import { JsonObject, JsonValue } from '@backstage/types';
/**
 * A serialized form of configuration data that carries additional context.
 *
 * @public
 */
export type AppConfig = {
    /**
     * A string representing the source of this configuration data, for example a filepath.
     */
    context: string;
    /**
     * The configuration data itself.
     */
    data: JsonObject;
    /**
     * A list of keys that where filtered out from the configuration when it was loaded.
     *
     * This can be used to warn the user if they try to read any of these keys.
     */
    filteredKeys?: string[];
    /**
     * A list of deprecated keys that were found in the  configuration when it was loaded.
     *
     * This can be used to warn the user if they are using deprecated properties.
     */
    deprecatedKeys?: {
        key: string;
        description: string;
    }[];
};
/**
 * The interface used to represent static configuration at runtime.
 *
 * @public
 */
export type Config = {
    /**
     * Subscribes to the configuration object in order to receive a notification
     * whenever any value within the configuration has changed.
     *
     * This method is optional to implement, and consumers need to check if it is
     * implemented before invoking it.
     */
    subscribe?(onChange: () => void): {
        unsubscribe: () => void;
    };
    /**
     * Checks whether the given key is present.
     */
    has(key: string): boolean;
    /**
     * Lists all available configuration keys.
     */
    keys(): string[];
    /**
     * Same as `getOptional`, but will throw an error if there's no value for the given key.
     */
    get<T = JsonValue>(key?: string): T;
    /**
     * Read out all configuration data for the given key.
     *
     * Usage of this method should be avoided as the typed alternatives provide
     * much better error reporting. The main use-case of this method is to determine
     * the type of a configuration value in the case where there are multiple possible
     * shapes of the configuration.
     */
    getOptional<T = JsonValue>(key?: string): T | undefined;
    /**
     * Same as `getOptionalConfig`, but will throw an error if there's no value for the given key.
     */
    getConfig(key: string): Config;
    /**
     * Creates a sub-view of the configuration object.
     * The configuration value at the position of the provided key must be an object.
     */
    getOptionalConfig(key: string): Config | undefined;
    /**
     * Same as `getOptionalConfigArray`, but will throw an error if there's no value for the given key.
     */
    getConfigArray(key: string): Config[];
    /**
     * Creates a sub-view of an array of configuration objects.
     * The configuration value at the position of the provided key must be an array of objects.
     */
    getOptionalConfigArray(key: string): Config[] | undefined;
    /**
     * Same as `getOptionalNumber`, but will throw an error if there's no value for the given key.
     */
    getNumber(key: string): number;
    /**
     * Reads a configuration value at the given key, expecting it to be a number.
     */
    getOptionalNumber(key: string): number | undefined;
    /**
     * Same as `getOptionalBoolean`, but will throw an error if there's no value for the given key.
     */
    getBoolean(key: string): boolean;
    /**
     * Reads a configuration value at the given key, expecting it to be a boolean.
     */
    getOptionalBoolean(key: string): boolean | undefined;
    /**
     * Same as `getOptionalString`, but will throw an error if there's no value for the given key.
     */
    getString(key: string): string;
    /**
     * Reads a configuration value at the given key, expecting it to be a string.
     */
    getOptionalString(key: string): string | undefined;
    /**
     * Same as `getOptionalStringArray`, but will throw an error if there's no value for the given key.
     */
    getStringArray(key: string): string[];
    /**
     * Reads a configuration value at the given key, expecting it to be an array of strings.
     */
    getOptionalStringArray(key: string): string[] | undefined;
};