import { PredefinedFormat } from 'convict';
export declare const nestedSchema: unique symbol;
/**
 * Transforms the loaded configurable field value into a new value/type.
 */
export declare type SchemaResult<T> = (value: any) => T;
export interface ConfigurableSchema<T = any> {
    [key: string]: any;
    /**
     * Human-readable description of the configurable field.
     */
    doc?: string;
    /**
     * A format name or a validation function used to check the loaded value.
     *
     * From the convict documentation, format can be a:
     *
     *   * predefined type,
     *   * an array of enumerated values, e.g. ["production", "development", "testing"]
     *   * built-in JavaScript type, i.e. Object, Array, String, Number, Boolean
     *   * function that performs validation and throws an Error on failure
     *
     * If omitted, format will be set to the value of Object.prototype.toString.call
     * for the default value
     */
    format?: PredefinedFormat | any[] | ((value: any) => asserts value is T) | ((value: any) => void);
    /**
     * An optional environment variable name, the value is loaded from.
     */
    env?: string;
    neverLoadFromEnv?: boolean;
    path?: string;
    /**
     * An optional command-line argument name, the value is loaded from.
     */
    arg?: string;
    /**
     * Whether the loaded value contains sensitive information. Sensitive values
     * are not displayed when printing.
     */
    sensitive?: boolean;
    /**
     * An optional transformer function, mapping the loaded value to some new value/type.
     */
    result?: SchemaResult<T>;
}
export interface ConfigurableSchemaWithValue extends ConfigurableSchema {
    /**
     * The loaded and, optionally, transformed value of the configurable field.
     */
    value: unknown;
}
/**
 * Metadata attached to a nested configuration of some configuration class.
 */
export interface NestedConfigurationSchemaWithDefaults {
    [key: string]: ConfigurableSchemaWithDefault | NestedConfigurationSchemaWithDefaults;
    [nestedSchema]: true;
}
/**
 * Metadata attached to configurable fields, describing the purpose,
 * format, origin and such of the field value.
 */
export interface ConfigurableSchemaWithDefault extends ConfigurableSchema {
    /**
     * The default value assigned to the configurable field.
     */
    default: unknown;
}
export declare type ConfigurationSchema = Record<string, ConfigurableSchema | NestedConfigurationSchema>;
export interface NestedConfigurationSchema {
    [key: string]: ConfigurableSchema | NestedConfigurationSchema;
    [nestedSchema]: true;
}
/**
 * Metadata attached to the configurable fields of a given configuration class. Each
 * enumerable key represents a configurable field or a nested configuration of the original class.
 */
export declare type ConfigurationSchemaWithDefaults = Record<string, ConfigurableSchemaWithDefault | NestedConfigurationSchemaWithDefaults>;
export declare function isNestedSchema(schema: any): schema is NestedConfigurationSchema;
export declare function isNestedSchemaWithDefaults(schema: ConfigurableSchemaWithDefault | NestedConfigurationSchemaWithDefaults): schema is NestedConfigurationSchemaWithDefaults;
export declare function isConfigurableSchemaWithDefaults(schema: ConfigurableSchemaWithDefault | NestedConfigurationSchemaWithDefaults): schema is ConfigurableSchemaWithDefault;