import { useCallback, useEffect, useState } from 'react'

const TOKEN_KEY = 'kairo_auth_token'

function apiHeaders(token) {
  const headers = { 'Content-Type': 'application/json' }
  if (token) headers['X-Auth-Token'] = token
  return headers
}

export default function App() {
  const [health, setHealth] = useState(null)
  const [healthError, setHealthError] = useState(null)
  const [token, setToken] = useState(() => localStorage.getItem(TOKEN_KEY) || '')
  const [email, setEmail] = useState('')
  const [password, setPassword] = useState('')
  const [authError, setAuthError] = useState(null)
  const [authBusy, setAuthBusy] = useState(false)
  const [me, setMe] = useState(null)
  const [context, setContext] = useState(null)

  useEffect(() => {
    fetch('/api/health')
      .then((res) => {
        if (!res.ok) throw new Error(`HTTP ${res.status}`)
        return res.json()
      })
      .then(setHealth)
      .catch((err) => setHealthError(err.message))
  }, [])

  const loadSession = useCallback(async (activeToken) => {
    if (!activeToken) {
      setMe(null)
      setContext(null)
      return
    }
    const meRes = await fetch('/api/me', { headers: apiHeaders(activeToken) })
    if (!meRes.ok) {
      localStorage.removeItem(TOKEN_KEY)
      setToken('')
      setMe(null)
      setContext(null)
      throw new Error(meRes.status === 401 ? 'Session abgelaufen' : `HTTP ${meRes.status}`)
    }
    setMe(await meRes.json())
    const ctxRes = await fetch('/api/me/context', { headers: apiHeaders(activeToken) })
    if (ctxRes.ok) setContext(await ctxRes.json())
  }, [])

  useEffect(() => {
    if (!token) return
    loadSession(token).catch((err) => setAuthError(err.message))
  }, [token, loadSession])

  async function handleLogin(event) {
    event.preventDefault()
    setAuthBusy(true)
    setAuthError(null)
    try {
      const res = await fetch('/api/auth/login', {
        method: 'POST',
        headers: apiHeaders(),
        body: JSON.stringify({ email, password }),
      })
      if (!res.ok) {
        const body = await res.json().catch(() => ({}))
        throw new Error(body.detail || `Login fehlgeschlagen (${res.status})`)
      }
      const data = await res.json()
      localStorage.setItem(TOKEN_KEY, data.token)
      setToken(data.token)
      setPassword('')
    } catch (err) {
      setAuthError(err.message)
    } finally {
      setAuthBusy(false)
    }
  }

  async function handleLogout() {
    setAuthBusy(true)
    setAuthError(null)
    try {
      if (token) {
        await fetch('/api/auth/logout', {
          method: 'POST',
          headers: apiHeaders(token),
        })
      }
    } catch {
      /* Session trotzdem lokal entfernen */
    } finally {
      localStorage.removeItem(TOKEN_KEY)
      setToken('')
      setMe(null)
      setContext(null)
      setAuthBusy(false)
    }
  }

  return (
    <main className="shell">
      <header className="hero">
        <h1>Jinkendo Kairo</h1>
        <p>Operativer Program Director — Sprint 0 / AP0.2</p>
        <p className="muted">Auth, Tenant &amp; Actor Foundation</p>
      </header>

      <section className="card">
        <h2>API Health</h2>
        {healthError && <p className="error">Fehler: {healthError}</p>}
        {!healthError && !health && <p>Lade …</p>}
        {health && <pre>{JSON.stringify(health, null, 2)}</pre>}
      </section>

      <section className="card">
        <h2>Session</h2>
        {!token && (
          <form className="form" onSubmit={handleLogin}>
            <label>
              E-Mail
              <input
                type="email"
                autoComplete="username"
                value={email}
                onChange={(e) => setEmail(e.target.value)}
                required
              />
            </label>
            <label>
              Passwort
              <input
                type="password"
                autoComplete="current-password"
                value={password}
                onChange={(e) => setPassword(e.target.value)}
                minLength={8}
                required
              />
            </label>
            <button type="submit" disabled={authBusy}>
              {authBusy ? 'Anmelden …' : 'Anmelden'}
            </button>
          </form>
        )}

        {token && me && (
          <div className="session">
            <p>
              Eingeloggt als <strong>{me.display_name}</strong> ({me.email})
            </p>
            <p className="muted">
              Portal-Rolle: {me.portal_role}
              {me.active_tenant_id && ` · Tenant: ${me.active_tenant_id}`}
            </p>
            <button type="button" className="secondary" onClick={handleLogout} disabled={authBusy}>
              Abmelden
            </button>
          </div>
        )}

        {authError && <p className="error">{authError}</p>}
      </section>

      {token && me && (
        <>
          <section className="card">
            <h2>/api/me</h2>
            <pre>{JSON.stringify(me, null, 2)}</pre>
          </section>
          {context && (
            <section className="card">
              <h2>/api/me/context</h2>
              <pre>{JSON.stringify(context, null, 2)}</pre>
            </section>
          )}
        </>
      )}
    </main>
  )
}