import ref = require("ref");

/**
 * This is the `constructor` of the Struct type that gets returned.
 *
 * Invoke it with `new` to create a new Buffer instance backing the union.
 * Pass it an existing Buffer instance to use that as the backing buffer.
 * Pass in an Object containing the union fields to auto-populate the
 * union with the data.
 */
interface UnionType extends ref.Type {
    /** Pass it an existing Buffer instance to use that as the backing buffer. */
    new(arg: Buffer, data?: {}): any;
    new(data?: {}): any;
    /** Pass it an existing Buffer instance to use that as the backing buffer. */
    (arg: Buffer, data?: {}): any;
    (data?: {}): any;

    fields: { [key: string]: { type: ref.Type } };

    /**
     * Adds a new field to the union instance with the given name and type.
     * Note that this function will throw an Error if any instances of the union
     * type have already been created, therefore this function must be called at the
     * beginning, before any instances are created.
     */
    defineProperty(name: string, type: ref.Type): void;

    /**
     * Adds a new field to the union instance with the given name and type.
     * Note that this function will throw an Error if any instances of the union
     * type have already been created, therefore this function must be called at the
     * beginning, before any instances are created.
     */
    defineProperty(name: string, type: string): void;

    /**
     * Custom for union type instances.
     * @override
     */
    toString(): string;
}

/** The union type meta-constructor. */
declare var UnionType: {
    new(fields?: {}): UnionType;
    new(fields?: any[]): UnionType;
    (fields?: {}): UnionType;
    (fields?: any[]): UnionType;
};

export = UnionType;