<?php
class DocumentProcessor {
    private $srcImage;
    private $processedImage;
    private $outputPath;
    
    public function __construct() {
        if (!extension_loaded('gd')) {
            throw new Exception('GD extension is required');
        }
    }

    public function processDocument($imagePath, $outputPath) {
        $this->outputPath = $outputPath;
        
        // Detecta o tipo da imagem e carrega
        $imageInfo = getimagesize($imagePath);
        if ($imageInfo === false) {
            throw new Exception('Failed to load image');
        }

        switch ($imageInfo[2]) {
            case IMAGETYPE_JPEG:
                $this->srcImage = imagecreatefromjpeg($imagePath);
                break;
            case IMAGETYPE_PNG:
                $this->srcImage = imagecreatefrompng($imagePath);
                break;
            default:
                throw new Exception('Unsupported image type');
        }

        if ($this->srcImage === false) {
            throw new Exception('Failed to create image resource');
        }

        // Simplifica o pipeline para focar apenas na detecção e recorte
        $this->detectAndCropDocument()
             ->saveResult();

        return $this->outputPath;
    }

    private function detectAndCropDocument() {
        $width = imagesx($this->srcImage);
        $height = imagesy($this->srcImage);
        
        // Cria imagem temporária em escala de cinza
        $gray = imagecreatetruecolor($width, $height);
        imagecopy($gray, $this->srcImage, 0, 0, 0, 0, $width, $height);
        imagefilter($gray, IMG_FILTER_GRAYSCALE);
        
        // Aplica threshold adaptativo para binarização
        $threshold = $this->getAdaptiveThreshold($gray, $width, $height);
        $binary = imagecreatetruecolor($width, $height);
        
        for ($x = 0; $x < $width; $x++) {
            for ($y = 0; $y < $height; $y++) {
                $rgb = imagecolorat($gray, $x, $y);
                $colors = imagecolorsforindex($gray, $rgb);
                $value = ($colors['red'] + $colors['green'] + $colors['blue']) / 3;
                
                if ($value > $threshold) {
                    imagesetpixel($binary, $x, $y, 0xFFFFFF);
                } else {
                    imagesetpixel($binary, $x, $y, 0x000000);
                }
            }
        }
        
        // Encontra os contornos do documento
        $bounds = $this->findDocumentBounds($binary);
        
        if ($bounds) {
            // Adiciona margem de segurança
            $margin = 10;
            $cropX = max(0, $bounds['left'] - $margin);
            $cropY = max(0, $bounds['top'] - $margin);
            $cropWidth = min($width - $cropX, $bounds['right'] - $bounds['left'] + 2 * $margin);
            $cropHeight = min($height - $cropY, $bounds['bottom'] - $bounds['top'] + 2 * $margin);
            
            $this->processedImage = imagecreatetruecolor($cropWidth, $cropHeight);
            imagecopy($this->processedImage, $this->srcImage, 0, 0, $cropX, $cropY, $cropWidth, $cropHeight);
        } else {
            $this->processedImage = $this->srcImage;
        }

        return $this;
    }

    private function getAdaptiveThreshold($image, $width, $height) {
        $total = 0;
        $count = 0;

        for ($x = 0; $x < $width; $x++) {
            for ($y = 0; $y < $height; $y++) {
                $rgb = imagecolorat($image, $x, $y);
                $colors = imagecolorsforindex($image, $rgb);
                $value = ($colors['red'] + $colors['green'] + $colors['blue']) / 3;
                $total += $value;
                $count++;
            }
        }

        return $total / $count;
    }

    private function findDocumentBounds($binary) {
        $width = imagesx($binary);
        $height = imagesy($binary);
        $left = $width;
        $right = 0;
        $top = $height;
        $bottom = 0;

        for ($x = 0; $x < $width; $x++) {
            for ($y = 0; $y < $height; $y++) {
                $rgb = imagecolorat($binary, $x, $y);
                if ($rgb == 0x000000) { // Pixel preto
                    if ($x < $left) $left = $x;
                    if ($x > $right) $right = $x;
                    if ($y < $top) $top = $y;
                    if ($y > $bottom) $bottom = $y;
                }
            }
        }

        if ($left < $right && $top < $bottom) {
            return ['left' => $left, 'right' => $right, 'top' => $top, 'bottom' => $bottom];
        }

        return null;
    }

    private function saveResult() {
        if (!isset($this->processedImage)) {
            throw new Exception('No processed image to save');
        }

        $extension = strtolower(pathinfo($this->outputPath, PATHINFO_EXTENSION));
        
        switch ($extension) {
            case 'jpg':
            case 'jpeg':
                imagejpeg($this->processedImage, $this->outputPath, 90);
                break;
            case 'png':
                imagepng($this->processedImage, $this->outputPath, 9);
                break;
            default:
                throw new Exception('Unsupported output image type');
        }

        if (is_resource($this->srcImage)) {
            imagedestroy($this->srcImage);
        }
        if (is_resource($this->processedImage)) {
            imagedestroy($this->processedImage);
        }

        return $this;
    }
}