'use client';

/**
 * LoginPage — Tenant admin sign-in page for the SentryAgent developer portal.
 *
 * Posts credentials to `POST /api/tenants/login` on the AgentIdP backend and
 * stores the returned JWT in localStorage so that protected pages (e.g.
 * /analytics) can read it via the `useAuth` hook.
 *
 * @module app/login/page
 */

import React, { useState, type FormEvent } from 'react';
import { useRouter } from 'next/navigation';
import { AUTH_TOKEN_KEY } from '@/hooks/useAuth';

/** Shape of the successful login response from the AgentIdP API. */
interface LoginResponse {
  access_token: string;
}

/**
 * Renders the portal login form and handles credential submission.
 *
 * @returns JSX element
 */
export default function LoginPage(): React.ReactElement {
  const router = useRouter();
  const apiUrl = process.env.NEXT_PUBLIC_API_URL ?? 'http://localhost:3000';

  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [error, setError] = useState<string | null>(null);
  const [submitting, setSubmitting] = useState(false);

  /**
   * Submits the login form and stores the JWT on success.
   *
   * @param e - The form submission event
   */
  async function handleSubmit(e: FormEvent<HTMLFormElement>): Promise<void> {
    e.preventDefault();
    setError(null);
    setSubmitting(true);

    try {
      const res = await fetch(`${apiUrl}/api/tenants/login`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ email, password }),
      });

      if (!res.ok) {
        const body = (await res.json().catch(() => ({}))) as { message?: string };
        setError(body.message ?? 'Invalid credentials. Please try again.');
        return;
      }

      const data = (await res.json()) as LoginResponse;
      localStorage.setItem(AUTH_TOKEN_KEY, data.access_token);
      router.replace('/analytics');
    } catch {
      setError('Network error. Please check your connection and try again.');
    } finally {
      setSubmitting(false);
    }
  }

  return (
    <div className="flex min-h-[70vh] items-center justify-center px-6 py-16">
      <div className="w-full max-w-md">
        <div className="mb-8 text-center">
          <h1 className="text-3xl font-extrabold text-slate-900">Sign in</h1>
          <p className="mt-2 text-slate-600">
            Access your SentryAgent tenant dashboard
          </p>
        </div>

        <form
          onSubmit={(e) => void handleSubmit(e)}
          className="rounded-2xl border border-slate-200 bg-white p-8 shadow-sm"
        >
          <div className="mb-4">
            <label
              htmlFor="email"
              className="mb-1.5 block text-sm font-medium text-slate-700"
            >
              Email address
            </label>
            <input
              id="email"
              type="email"
              required
              autoComplete="email"
              value={email}
              onChange={(e) => setEmail(e.target.value)}
              className="w-full rounded-lg border border-slate-300 px-3 py-2 text-sm focus:border-brand-500 focus:outline-none focus:ring-1 focus:ring-brand-500"
              placeholder="admin@example.com"
            />
          </div>

          <div className="mb-6">
            <label
              htmlFor="password"
              className="mb-1.5 block text-sm font-medium text-slate-700"
            >
              Password
            </label>
            <input
              id="password"
              type="password"
              required
              autoComplete="current-password"
              value={password}
              onChange={(e) => setPassword(e.target.value)}
              className="w-full rounded-lg border border-slate-300 px-3 py-2 text-sm focus:border-brand-500 focus:outline-none focus:ring-1 focus:ring-brand-500"
            />
          </div>

          {error !== null && (
            <p className="mb-4 rounded-lg bg-red-50 px-4 py-3 text-sm text-red-700">
              {error}
            </p>
          )}

          <button
            type="submit"
            disabled={submitting}
            className="w-full rounded-lg bg-brand-600 py-2.5 text-sm font-semibold text-white shadow-sm transition-colors hover:bg-brand-700 disabled:opacity-60"
          >
            {submitting ? 'Signing in…' : 'Sign in'}
          </button>
        </form>
      </div>
    </div>
  );
}