<?php
/**
 *  PDFMerger created by Jarrod Nettles December 2009
 *  jarrod@squarecrow.com
 *
 *  v1.0
 *
 * Class for easily merging PDFs (or specific pages of PDFs) together into one. Output to a file, browser, download, or return as a string.
 * Unfortunately, this class does not preserve many of the enhancements your original PDF might contain. It treats
 * your PDF page as an image and then concatenates them all together.
 *
 * Note that your PDFs are merged in the order that you provide them using the addPDF function, same as the pages.
 * If you put pages 12-14 before 1-5 then 12-15 will be placed first in the output.
 *
 *
 * Uses FPDI 1.3.1 from Setasign
 * Uses FPDF 1.6 by Olivier Plathey with FPDF_TPL extension 1.1.3 by Setasign
 *
 * Both of these packages are free and open source software, bundled with this class for ease of use.
 * They are not modified in any way. PDFMerger has all the limitations of the FPDI package - essentially, it cannot import dynamic content
 * such as form fields, links or page annotations (anything not a part of the page content stream).
 *
 */
class PDFMerger
{
	private $_files;	//['form.pdf']  ["1,2,4, 5-19"]
	private $_fpdi;

	/**
	 * Merge PDFs.
	 * @return void
	 */
	public function __construct()
	{
		require_once('fpdf/fpdf.php');
		require_once('fpdi/fpdi.php');
	}

	/**
	 * Add a PDF for inclusion in the merge with a valid file path. Pages should be formatted: 1,3,6, 12-16.
	 * @param $filepath
	 * @param $pages
	 * @return void
	 */
	public function addPDF($filepath, $pages = 'all')
	{
		if(file_exists($filepath))
		{
			if(strtolower($pages) != 'all')
			{
				$pages = $this->_rewritepages($pages);
			}

			$this->_files[] = array($filepath, $pages);
		}
		else
		{
			throw new exception("Could not locate PDF on '$filepath'");
		}

		return $this;
	}

	/**
	 * Merges your provided PDFs and outputs to specified location.
	 * @param $outputmode
	 * @param $outputname
	 * @return PDF
	 */
	public function merge($outputmode = 'browser', $outputpath = 'newfile.pdf')
	{
		if(!isset($this->_files) || !is_array($this->_files)): throw new exception("No PDFs to merge."); endif;

		$fpdi = new FPDI;

		//merger operations
		foreach($this->_files as $file)
		{
			$filename  = $file[0];
			$filepages = $file[1];

			$count = $fpdi->setSourceFile($filename);

			//add the pages
			if($filepages == 'all')
			{
				for($i=1; $i<=$count; $i++)
				{
					$template 	= $fpdi->importPage($i);
					$size 		= $fpdi->getTemplateSize($template);
					$orientation = ($size['h'] > $size['w']) ? 'P' : 'L';

					$fpdi->AddPage($orientation, array($size['w'], $size['h']));
					$fpdi->useTemplate($template);
				}
			}
			else
			{
				foreach($filepages as $page)
				{
					if(!$template = $fpdi->importPage($page)): throw new exception("Could not load page '$page' in PDF '$filename'. Check that the page exists."); endif;
					$size = $fpdi->getTemplateSize($template);
					$orientation = ($size['h'] > $size['w']) ? 'P' : 'L';

					$fpdi->AddPage($orientation, array($size['w'], $size['h']));
					$fpdi->useTemplate($template);
				}
			}
		}

		//output operations
		$mode = $this->switchmode($outputmode);

		if($mode == 'S') {
			return $fpdi->Output($outputpath, 'S');
		} else {
			if ($fpdi->Output($outputpath, $mode) == '') {
				return true;
			} else {
				throw new exception("Error outputting PDF to '$outputmode'.");
			}
		}
	}

	/**
	 * FPDI uses single characters for specifying the output location. Change our more descriptive string into proper format.
	 * @param $mode
	 * @return string
	 */
	private function switchmode($mode)
	{
		switch (strtolower($mode)) {
			case 'download':
				return 'D';
				break;
			case 'browser':
				return 'I';
				break;
			case 'file':
				return 'F';
				break;
			case 'string':
				return 'S';
				break;
			default:
				return 'I';
				break;
		}
	}

    /**
     * Takes our provided pages in the form of 1,3,4,16-50 and creates an array of all pages
     *
     * @param $pages
     * @return bool|array
     * @throws exception
     */
	private function _rewritepages($pages)
	{
		$pages = str_replace(' ', '', $pages);
		$part = explode(',', $pages);
        $newpages = array();

		//parse hyphens
		foreach($part as $i) {
			$ind = explode('-', $i);

			if (count($ind) == 2) {
				$x = $ind[0]; //start page
				$y = $ind[1]; //end page

				if ($x > $y) {
				    throw new Exception("Starting page, '$x' is greater than ending page '$y'.");
                }

				//add middle pages
				while ($x <= $y) {
				    $newpages[] = (int) $x;
                    $x++;
                }
			} else {
				$newpages[] = (int) $ind[0];
			}
		}

		return $newpages;
	}

}