'use client';

import Link from 'next/link';
import { useRouter, useSearchParams } from 'next/navigation';
import { useState } from 'react';
import { Loader2 } from 'lucide-react';

import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { BrandedAuthShell } from '@/components/shared/branded-auth-shell';

/**
 * Validate the `?next=` post-login redirect target. auth-flow-auditor M10:
 * an unvalidated `next` lets `/portal/login?next=https://evil.example`
 * navigate cross-site after sign-in. Only allow same-origin paths
 * scoped to the portal surface - anything else falls back to the
 * dashboard.
 */
function safeNextPath(raw: string | null): string {
  const fallback = '/portal/dashboard';
  if (!raw) return fallback;
  // Reject absolute URLs (http://, https://, //evil.example) and
  // protocol-relative URLs. Only `/portal/...` paths are kept.
  if (!raw.startsWith('/portal/')) return fallback;
  if (raw.startsWith('//')) return fallback;
  return raw;
}

export default function PortalLoginPage() {
  const router = useRouter();
  const search = useSearchParams();
  // The middleware backstop (src/proxy.ts) redirects unauthenticated
  // portal visitors with `?redirect=`; older links / manual callers may
  // still use `?next=`. Accept either, preferring `redirect`.
  const next = safeNextPath(search.get('redirect') ?? search.get('next'));

  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState('');

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    setError('');
    setLoading(true);

    try {
      const res = await fetch('/api/portal/auth/sign-in', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ email, password }),
      });

      if (!res.ok) {
        const data = await res.json().catch(() => ({}));
        setError((data as { error?: string }).error ?? 'Invalid email or password');
        return;
      }

      // typedRoutes: `next` is a runtime string we can't statically check.
      router.replace(next as never);
      router.refresh();
    } catch {
      setError('Unable to connect. Please try again.');
    } finally {
      setLoading(false);
    }
  }

  return (
    <BrandedAuthShell>
      <div className="text-center mb-6">
        <h1 className="text-xl font-semibold text-gray-900">Client Portal</h1>
        <p className="text-sm text-gray-500 mt-1">Sign in to your account</p>
      </div>

      <form onSubmit={handleSubmit} className="space-y-4">
        <div className="space-y-1.5">
          <Label htmlFor="email">Email address</Label>
          <Input
            id="email"
            type="email"
            placeholder="you@example.com"
            value={email}
            onChange={(e) => setEmail(e.target.value)}
            required
            autoFocus
            autoComplete="email"
            disabled={loading}
          />
        </div>

        <div className="space-y-1.5">
          <div className="flex items-center justify-between">
            <Label htmlFor="password">Password</Label>
            <Link
              href="/portal/forgot-password"
              className="text-xs text-[#0058b3] underline-offset-2 underline hover:no-underline"
            >
              Forgot password?
            </Link>
          </div>
          <Input
            id="password"
            type="password"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            required
            autoComplete="current-password"
            disabled={loading}
          />
        </div>

        {error && <p className="text-sm text-red-600">{error}</p>}

        <Button
          type="submit"
          className="w-full bg-[#007bff] hover:bg-[#0069d9] text-white"
          disabled={loading || !email || !password}
        >
          {loading ? (
            <>
              <Loader2 className="h-4 w-4 mr-2 animate-spin" />
              Signing in…
            </>
          ) : (
            'Sign in'
          )}
        </Button>
      </form>

      <p className="text-center text-xs text-gray-400 mt-6">
        This portal is for existing clients only.
      </p>
    </BrandedAuthShell>
  );
}
