<?php
$min_pixels_before_compression = 999;

function generate_unique_filename(string $prefix = ''): string {
    $timestamp = microtime(true); // Current timestamp with microseconds
    $random = mt_rand(); // Random number (better than rand() for uniqueness)
    $hash = md5($timestamp . $random); // MD5 hash of timestamp and random number

    // Combine prefix (if provided) with the hash
    $filename = $prefix . $hash;

    return $filename;
}

    /**
     * Make sure uploads (LIKE Images, etc...) do NOT run PHP code!!
     * Checks for PHP tags inside of file.
     * @param string $file
     * @return bool true if PHP was found
     */
function file_contains_php(string $file): bool {
	$file_handle = fopen($file, "r");
    while (!feof($file_handle)) {
		$line = fgets($file_handle);
        $pos = strpos($line, '<?php');
        if ($pos !== false) {
			fclose($file_handle);
            return true;
        }
	}
    fclose($file_handle);
    return false;
}

function rename_upload(string $uploadName, string $fileName, false|string $rndFile): false|string {
	if (file_contains_php($uploadName)) {
		@unlink($uploadName); // stop attacks by a Delete of the PHP Image file!!
		return false;
	}
	if ($rndFile === false) {
		return false;
	}
	
    list($originalWidth, $originalHeight, $imageType) = getimagesize($uploadName);
    if ($originalWidth == 0 || $originalHeight == 0) {
		return false;
	}
        
    // File Name without EXT type or Path
    $fileNameWithoutExt = pathinfo($uploadName, PATHINFO_FILENAME);
    
    $type = match($imageType) {
        IMAGETYPE_JPEG => '.jpg',
		IMAGETYPE_PNG => '.png', 
		IMAGETYPE_GIF => '.gif',
        default => false,
    };
    if ($type === false) {
		return false;
	}	
	
	$success = rename($uploadName, $GLOBALS['uploadDir'] . 'orignal_' . $rndFile . '_' . $fileNameWithoutExt . $type);
	return ($success) ? 'orignal_' . $rndFile . '_' . $fileNameWithoutExt . $type : false;
}

function get_size(int $target, int $original): int {
	$min_pixels_before_compression = $GLOBALS['min_pixels_before_compression'];
	if ($target == 0) {
		return ($original > $min_pixels_before_compression) ? $original / 2 : $original;
	}
	if ($target < $original) {
		return $target;
	}
	return $original;
}

function image_compression(string $uploadName, string $fileName, array $images): array {
	$rnd_name = generate_unique_filename();
	if (!count($images)) {
		return [];
	}
	$a_of_images = [];
	foreach($images as $image) {
		$name = $image['name'] ?? false;
		$width = $image['width'] ?? false;
		$height = $image['height'] ?? false;
		$crop = $image['crop'] ?? false;
		if ($name === false || $width === false || $height === false) {
			continue;
		}
		$name .= '_' . $rnd_name;
		if ($crop) {
			$file = do_image_crop($uploadName, $fileName, $name, $width, $height, $rnd_name);
		} else {
			$file = do_image_compression($uploadName, $fileName, $name, $width, $height);
		}
		if ($file === false) {
			continue;
		}
		$a_of_images[] = $file;
	}
	$org_file = rename_upload($uploadName, $fileName, $rnd_name);
	if ($org_file !== false) {
		$a_of_images[] = $org_file;
	}
	return $a_of_images;
}

function do_image_compression(string $uploadName, string $fileName, string $newName, int $targetWidth, int $targetHeight): false|string {
    
    list($originalWidth, $originalHeight, $imageType) = getimagesize($uploadName);
    if ($originalWidth == 0 || $originalHeight == 0) {
		return $GLOBALS['image_error'];
	}
        
    // File Name without EXT type or Path
    $fileNameWithoutExt = pathinfo($fileName, PATHINFO_FILENAME);
    
    switch ($imageType) {
        case IMAGETYPE_JPEG:
            $img = imagecreatefromjpeg($uploadName);
            $type = '.jpg';
            break;
        case IMAGETYPE_PNG:
            $img = imagecreatefrompng($uploadName);
            $type = '.png';
            break;
        case IMAGETYPE_GIF:
            $img = imagecreatefromgif($uploadName);
            $type = '.gif';
            break;
        default:
            return false;
    }
    if ($img === false) {
		return false;
	}

    $scaledFileName = $GLOBALS['uploadDir'] . $newName . '_' . $fileNameWithoutExt . $type;
    
	// Calculate half image sizes for scaling
	$newWidth = get_size($targetWidth, $originalWidth);
	$newHeight = get_size($targetHeight, $originalHeight);
   
	// Create a new true color image
    $scaledImage = imagecreatetruecolor($newWidth, $newHeight);
    // Enable transparency
	imagealphablending($scaledImage, false);
	imagesavealpha($scaledImage, true);

    // Copy and resize the original image into the new image
    imagecopyresampled(
        $scaledImage, $img,
        0, 0, 0, 0,
        $newWidth, $newHeight,
        $originalWidth, $originalHeight
    );   

    switch ($imageType) {
        case IMAGETYPE_JPEG:
			$quality = $GLOBALS['JPEG_quality'];
			imagejpeg($scaledImage, $scaledFileName, $quality);
            break;
        case IMAGETYPE_PNG:
			$compression =$GLOBALS['PNG_compression'];
			$transparentColor = imagecolorallocatealpha($scaledImage, 0, 0, 0, 127);
			imagefill($scaledImage, 0, 0, $transparentColor);			
			imagepng($scaledImage, $scaledFileName, $compression);
            break;
        case IMAGETYPE_GIF:
			$number_of_colors = $GLOBALS['GIF_number_of_colors'];
			// Reduce the number of colors to make the file smaller
			imagetruecolortopalette($scaledImage, false, $number_of_colors);
			imagegif($scaledImage, $scaledFileName);
            break;
    }   

    // Free up memory
    imagedestroy($img);
    imagedestroy($scaledImage);

    return $newName . '_' . $fileNameWithoutExt . $type;
}

function do_image_crop(string $uploadName, string $fileName, string $newName, int $targetWidth, int $targetHeight, string $rnd_name): false|string {
	
	if (! file_exists($GLOBALS['uploadDir'] . 'half_' . $rnd_name . '_' . $fileName)) {
		$scaledFileName = $GLOBALS['uploadDir'] . do_image_compression($uploadName, $fileName, "half_" . $rnd_name, $targetWidth, $targetHeight);
	} else {
		$scaledFileName = $GLOBALS['uploadDir'] . 'half_' . $rnd_name . '_' . $fileName;
	}
    list($originalWidth, $originalHeight, $imageType) = getimagesize($scaledFileName);
        
    // File Name without EXT type or Path
    $fileNameWithoutExt = pathinfo($fileName, PATHINFO_FILENAME);
    
    switch ($imageType) {
        case IMAGETYPE_JPEG:
            $img = imagecreatefromjpeg($scaledFileName);
            $type = '.jpg';
            break;
        case IMAGETYPE_PNG:
            $img = imagecreatefrompng($scaledFileName);
            $type = '.png';
            break;
        case IMAGETYPE_GIF:
            $img = imagecreatefromgif($scaledFileName);
            $type = '.gif';
            break;
        default:
            return false;
    }
    if ($img === false) {
		return false;
	}
    $croppedFileName = $GLOBALS['uploadDir'] . $newName . '_' . $fileNameWithoutExt . $type;

	// Calculate the coordinates for the cropping
	if ($originalWidth <= $targetWidth) {
		$cropX = 0;
		$targetWidth = $originalWidth;
	} else {
		$cropX = ($originalWidth - $targetWidth) / 2; // Crop from the center horizontally
	}	
	if ($originalHeight <= $targetHeight) {
		$cropY = 0;
		$targetHeight = $originalHeight;
	} else {
		$cropY = ($originalHeight - $targetHeight) / 2; // Crop from the center vertically
	}
	
    switch ($imageType) {
        case IMAGETYPE_JPEG:
            // Create a new image with the cropped dimensions
			$croppedImg = imagecrop($img, ['x' => $cropX, 'y' => $cropY, 'width' => $targetWidth, 'height' => $targetHeight]);
			
			$quality = $GLOBALS['JPEG_quality'];
			imagejpeg($croppedImg, $croppedFileName, $quality);
            break;
        case IMAGETYPE_PNG:
			// Create a new true color image with the desired dimensions
			$croppedImg = imagecreatetruecolor($targetWidth, $targetHeight);

			// Enable transparency
			imagealphablending($croppedImg, false);
			imagesavealpha($croppedImg, true);

			// Allocate a color for the background (fully transparent)
			$transparentColor = imagecolorallocatealpha($croppedImg, 0, 0, 0, 127);
			imagefill($croppedImg, 0, 0, $transparentColor);

			// Copy the relevant portion of the source image to the new image
			imagecopy($croppedImg, $img, 0, 0, $cropX, $cropY, $targetWidth, $targetHeight);	

			$compression = $GLOBALS['PNG_compression'];
			// Save the cropped image
			imagepng($croppedImg, $croppedFileName, $compression);
            break;
        case IMAGETYPE_GIF:
			// Create a new image with the cropped dimensions
			$croppedImg = imagecrop($img, ['x' => $cropX, 'y' => $cropY, 'width' => $targetWidth, 'height' => $targetHeight]);

			$number_of_colors = $GLOBALS['GIF_number_of_colors'];
			// Reduce the number of colors to make the file smaller
			imagetruecolortopalette($croppedImg, false, $number_of_colors);
			
			imagegif($croppedImg, $croppedFileName);
            break;
    }   

    // Free up memory
    imagedestroy($img);
    imagedestroy($croppedImg);
	
    return $newName . '_' . $fileNameWithoutExt . $type;
}