/**
 * Initialize backoff timer with `opts`.
 *
 * - `min` initial timeout in milliseconds [100]
 * - `max` max timeout [10000]
 * - `jitter` [0]
 * - `factor` [2]
 *
 * @param {Object} opts
 * @api public
 */

export function Backoff(this: any, opts) {
    opts = opts || {}
    this.ms = opts.min || 100
    this.max = opts.max || 10000
    this.factor = opts.factor || 2
    this.jitter = opts.jitter > 0 && opts.jitter <= 1 ? opts.jitter : 0
    this.attempts = 0
}

/**
 * Return the backoff duration.
 *
 * @return {Number}
 * @api public
 */

Backoff.prototype.duration = function () {
    var ms = this.ms * Math.pow(this.factor, this.attempts++)
    if (this.jitter) {
        var rand = Math.random()
        var deviation = Math.floor(rand * this.jitter * ms)
        ms = (Math.floor(rand * 10) & 1) == 0 ? ms - deviation : ms + deviation
    }
    return Math.min(ms, this.max) | 0
}

/**
 * Reset the number of attempts.
 *
 * @api public
 */

Backoff.prototype.reset = function () {
    this.attempts = 0
}

/**
 * Set the minimum duration
 *
 * @api public
 */

Backoff.prototype.setMin = function (min) {
    this.ms = min
}

/**
 * Set the maximum duration
 *
 * @api public
 */

Backoff.prototype.setMax = function (max) {
    this.max = max
}

/**
 * Set the jitter
 *
 * @api public
 */

Backoff.prototype.setJitter = function (jitter) {
    this.jitter = jitter
}