'use client';

import { useState } from 'react';
import { useRouter } from 'next/navigation';
import Link from 'next/link';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import { z } from 'zod';
import { toast } from 'sonner';
import { authClient } from '@/lib/auth/client';
import { cn } from '@/lib/utils';
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';

// `identifier` accepts either an email address or a username (3–30 lowercase
// letters / digits / dot / underscore / hyphen). The page resolves usernames
// to the canonical Better-Auth email via /api/auth/resolve-identifier before
// the actual sign-in call.
const loginSchema = z.object({
  identifier: z.string().min(1, 'Email or username is required'),
  password: z.string().min(1, 'Password is required'),
});

type LoginFormData = z.infer<typeof loginSchema>;

export default function LoginPage() {
  const router = useRouter();
  const [isLoading, setIsLoading] = useState(false);

  const {
    register,
    handleSubmit,
    formState: { errors },
  } = useForm<LoginFormData>({
    resolver: zodResolver(loginSchema),
  });

  async function onSubmit(data: LoginFormData) {
    setIsLoading(true);
    try {
      // Resolve username → email when the input isn't already an email.
      // The endpoint always returns SOMETHING (the input itself on miss)
      // so the auth call below fails uniformly with "invalid credentials"
      // either way — no username enumeration.
      const identifier = data.identifier.trim();
      let email = identifier;
      if (!identifier.includes('@')) {
        const res = await fetch('/api/auth/resolve-identifier', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ identifier }),
        });
        const payload = (await res.json().catch(() => ({}))) as { email?: string };
        email = payload.email?.trim() || identifier;
      }

      const result = await authClient.signIn.email({
        email,
        password: data.password,
      });

      if (result.error) {
        toast.error(result.error.message ?? 'Invalid credentials');
        return;
      }

      router.push('/dashboard');
    } catch {
      toast.error('Something went wrong. Please try again.');
    } finally {
      setIsLoading(false);
    }
  }

  return (
    <BrandedAuthShell>
      <div className="text-center mb-6">
        <h1 className="text-xl font-semibold text-gray-900">Port Nimara CRM</h1>
        <p className="text-sm text-gray-500 mt-1">Sign in to continue</p>
      </div>

      <form onSubmit={handleSubmit(onSubmit)} className="space-y-4" noValidate>
        <div className="space-y-1.5">
          <Label htmlFor="identifier">Email or username</Label>
          <Input
            id="identifier"
            type="text"
            autoComplete="username"
            autoCapitalize="none"
            spellCheck={false}
            placeholder="you@example.com  or  yourname"
            disabled={isLoading}
            className={cn(errors.identifier && 'border-destructive focus-visible:ring-destructive')}
            {...register('identifier')}
          />
          {errors.identifier && (
            <p className="text-sm text-destructive">{errors.identifier.message}</p>
          )}
        </div>

        <div className="space-y-1.5">
          <div className="flex items-center justify-between">
            <Label htmlFor="password">Password</Label>
            <Link href="/reset-password" className="text-xs text-[#007bff] hover:underline">
              Forgot password?
            </Link>
          </div>
          <Input
            id="password"
            type="password"
            autoComplete="current-password"
            disabled={isLoading}
            className={cn(errors.password && 'border-destructive focus-visible:ring-destructive')}
            {...register('password')}
          />
          {errors.password && <p className="text-sm text-destructive">{errors.password.message}</p>}
        </div>

        <Button
          type="submit"
          className="w-full bg-[#007bff] hover:bg-[#0069d9] text-white"
          disabled={isLoading}
        >
          {isLoading ? 'Signing in…' : 'Sign in'}
        </Button>
      </form>
    </BrandedAuthShell>
  );
}
