Implement text input component (Task 9)

- Create TextInputSection component with large multiline textarea
- Add 'Next: Assign voices' button
- Implement text validation (non-empty)
- Show validation message for empty text
- Disable button when text is empty
- Update App.tsx to integrate TextInputSection
- Requirements: 1.1, 1.2, 1.3, 1.4

frontend/src/App.tsx

@@ -1,34 +1,50 @@
 import { useState } from 'react'
-import reactLogo from './assets/react.svg'
-import viteLogo from '/vite.svg'
 import './App.css'
+import TextInputSection from './components/TextInputSection'
 
 function App() {
-  const [count, setCount] = useState(0)
+  const [text, setText] = useState('')
+  const [phase, setPhase] = useState<'input' | 'assignment' | 'generated'>('input')
+  const [isLoading] = useState(false)
+
+  const handleTextChange = (newText: string) => {
+    setText(newText)
+  }
+
+  const handleNext = () => {
+    // TODO: Implement role detection and phase transition
+    console.log('Moving to voice assignment phase with text:', text)
+    setPhase('assignment')
+  }
 
   return (
-    <>
+    <div className="min-h-screen bg-gray-50">
-      <div>
+      <div className="container mx-auto py-8">
-        <a href="https://vite.dev" target="_blank">
+        <h1 className="text-4xl font-bold text-center mb-8">Text to Audiobook</h1>
-          <img src={viteLogo} className="logo" alt="Vite logo" />
+        
-        </a>
+        {phase === 'input' && (
-        <a href="https://react.dev" target="_blank">
+          <TextInputSection
-          <img src={reactLogo} className="logo react" alt="React logo" />
+            text={text}
-        </a>
+            onChange={handleTextChange}
+            onNext={handleNext}
+            isLoading={isLoading}
+            disabled={false}
+          />
+        )}
+
+        {phase === 'assignment' && (
+          <div className="text-center">
+            <p>Voice assignment phase (to be implemented)</p>
+          </div>
+        )}
+
+        {phase === 'generated' && (
+          <div className="text-center">
+            <p>Audio player phase (to be implemented)</p>
+          </div>
+        )}
       </div>
-      <h1>Vite + React</h1>
+    </div>
-      <div className="card">
-        <button onClick={() => setCount((count) => count + 1)}>
-          count is {count}
-        </button>
-        <p>
-          Edit <code>src/App.tsx</code> and save to test HMR
-        </p>
-      </div>
-      <p className="read-the-docs">
-        Click on the Vite and React logos to learn more
-      </p>
-    </>
   )
 }
 

frontend/src/components/TextInputSection.tsx

@@ -0,0 +1,71 @@
+import { useState } from 'react';
+
+interface TextInputSectionProps {
+  text: string;
+  onChange: (text: string) => void;
+  onNext: () => void;
+  isLoading: boolean;
+  disabled: boolean;
+}
+
+export default function TextInputSection({
+  text,
+  onChange,
+  onNext,
+  isLoading,
+  disabled
+}: TextInputSectionProps) {
+  const [showValidation, setShowValidation] = useState(false);
+
+  const handleNext = () => {
+    if (text.trim() === '') {
+      setShowValidation(true);
+      return;
+    }
+    setShowValidation(false);
+    onNext();
+  };
+
+  const handleTextChange = (e: React.ChangeEvent<HTMLTextAreaElement>) => {
+    onChange(e.target.value);
+    if (e.target.value.trim() !== '') {
+      setShowValidation(false);
+    }
+  };
+
+  const isButtonDisabled = disabled || isLoading || text.trim() === '';
+
+  return (
+    <div className="w-full max-w-4xl mx-auto p-6">
+      <h2 className="text-2xl font-bold mb-4">Enter Your Text</h2>
+      
+      <div className="mb-4">
+        <textarea
+          value={text}
+          onChange={handleTextChange}
+          placeholder="Enter your text here. Use patterns like 'Name:' or '[Name]' to mark different speakers..."
+          className="w-full h-96 p-4 border-2 border-gray-300 rounded-lg focus:border-blue-500 focus:outline-none resize-y text-base"
+          disabled={disabled || isLoading}
+        />
+      </div>
+
+      {showValidation && text.trim() === '' && (
+        <div className="mb-4 p-3 bg-red-100 border border-red-400 text-red-700 rounded">
+          Please enter some text before proceeding.
+        </div>
+      )}
+
+      <button
+        onClick={handleNext}
+        disabled={isButtonDisabled}
+        className={`px-6 py-3 rounded-lg font-semibold text-white transition-colors ${
+          isButtonDisabled
+            ? 'bg-gray-400 cursor-not-allowed'
+            : 'bg-blue-600 hover:bg-blue-700 cursor-pointer'
+        }`}
+      >
+        {isLoading ? 'Processing...' : 'Next: Assign voices'}
+      </button>
+    </div>
+  );
+}