1:   2:   3:   4:   5:   6:   7:   8:   9:  10:  11:  12:  13:  14:  15:  16:  17:  18:  19:  20:  21:  22:  23:  24:  25:  26:  27:  28:  29:  30:  31:  32:  33:  34:  35:  36:  37:  38:  39:  40:  41:  42:  43:  44:  45:  46:  47:  48:  49:  50:  51:  52:  53:  54:  55:  56:  57:  58:  59:  60:  61:  62:  63:  64:  65:  66:  67:  68:  69:  70:  71:  72:  73:  74:  75:  76:  77:  78:  79:  80:  81:  82:  83:  84:  85:  86:  87:  88:  89:  90:  91:  92:  93:  94:  95:  96:  97:  98:  99: 100: 101: 102: 103: 104: 105: 106: 107: 108: 109: 110: 111: 112: 113: 114: 115: 116: 117: 118: 119: 120: 121: 122: 123: 124: 125: 126: 127: 128: 129: 130: 131: 132: 133: 134: 135: 136: 137: 138: 139: 140: 141: 142: 143: 144: 145: 146: 147: 148: 149: 150: 151: 152: 153: 154: 155: 156: 157: 158: 159: 160: 161: 162: 163: 164: 165: 166: 167: 168: 169: 170: 

<?php

/**
 * MvcCore
 *
 * This source file is subject to the BSD 3 License
 * For the full copyright and license information, please view 
 * the LICENSE.md file that are distributed with this source code.
 *
 * @copyright   Copyright (c) 2016 Tom Flidr (https://github.com/mvccore)
 * @license     https://mvccore.github.io/docs/mvccore/5.0.0/LICENCE.md
 */

namespace MvcCore\Ext\Forms\Validators\Files\Validations\BombScanners;

class PngImage implements \MvcCore\Ext\Forms\Validators\Files\Validations\IBombScanner {

    const ERR_INVALID_PNG_FILE = "Uploaded file is inconsistent PNG image (`{1}`).";

    const ERR_INVALID_SIZES = "Uploaded file has invalid sizes (`{1}`).";
    
    /**
     * @var \MvcCore\Ext\Forms\Validators\Files
     */
    protected $validator = NULL;

    /**
     * @var \SplFileObject
     */
    protected $spl = NULL;

    /**
     * @var bool
     */
    protected $ihdrFound = FALSE;

    /**
     * @var bool
     */
    protected $invalidSizes = FALSE;
    
    /**
     * @param string $firstFourBytes
     * @return bool
     */
    public static function MatchMagicBytes ($firstFourBytes) {
        return $firstFourBytes === chr(0x89) . "PNG";
    }

    /**
     * @return bool
     */
    public static function IsArchive () {
        return FALSE; 
    }
    
    /**
     * @return bool
     */
    public static function IsSupported () {
        return TRUE;
    }
    
    /**
     * @return string
     */
    public static function GetNotSupportedError () {
        return '';
    }

    /**
     * @param \MvcCore\Ext\Forms\Validators\Files $validator
     * @param \SplFileObject $spl
     * @return void
     */
    public function __construct (\MvcCore\Ext\Forms\Validators\IFiles $validator, \SplFileObject $spl) {
        $this->validator = $validator;
        $this->spl = $spl;
    }

    /**
     * @return bool
     */
    public function Open () {
        $this->spl->rewind();
        $this->spl->fread(12);
        $ihdrBytes = (string) $this->spl->fread(4);
        
        $this->ihdrFound = $ihdrBytes === 'IHDR';
        
        if (!$this->ihdrFound) 
            return FALSE;
        
        // PNG stores width and height integers in big-endian
        $widthBinnary = (string) $this->spl->fread(4);
        $heightBinnary = (string) $this->spl->fread(4);
        $widthUnpacked = unpack('N', $widthBinnary);
        $heightUnpacked = unpack('N', $heightBinnary);
        $width = isset($widthUnpacked[1])
            ? $widthUnpacked[1]
            : 0;
        $height = isset($heightUnpacked[1])
            ? $heightUnpacked[1]
            : 0;
        
        $maxPngSize = $this->validator->GetPngImageMaxWidthHeight();
        $this->invalidSizes = ($width > $maxPngSize || $height > $maxPngSize);

        if ($this->invalidSizes)
            return FALSE;

        return TRUE;
    }

    /**
     * @return int
     */
    public function GetCompressedSize () {
        return $this->spl->getSize();
    }

    /**
     * @return string
     */
    public function GetError () {
        if (!$this->ihdrFound) 
            return static::ERR_INVALID_PNG_FILE;
        if ($this->invalidSizes)
            return static::ERR_INVALID_SIZES;
        return '';
    }

    /**
     *
     * @return void
     */
    public function Close() {
        unset($this->spl);
    }

    /**
     *
     * @return boolean
     */
    public function Move() {
        return FALSE;
    }

    /**
     * @return int
     */
    public function GetEntrySize () {
        return 0;
    }

    /**
     * @return string
     */
    public function GetEntryName () {
        return '';
    }

    /**
     * @param string $destinationFullPath
     * @return string|NULL
     */
    public function ExtractEntry ($destinationFullPath) {
        return NULL;
    }
}