import { inDoc, isBrowser, target } from '@vue-devtools/shared-utils'

function createRect() {
  const rect = {
    top: 0,
    bottom: 0,
    left: 0,
    right: 0,
    get width() { return rect.right - rect.left },
    get height() { return rect.bottom - rect.top },
  }
  return rect
}

function mergeRects(a, b) {
  if (!a.top || b.top < a.top) {
    a.top = b.top
  }
  if (!a.bottom || b.bottom > a.bottom) {
    a.bottom = b.bottom
  }
  if (!a.left || b.left < a.left) {
    a.left = b.left
  }
  if (!a.right || b.right > a.right) {
    a.right = b.right
  }
  return a
}

/**
 * Get the client rect for an instance.
 */
export function getInstanceOrVnodeRect(instance) {
  const el = instance.$el || instance.elm

  if (!isBrowser) {
    // TODO: Find position from instance or a vnode (for functional components).

    return
  }
  if (!inDoc(el)) {
    return
  }

  if (instance._isFragment) {
    return addIframePosition(getLegacyFragmentRect(instance), getElWindow(instance.$root.$el))
  }
  else if (el.nodeType === 1) {
    return addIframePosition(el.getBoundingClientRect(), getElWindow(el))
  }
}

/**
 * Highlight a fragment instance.
 * Loop over its node range and determine its bounding box.
 */
function getLegacyFragmentRect({ _fragmentStart, _fragmentEnd }) {
  const rect = createRect()
  util().mapNodeRange(_fragmentStart, _fragmentEnd, (node) => {
    let childRect
    if (node.nodeType === 1 || node.getBoundingClientRect) {
      childRect = node.getBoundingClientRect()
    }
    else if (node.nodeType === 3 && node.data.trim()) {
      childRect = getTextRect(node)
    }
    if (childRect) {
      mergeRects(rect, childRect)
    }
  })
  return rect
}

let range: Range
/**
 * Get the bounding rect for a text node using a Range.
 */
function getTextRect(node: Text) {
  if (!isBrowser) {
    return
  }
  if (!range) {
    range = document.createRange()
  }

  range.selectNode(node)

  return range.getBoundingClientRect()
}

/**
 * Get Vue's util
 */
function util() {
  return target.__VUE_DEVTOOLS_GLOBAL_HOOK__.Vue.util
}

export function findRelatedComponent(el) {
  while (!el.__vue__ && el.parentElement) {
    el = el.parentElement
  }
  return el.__vue__
}

function getElWindow(el: HTMLElement) {
  return el.ownerDocument.defaultView
}

function addIframePosition(bounds, win: any) {
  if (win.__VUE_DEVTOOLS_IFRAME__) {
    const rect = mergeRects(createRect(), bounds)
    const iframeBounds = win.__VUE_DEVTOOLS_IFRAME__.getBoundingClientRect()
    rect.top += iframeBounds.top
    rect.bottom += iframeBounds.top
    rect.left += iframeBounds.left
    rect.right += iframeBounds.left
    if (win.parent) {
      return addIframePosition(rect, win.parent)
    }
    return rect
  }
  return bounds
}

export function getRootElementsFromComponentInstance(instance) {
  if (instance._isFragment) {
    const list = []
    const { _fragmentStart, _fragmentEnd } = instance
    util().mapNodeRange(_fragmentStart, _fragmentEnd, (node) => {
      list.push(node)
    })
    return list
  }
  return [instance.$el]
}