feat: multisign embedding (#1823)

Adds the ability to use a multisign embedding for cases where multiple
documents need to be signed in a convenient manner.

packages/lib/client-only/hooks/use-element-bounds.ts

@@ -0,0 +1,75 @@
+import { useEffect, useState } from 'react';
+
+import { getBoundingClientRect } from '@documenso/lib/client-only/get-bounding-client-rect';
+
+export const useElementBounds = (elementOrSelector: HTMLElement | string, withScroll = false) => {
+  const [bounds, setBounds] = useState({
+    top: 0,
+    left: 0,
+    height: 0,
+    width: 0,
+  });
+
+  const calculateBounds = () => {
+    const $el =
+      typeof elementOrSelector === 'string'
+        ? document.querySelector<HTMLElement>(elementOrSelector)
+        : elementOrSelector;
+
+    if (!$el) {
+      throw new Error('Element not found');
+    }
+
+    if (withScroll) {
+      return getBoundingClientRect($el);
+    }
+
+    const { top, left, width, height } = $el.getBoundingClientRect();
+
+    return {
+      top,
+      left,
+      width,
+      height,
+    };
+  };
+
+  useEffect(() => {
+    setBounds(calculateBounds());
+  }, [calculateBounds]);
+
+  useEffect(() => {
+    const onResize = () => {
+      setBounds(calculateBounds());
+    };
+
+    window.addEventListener('resize', onResize);
+
+    return () => {
+      window.removeEventListener('resize', onResize);
+    };
+  }, [calculateBounds]);
+
+  useEffect(() => {
+    const $el =
+      typeof elementOrSelector === 'string'
+        ? document.querySelector<HTMLElement>(elementOrSelector)
+        : elementOrSelector;
+
+    if (!$el) {
+      return;
+    }
+
+    const observer = new ResizeObserver(() => {
+      setBounds(calculateBounds());
+    });
+
+    observer.observe($el);
+
+    return () => {
+      observer.disconnect();
+    };
+  }, [calculateBounds]);
+
+  return bounds;
+};