<?php

/**
 * Text extractor that calls pdftotext to do the conversion.
 * @author mstephens
 *
 */
class PDFTextExtractor extends FileTextExtractor
{
    public function isAvailable()
    {
        $bin = $this->bin('pdftotext');
        return (file_exists($bin) && is_executable($bin));
    }
    
    public function supportsExtension($extension)
    {
        return strtolower($extension) === 'pdf';
    }

    public function supportsMime($mime)
    {
        return in_array(
            strtolower($mime),
            array(
                'application/pdf',
                'application/x-pdf',
                'application/x-bzpdf',
                'application/x-gzpdf'
            )
        );
    }

    /**
     * Accessor to get the location of the binary
     *
     * @param string $prog Name of binary
     * @return string
     */
    protected function bin($prog = '')
    {
        if ($this->config()->binary_location) {
            // By config
            $path = $this->config()->binary_location;
        } elseif (file_exists('/usr/bin/pdftotext')) {
            // By searching common directories
            $path = '/usr/bin';
        } elseif (file_exists('/usr/local/bin/pdftotext')) {
            $path = '/usr/local/bin';
        } else {
            $path = '.'; // Hope it's in path
        }

        return ($path ? $path . '/' : '') . $prog;
    }
    
    public function getContent($path)
    {
        if (!$path) {
            return "";
        } // no file
        $content = $this->getRawOutput($path);
        return $this->cleanupLigatures($content);
    }

    /**
     * Invoke pdftotext with the given path
     *
     * @param string $path
     * @return string Output
     * @throws FileTextExtractor_Exception
     */
    protected function getRawOutput($path)
    {
        exec(sprintf('%s %s - 2>&1', $this->bin('pdftotext'), escapeshellarg($path)), $content, $err);
        if ($err) {
            throw new FileTextExtractor_Exception(sprintf(
                'PDFTextExtractor->getContent() failed for %s: %s',
                $path,
                implode('', $err)
            ));
        }
        return implode('', $content);
    }

    /**
     * Removes utf-8 ligatures.
     *
     * @link http://en.wikipedia.org/wiki/Typographic_ligature#Computer_typesetting
     *
     * @param string $input
     * @return string
     */
    protected function cleanupLigatures($input)
    {
        $mapping = array(
            'ﬀ' => 'ff',
            'ﬁ' => 'fi',
            'ﬂ' => 'fl',
            'ﬃ' => 'ffi',
            'ﬄ' => 'ffl',
            'ﬅ' => 'ft',
            'ﬆ' => 'st'
        );
        return str_replace(array_keys($mapping), array_values($mapping), $input);
    }
}