<?php

declare(strict_types=1);

class ImageHandler {
    private string $uploadDir;
    private string $baseUrl;

    public function __construct(?string $uploadDir = null, ?string $baseUrl = null) {
        $this->uploadDir = $uploadDir ?? __DIR__ . '/../public/images/';
        $this->baseUrl = $baseUrl ?? '/images/';

        // Ensure upload directory exists
        if (!file_exists($this->uploadDir)) {
            mkdir($this->uploadDir, 0755, true);
        }
    }

    /**
     * Process base64 image data and save to file
     *
     * @param string $base64Data Base64 encoded image data
     * @param string $prefix Prefix for filename (e.g., 'poster', 'banner')
     * @return string|null Relative path to saved image, or null if invalid
     */
    public function saveBase64Image(string $base64Data, string $prefix = 'image'): ?string {
        error_log("ImageHandler: Starting to process base64 image, length: " . strlen($base64Data));
        
        if (empty($base64Data)) {
            error_log("ImageHandler: Empty base64 data");
            return null;
        }
        
        // Check if it's already a URL (not base64)
        if (filter_var($base64Data, FILTER_VALIDATE_URL)) {
            error_log("ImageHandler: Data is already a URL: " . $base64Data);
            return $base64Data;
        }
        
        // Check if it's already a file path
        if (strpos($base64Data, '/images/') === 0) {
            error_log("ImageHandler: Data is already a file path: " . $base64Data);
            return $base64Data;
        }
        
        // Parse base64 data
        if (preg_match('/^data:image\/(\w+);base64,(.+)$/', $base64Data, $matches)) {
            $extension = $matches[1];
            $base64String = $matches[2];
            error_log("ImageHandler: Data URI format detected, extension: " . $extension);
        } elseif (preg_match('/^\/9j\//', $base64Data)) {
            // Raw base64 without data URI prefix (JPEG)
            $extension = 'jpg';
            $base64String = $base64Data;
            error_log("ImageHandler: Raw JPEG base64 detected");
        } else {
            // Try to detect from the base64 string itself
            $extension = $this->detectImageFormat($base64Data);
            if (!$extension) {
                error_log("ImageHandler: Could not detect image format, defaulting to jpg");
                $extension = 'jpg';
                $base64String = $base64Data;
            } else {
                $base64String = $base64Data;
                error_log("ImageHandler: Detected format: " . $extension);
            }
        }
        
        // Decode base64
        $imageData = base64_decode($base64String);
        if ($imageData === false) {
            error_log("ImageHandler: Base64 decode failed");
            return null;
        }
        
        error_log("ImageHandler: Decoded image data size: " . strlen($imageData) . " bytes");
        
        // Skip GD validation - just check if data looks reasonable
        if (strlen($imageData) < 100) {
            error_log("ImageHandler: Image data too small, likely invalid");
            return null;
        }
        
        // Generate unique filename
        $filename = $this->generateUniqueFilename($prefix, $extension);
        $filepath = $this->uploadDir . $filename;
        
        error_log("ImageHandler: Attempting to save to: " . $filepath);
        
        // Ensure directory exists and is writable (handle subdirectories)
        $directory = dirname($filepath);
        if (!file_exists($directory)) {
            error_log("ImageHandler: Creating directory: " . $directory);
            if (!mkdir($directory, 0755, true)) {
                error_log("ImageHandler: Failed to create directory");
                return null;
            }
        }
        
        if (!is_writable($directory)) {
            error_log("ImageHandler: Directory not writable: " . $directory);
            error_log("ImageHandler: Attempting to chmod directory");
            chmod($directory, 0755);
        }
        
        // Save file
        $bytesWritten = file_put_contents($filepath, $imageData);
        if ($bytesWritten === false) {
            error_log("ImageHandler: Failed to save file to: " . $filepath);
            error_log("ImageHandler: Upload directory exists: " . (file_exists($this->uploadDir) ? 'yes' : 'no'));
            error_log("ImageHandler: Upload directory writable: " . (is_writable($this->uploadDir) ? 'yes' : 'no'));
            return null;
        }
        
        error_log("ImageHandler: Successfully saved " . $bytesWritten . " bytes to: " . $filepath);
        
        // Return relative path
        return $this->baseUrl . $filename;
    }
    
    /**
     * Detect image format from base64 string
     */
    private function detectImageFormat(string $base64String): ?string {
        // Decode first few bytes to check magic numbers
        $data = base64_decode(substr($base64String, 0, 100));
        
        if (substr($data, 0, 3) === "\xFF\xD8\xFF") {
            return 'jpg';
        } elseif (substr($data, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A") {
            return 'png';
        } elseif (substr($data, 0, 6) === "GIF87a" || substr($data, 0, 6) === "GIF89a") {
            return 'gif';
        } elseif (substr($data, 0, 4) === "RIFF" && substr($data, 8, 4) === "WEBP") {
            return 'webp';
        }
        
        // Default to jpg for game posters
        return 'jpg';
    }
    
    /**
     * Validate that data is a valid image
     */
    private function isValidImage(string $data): bool {
        try {
            $image = imagecreatefromstring($data);
            if ($image !== false) {
                imagedestroy($image);
                return true;
            }
        } catch (Exception $e) {
            return false;
        }
        return false;
    }
    
    /**
     * Generate unique filename
     */
    private function generateUniqueFilename(string $prefix, string $extension): string {
        return $prefix . '_' . uniqid() . '_' . time() . '.' . $extension;
    }
    
    /**
     * Delete an image file
     */
    public function deleteImage(?string $imagePath): bool {
        if (empty($imagePath)) {
            return false;
        }
        
        // Convert URL to filesystem path
        if (strpos($imagePath, $this->baseUrl) === 0) {
            $filename = substr($imagePath, strlen($this->baseUrl));
            $filepath = $this->uploadDir . $filename;
            
            if (file_exists($filepath)) {
                return unlink($filepath);
            }
        }
        
        return false;
    }
}