1 files changed, 113 insertions, 0 deletions
diff --git a/packages/taler-wallet-webextension/src/mui/Portal.tsx b/packages/taler-wallet-webextension/src/mui/Portal.tsx
new file mode 100644
index 000000000..828a574fd
--- /dev/null
+++ b/packages/taler-wallet-webextension/src/mui/Portal.tsx
@@ -0,0 +1,113 @@
+import { css } from "@linaria/core";
+import { createPortal, forwardRef } from "preact/compat";
+import {
+  h,
+  JSX,
+  VNode,
+  ComponentChildren,
+  RefObject,
+  isValidElement,
+  cloneElement,
+  Fragment,
+} from "preact";
+import { Ref, useEffect, useMemo, useState } from "preact/hooks";
+// eslint-disable-next-line import/extensions
+import { alpha } from "./colors/manipulation";
+// eslint-disable-next-line import/extensions
+import { theme } from "./style";
+
+const baseStyle = css`
+  position: fixed;
+  z-index: ${theme.zIndex.modal};
+  right: 0px;
+  bottom: 0px;
+  top: 0px;
+  left: 0px;
+`;
+
+interface Props {
+  class: string;
+  children: ComponentChildren;
+  disablePortal?: boolean;
+  container?: VNode;
+}
+
+export const Portal = forwardRef(function Portal(
+  { container, disablePortal, children }: Props,
+  ref: Ref<any>,
+): VNode {
+  const [mountNode, setMountNode] = useState<HTMLElement | undefined>(
+    undefined,
+  );
+  const handleRef = useForkRef(
+    isValidElement(children) ? children.ref : null,
+    ref,
+  );
+
+  useEffect(() => {
+    if (!disablePortal) {
+      setMountNode(getContainer(container) || document.body);
+    }
+  }, [container, disablePortal]);
+
+  useEffect(() => {
+    if (mountNode && !disablePortal) {
+      setRef(ref, mountNode);
+      return () => {
+        setRef(ref, null);
+      };
+    }
+
+    return undefined;
+  }, [ref, mountNode, disablePortal]);
+
+  if (disablePortal) {
+    if (isValidElement(children)) {
+      return cloneElement(children, {
+        ref: handleRef,
+      });
+    }
+    return <Fragment>{children}</Fragment>;
+  }
+
+  return mountNode ? (
+    createPortal(<Fragment>{children}</Fragment>, mountNode)
+  ) : (
+    <Fragment />
+  );
+});
+
+function getContainer(container: any): any {
+  return typeof container === "function" ? container() : container;
+}
+
+function useForkRef<Instance>(
+  refA: React.Ref<Instance> | null | undefined,
+  refB: React.Ref<Instance> | null | undefined,
+): React.Ref<Instance> | null {
+  /**
+   * This will create a new function if the ref props change and are defined.
+   * This means react will call the old forkRef with `null` and the new forkRef
+   * with the ref. Cleanup naturally emerges from this behavior.
+   */
+  return useMemo(() => {
+    if (refA == null && refB == null) {
+      return null;
+    }
+    return (refValue) => {
+      setRef(refA, refValue);
+      setRef(refB, refValue);
+    };
+  }, [refA, refB]);
+}
+
+function setRef<T>(
+  ref: RefObject<T | null> | ((instance: T | null) => void) | null | undefined,
+  value: T | null,
+): void {
+  if (typeof ref === "function") {
+    ref(value);
+  } else if (ref) {
+    ref.current = value;
+  }
+}