/**
 * ConfigLoader - JSON config file loader with env var interpolation.
 *
 * Supports ${VAR|default} syntax for env var substitution and
 * dot-notation access for nested values.
 */
/** JSON configuration file loader with environment variable interpolation and dot-notation access. */
export declare class ConfigLoader {
    private static readonly DANGEROUS_KEYS;
    private data;
    private filePath;
    /** The ordered list of config file paths that were searched or provided. */
    private _configPaths;
    /**
     * Create a new ConfigLoader, optionally loading a JSON file immediately.
     *
     * Accepts a single file path or an array of paths. When given an array,
     * the loader iterates in order and loads the first file that exists
     * (mirroring Python's ordered-search behaviour).
     *
     * @param filePaths - Path(s) to a JSON config file to load on construction.
     */
    constructor(filePaths?: string | string[]);
    /**
     * Get the ordered list of config file paths that were passed/searched.
     * @returns The array of config paths.
     */
    get configPaths(): string[];
    /**
     * Load configuration from a JSON file, performing `${VAR|default}` env var interpolation on the raw text.
     * @param filePath - Path to the JSON config file.
     * @returns This instance for chaining.
     */
    load(filePath: string): this;
    /**
     * Search for a config file in standard locations.
     *
     * Default search paths: CWD, `./config`, `$HOME/.signalwire`,
     * `.swml/`, `$HOME/.swml/`, `/etc/swml/`.
     *
     * @param filename - The config file name to search for.
     * @param additionalPaths - Extra directories to search before the defaults.
     * @param serviceName - Optional service name; prepends service-specific filenames to the search.
     * @returns A loaded ConfigLoader if found, or null if the file does not exist in any search path.
     */
    static search(filename: string, additionalPaths?: string[], serviceName?: string): ConfigLoader | null;
    /**
     * Find a config file path without loading it.
     *
     * Searches service-specific filenames, additional paths, and default paths.
     * Returns the first found path string or null.
     *
     * @param serviceName - Optional service name for service-specific config filenames.
     * @param additionalPaths - Additional file paths to check.
     * @returns Path to the first config file found, or null.
     */
    static findConfigFile(serviceName?: string, additionalPaths?: string[]): string | null;
    /**
     * Build the list of file paths to search.
     */
    private static _buildSearchPaths;
    /**
     * Retrieve a configuration value using a dot-notation path (e.g. `'server.port'`).
     * @param path - Dot-separated key path into the config object.
     * @param defaultValue - Value returned when the path does not exist.
     * @returns The resolved value, or defaultValue if not found.
     */
    get<T = unknown>(path: string, defaultValue?: T): T;
    /**
     * Set a configuration value at the given dot-notation path, creating intermediate objects as needed.
     * @param path - Dot-separated key path into the config object.
     * @param value - The value to store.
     * @returns This instance for chaining.
     */
    set(path: string, value: unknown): this;
    /**
     * Check whether a dot-notation path exists in the loaded configuration.
     * @param path - Dot-separated key path to check.
     * @returns True if the path resolves to a defined value.
     */
    has(path: string): boolean;
    /**
     * Return a shallow copy of the entire configuration object.
     * @returns A copy of the top-level config data.
     */
    getAll(): Record<string, unknown>;
    /**
     * Alias for {@link getAll} — matches the Python SDK's `get_config()` method name.
     * @returns A copy of the top-level config data.
     */
    getConfig(): Record<string, unknown>;
    /**
     * Return the absolute path of the loaded config file, if any.
     * @returns The file path, or null if config was loaded from an object.
     */
    getFilePath(): string | null;
    /**
     * Alias for {@link getFilePath} — matches the Python SDK's `get_config_file()` method name.
     * @returns The file path, or null if config was loaded from an object.
     */
    getConfigFile(): string | null;
    /**
     * Check if a configuration was loaded.
     *
     * **Deliberate deviation from Python `has_config()`:** Python returns `True`
     * only when a file was loaded (`self._config is not None`). This TypeScript
     * implementation also returns `true` when data was loaded via
     * {@link loadFromObject}, because `loadFromObject` is an extra TS-only method
     * with no Python equivalent. Treating object-loaded data as "configured" is
     * the correct semantic for the TS API surface.
     *
     * If you need file-load-only detection, check `this.getFilePath() !== null`.
     *
     * @returns True if configuration data exists (from file or object).
     */
    hasConfig(): boolean;
    /**
     * Get an entire configuration section with all environment variables substituted.
     * @param section - The top-level section name (e.g. 'security', 'server').
     * @returns The configuration section as an object, or an empty object if not found.
     */
    getSection(section: string): Record<string, unknown>;
    /**
     * Recursively substitute `${VAR|default}` environment variables in any value.
     *
     * Walks strings, objects, and arrays. Coerces result strings to boolean
     * (`"true"` / `"false"`) or number when appropriate.
     *
     * @param value - The value to process (string, object, array, or primitive).
     * @param maxDepth - Maximum recursion depth to prevent infinite loops (default: 10).
     * @returns The value with all environment variables substituted.
     */
    substituteVars(value: unknown, maxDepth?: number): unknown;
    /**
     * Merge configuration with environment variables that match a prefix.
     *
     * Config file values take precedence over environment variables. Matching
     * env var keys are stripped of the prefix, lowercased, split on `_`, and
     * written into a nested object (e.g. `SWML_FOO_BAR` → `{ foo: { bar: v } }`).
     * Mirrors Python's `merge_with_env` in
     * `signalwire/signalwire/core/config_loader.py`.
     *
     * @param envPrefix - Prefix for environment variables to consider (default: `'SWML_'`).
     * @returns Merged configuration dictionary.
     */
    mergeWithEnv(envPrefix?: string): Record<string, unknown>;
    /**
     * Check if a nested key (underscore-separated path) exists in a dict.
     * Used by {@link mergeWithEnv} to mirror Python's `_has_nested_key`.
     */
    private _hasNestedKey;
    /**
     * Set a value in a dict using an underscore-separated path, creating
     * intermediate objects as needed.
     * Used by {@link mergeWithEnv} to mirror Python's `_set_nested_key`.
     */
    private _setNestedKey;
    /**
     * Load configuration from a plain object instead of a file, useful for testing or programmatic setup.
     * @param obj - The configuration object to use.
     * @returns This instance for chaining.
     */
    loadFromObject(obj: Record<string, unknown>): this;
    /**
     * Interpolate ${VAR|default} patterns in a raw string.
     * @param input - The string containing env var references.
     * @returns The string with all env var references resolved.
     */
    interpolateEnvVars(input: string): string;
}