function off (type, listener, options) {
  if (utils.is.string(type) && type.search(' ') !== -1) {
    type = type.trim().split(/ +/)
  }

  if (utils.is.array(type)) {
    for (const eventType of type) {
      interact.off(eventType, listener, options)
    }

    return interact
  }

  if (utils.is.object(type)) {
    for (const prop in type) {
      interact.off(prop, type[prop], listener)
    }

    return interact
  }

  if (!utils.arr.contains(scope.actions.eventTypes, type)) {
    events.remove(scope.document, type, listener, options)
  }
  else {
    let index

    if (type in globalEvents &&
        (index = globalEvents[type].indexOf(listener)) !== -1) {
      globalEvents[type].splice(index, 1)
    }
  }

  return interact
}

function collectDrops ({ interactables }, draggableElement) {
  const drops = []

  // collect all dropzones and their elements which qualify for a drop
  for (const dropzone of interactables.list) {
    if (!dropzone.options.drop.enabled) { continue }

    const accept = dropzone.options.drop.accept

    // test the draggable draggableElement against the dropzone's accept setting
    if ((utils.is.element(accept) && accept !== draggableElement) ||
        (utils.is.string(accept) &&
        !utils.dom.matchesSelector(draggableElement, accept)) ||
        (utils.is.func(accept) && !accept({ dropzone, draggableElement }))) {
      continue
    }

    // query for new elements if necessary
    const dropElements = utils.is.string(dropzone.target)
      ? dropzone._context.querySelectorAll(dropzone.target)
      : utils.is.array(dropzone.target) ? dropzone.target : [dropzone.target]

    for (const dropzoneElement of dropElements) {
      if (dropzoneElement !== draggableElement) {
        drops.push({
          dropzone,
          element: dropzoneElement,
        })
      }
    }
  }

  return drops
}

function resizable (interactable: Interact.Interactable, options: Interact.OrBoolean<Interact.ResizableOptions> | boolean, scope: Scope) {
  if (utils.is.object(options)) {
    interactable.options.resize.enabled = options.enabled !== false
    interactable.setPerAction('resize', options)
    interactable.setOnEvents('resize', options)

    if (utils.is.string(options.axis) && /^x$|^y$|^xy$/.test(options.axis)) {
      interactable.options.resize.axis = options.axis
    }
    else if (options.axis === null) {
      interactable.options.resize.axis = scope.defaults.actions.resize.axis
    }

    if (utils.is.bool(options.preserveAspectRatio)) {
      interactable.options.resize.preserveAspectRatio = options.preserveAspectRatio
    }
    else if (utils.is.bool(options.square)) {
      interactable.options.resize.square = options.square
    }

    return interactable
  }
  if (utils.is.bool(options)) {
    interactable.options.resize.enabled = options

    return interactable
  }
  return interactable.options.resize
}

function dropzoneMethod (interactable: Interact.Interactable, options?: Interact.DropzoneOptions | boolean) {
  if (utils.is.object(options)) {
    interactable.options.drop.enabled = options.enabled !== false

    if (options.listeners) {
      const normalized = utils.normalizeListeners(options.listeners)
      // rename 'drop' to '' as it will be prefixed with 'drop'
      const corrected = Object.keys(normalized).reduce((acc, type) => {
        const correctedType = /^(enter|leave)/.test(type)
          ? `drag${type}`
          : /^(activate|deactivate|move)/.test(type)
            ? `drop${type}`
            : type

        acc[correctedType] = normalized[type]

        return acc
      }, {})

      interactable.off(interactable.options.drop.listeners)
      interactable.on(corrected)
      interactable.options.drop.listeners = corrected
    }

    if (utils.is.func(options.ondrop)) { interactable.on('drop', options.ondrop) }
    if (utils.is.func(options.ondropactivate)) { interactable.on('dropactivate', options.ondropactivate) }
    if (utils.is.func(options.ondropdeactivate)) { interactable.on('dropdeactivate', options.ondropdeactivate) }
    if (utils.is.func(options.ondragenter)) { interactable.on('dragenter', options.ondragenter) }
    if (utils.is.func(options.ondragleave)) { interactable.on('dragleave', options.ondragleave) }
    if (utils.is.func(options.ondropmove)) { interactable.on('dropmove', options.ondropmove) }

    if (/^(pointer|center)$/.test(options.overlap as string)) {
      interactable.options.drop.overlap = options.overlap
    }
    else if (utils.is.number(options.overlap)) {
      interactable.options.drop.overlap = Math.max(Math.min(1, options.overlap), 0)
    }
    if ('accept' in options) {
      interactable.options.drop.accept = options.accept
    }
    if ('checker' in options) {
      interactable.options.drop.checker = options.checker
    }

    return interactable
  }

  if (utils.is.bool(options)) {
    interactable.options.drop.enabled = options

    return interactable
  }

  return interactable.options.drop
}

function getActionInfo (interaction: Interact.Interaction, pointer: Interact.PointerType, event: Interact.PointerEventType, eventTarget: Element, scope: Interact.Scope) {
  let matches = []
  let matchElements = []

  let element = eventTarget

  function pushMatches (interactable) {
    matches.push(interactable)
    matchElements.push(element)
  }

  while (utils.is.element(element)) {
    matches = []
    matchElements = []

    scope.interactables.forEachMatch(element, pushMatches)

    const actionInfo = validateMatches(interaction, pointer, event, matches, matchElements, eventTarget, scope)

    if (actionInfo.action &&
      !actionInfo.interactable.options[actionInfo.action.name].manualStart) {
      return actionInfo
    }

    element = utils.dom.parentNode(element)
  }

  return { action: null, interactable: null, element: null }
}

  Interactable.prototype.gesturable = function (this: Interact.Interactable, options: Interact.GesturableOptions | boolean) {
    if (utils.is.object(options)) {
      this.options.gesture.enabled = options.enabled !== false
      this.setPerAction('gesture', options)
      this.setOnEvents('gesture', options)

      return this
    }

    if (utils.is.bool(options)) {
      this.options.gesture.enabled = options

      return this
    }

    return this.options.gesture as Interact.Options
  } as GesturableMethod

function dropCheckMethod (
  interactable: Interact.Interactable,
  dragEvent: InteractEvent,
  event: Interact.PointerEventType,
  draggable: Interact.Interactable,
  draggableElement: Element,
  dropElement: Element,
  rect: any
) {
  let dropped = false

  // if the dropzone has no rect (eg. display: none)
  // call the custom dropChecker or just return false
  if (!(rect = rect || interactable.getRect(dropElement))) {
    return (interactable.options.drop.checker
      ? interactable.options.drop.checker(dragEvent, event, dropped, interactable, dropElement, draggable, draggableElement)
      : false)
  }

  const dropOverlap = interactable.options.drop.overlap

  if (dropOverlap === 'pointer') {
    const origin = utils.getOriginXY(draggable, draggableElement, 'drag')
    const page = utils.pointer.getPageXY(dragEvent)

    page.x += origin.x
    page.y += origin.y

    const horizontal = (page.x > rect.left) && (page.x < rect.right)
    const vertical   = (page.y > rect.top) && (page.y < rect.bottom)

    dropped = horizontal && vertical
  }

  const dragRect = draggable.getRect(draggableElement)

  if (dragRect && dropOverlap === 'center') {
    const cx = dragRect.left + dragRect.width  / 2
    const cy = dragRect.top  + dragRect.height / 2

    dropped = cx >= rect.left && cx <= rect.right && cy >= rect.top && cy <= rect.bottom
  }

  if (dragRect && utils.is.number(dropOverlap)) {
    const overlapArea  = (Math.max(0, Math.min(rect.right, dragRect.right) - Math.max(rect.left, dragRect.left)) *
                          Math.max(0, Math.min(rect.bottom, dragRect.bottom) - Math.max(rect.top, dragRect.top)))

    const overlapRatio = overlapArea / (dragRect.width * dragRect.height)

    dropped = overlapRatio >= dropOverlap
  }

  if (interactable.options.drop.checker) {
    dropped = interactable.options.drop.checker(dragEvent, event, dropped, interactable, dropElement, draggable, draggableElement)
  }

  return dropped
}

function maxInteractions (newValue, scope: Interact.Scope) {
  if (utils.is.number(newValue)) {
    scope.autoStart.maxInteractions = newValue

    return this
  }

  return scope.autoStart.maxInteractions
}

function pointerMoveTolerance (newValue) {
  if (utils.is.number(newValue)) {
    scope.interactions.pointerMoveTolerance = newValue

    return interact
  }

  return scope.interactions.pointerMoveTolerance
}

export function uniqueProps (obj) {
  for (const prop in obj) {
    if (!obj.hasOwnProperty(prop)) { continue }

    if (utils.is.object(obj)) {
      uniqueProps(obj[prop])
    }
    else {
      obj[prop] = (counter++)
    }
  }
}