<?php
/**
 * FastImage - Because sometimes you just want the size!
 * Based on the Ruby Implementation by Steven Sykes (https://github.com/sdsykes/fastimage)
 *
 * Copyright (c) 2012 Tom Moor
 * Tom Moor, http://tommoor.com
 *
 * MIT Licensed
 * @version 0.1
 */
class FastImage
{
    private $strpos = 0;
    private $str;
    private $type;
    private $handle;
    public function __construct($uri = null)
    {
        if ($uri) $this->load($uri);
    }
    public function load($uri)
    {
        if ($this->handle) $this->close();
        $this->handle = @fopen($uri, 'r');
        if ( false === $this->handle ) {
            return false;
        }
    }
    public function close()
    {
        if ($this->handle)
        {
            fclose($this->handle);
            $this->handle = null;
            $this->type = null;
            $this->str = null;
        }
    }
    public function getSize()
    {
        if (!$this->handle)
        {
            return false;
        }
        $this->strpos = 0;
        if ($this->getType())
        {
            return array_values($this->parseSize());
        }
        return false;
    }
    public function getType()
    {
        if (!$this->handle)
        {
            return false;
        }
        $this->strpos = 0;
        if (!$this->type)
        {
            switch ($this->getChars(2))
            {
                case "BM":
                    return $this->type = 'bmp';
                case "GI":
                    return $this->type = 'gif';
                case chr(0xFF).chr(0xd8):
                    return $this->type = 'jpeg';
                case chr(0x89).'P':
                    return $this->type = 'png';
                default:
                    $this->strpos = 0;
                    $markup = $this->getChars( 1024 );
                    $this->strpos = 0;
                    if ( false !== strpos( $markup, '<svg' ) ) {
                        $this->type = 'svg';
                    } else {
                        return false;
                    }
            }
        }
        return $this->type;
    }
    private function parseSize()
    {
        $this->strpos = 0;
        switch ($this->type)
        {
            case 'png':
                return $this->parseSizeForPNG();
            case 'gif':
                return $this->parseSizeForGIF();
            case 'bmp':
                return $this->parseSizeForBMP();
            case 'jpeg':
                return $this->parseSizeForJPEG();
            case 'svg':
                return $this->parseSizeForSVG();
        }
        return null;
    }
    private function parseSizeForPNG()
    {
        $chars = $this->getChars(25);
        return unpack("N*", substr($chars, 16, 8));
    }
    private function parseSizeForGIF()
    {
        $chars = $this->getChars(11);
        return unpack("S*", substr($chars, 6, 4));
    }
    private function parseSizeForBMP()
    {
        $chars = $this->getChars(29);
        $chars = substr($chars, 14, 14);
        $type = unpack('C', $chars);
        return (reset($type) == 40) ? unpack('L*', substr($chars, 4)) : unpack('L*', substr($chars, 4, 8));
    }
    private function parseSizeForJPEG()
    {
        $state = null;
        $i = 0;
        while (true)
        {
            switch ($state)
            {
                default:
                    $this->getChars(2);
                    $state = 'started';
                    break;
                case 'started':
                    $b = $this->getByte();
                    if ($b === false) return false;
                    $state = $b == 0xFF ? 'sof' : 'started';
                    break;
                case 'sof':
                    $b = $this->getByte();
                    if (in_array($b, range(0xe0, 0xef)))
                    {
                        $state = 'skipframe';
                    }
                    elseif (in_array($b, array_merge(range(0xC0,0xC3), range(0xC5,0xC7), range(0xC9,0xCB), range(0xCD,0xCF))))
                    {
                        $state = 'readsize';
                    }
                    elseif ($b == 0xFF)
                    {
                        $state = 'sof';
                    }
                    else
                    {
                        $state = 'skipframe';
                    }
                    break;
                case 'skipframe':
                    $skip = $this->readInt($this->getChars(2)) - 2;
                    $state = 'doskip';
                    break;
                case 'doskip':
                    $this->getChars($skip);
                    $state = 'started';
                    break;
                case 'readsize':
                    $c = $this->getChars(7);
                    return array($this->readInt(substr($c, 5, 2)), $this->readInt(substr($c, 3, 2)));
            }
        }
    }

    private function parseSizeForSVG()
    {
        $this->strpos = 0;
        $markup = $this->getChars( 1024 );
        if ( ! preg_match( '#<svg.*?>#s', $markup, $matches ) ) {
            return null;
        }
        $svg_start_tag = $matches[0];
        $width = null;
        $height = null;
        if ( preg_match( '/\swidth=([\'"])(\d+(\.\d+)?)(px)?\1/', $svg_start_tag, $matches ) ) {
            $width = floatval( $matches[2] );
        }
        if ( preg_match( '/\sheight=([\'"])(\d+(\.\d+)?)(px)?\1/', $svg_start_tag, $matches ) ) {
            $height = floatval( $matches[2] );
        }
        if ( $width && $height ) {
            return array( $width, $height );
        }
        if ( preg_match( '/\sviewBox=([\'"])[^\1]*(?:,|\s)+(?P<width>\d+(?:\.\d+)?)(?:px)?(?:,|\s)+(?P<height>\d+(?:\.\d+)?)(?:px)?\s*\1/', $svg_start_tag, $matches ) ) {
            return array(
                floatval( $matches['width'] ),
                floatval( $matches['height'] )
            );
        }
        return null;
    }

    private function getChars($n)
    {
        $response = null;
        // do we need more data?
        if ($this->strpos + $n -1 >= strlen($this->str))
        {
            $end = ($this->strpos + $n);
            while (strlen($this->str) < $end && $response !== false)
            {
                // read more from the file handle
                $need = $end - ftell($this->handle);
                if ($response = fread($this->handle, $need))
                {
                    $this->str .= $response;
                }
                else
                {
                    return false;
                }
            }
        }
        $result = substr($this->str, $this->strpos, $n);
        $this->strpos += $n;
        return $result;
    }
    private function getByte()
    {
        $c = $this->getChars(1);
        $b = unpack("C", $c);
        return reset($b);
    }
    private function readInt($str)
    {
        $size = unpack("C*", $str);
        return ($size[1] << 8) + $size[2];
    }
    public function __destruct()
    {
        $this->close();
    }
}