'use client'

import { useCallback, useEffect, useRef, useState, FormEvent } from 'react'
import Image from 'next/image'
import { Button } from '@/components/ui/button'

interface GoogleCredentialResponse {
  credential?: string
}

interface GoogleAccountsIdApi {
  initialize(config: {
    client_id: string
    callback: (response: GoogleCredentialResponse) => void
  }): void
  prompt(): void
}

interface GoogleApi {
  accounts: {
    id: GoogleAccountsIdApi
  }
}

type LoginRequestBody =
  | { username: string; password: string }
  | { credential?: string }

type LoginErrorPayload = {
  code?: string
  error?: string
}

function readLoginErrorPayload(value: unknown): LoginErrorPayload {
  if (!value || typeof value !== 'object') return {}
  const record = value as Record<string, unknown>
  return {
    code: typeof record.code === 'string' ? record.code : undefined,
    error: typeof record.error === 'string' ? record.error : undefined,
  }
}

declare global {
  interface Window {
    google?: GoogleApi
  }
}

function GoogleIcon({ className }: { className?: string }) {
  return (
    <svg className={className} viewBox="0 0 24 24" fill="none">
      <path d="M22.56 12.25c0-.78-.07-1.53-.2-2.25H12v4.26h5.92a5.06 5.06 0 01-2.2 3.32v2.77h3.57c2.08-1.92 3.28-4.74 3.28-8.1z" fill="#4285F4" />
      <path d="M12 23c2.97 0 5.46-.98 7.28-2.66l-3.57-2.77c-.98.66-2.23 1.06-3.71 1.06-2.86 0-5.29-1.93-6.16-4.53H2.18v2.84C3.99 20.53 7.7 23 12 23z" fill="#34A853" />
      <path d="M5.84 14.09c-.22-.66-.35-1.36-.35-2.09s.13-1.43.35-2.09V7.07H2.18A10.96 10.96 0 001 12c0 1.77.42 3.45 1.18 4.93l3.66-2.84z" fill="#FBBC05" />
      <path d="M12 5.38c1.62 0 3.06.56 4.21 1.64l3.15-3.15C17.45 2.09 14.97 1 12 1 7.7 1 3.99 3.47 2.18 7.07l3.66 2.84c.87-2.6 3.3-4.53 6.16-4.53z" fill="#EA4335" />
    </svg>
  )
}

export default function LoginPage() {
  const [username, setUsername] = useState('')
  const [password, setPassword] = useState('')
  const [error, setError] = useState('')
  const [pendingApproval, setPendingApproval] = useState(false)
  const [loading, setLoading] = useState(false)
  const [googleLoading, setGoogleLoading] = useState(false)
  const [googleReady, setGoogleReady] = useState(false)
  const googleCallbackRef = useRef<((response: GoogleCredentialResponse) => void) | null>(null)

  const googleClientId = process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID || ''

  const completeLogin = useCallback(async (path: string, body: LoginRequestBody) => {
    const res = await fetch(path, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(body),
    })

    if (!res.ok) {
      const data = readLoginErrorPayload(await res.json().catch(() => null))
      if (data.code === 'PENDING_APPROVAL') {
        setPendingApproval(true)
        setError('')
        setLoading(false)
        setGoogleLoading(false)
        return false
      }
      setError(data.error || 'Login failed')
      setPendingApproval(false)
      setLoading(false)
      setGoogleLoading(false)
      return false
    }

    // Full reload ensures the session cookie is sent on all subsequent requests.
    // router.push() + refresh() can race and use stale RSC payloads.
    window.location.href = '/'
    return true
  }, [])

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

    // Read DOM values directly to handle browser autofill (which doesn't fire onChange)
    const form = e.target as HTMLFormElement
    const formUsername = (form.elements.namedItem('username') as HTMLInputElement)?.value || username
    const formPassword = (form.elements.namedItem('password') as HTMLInputElement)?.value || password

    try {
      await completeLogin('/api/auth/login', { username: formUsername, password: formPassword })
    } catch {
      setError('Network error')
      setLoading(false)
    }
  }

  // Initialize Google Sign-In SDK (hidden prompt mode)
  useEffect(() => {
    if (!googleClientId) return

    const onScriptLoad = () => {
      if (!window.google) return
      googleCallbackRef.current = async (response: GoogleCredentialResponse) => {
        setError('')
        setGoogleLoading(true)
        try {
          const ok = await completeLogin('/api/auth/google', { credential: response?.credential })
          if (!ok) return
        } catch {
          setError('Google sign-in failed')
          setGoogleLoading(false)
        }
      }
      window.google.accounts.id.initialize({
        client_id: googleClientId,
        callback: (response: GoogleCredentialResponse) => googleCallbackRef.current?.(response),
      })
      setGoogleReady(true)
    }

    const existing = document.querySelector('script[data-google-gsi="1"]') as HTMLScriptElement | null
    if (existing) {
      if (window.google) onScriptLoad()
      return
    }

    const script = document.createElement('script')
    script.src = 'https://accounts.google.com/gsi/client'
    script.async = true
    script.defer = true
    script.setAttribute('data-google-gsi', '1')
    script.onload = onScriptLoad
    script.onerror = () => setError('Failed to load Google Sign-In')
    document.head.appendChild(script)
  }, [googleClientId, completeLogin])

  const handleGoogleSignIn = () => {
    if (!window.google || !googleReady) return
    window.google.accounts.id.prompt()
  }

  return (
    <div className="min-h-screen flex items-center justify-center bg-background p-4">
      <div className="w-full max-w-sm">
        <div className="flex flex-col items-center mb-8">
          <div className="w-12 h-12 rounded-lg overflow-hidden bg-background border border-border/50 flex items-center justify-center mb-3">
            <Image
              src="/brand/mc-logo-128.png"
              alt="Mission Control logo"
              width={48}
              height={48}
              className="h-full w-full object-cover"
              priority
            />
          </div>
          <h1 className="text-xl font-semibold text-foreground">Mission Control</h1>
          <p className="text-sm text-muted-foreground mt-1">Sign in to continue</p>
        </div>

        {pendingApproval && (
          <div className="mb-4 p-4 rounded-lg bg-amber-500/10 border border-amber-500/20 text-center">
            <div className="flex justify-center mb-2">
              <svg className="w-8 h-8 text-amber-400" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round">
                <circle cx="12" cy="12" r="10" />
                <polyline points="12,6 12,12 16,14" />
              </svg>
            </div>
            <div className="text-sm font-medium text-amber-200">Access Request Submitted</div>
            <p className="text-xs text-muted-foreground mt-1">
              Your request has been sent to an administrator for review. You&apos;ll be able to sign in once approved.
            </p>
            <Button
              onClick={() => { setPendingApproval(false); setError(''); setGoogleLoading(false) }}
              variant="ghost"
              size="sm"
              className="mt-3 text-xs"
            >
              Try again
            </Button>
          </div>
        )}

        {error && (
          <div role="alert" className="mb-4 p-3 rounded-lg bg-destructive/10 border border-destructive/20 text-sm text-destructive">
            {error}
          </div>
        )}

        {/* Google Sign-In button — shown only when client ID is configured */}
        {googleClientId && (
          <div className={pendingApproval ? 'opacity-50 pointer-events-none' : ''}>
            <button
              type="button"
              onClick={handleGoogleSignIn}
              disabled={!googleReady || googleLoading || loading}
              className="w-full h-10 flex items-center justify-center gap-3 rounded-lg border border-border bg-white text-[#3c4043] text-sm font-medium hover:bg-gray-50 focus:outline-none focus:ring-2 focus:ring-primary/50 transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
            >
              {googleLoading ? (
                <>
                  <div className="w-4 h-4 border-2 border-gray-300 border-t-gray-600 rounded-full animate-spin" />
                  Signing in...
                </>
              ) : (
                <>
                  <GoogleIcon className="w-[18px] h-[18px]" />
                  Sign in with Google
                </>
              )}
            </button>
            {!googleReady && (
              <p className="text-center text-xs text-muted-foreground mt-2">Loading Google Sign-In...</p>
            )}

            {/* Divider */}
            <div className="my-4 flex items-center gap-2">
              <div className="h-px flex-1 bg-border" />
              <span className="text-xs text-muted-foreground">or</span>
              <div className="h-px flex-1 bg-border" />
            </div>
          </div>
        )}

        <form onSubmit={handleSubmit} className={`space-y-4 ${pendingApproval ? 'opacity-50 pointer-events-none' : ''}`}>
          <div>
            <label htmlFor="username" className="block text-sm font-medium text-foreground mb-1.5">Username</label>
            <input
              id="username"
              type="text"
              value={username}
              onChange={(e) => setUsername(e.target.value)}
              className="w-full h-10 px-3 rounded-lg bg-secondary border border-border text-foreground text-sm placeholder:text-muted-foreground focus:outline-none focus:ring-2 focus:ring-primary/50 focus:border-primary transition-smooth"
              placeholder="Enter username"
              autoComplete="username"
              autoFocus
              required
              aria-required="true"
            />
          </div>

          <div>
            <label htmlFor="password" className="block text-sm font-medium text-foreground mb-1.5">Password</label>
            <input
              id="password"
              type="password"
              value={password}
              onChange={(e) => setPassword(e.target.value)}
              className="w-full h-10 px-3 rounded-lg bg-secondary border border-border text-foreground text-sm placeholder:text-muted-foreground focus:outline-none focus:ring-2 focus:ring-primary/50 focus:border-primary transition-smooth"
              placeholder="Enter password"
              autoComplete="current-password"
              required
              aria-required="true"
            />
          </div>

          <Button
            type="submit"
            disabled={loading}
            size="lg"
            className="w-full rounded-lg"
          >
            {loading ? (
              <>
                <div className="w-4 h-4 border-2 border-primary-foreground/30 border-t-primary-foreground rounded-full animate-spin" />
                Signing in...
              </>
            ) : (
              'Sign in'
            )}
          </Button>
        </form>

        <p className="text-center text-xs text-muted-foreground mt-6">OpenClaw Agent Orchestration</p>
      </div>
    </div>
  )
}
