text: import isObject from './isObject.js'
  import root from './.internal/root.js'
  
  /**
   * Creates a debounced function that delays invoking `func` until after `wait`
   * milliseconds have elapsed since the last time the debounced function was
   * invoked, or until the next browser frame is drawn. The debounced function
   * comes with a `cancel` method to cancel delayed `func` invocations and a
   * `flush` method to immediately invoke them. Provide `options` to indicate
   * whether `func` should be invoked on the leading and/or trailing edge of the
   * `wait` timeout. The `func` is invoked with the last arguments provided to the
   * debounced function. Subsequent calls to the debounced function return the
   * result of the last `func` invocation.
   *
   * **Note:** If `leading` and `trailing` options are `true`, `func` is
   * invoked on the trailing edge of the timeout only if the debounced function
   * is invoked more than once during the `wait` timeout.
   *
   * If `wait` is `0` and `leading` is `false`, `func` invocation is deferred
   * until the next tick, similar to `setTimeout` with a timeout of `0`.
   *
   * If `wait` is omitted in an environment with `requestAnimationFrame`, `func`
   * invocation will be deferred until the next frame is drawn (typically about
   * 16ms).
   *
   * See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/)
   * for details over the differences between `debounce` and `throttle`.
   *
   * @since 0.1.0
   * @category Function
   * @param {Function} func The function to debounce.
   * @param {number} [wait=0]
   *  The number of milliseconds to delay; if omitted, `requestAnimationFrame` is
   *  used (if available).
   * @param {Object} [options={}] The options object.
   * @param {boolean} [options.leading=false]
   *  Specify invoking on the leading edge of the timeout.
   * @param {number} [options.maxWait]
   *  The maximum time `func` is allowed to be delayed before it's invoked.
   * @param {boolean} [options.trailing=true]
   *  Specify invoking on the trailing edge of the timeout.
   * @returns {Function} Returns the new debounced function.
   * @example
   *
   * // Avoid costly calculations while the window size is in flux.
   * jQuery(window).on('resize', debounce(calculateLayout, 150))
   *
   * // Invoke `sendMail` when clicked, debouncing subsequent calls.
   * jQuery(element).on('click', debounce(sendMail, 300, {
   *   'leading': true,
   *   'trailing': false
   * }))
   *
   * // Ensure `batchLog` is invoked once after 1 second of debounced calls.
   * const debounced = debounce(batchLog, 250, { 'maxWait': 1000 })
   * const source = new EventSource('/stream')
   * jQuery(source).on('message', debounced)
   *
   * // Cancel the trailing debounced invocation.
   * jQuery(window).on('popstate', debounced.cancel)
   *
   * // Check for pending invocations.
   * const status = debounced.pending() ? "Pending..." : "Ready"
   */
  function debounce(func, wait, options) {
    let lastArgs,
      lastThis,
      maxWait,
      result,
      timerId,
      lastCallTime
  
    let lastInvokeTime = 0
    let leading = false
    let maxing = false
    let trailing = true
  
    // Bypass `requestAnimationFrame` by explicitly setting `wait=0`.
    const useRAF = (!wait && wait !== 0 && typeof root.requestAnimationFrame === 'function')
  
    if (typeof func !== 'function') {
      throw new TypeError('Expected a function')
    }
    wait = +wait || 0
    if (isObject(options)) {
      leading = !!options.leading
      maxing = 'maxWait' in options
      maxWait = maxing ? Math.max(+options.maxWait || 0, wait) : maxWait
      trailing = 'trailing' in options ? !!options.trailing : trailing
    }
  
    function invokeFunc(time) {
      const args = lastArgs
      const thisArg = lastThis
  
      lastArgs = lastThis = undefined
      lastInvokeTime = time
      result = func.apply(thisArg, args)
      return result
    }
  
    function startTimer(pendingFunc, wait) {
      if (useRAF) {
        root.cancelAnimationFrame(timerId);
        return root.requestAnimationFrame(pendingFunc)
      }
      return setTimeout(pendingFunc, wait)
    }
  
    function cancelTimer(id) {
      if (useRAF) {
        return root.cancelAnimationFrame(id)
      }
      clearTimeout(id)
    }
  
    function leadingEdge(time) {
      // Reset any `maxWait` timer.
      lastInvokeTime = time
      // Start the timer for the trailing edge.
      timerId = startTimer(timerExpired, wait)
      // Invoke the leading edge.
      return leading ? invokeFunc(time) : result
    }
  
    function remainingWait(time) {
      const timeSinceLastCall = time - lastCallTime
      const timeSinceLastInvoke = time - lastInvokeTime
      const timeWaiting = wait - timeSinceLastCall
  
      return maxing
        ? Math.min(timeWaiting, maxWait - timeSinceLastInvoke)
        : timeWaiting
    }
  
    function shouldInvoke(time) {
      const timeSinceLastCall = time - lastCallTime
      const timeSinceLastInvoke = time - lastInvokeTime
  
      // Either this is the first call, activity has stopped and we're at the
      // trailing edge, the system time has gone backwards and we're treating
      // it as the trailing edge, or we've hit the `maxWait` limit.
      return (lastCallTime === undefined || (timeSinceLastCall >= wait) ||
        (timeSinceLastCall < 0) || (maxing && timeSinceLastInvoke >= maxWait))
    }
  
    function timerExpired() {
      const time = Date.now()
      if (shouldInvoke(time)) {
        return trailingEdge(time)
      }
      // Restart the timer.
      timerId = startTimer(timerExpired, remainingWait(time))
    }
  
    function trailingEdge(time) {
      timerId = undefined
  
      // Only invoke if we have `lastArgs` which means `func` has been
      // debounced at least once.
      if (trailing && lastArgs) {
        return invokeFunc(time)
      }
      lastArgs = lastThis = undefined
      return result
    }
  
    function cancel() {
      if (timerId !== undefined) {
        cancelTimer(timerId)
      }
      lastInvokeTime = 0
      lastArgs = lastCallTime = lastThis = timerId = undefined
    }
  
    function flush() {
      return timerId === undefined ? result : trailingEdge(Date.now())
    }
  
    function pending() {
      return timerId !== undefined
    }
  
    function debounced(...args) {
      const time = Date.now()
      const isInvoking = shouldInvoke(time)
  
      lastArgs = args
      lastThis = this
      lastCallTime = time
  
      if (isInvoking) {
        if (timerId === undefined) {
          return leadingEdge(lastCallTime)
        }
        if (maxing) {
          // Handle invocations in a tight loop.
          timerId = startTimer(timerExpired, wait)
          return invokeFunc(lastCallTime)
        }
      }
      if (timerId === undefined) {
        timerId = startTimer(timerExpired, wait)
      }
      return result
    }
    debounced.cancel = cancel
    debounced.flush = flush
    debounced.pending = pending
    return debounced
  }
  
  export default debounce
  