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

$response = [];

// The directory where recordings will be stored.
$uploadDir = 'uploads/';

// Check if the upload directory exists and is writable.
if (!is_dir($uploadDir)) {
    // Try to create it if it doesn't exist.
    if (!mkdir($uploadDir, 0775, true)) {
        $response = ['success' => false, 'error' => 'Server error: Cannot create upload directory.'];
        echo json_encode($response);
        exit;
    }
}

if (!is_writable($uploadDir)) {
    $response = ['success' => false, 'error' => 'Server error: The uploads directory is not writable. Please check file permissions.'];
    echo json_encode($response);
    exit;
}

// Check if a file was uploaded and there are no errors.
if (isset($_FILES['audio_data']) && $_FILES['audio_data']['error'] == UPLOAD_ERR_OK) {
    
    // Get the temporary file path of the uploaded file.
    $tmpName = $_FILES['audio_data']['tmp_name'];

    // Generate a unique filename to prevent overwriting existing files.
    $fileName = 'recording_' . date('Y-m-d_H-i-s') . '_' . uniqid() . '.wav';
    $filePath = $uploadDir . $fileName;

    // Move the uploaded file from the temporary directory to the final destination.
    if (move_uploaded_file($tmpName, $filePath)) {
        $response['success'] = true;
        $response['message'] = 'Audio saved successfully.';
        $response['file_path'] = $filePath;
    } else {
        $response['success'] = false;
        $response['error'] = 'Error saving audio file after upload. Check directory permissions.';
    }
} else {
    // Handle potential upload errors.
    $error_message = 'No audio data received or an upload error occurred.';
    if (isset($_FILES['audio_data']['error'])) {
        switch ($_FILES['audio_data']['error']) {
            case UPLOAD_ERR_INI_SIZE:
                $error_message = 'The uploaded file exceeds the upload_max_filesize directive in php.ini.';
                break;
            case UPLOAD_ERR_FORM_SIZE:
                $error_message = 'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form.';
                break;
            case UPLOAD_ERR_PARTIAL:
                $error_message = 'The uploaded file was only partially uploaded.';
                break;
            case UPLOAD_ERR_NO_FILE:
                $error_message = 'No file was uploaded.';
                break;
            case UPLOAD_ERR_NO_TMP_DIR:
                $error_message = 'Missing a temporary folder.';
                break;
            case UPLOAD_ERR_CANT_WRITE:
                $error_message = 'Failed to write file to disk.';
                break;
            case UPLOAD_ERR_EXTENSION:
                $error_message = 'A PHP extension stopped the file upload.';
                break;
        }
    }
    $response['success'] = false;
    $response['error'] = $error_message;
}

echo json_encode($response);
?>