<?php

class ImageProcessor {
    private static $uploadDir = 'assets/images/uploads/';
    private static $maxWidth = 400; // Default max width for thumbnails
    private static $maxHeight = 800; // Default max height for thumbnails (double the max width)

    /**
     * Handles the uploaded image, moves it to the upload directory, and resizes it.
     *
     * @param array $file The $_FILES array entry for the uploaded file.
     * @return string|false The path to the saved thumbnail or false on error.
     */
    public static function processAndSaveImage(array $file) {
        if (!isset($file['tmp_name']) || $file['error'] !== UPLOAD_ERR_OK) {
            error_log("ImageProcessor: No file uploaded or an error occurred. File error code: " . ($file['error'] ?? 'unknown'));
            return false; // No file uploaded or an error occurred
        }

        // Validate file type
        $allowedTypes = ['image/jpeg', 'image/png', 'image/gif'];
        if (!in_array($file['type'], $allowedTypes)) {
            error_log("ImageProcessor: Invalid file type uploaded: " . $file['type']);
            return false; // Invalid file type
        }

        // Ensure upload directory exists
        if (!is_dir(self::$uploadDir)) {
            mkdir(self::$uploadDir, 0775, true);
        }

        // Generate a unique file name
        $extension = pathinfo($file['name'], PATHINFO_EXTENSION);
        $fileName = uniqid('thumbnail_') . '.' . $extension;
        $targetPath = self::$uploadDir . $fileName;

        // Move the uploaded file
        if (!move_uploaded_file($file['tmp_name'], $targetPath)) {
            error_log("ImageProcessor: Failed to move uploaded file from " . $file['tmp_name'] . " to " . $targetPath);
            return false; // Failed to move uploaded file
        }

        // Resize image
        if (!self::resizeImage($targetPath, $file['type'])) {
            error_log("ImageProcessor: Failed to resize image: " . $targetPath);
            // If resizing fails, you might want to delete the original uploaded file
            unlink($targetPath);
            return false;
        }

        return $targetPath; // Return the path to the saved and resized image
    }

    /**
     * Resizes an image to a maximum width, maintaining aspect ratio.
     *
     * @param string $imagePath The path to the image file.
     * @param string $mimeType The MIME type of the image.
     * @return bool True on success, false on failure.
     */
    private static function resizeImage(string $imagePath, string $mimeType) {
        list($width, $height) = getimagesize($imagePath);

        if ($width <= self::$maxWidth && $height <= self::$maxHeight) {
            return true; // No resizing needed
        }

        $aspectRatio = $width / $height;
        $newWidth = $width;
        $newHeight = $height;

        // Resize based on width if it exceeds maxWidth or if new height based on maxWidth is less than maxHeight
        if ($newWidth > self::$maxWidth) {
            $newWidth = self::$maxWidth;
            $newHeight = (int) (self::$maxWidth / $aspectRatio);
        }

        // Resize based on height if it exceeds maxHeight or if new width based on maxHeight is less than maxWidth
        if ($newHeight > self::$maxHeight) {
            $newHeight = self::$maxHeight;
            $newWidth = (int) (self::$maxHeight * $aspectRatio);
        }

        // Final check to ensure it fits within both dimensions after initial adjustments
        if ($newWidth > self::$maxWidth) {
            $newWidth = self::$maxWidth;
            $newHeight = (int) (self::$maxWidth / $aspectRatio);
        }

        if ($newHeight > self::$maxHeight) {
            $newHeight = self::$maxHeight;
            $newWidth = (int) (self::$maxHeight * $aspectRatio);
        }


        $image = null;
        switch ($mimeType) {
            case 'image/jpeg':
                $image = imagecreatefromjpeg($imagePath);
                break;
            case 'image/png':
                $image = imagecreatefrompng($imagePath);
                break;
            case 'image/gif':
                $image = imagecreatefromgif($imagePath);
                break;
            default:
                error_log("ImageProcessor: Unsupported image type for resizing: " . $mimeType);
                return false; // Unsupported image type for resizing
        }

        if (!$image) {
            return false;
        }

        $resizedImage = imagecreatetruecolor($newWidth, $newHeight);

        // Preserve transparency for PNG and GIF
        if ($mimeType == 'image/png') {
            imagealphablending($resizedImage, false);
            imagesavealpha($resizedImage, true);
            $transparent = imagecolorallocatealpha($resizedImage, 255, 255, 255, 127);
            imagefilledrectangle($resizedImage, 0, 0, $newWidth, $newHeight, $transparent);
        } elseif ($mimeType == 'image/gif') {
            $trnprt_indx = imagecolortransparent($image);
            if ($trnprt_indx >= 0) {
                // Get the transparent color from the original image
                $trnprt_color = imagecolorsforindex($image, $trnprt_indx);
                // Allocate the same color in the new image
                $trnprt_indx = imagecolorallocate($resizedImage, $trnprt_color['red'], $trnprt_color['green'], $trnprt_color['blue']);
                imagefill($resizedImage, 0, 0, $trnprt_indx);
                imagecolortransparent($resizedImage, $trnprt_indx);
            }
        }

        imagecopyresampled($resizedImage, $image, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);

        $success = false;
        switch ($mimeType) {
            case 'image/jpeg':
                $success = imagejpeg($resizedImage, $imagePath, 90); // 90% quality
                break;
            case 'image/png':
                $success = imagepng($resizedImage, $imagePath);
                break;
            case 'image/gif':
                $success = imagegif($resizedImage, $imagePath);
                break;
        }

        imagedestroy($image);
        imagedestroy($resizedImage);

        return $success;
    }
}