Change onboarding flow in web UI (#32998)

app/javascript/mastodon/components/column_search_header.tsx

@@ -0,0 +1,67 @@
+import { useCallback, useState, useEffect, useRef } from 'react';
+
+import { FormattedMessage } from 'react-intl';
+
+export const ColumnSearchHeader: React.FC<{
+  onBack: () => void;
+  onSubmit: (value: string) => void;
+  onActivate: () => void;
+  placeholder: string;
+  active: boolean;
+}> = ({ onBack, onActivate, onSubmit, placeholder, active }) => {
+  const inputRef = useRef<HTMLInputElement>(null);
+  const [value, setValue] = useState('');
+
+  useEffect(() => {
+    if (!active) {
+      setValue('');
+    }
+  }, [active]);
+
+  const handleChange = useCallback(
+    ({ target: { value } }: React.ChangeEvent<HTMLInputElement>) => {
+      setValue(value);
+      onSubmit(value);
+    },
+    [setValue, onSubmit],
+  );
+
+  const handleKeyUp = useCallback(
+    (e: React.KeyboardEvent<HTMLInputElement>) => {
+      if (e.key === 'Escape') {
+        e.preventDefault();
+        onBack();
+        inputRef.current?.blur();
+      }
+    },
+    [onBack],
+  );
+
+  const handleFocus = useCallback(() => {
+    onActivate();
+  }, [onActivate]);
+
+  const handleSubmit = useCallback(() => {
+    onSubmit(value);
+  }, [onSubmit, value]);
+
+  return (
+    <form className='column-search-header' onSubmit={handleSubmit}>
+      <input
+        ref={inputRef}
+        type='search'
+        value={value}
+        onChange={handleChange}
+        onKeyUp={handleKeyUp}
+        placeholder={placeholder}
+        onFocus={handleFocus}
+      />
+
+      {active && (
+        <button type='button' className='link-button' onClick={onBack}>
+          <FormattedMessage id='column_search.cancel' defaultMessage='Cancel' />
+        </button>
+      )}
+    </form>
+  );
+};