<template>
  <Teleport to="body">
    <div class="overlay"></div>
  </Teleport>
</template>
<style scoped>
  .verlay {
    z-index: 9999;
  }
</style>

// packages/runtime-core/src/components/Teleport.ts
export const TeleportImpl = {
  // Teleport 組件獨(dú)有的特性，用作標(biāo)識(shí)
  __isTeleport: true,
  // 客戶端渲染 Teleport 組件
  process() {},
  // 移除 Teleport
  remove() {},
  //  移動(dòng) Teleport
  move: moveTeleport,
  // 服務(wù)端渲染 Teleport
  hydrate: hydrateTeleport
}
export const Teleport = TeleportImpl as any as {
  __isTeleport: true
  new (): { $props: VNodeProps & TeleportProps }
}

// packages/runtime-core/src/renderer.ts
const patch: PatchFn = (
    n1,
    n2,
    container,
    anchor = null,
    parentComponent = null,
    parentSuspense = null,
    isSVG = false,
    slotScopeIds = null,
    optimized = __DEV__ && isHmrUpdating ? false : !!n2.dynamicChildren
  ) => {
    // 省略部分代碼
    const { type, ref, shapeFlag } = n2
    switch (type) {
      // 省略部分代碼
      default:
        // 省略部分代碼
        // shapeFlag 的類型為 TELEPORT，則它是 Teleport 組件
        // 調(diào)用 Teleport 組件選項(xiàng)中的 process 函數(shù)將控制權(quán)交接出去
        // 傳遞給 process 函數(shù)的第五個(gè)參數(shù)是渲染器的一些內(nèi)部方法
        else if (shapeFlag & ShapeFlags.TELEPORT) {
          ;(type as typeof TeleportImpl).process(
            n1 as TeleportVNode,
            n2 as TeleportVNode,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        }
        // 省略部分代碼
    }
    // 省略部分代碼
  }

// packages/runtime-core/src/components/Teleport.ts
if (n1 == null) {
  // 首次渲染 Teleport
  // insert anchors in the main view
  // 往 container 中插入 Teleport 的注釋
  const placeholder = (n2.el = __DEV__
    ? createComment('teleport start')
    : createText(''))
  const mainAnchor = (n2.anchor = __DEV__
    ? createComment('teleport end')
    : createText(''))
  insert(placeholder, container, anchor)
  insert(mainAnchor, container, anchor)
  // 獲取容器，即掛載點(diǎn)
  const target = (n2.target = resolveTarget(n2.props, querySelector))
  const targetAnchor = (n2.targetAnchor = createText(''))
  // 如果掛載點(diǎn)存在，則將
  if (target) {
    insert(targetAnchor, target)
    // #2652 we could be teleporting from a non-SVG tree into an SVG tree
    isSVG = isSVG || isTargetSVG(target)
  } else if (__DEV__ && !disabled) {
    warn('Invalid Teleport target on mount:', target, `(${typeof target})`)
  }
  // 將 n2.children 渲染到指定掛載點(diǎn)
  const mount = (container: RendererElement, anchor: RendererNode) => {
    // Teleport *always* has Array children. This is enforced in both the
    // compiler and vnode children normalization.
    if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
      // 調(diào)用渲染器內(nèi)部的 mountChildren 方法渲染 Teleport 組件的插槽內(nèi)容
      mountChildren(
        children as VNodeArrayChildren,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }
  // 掛載 Teleport
  if (disabled) {
    // 如果 Teleport 組件的 disabled 為 true，說明禁用了 <teleport> 的功能，Teleport 只會(huì)在 container 中渲染
    mount(container, mainAnchor)
  } else if (target) {
    // 如果沒有禁用 <teleport> 的功能，并且存在掛載點(diǎn)，則將其插槽內(nèi)容渲染到target容中
    mount(target, targetAnchor)
  }
}

// packages/runtime-core/src/components/Teleport.ts
else {
  // 更新 Teleport 組件
  // update content
  n2.el = n1.el
  const mainAnchor = (n2.anchor = n1.anchor)!
  // 掛載點(diǎn)
  const target = (n2.target = n1.target)!
  // 錨點(diǎn)
  const targetAnchor = (n2.targetAnchor = n1.targetAnchor)!
  // 判斷 Teleport 組件是否禁用了 
  const wasDisabled = isTeleportDisabled(n1.props)
  // 如果禁用了 <teleport> 的功能，那么掛載點(diǎn)就是周圍父組件，否則就是 to 指定的目標(biāo)掛載點(diǎn)
  const currentContainer = wasDisabled ? container : target
  const currentAnchor = wasDisabled ? mainAnchor : targetAnchor
  // 目標(biāo)掛載點(diǎn)是否是 SVG 標(biāo)簽元素
  isSVG = isSVG || isTargetSVG(target)
  // 動(dòng)態(tài)子節(jié)點(diǎn)的更新
  if (dynamicChildren) {
    // fast path when the teleport happens to be a block root
    patchBlockChildren(
      n1.dynamicChildren!,
      dynamicChildren,
      currentContainer,
      parentComponent,
      parentSuspense,
      isSVG,
      slotScopeIds
    )
    // even in block tree mode we need to make sure all root-level nodes
    // in the teleport inherit previous DOM references so that they can
    // be moved in future patches.
    // 確保所有根級(jí)節(jié)點(diǎn)在移動(dòng)之前可以繼承之前的 DOM 引用，以便它們?cè)谖磥淼难a(bǔ)丁中移動(dòng)
    traverseStaticChildren(n1, n2, true)
  } else if (!optimized) {
    // 更新子節(jié)點(diǎn)
    patchChildren(
      n1,
      n2,
      currentContainer,
      currentAnchor,
      parentComponent,
      parentSuspense,
      isSVG,
      slotScopeIds,
      false
    )
  }
  // 如果禁用了 <teleport> 的功能
  if (disabled) {
    if (!wasDisabled) {
      // enabled -> disabled
      // move into main container
      // 將 Teleport 移動(dòng)到container容器中
      moveTeleport(
        n2,
        container,
        mainAnchor,
        internals,
        TeleportMoveTypes.TOGGLE
      )
    }
  } else {
    // 沒有禁用 <teleport> 的功能，判斷 to 是否發(fā)生變化
    // target changed
    // 如果新舊 to 的值不同，則需要對(duì)內(nèi)容進(jìn)行移動(dòng)
    if ((n2.props && n2.props.to) !== (n1.props && n1.props.to)) {
      // 獲取新的目標(biāo)容器
      const nextTarget = (n2.target = resolveTarget(
        n2.props,
        querySelector
      ))
      if (nextTarget) {
        // 移動(dòng)到新的容器中
        moveTeleport(
          n2,
          nextTarget,
          null,
          internals,
          TeleportMoveTypes.TARGET_CHANGE
        )
      } else if (__DEV__) {
        warn(
          'Invalid Teleport target on update:',
          target,
          `(${typeof target})`
        )
      }
    } else if (wasDisabled) {
      // disabled -> enabled
      // move into teleport target
      // 
      moveTeleport(
        n2,
        target,
        targetAnchor,
        internals,
        TeleportMoveTypes.TOGGLE
      )
    }
  }
}

// packages/runtime-core/src/components/Teleport.ts
function moveTeleport(
  vnode: VNode,
  container: RendererElement,
  parentAnchor: RendererNode | null,
  { o: { insert }, m: move }: RendererInternals,
  moveType: TeleportMoveTypes = TeleportMoveTypes.REORDER
) {
  // move target anchor if this is a target change.
  // 插入到目標(biāo)容器中
  if (moveType === TeleportMoveTypes.TARGET_CHANGE) {
    insert(vnode.targetAnchor!, container, parentAnchor)
  }
  const { el, anchor, shapeFlag, children, props } = vnode
  const isReorder = moveType === TeleportMoveTypes.REORDER
  // move main view anchor if this is a re-order.
  if (isReorder) {
    // 插入到目標(biāo)容器中
    insert(el!, container, parentAnchor)
  }
  // if this is a re-order and teleport is enabled (content is in target)
  // do not move children. So the opposite is: only move children if this
  // is not a reorder, or the teleport is disabled
  if (!isReorder || isTeleportDisabled(props)) {
    // Teleport has either Array children or no children.
    if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
      // 遍歷子節(jié)點(diǎn)
      for (let i = 0; i < (children as VNode[]).length; i++) {
        // 調(diào)用 渲染器的黑布方法 move將子節(jié)點(diǎn)移動(dòng)到目標(biāo)元素中
        move(
          (children as VNode[])[i],
          container,
          parentAnchor,
          MoveType.REORDER
        )
      }
    }
  }
  // move main view anchor if this is a re-order.
  if (isReorder) {
    // 插入到目標(biāo)容器中
    insert(anchor!, container, parentAnchor)
  }
}

// packages/runtime-core/src/components/Teleport.ts
// 服務(wù)端渲染 Teleport
function hydrateTeleport(
  node: Node,
  vnode: TeleportVNode,
  parentComponent: ComponentInternalInstance | null,
  parentSuspense: SuspenseBoundary | null,
  slotScopeIds: string[] | null,
  optimized: boolean,
  {
    o: { nextSibling, parentNode, querySelector }
  }: RendererInternals<Node, Element>,
  hydrateChildren: (
    node: Node | null,
    vnode: VNode,
    container: Element,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => Node | null
): Node | null {
  // 獲取掛載點(diǎn)
  const target = (vnode.target = resolveTarget<Element>(
    vnode.props,
    querySelector
  ))
  if (target) {
    // if multiple teleports rendered to the same target element, we need to
    // pick up from where the last teleport finished instead of the first node
    const targetNode =
      (target as TeleportTargetElement)._lpa || target.firstChild
    if (vnode.shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
      // <teleport> 的功能被禁用，將 Teleport 渲染到父組件中指定了 <teleport> 的位置
      if (isTeleportDisabled(vnode.props)) {
        vnode.anchor = hydrateChildren(
          nextSibling(node),
          vnode,
          parentNode(node)!,
          parentComponent,
          parentSuspense,
          slotScopeIds,
          optimized
        )
        vnode.targetAnchor = targetNode
      } else {
        vnode.anchor = nextSibling(node)
        // 將 Teleport 渲染到目標(biāo)容器中
        vnode.targetAnchor = hydrateChildren(
          targetNode,
          vnode,
          target,
          parentComponent,
          parentSuspense,
          slotScopeIds,
          optimized
        )
      }
      ;(target as TeleportTargetElement)._lpa =
        vnode.targetAnchor && nextSibling(vnode.targetAnchor as Node)
    }
  }
  return vnode.anchor && nextSibling(vnode.anchor as Node)
}