feat: implement client filesystem utilities

src/client/filesystem.ts

@@ -0,0 +1,49 @@
+export const uploadFile = (file: File, type: "dataUrl" | "text" = "text") => {
+  return new Promise<string>((resolve, reject) => {
+    const reader = new FileReader();
+    reader.addEventListener("load", () => {
+      if (reader.error) {
+        return reject(reader.error);
+      }
+      if (reader.result == null) {
+        return reject(new Error("Result was empty"));
+      }
+      resolve(reader.result.toString());
+    });
+
+    if (type === "dataUrl") {
+      reader.readAsDataURL(file);
+    }
+    if (type === "text") {
+      reader.readAsText(file);
+    }
+  });
+};
+
+export const saveFile = (name: string, type: string, content: string) => {
+  const a = document.createElement("a");
+  const blob = new Blob([content], {
+    type,
+  });
+  const url = URL.createObjectURL(blob);
+  a.setAttribute("href", url);
+  a.setAttribute("download", name);
+  a.click();
+};
+
+export const selectLocalFiles = (type: string[]) => {
+  return new Promise<FileList>((resolve, reject) => {
+    const fileInput = document.createElement("input");
+    fileInput.type = "file";
+    fileInput.accept = type.join(",");
+    fileInput.oninput = (evt) => {
+      const files: FileList | undefined = (evt.currentTarget as any).files;
+      if (!files) {
+        return resolve(new FileList());
+      }
+
+      resolve(files);
+    };
+    fileInput.click();
+  });
+};