/*
* @license Apache-2.0
*
* Copyright (c) 2019 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

// TypeScript Version: 4.1

/// <reference types="@stdlib/types"/>

import * as random from '@stdlib/types/random';
import { TypedIterator } from '@stdlib/types/iter';

/**
* Interface defining function options.
*/
interface Options {
	/**
	* Pseudorandom number generator which generates uniformly distributed pseudorandom numbers.
	*/
	prng?: random.PRNG;

	/**
	* Pseudorandom number generator seed.
	*/
	seed?: random.PRNGSeedMT19937;

	/**
	* Pseudorandom number generator state.
	*/
	state?: random.PRNGStateMT19937;

	/**
	* Specifies whether to copy a provided pseudorandom number generator state (default: `true`).
	*/
	copy?: boolean;

	/**
	* Number of iterations.
	*/
	iter?: number;
}

/**
* Interface for iterators of pseudorandom numbers drawn from a Kumaraswamy's double bounded distribution.
*/
interface Iterator<T> extends TypedIterator<T> {
	/**
	* Underlying PRNG.
	*/
	readonly PRNG: random.PRNG;

	/**
	* PRNG seed.
	*/
	readonly seed: random.PRNGSeedMT19937;

	/**
	* PRNG seed length.
	*/
	readonly seedLength: number;

	/**
	* PRNG state.
	*/
	state: random.PRNGStateMT19937;

	/**
	* PRNG state length.
	*/
	readonly stateLength: number;

	/**
	* PRNG state size (in bytes).
	*/
	readonly byteLength: number;
}

/**
* Returns an iterator for generating pseudorandom numbers drawn from a Kumaraswamy's double bounded distribution.
*
* @param a - first shape parameter
* @param b  - second shape parameter
* @param options - function options
* @throws `a` must be a positive number
* @throws `b` must be a positive number
* @throws must provide valid options
* @throws must provide a valid state
* @returns iterator
*
* @example
* var iter = iterator( 2.0, 5.0 );
*
* var r = iter.next().value;
* // returns <number>
*
* r = iter.next().value;
* // returns <number>
*
* r = iter.next().value;
* // returns <number>
*
* // ...
*/
declare function iterator( a: number, b: number, options?: Options ): Iterator<number>;


// EXPORTS //

export = iterator;