<?php
header('Content-Type: application/json');

// Define absolute paths for security and reliability
$uploadDir = '/home/ubuntu/executor/workspace/uploads/';
$pythonScriptPath = '/home/ubuntu/executor/workspace/ml/predict.py';
// It's better to use a specific python version if possible
$pythonExecutable = 'python3';

$response = [];

// Check if a file was uploaded and there were no errors
if (isset($_FILES['mri_image']) && $_FILES['mri_image']['error'] === UPLOAD_ERR_OK) {
    $tmpName = $_FILES['mri_image']['tmp_name'];
    
    // Sanitize the original filename and create a unique, safe path
    $originalName = basename($_FILES['mri_image']['name']);
    $safeName = preg_replace("/[^A-Za-z0-9._-]/", "", $originalName);
    $fileExtension = pathinfo($safeName, PATHINFO_EXTENSION) ?: 'tmp';
    $uniqueName = 'mri_' . microtime(true) . '.' . $fileExtension;
    $uploadFilePath = $uploadDir . $uniqueName;

    // Move the uploaded file from the temporary location to our uploads directory
    if (move_uploaded_file($tmpName, $uploadFilePath)) {
        // Prepare the shell command to execute the Python script
        // escapeshellarg() is crucial for security to prevent command injection
        $command = $pythonExecutable . ' ' . escapeshellarg($pythonScriptPath) . ' ' . escapeshellarg($uploadFilePath);
        
        // Execute the command and capture the output
        $ml_output = shell_exec($command);

        // IMPORTANT: Clean up the uploaded file immediately after use
        unlink($uploadFilePath);

        if ($ml_output) {
            // Decode the JSON output from the Python script
            $ml_response = json_decode(trim($ml_output), true);

            if ($ml_response && isset($ml_response['label']) && isset($ml_response['confidence'])) {
                // If the response is valid, format it for the frontend
                $response = [
                    'success' => true,
                    'prediction' => $ml_response['label'],
                    'confidence' => $ml_response['confidence'],
                    'filename' => htmlspecialchars($safeName)
                ];
            } else {
                $response = ['success' => false, 'error' => 'ML script returned invalid data.'];
            }
        } else {
            $response = ['success' => false, 'error' => 'Failed to execute the ML model script. Check server logs for details.'];
        }
    } else {
        $response = ['success' => false, 'error' => 'Failed to save the uploaded file. Check directory permissions.'];
    }
} else {
    // Handle various upload errors
    $uploadErrors = [
        UPLOAD_ERR_INI_SIZE => 'File is too large (server limit).',
        UPLOAD_ERR_FORM_SIZE => 'File is too large (form limit).',
        UPLOAD_ERR_PARTIAL => 'File was only partially uploaded.',
        UPLOAD_ERR_NO_FILE => 'No file was uploaded.',
        UPLOAD_ERR_NO_TMP_DIR => 'Missing a temporary folder.',
        UPLOAD_ERR_CANT_WRITE => 'Failed to write file to disk.',
        UPLOAD_ERR_EXTENSION => 'A PHP extension stopped the file upload.',
    ];
    $errorCode = $_FILES['mri_image']['error'] ?? UPLOAD_ERR_NO_FILE;
    $errorMsg = $uploadErrors[$errorCode] ?? 'An unknown upload error occurred.';
    $response = ['success' => false, 'error' => $errorMsg];
}

echo json_encode($response);