import { useEffect, useState, type FormEvent } from 'react'
import { useNavigate, useSearch } from '@tanstack/react-router'
import { useQueryClient } from '@tanstack/react-query'
import { EyeIcon, EyeOffIcon, FingerprintIcon } from 'lucide-react'
import {
  browserSupportsWebAuthn,
  browserSupportsWebAuthnAutofill,
  startAuthentication,
  WebAuthnAbortService,
} from '@simplewebauthn/browser'
import type { PublicKeyCredentialRequestOptionsJSON } from '@simplewebauthn/browser'
import {
  buildSsoRedirectUrl,
  isPortalOidcAuthorizeUrl,
  isReturnToAllowed,
  type LoginResponse,
} from '@authportal/shared'
import { Button } from '@authportal/ui/components/button'
import { Field, FieldGroup, FieldLabel } from '@authportal/ui/components/field'
import { Input } from '@authportal/ui/components/input'
import {
  InputGroup,
  InputGroupAddon,
  InputGroupButton,
  InputGroupInput,
} from '@authportal/ui/components/input-group'
import { Separator } from '@authportal/ui/components/separator'
import {
  Alert,
  AlertDescription,
  AlertTitle,
} from '@/components/reui/alert'
import { ensureAuthConfig, setToken } from '@/lib/auth'
import { ApiError } from '@/lib/api-client'
import { login, meQueryKey } from '@/queries/auth'
import { webauthnLogin, webauthnLoginOptions } from '@/queries/webauthn'
import { AuthLogo } from '@/components/auth-logo'

export function PortalLoginForm() {
  const navigate = useNavigate()
  const queryClient = useQueryClient()
  const search = useSearch({ from: '/' }) as { return_to?: string }
  const [showPassword, setShowPassword] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [pending, setPending] = useState(false)
  const [passkeySupported, setPasskeySupported] = useState(false)

  async function applySession(res: LoginResponse) {
    setToken(res.access_token)
    queryClient.setQueryData(meQueryKey, res.user)

    const returnTo = search.return_to
    const { returnToAllowlist: allowlist, issuer } = await ensureAuthConfig()
    if (returnTo && isReturnToAllowed(returnTo, allowlist)) {
      if (isPortalOidcAuthorizeUrl(returnTo, issuer)) {
        window.location.href = returnTo
        return
      }
      window.location.href = buildSsoRedirectUrl(
        returnTo,
        res.access_token,
        res.expires_at,
      )
      return
    }

    if (res.user.is_admin) {
      await navigate({ to: '/admin' })
    } else {
      await navigate({ to: '/apps' })
    }
  }

  async function runPasskeyLogin() {
    const { challenge_id, options } = await webauthnLoginOptions()
    const assertion = await startAuthentication({
      optionsJSON: options as unknown as PublicKeyCredentialRequestOptionsJSON,
    })
    const res = await webauthnLogin(challenge_id, assertion, search.return_to)
    await applySession(res)
  }

  useEffect(() => {
    if (!browserSupportsWebAuthn()) return
    setPasskeySupported(true)
    let cancelled = false

    async function startConditional() {
      if (!(await browserSupportsWebAuthnAutofill())) return
      try {
        const { challenge_id, options } = await webauthnLoginOptions()
        if (cancelled) return
        const assertion = await startAuthentication({
          optionsJSON:
            options as unknown as PublicKeyCredentialRequestOptionsJSON,
          useBrowserAutofill: true,
        })
        if (cancelled) return
        setPending(true)
        setError(null)
        const res = await webauthnLogin(
          challenge_id,
          assertion,
          search.return_to,
        )
        await applySession(res)
      } catch {
        /* abort / unsupported / user dismissed */
      } finally {
        if (!cancelled) setPending(false)
      }
    }

    void startConditional()
    return () => {
      cancelled = true
      WebAuthnAbortService.cancelCeremony()
    }
    // Login page mount only — return_to is stable for the visit.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [])

  async function handleSubmit(event: FormEvent<HTMLFormElement>) {
    event.preventDefault()
    WebAuthnAbortService.cancelCeremony()
    setError(null)
    setPending(true)
    const form = new FormData(event.currentTarget)
    const email = String(form.get('email') ?? '')
    const password = String(form.get('password') ?? '')
    try {
      const res = await login(email, password, search.return_to)
      await applySession(res)
    } catch (err) {
      setError(err instanceof ApiError ? err.message : 'Не удалось войти')
    } finally {
      setPending(false)
    }
  }

  async function handlePasskeyClick() {
    WebAuthnAbortService.cancelCeremony()
    setError(null)
    setPending(true)
    try {
      await runPasskeyLogin()
    } catch (err) {
      setError(
        err instanceof ApiError ? err.message : 'Не удалось войти с passkey',
      )
    } finally {
      setPending(false)
    }
  }

  return (
    <section className="flex min-h-svh min-w-0 flex-col justify-center py-8">
      <div className="mx-auto flex w-full max-w-90 flex-col gap-6 px-4">
        <div className="flex flex-col items-center gap-3 text-center">
          <AuthLogo />
          <div className="flex flex-col gap-1">
            <h1 className="text-xl font-semibold tracking-tight">
              Auth Portal
            </h1>
            <p className="text-muted-foreground text-sm">
              Единый вход в приложения shnt.top
            </p>
          </div>
        </div>

        {error ? (
          <Alert variant="destructive">
            <AlertTitle>Ошибка входа</AlertTitle>
            <AlertDescription>{error}</AlertDescription>
          </Alert>
        ) : null}

        <form className="flex flex-col gap-4" onSubmit={handleSubmit}>
          <FieldGroup className="gap-3.5">
            <Field className="gap-2">
              <FieldLabel htmlFor="email">Email</FieldLabel>
              <Input
                id="email"
                name="email"
                type="email"
                autoComplete="username webauthn"
                placeholder="admin@shnt.top"
                className="bg-background"
                required
              />
            </Field>

            <Field className="gap-2">
              <FieldLabel htmlFor="password">Пароль</FieldLabel>
              <InputGroup className="bg-background w-full">
                <InputGroupInput
                  id="password"
                  name="password"
                  type={showPassword ? 'text' : 'password'}
                  autoComplete="current-password"
                  placeholder="Пароль"
                  required
                />
                <InputGroupAddon align="inline-end">
                  <InputGroupButton
                    type="button"
                    size="icon-xs"
                    aria-label={showPassword ? 'Скрыть пароль' : 'Показать пароль'}
                    onClick={() => setShowPassword((v) => !v)}
                  >
                    {showPassword ? <EyeOffIcon /> : <EyeIcon />}
                  </InputGroupButton>
                </InputGroupAddon>
              </InputGroup>
            </Field>
          </FieldGroup>

          <Button type="submit" className="w-full" disabled={pending}>
            {pending ? 'Вход…' : 'Войти'}
          </Button>
        </form>

        {passkeySupported ? (
          <div className="flex flex-col gap-3">
            <div className="flex items-center gap-3">
              <Separator className="flex-1" />
              <span className="text-muted-foreground text-xs">или</span>
              <Separator className="flex-1" />
            </div>
            <Button
              type="button"
              variant="outline"
              className="w-full"
              disabled={pending}
              onClick={() => void handlePasskeyClick()}
            >
              <FingerprintIcon aria-hidden="true" />
              Войти с passkey
            </Button>
          </div>
        ) : null}
      </div>
    </section>
  )
}