first commit

calcom/apps/web/lib/hooks/useFileReader.ts

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+import { useEffect, useState } from "react";
+
+type ReadAsMethod = "readAsText" | "readAsDataURL" | "readAsArrayBuffer" | "readAsBinaryString";
+
+type UseFileReaderProps = {
+  method: ReadAsMethod;
+  onLoad?: (result: unknown) => void;
+};
+
+export const useFileReader = (options: UseFileReaderProps) => {
+  const { method = "readAsText", onLoad } = options;
+  const [file, setFile] = useState<File | null>(null);
+  const [loading, setLoading] = useState<boolean>(false);
+  const [error, setError] = useState<DOMException | null>(null);
+  const [result, setResult] = useState<string | ArrayBuffer | null>(null);
+
+  useEffect(() => {
+    if (!file && result) {
+      setResult(null);
+    }
+  }, [file, result]);
+
+  useEffect(() => {
+    if (!file) {
+      return;
+    }
+
+    const reader = new FileReader();
+    reader.onloadstart = () => setLoading(true);
+    reader.onloadend = () => setLoading(false);
+    reader.onerror = () => setError(reader.error);
+
+    reader.onload = (e: ProgressEvent<FileReader>) => {
+      setResult(e.target?.result ?? null);
+      if (onLoad) {
+        onLoad(e.target?.result ?? null);
+      }
+    };
+    reader[method](file);
+  }, [file, method, onLoad]);
+
+  return [{ result, error, file, loading }, setFile] as const;
+};