<?php
/**
 * @package     Joomla.Libraries
 * @subpackage  HTML
 *
 * @copyright   Copyright (C) 2005 - 2018 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('JPATH_PLATFORM') or die;

use Joomla\String\StringHelper;

/**
 * HTML helper class for rendering manipulated strings.
 *
 * @since  1.6
 */
abstract class JHtmlString
{
	/**
	 * Truncates text blocks over the specified character limit and closes
	 * all open HTML tags. The method will optionally not truncate an individual
	 * word, it will find the first space that is within the limit and
	 * truncate at that point. This method is UTF-8 safe.
	 *
	 * @param   string   $text       The text to truncate.
	 * @param   integer  $length     The maximum length of the text.
	 * @param   boolean  $noSplit    Don't split a word if that is where the cutoff occurs (default: true).
	 * @param   boolean  $allowHtml  Allow HTML tags in the output, and close any open tags (default: true).
	 *
	 * @return  string   The truncated text.
	 *
	 * @since   1.6
	 */
	public static function truncate($text, $length = 0, $noSplit = true, $allowHtml = true)
	{
		// Assume a lone open tag is invalid HTML.
		if ($length === 1 && $text[0] === '<')
		{
			return '...';
		}

		// Check if HTML tags are allowed.
		if (!$allowHtml)
		{
			// Deal with spacing issues in the input.
			$text = str_replace('>', '> ', $text);
			$text = str_replace(array('&nbsp;', '&#160;'), ' ', $text);
			$text = StringHelper::trim(preg_replace('#\s+#mui', ' ', $text));

			// Strip the tags from the input and decode entities.
			$text = strip_tags($text);
			$text = html_entity_decode($text, ENT_QUOTES, 'UTF-8');

			// Remove remaining extra spaces.
			$text = str_replace('&nbsp;', ' ', $text);
			$text = StringHelper::trim(preg_replace('#\s+#mui', ' ', $text));
		}

		// Whether or not allowing HTML, truncate the item text if it is too long.
		if ($length > 0 && StringHelper::strlen($text) > $length)
		{
			$tmp = trim(StringHelper::substr($text, 0, $length));

			if ($tmp[0] === '<' && strpos($tmp, '>') === false)
			{
				return '...';
			}

			// $noSplit true means that we do not allow splitting of words.
			if ($noSplit)
			{
				// Find the position of the last space within the allowed length.
				$offset = StringHelper::strrpos($tmp, ' ');
				$tmp = StringHelper::substr($tmp, 0, $offset + 1);

				// If there are no spaces and the string is longer than the maximum
				// we need to just use the ellipsis. In that case we are done.
				if ($offset === false && strlen($text) > $length)
				{
					return '...';
				}

				if (StringHelper::strlen($tmp) > $length - 3)
				{
					$tmp = trim(StringHelper::substr($tmp, 0, StringHelper::strrpos($tmp, ' ')));
				}
			}

			if ($allowHtml)
			{
				// Put all opened tags into an array
				preg_match_all("#<([a-z][a-z0-9]*)\b.*?(?!/)>#i", $tmp, $result);
				$openedTags = $result[1];

				// Some tags self close so they do not need a separate close tag.
				$openedTags = array_diff($openedTags, array('img', 'hr', 'br'));
				$openedTags = array_values($openedTags);

				// Put all closed tags into an array
				preg_match_all("#</([a-z][a-z0-9]*)\b(?:[^>]*?)>#iU", $tmp, $result);
				$closedTags = $result[1];

				$numOpened = count($openedTags);

				// Not all tags are closed so trim the text and finish.
				if (count($closedTags) !== $numOpened)
				{
					// Closing tags need to be in the reverse order of opening tags.
					$openedTags = array_reverse($openedTags);

					// Close tags
					for ($i = 0; $i < $numOpened; $i++)
					{
						if (!in_array($openedTags[$i], $closedTags))
						{
							$tmp .= '</' . $openedTags[$i] . '>';
						}
						else
						{
							unset($closedTags[array_search($openedTags[$i], $closedTags)]);
						}
					}
				}

				// Check if we are within a tag
				if (StringHelper::strrpos($tmp, '<') > StringHelper::strrpos($tmp, '>'))
				{
					$offset = StringHelper::strrpos($tmp, '<');
					$tmp = StringHelper::trim(StringHelper::substr($tmp, 0, $offset));
				}
			}

			if ($tmp === false || strlen($text) > strlen($tmp))
			{
				$text = trim($tmp) . '...';
			}
		}

		// Clean up any internal spaces created by the processing.
		$text = str_replace(' </', '</', $text);
		$text = str_replace(' ...', '...', $text);

		return $text;
	}

	/**
	 * Method to extend the truncate method to more complex situations
	 *
	 * The goal is to get the proper length plain text string with as much of
	 * the html intact as possible with all tags properly closed.
	 *
	 * @param   string   $html       The content of the introtext to be truncated
	 * @param   integer  $maxLength  The maximum number of characters to render
	 * @param   boolean  $noSplit    Don't split a word if that is where the cutoff occurs (default: true).
	 *
	 * @return  string  The truncated string. If the string is truncated an ellipsis
	 *                  (...) will be appended.
	 *
	 * @note    If a maximum length of 3 or less is selected and the text has more than
	 *          that number of characters an ellipsis will be displayed.
	 *          This method will not create valid HTML from malformed HTML.
	 *
	 * @since   3.1
	 */
	public static function truncateComplex($html, $maxLength = 0, $noSplit = true)
	{
		// Start with some basic rules.
		$baseLength = strlen($html);

		// If the original HTML string is shorter than the $maxLength do nothing and return that.
		if ($baseLength <= $maxLength || $maxLength === 0)
		{
			return $html;
		}

		// Take care of short simple cases.
		if ($maxLength <= 3 && $html[0] !== '<' && strpos(substr($html, 0, $maxLength - 1), '<') === false && $baseLength > $maxLength)
		{
			return '...';
		}

		// Deal with maximum length of 1 where the string starts with a tag.
		if ($maxLength === 1 && $html[0] === '<')
		{
			$endTagPos = strlen(strstr($html, '>', true));
			$tag = substr($html, 1, $endTagPos);

			$l = $endTagPos + 1;

			if ($noSplit)
			{
				return substr($html, 0, $l) . '</' . $tag . '...';
			}

			// TODO: $character doesn't seem to be used...
			$character = substr(strip_tags($html), 0, 1);

			return substr($html, 0, $l) . '</' . $tag . '...';
		}

		// First get the truncated plain text string. This is the rendered text we want to end up with.
		$ptString = JHtml::_('string.truncate', $html, $maxLength, $noSplit, $allowHtml = false);

		// It's all HTML, just return it.
		if ($ptString === '')
		{
				return $html;
		}

		// If the plain text is shorter than the max length the variable will not end in ...
		// In that case we use the whole string.
		if (substr($ptString, -3) !== '...')
		{
				return $html;
		}

		// Regular truncate gives us the ellipsis but we want to go back for text and tags.
		if ($ptString === '...')
		{
			$stripped = substr(strip_tags($html), 0, $maxLength);
			$ptString = JHtml::_('string.truncate', $stripped, $maxLength, $noSplit, $allowHtml = false);
		}

		// We need to trim the ellipsis that truncate adds.
		$ptString = rtrim($ptString, '.');

		// Now deal with more complex truncation.
		while ($maxLength <= $baseLength)
		{
			// Get the truncated string assuming HTML is allowed.
			$htmlString = JHtml::_('string.truncate', $html, $maxLength, $noSplit, $allowHtml = true);

			if ($htmlString === '...' && strlen($ptString) + 3 > $maxLength)
			{
				return $htmlString;
			}

			$htmlString = rtrim($htmlString, '.');

			// Now get the plain text from the HTML string and trim it.
			$htmlStringToPtString = JHtml::_('string.truncate', $htmlString, $maxLength, $noSplit, $allowHtml = false);
			$htmlStringToPtString = rtrim($htmlStringToPtString, '.');

			// If the new plain text string matches the original plain text string we are done.
			if ($ptString === $htmlStringToPtString)
			{
				return $htmlString . '...';
			}

			// Get the number of HTML tag characters in the first $maxLength characters
			$diffLength = strlen($ptString) - strlen($htmlStringToPtString);

			if ($diffLength <= 0)
			{
				return $htmlString . '...';
			}

			// Set new $maxlength that adjusts for the HTML tags
			$maxLength += $diffLength;
		}
	}

	/**
	 * Abridges text strings over the specified character limit. The
	 * behavior will insert an ellipsis into the text replacing a section
	 * of variable size to ensure the string does not exceed the defined
	 * maximum length. This method is UTF-8 safe.
	 *
	 * For example, it transforms "Really long title" to "Really...title".
	 *
	 * Note that this method does not scan for HTML tags so will potentially break them.
	 *
	 * @param   string   $text    The text to abridge.
	 * @param   integer  $length  The maximum length of the text (default is 50).
	 * @param   integer  $intro   The maximum length of the intro text (default is 30).
	 *
	 * @return  string   The abridged text.
	 *
	 * @since   1.6
	 */
	public static function abridge($text, $length = 50, $intro = 30)
	{
		// Abridge the item text if it is too long.
		if (StringHelper::strlen($text) > $length)
		{
			// Determine the remaining text length.
			$remainder = $length - ($intro + 3);

			// Extract the beginning and ending text sections.
			$beg = StringHelper::substr($text, 0, $intro);
			$end = StringHelper::substr($text, StringHelper::strlen($text) - $remainder);

			// Build the resulting string.
			$text = $beg . '...' . $end;
		}

		return $text;
	}
}
