<?php

namespace SilverStripe\Control\RSS;

use SilverStripe\Control\Director;
use SilverStripe\ORM\FieldType\DBField;
use SilverStripe\ORM\FieldType\DBHTMLText;
use SilverStripe\View\ViewableData;
use BadMethodCallException;

/**
 * RSSFeed_Entry class
 *
 * This class is used for entries of an RSS feed.
 *
 * @see RSSFeed
 */
class RSSFeed_Entry extends ViewableData
{
	/**
	 * The object that represents the item, it contains all the data.
	 *
	 * @var mixed
	 */
	protected $failover;

	/**
	 * Name of the title field of feed entries
	 *
	 * @var string
	 */
	protected $titleField;

	/**
	 * Name of the description field of feed entries
	 *
	 * @var string
	 */
	protected $descriptionField;

	/**
	 * Name of the author field of feed entries
	 *
	 * @var string
	 */
	protected $authorField;

	/**
	 * Create a new RSSFeed entry.
	 * @param ViewableData $entry
	 * @param string $titleField
	 * @param string $descriptionField
	 * @param string $authorField
	 */
	public function __construct($entry, $titleField, $descriptionField, $authorField)
	{
		$this->failover = $entry;
		$this->titleField = $titleField;
		$this->descriptionField = $descriptionField;
		$this->authorField = $authorField;

		parent::__construct();
	}

	/**
	 * Get the description of this entry
	 *
	 * @return DBField Returns the description of the entry.
	 */
	public function Title()
	{
		return $this->rssField($this->titleField);
	}

	/**
	 * Get the description of this entry
	 *
	 * @return DBField Returns the description of the entry.
	 */
	public function Description()
	{
		$description = $this->rssField($this->descriptionField);

		// HTML fields need links re-written
		if ($description instanceof DBHTMLText) {
			return $description->obj('AbsoluteLinks');
		}

		return $description;
	}

	/**
	 * Get the author of this entry
	 *
	 * @return DBField Returns the author of the entry.
	 */
	public function Author()
	{
		return $this->rssField($this->authorField);
	}

	/**
	 * Return the safely casted field
	 *
	 * @param string $fieldName Name of field
	 * @return DBField
	 */
	public function rssField($fieldName)
	{
		if ($fieldName) {
			return $this->failover->obj($fieldName);
		}
		return null;
	}

	/**
	 * Get a link to this entry
	 *
	 * @return string Returns the URL of this entry
	 * @throws BadMethodCallException
	 */
	public function AbsoluteLink()
	{
		if ($this->failover->hasMethod('AbsoluteLink')) {
			return $this->failover->AbsoluteLink();
		} else {
			if ($this->failover->hasMethod('Link')) {
				return Director::absoluteURL($this->failover->Link());
			}
		}

		throw new BadMethodCallException(
			$this->failover->class .
			" object has neither an AbsoluteLink nor a Link method." .
			" Can't put a link in the RSS feed", E_USER_WARNING
		);
	}
}