3dom4wf7p: Publish public text posts from a feed composer

src/components/Composer.tsx

@@ -0,0 +1,36 @@
+import type { FormEvent } from "react";
+
+export interface ComposerProps {
+  value: string;
+  busy: boolean;
+  error: boolean;
+  onChange: (value: string) => void;
+  onSubmit: () => void;
+}
+
+export function Composer({ value, busy, error, onChange, onSubmit }: ComposerProps) {
+  const empty = value.trim().length === 0;
+  function submit(e: FormEvent) {
+    e.preventDefault();
+    if (!empty && !busy) onSubmit();
+  }
+  return (
+    <form className="composer" onSubmit={submit}>
+      <label htmlFor="composer-text" className="composer-label">New post</label>
+      <textarea
+        id="composer-text"
+        value={value}
+        rows={3}
+        placeholder="Share something with the feed"
+        disabled={busy}
+        onChange={(e) => onChange(e.target.value)}
+      />
+      {error ? (
+        <p className="error" role="alert">Publishing the post failed. Your text is still here.</p>
+      ) : null}
+      <button type="submit" className="composer-post" disabled={empty || busy}>
+        {busy ? "Posting" : "Post"}
+      </button>
+    </form>
+  );
+}