activeItemTemplate);
		}
		echo Html::tag($this->tag, implode('', $links), $this->options);
	}

	/**
	 * Renders a single breadcrumb item.
	 * @param array $link the link to be rendered. It must contain the "label" element. The "url" element is optional.
	 * @param string $template the template to be used to rendered the link. The token "{link}" will be replaced by the link.
	 * @return string the rendering result
	 * @throws InvalidConfigException if `$link` does not have "label" element.
	 */
	protected function renderItem($link, $template)
	{
		if (isset($link['label'])) {
			$label = $this->encodeLabels ? Html::encode($link['label']) : $link['label'];
		} else {
			throw new InvalidConfigException('The "label" element is required for each link.');
		}
		if (isset($link['url'])) {
			return strtr($template, ['{link}' => Html::a($label, $link['url'])]);
		} else {
			return strtr($template, ['{link}' => $label]);
		}
	}
}
