hell-world/frontend/app/page.tsx

'use client'

import { useEffect, useState } from 'react'

interface ApiResponse {
  message: string
  db_status: string
}

export default function Home() {
  const [data, setData] = useState<ApiResponse | null>(null)
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)

  useEffect(() => {
    const apiUrl = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:8080'

    fetch(`${apiUrl}/api/hello`)
      .then((res) => res.json())
      .then((data) => {
        setData(data)
        setLoading(false)
      })
      .catch((err) => {
        setError(err.message)
        setLoading(false)
      })
  }, [])

  return (
    <main style={styles.main}>
      <div style={styles.container}>
        <h1 style={styles.title}>Hello World!</h1>
        <p style={styles.subtitle}>Go + PostgreSQL + Next.js</p>

        <div style={styles.card}>
          {loading && <p>Loading...</p>}
          {error && <p style={styles.error}>Error: {error}</p>}
          {data && (
            <>
              <p style={styles.message}>{data.message}</p>
              <p style={styles.status}>
                Database:
                <span style={{
                  color: data.db_status === 'connected' ? '#22c55e' : '#ef4444',
                  marginLeft: '8px'
                }}>
                  {data.db_status}
                </span>
              </p>
            </>
          )}
        </div>

        <div style={styles.techStack}>
          <span style={styles.badge}>Go</span>
          <span style={styles.badge}>PostgreSQL</span>
          <span style={styles.badge}>Next.js</span>
        </div>
      </div>
    </main>
  )
}

const styles: { [key: string]: React.CSSProperties } = {
  main: {
    minHeight: '100vh',
    display: 'flex',
    alignItems: 'center',
    justifyContent: 'center',
    background: 'linear-gradient(135deg, #667eea 0%, #764ba2 100%)',
    fontFamily: 'system-ui, -apple-system, sans-serif',
  },
  container: {
    textAlign: 'center',
    color: 'white',
  },
  title: {
    fontSize: '4rem',
    marginBottom: '0.5rem',
    textShadow: '2px 2px 4px rgba(0,0,0,0.2)',
  },
  subtitle: {
    fontSize: '1.25rem',
    opacity: 0.9,
    marginBottom: '2rem',
  },
  card: {
    background: 'rgba(255,255,255,0.95)',
    borderRadius: '12px',
    padding: '2rem',
    color: '#333',
    boxShadow: '0 10px 40px rgba(0,0,0,0.2)',
    marginBottom: '2rem',
  },
  message: {
    fontSize: '1.25rem',
    fontWeight: 500,
  },
  status: {
    marginTop: '1rem',
    fontSize: '1rem',
  },
  error: {
    color: '#ef4444',
  },
  techStack: {
    display: 'flex',
    gap: '1rem',
    justifyContent: 'center',
  },
  badge: {
    background: 'rgba(255,255,255,0.2)',
    padding: '0.5rem 1rem',
    borderRadius: '20px',
    fontSize: '0.875rem',
  },
}