<?php

namespace App\Filters;

use CodeIgniter\HTTP\RequestInterface;
use CodeIgniter\HTTP\ResponseInterface;
use CodeIgniter\Filters\FilterInterface;
use Config\Services;
use finfo;

class GlobalPostFileUploadGuard implements FilterInterface
{
    /**
     * Max file size (in bytes) → 25MB
     */
    protected int $maxFileSize = 25 * 1024 * 1024;

    /**
     * Allowed MIME types mapped to extensions
     */
    protected array $allowedMimeMap = [
        'image/jpeg'      => ['jpg', 'jpeg'],
        'image/png'       => ['png'],
        'image/gif'       => ['gif'],
        'image/webp'      => ['webp'],
        'image/svg+xml'   => ['svg'],
        'application/pdf' => ['pdf'],
        'application/msword' => ['doc'],
        'application/vnd.openxmlformats-officedocument.wordprocessingml.document' => ['docx'],
        'application/vnd.oasis.opendocument.text' => ['odt'],
        'text/rtf' => ['rtf'],
        'application/rtf' => ['rtf'],
        'application/vnd.ms-excel' => ['xls'],
        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' => ['xlsx'],
        'application/vnd.oasis.opendocument.spreadsheet' => ['ods'],
        'text/csv' => ['csv'],
        'application/csv' => ['csv'],
        'text/plain' => ['txt', 'csv'], 
    ];

    protected array $blockedExtensions = [
        'php', 'phtml', 'html', 'pht', 'phar', 'php3', 'php4', 'php5', 'php7', 'php8', 'phps',
        'cgi', 'fcgi', 'pl', 'py', 'rb', 'lua', 'tcl', 'go', 'rs', 'jar', 'class',
        'exe', 'dll', 'com', 'bat', 'cmd', 'msi', 'vbs', 'ps1', 'scr',
        'sh', 'bash', 'zsh', 'apk', 'app', 'deb', 'rpm', 'bin', 'run',
        'js', 'mjs', 'jsp', 'asp', 'aspx', 'cer', 'swf',
        'env', 'ini', 'user.ini', 'htaccess', 'htpasswd', 'conf', 'config', 'log', 'sql',
        'zip', 'rar', '7z', 'tar', 'gz', 'bz2', 'xz', 'iso',
        'lnk', 'url', 'reg', 'sys', 'drv', 'vxd', 'tmp', 'bak', 'old', 'backup', 'key', 'pem'
    ];

    public function before(RequestInterface $request, $arguments = null)
    {
        if ($request->getMethod() !== 'post') {
            return;
        }

        $files = $request->getFiles();
        if (empty($files)) {
            return;
        }

        foreach ($files as $inputName => $fileData) {
            $this->validateFileInput($fileData, $inputName);
        }
    }

    private function validateFileInput($fileData, string $inputName): void
    {
        if (is_array($fileData)) {
            foreach ($fileData as $file) {
                $this->validateSingleFile($file, $inputName);
            }
        } else {
            $this->validateSingleFile($fileData, $inputName);
        }
    }

    private function validateSingleFile($file, string $inputName): void
    {
        $request = Services::request();
        $clientIp = $request->getIPAddress();
        $uri      = $request->getUri()->getPath();

        if (!$file->isValid()) {
            if ($file->getError() === UPLOAD_ERR_INI_SIZE || $file->getError() === UPLOAD_ERR_FORM_SIZE) {
                $this->block("File exceeds server-side size limit", $clientIp, $uri, $inputName, $file->getClientName(), 'unknown', 'unknown', 0);
            }
            return; 
        }

        $originalName = $file->getClientName();
        $extension    = strtolower($file->getExtension());
        $mime         = $file->getMimeType(); 
        $size         = $file->getSize();

        // --- 1. Fixed Null Byte & Path Traversal Check ---
        if (preg_match('/\0|[\/\\\]/', $originalName)) {
            $this->block("Malicious filename characters", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }

        // --- 2. Double Extension Attack Check ---
        if (preg_match('/\.(php|phtml|html|phar|exe|sh|bat|cmd|js|jsp|asp|aspx|py|pl)\./i', $originalName)) {
            $this->block("Double extension attack", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }

        // --- 3. Forbidden Extension ---
        if (in_array($extension, $this->blockedExtensions, true)) {
            $this->block("Forbidden extension", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }

        // --- 4. File Size Limit ---
        if ($size > $this->maxFileSize) {
            $this->block("File too large", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }

        // --- 5. MIME Allow-list Check ---
        if (!array_key_exists($mime, $this->allowedMimeMap)) {
            $this->block("MIME type not allowed ($mime)", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }

        // --- 6. MIME-Extension Consistency ---
        if (!in_array($extension, $this->allowedMimeMap[$mime], true)) {
            $this->block("MIME-extension mismatch", $clientIp, $uri, $inputName, $originalName, $mime, $extension, $size);
        }
    }

    private function block(string $reason, string $ip, string $uri, string $field, string $filename, string $mime, string $ext, int $size): void
    {
        log_message('critical',
            '[UPLOAD_BLOCKED] {reason} | IP: {ip} | URI: {uri} | Field: {field} | File: {file} | MIME: {mime} | EXT: {ext} | SIZE: {size}',
            ['reason'=>$reason, 'ip'=>$ip, 'uri'=>$uri, 'field'=>$field, 'file'=>$filename, 'mime'=>$mime, 'ext'=>$ext, 'size'=>$size]
        );

        $response = Services::response();
        $response->setStatusCode(403)
                 ->setJSON([
                     'status'  => 'error',
                     'message' => 'File upload rejected: Security policy violation.',
                     'debug'   => (ENVIRONMENT === 'development') ? $reason : null
                 ])
                 ->send();
        exit;
    }

    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null) {}
}