'use client'

import { useEffect, useState } from 'react'
import Link from 'next/link'
import { useRouter } from 'next/navigation'
import { Mail, Lock, Loader2, Sparkles, AlertCircle } from 'lucide-react'
import { useAuth } from '@/context/AuthContext'
import { login as authLogin } from '@/lib/auth'
import { cn } from '@/lib/utils'

export default function LoginPage() {
  const router = useRouter()
  const { refreshUser, isAuthenticated } = useAuth()
  
  const [email, setEmail] = useState('')
  const [password, setPassword] = useState('')
  const [error, setError] = useState('')
  const [loading, setLoading] = useState(false)

  // Redirect if already authenticated (client-side effect to avoid rendering push)
  useEffect(() => {
    if (isAuthenticated) {
      router.push('/')
    }
  }, [isAuthenticated, router])

  if (isAuthenticated) {
    return null
  }

  const validateForm = (currentEmail: string, currentPassword: string): string | null => {
    if (!currentEmail.trim()) {
      return 'Введіть email адресу'
    }
    // Basic email validation
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
    if (!emailRegex.test(currentEmail)) {
      return 'Введіть коректну email адресу'
    }
    if (!currentPassword) {
      return 'Введіть пароль'
    }
    if (currentPassword.length < 8) {
      return 'Пароль повинен містити мінімум 8 символів'
    }
    return null
  }

  const handleSubmit = async (e: React.FormEvent<HTMLFormElement>) => {
    e.preventDefault()
    setError('')

    const formData = new FormData(e.currentTarget)
    const fallbackEmail = (formData.get('email')?.toString() ?? '').trim()
    const fallbackPassword = formData.get('password')?.toString() ?? ''
    const currentEmail = email.trim() || fallbackEmail
    const currentPassword = password || fallbackPassword

    if (!email && currentEmail) setEmail(currentEmail)
    if (!password && currentPassword) setPassword(currentPassword)

    const validationError = validateForm(currentEmail, currentPassword)
    if (validationError) {
      setError(validationError)
      return
    }
    
    setLoading(true)
    try {
      await authLogin(currentEmail, currentPassword)
      await refreshUser()
      router.push('/')
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Помилка входу. Перевірте дані та спробуйте ще раз.')
    } finally {
      setLoading(false)
    }
  }

  return (
    <div className="min-h-screen flex items-center justify-center px-4 py-12">
      <div className="w-full max-w-md">
        {/* Logo */}
        <div className="text-center mb-8">
          <Link href="/" className="inline-flex items-center gap-2">
            <Sparkles className="w-10 h-10 text-cyan-400" />
            <span className="text-2xl font-bold bg-gradient-to-r from-cyan-400 to-blue-500 bg-clip-text text-transparent">
              DAARION
            </span>
          </Link>
          <h1 className="mt-6 text-2xl font-bold text-white">Вхід в акаунт</h1>
          <p className="mt-2 text-slate-400">
            Увійдіть, щоб продовжити у DAARION.city
          </p>
        </div>

        {/* Form */}
        <div className="glass-panel p-8">
          <form onSubmit={handleSubmit} noValidate className="space-y-6">
            {/* Error */}
            {error && (
              <div className="flex items-center gap-2 p-3 bg-red-500/10 border border-red-500/20 rounded-xl text-red-400 text-sm">
                <AlertCircle className="w-4 h-4 flex-shrink-0" />
                {error}
              </div>
            )}

            {/* Email */}
            <div>
              <label htmlFor="email" className="block text-sm font-medium text-slate-300 mb-2">
                Email
              </label>
              <div className="relative">
                <Mail className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-500" />
                <input
                  id="email"
                  name="email"
                  type="email"
                  value={email}
                  onChange={(e) => setEmail(e.target.value)}
                  placeholder="your@email.com"
                  autoComplete="email"
                  className={cn(
                    'w-full pl-10 pr-4 py-3 bg-slate-800/50 border border-white/10 rounded-xl',
                    'text-white placeholder-slate-500',
                    'focus:outline-none focus:border-cyan-500/50 focus:ring-1 focus:ring-cyan-500/20',
                    'transition-all'
                  )}
                />
              </div>
            </div>

            {/* Password */}
            <div>
              <label htmlFor="password" className="block text-sm font-medium text-slate-300 mb-2">
                Пароль
              </label>
              <div className="relative">
                <Lock className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-500" />
                <input
                  id="password"
                  name="password"
                  type="password"
                  value={password}
                  onChange={(e) => setPassword(e.target.value)}
                  placeholder="••••••••"
                  autoComplete="current-password"
                  className={cn(
                    'w-full pl-10 pr-4 py-3 bg-slate-800/50 border border-white/10 rounded-xl',
                    'text-white placeholder-slate-500',
                    'focus:outline-none focus:border-cyan-500/50 focus:ring-1 focus:ring-cyan-500/20',
                    'transition-all'
                  )}
                />
              </div>
            </div>

            {/* Submit */}
            <button
              type="submit"
              disabled={loading}
              className={cn(
                'w-full py-3 rounded-xl font-medium transition-all',
                'bg-gradient-to-r from-cyan-500 to-blue-600 text-white',
                'hover:from-cyan-400 hover:to-blue-500',
                'shadow-lg shadow-cyan-500/20 hover:shadow-cyan-500/40',
                'disabled:opacity-50 disabled:cursor-not-allowed'
              )}
            >
              {loading ? (
                <Loader2 className="w-5 h-5 mx-auto animate-spin" />
              ) : (
                'Увійти'
              )}
            </button>

          </form>

          {/* Divider */}
          <div className="my-6 flex items-center gap-4">
            <div className="flex-1 h-px bg-white/10" />
            <span className="text-sm text-slate-500">або</span>
            <div className="flex-1 h-px bg-white/10" />
          </div>

          {/* Register link */}
          <p className="text-center text-slate-400">
            Немає акаунту?{' '}
            <Link href="/register" className="text-cyan-400 hover:text-cyan-300 font-medium">
              Зареєструватися
            </Link>
          </p>
        </div>

        {/* Back to home */}
        <p className="mt-6 text-center">
          <Link href="/" className="text-slate-500 hover:text-slate-400 text-sm">
            ← Повернутися на головну
          </Link>
        </p>
      </div>
    </div>
  )
}