'use client'

import { zodResolver } from '@hookform/resolvers/zod'
import { useRouter, useSearchParams } from 'next/navigation'
import { useCallback, useEffect, useRef, useState } from 'react'
import { useForm } from 'react-hook-form'

import { addToast } from '@/lib/toast'
import type { ServiceError } from '@/services/errorHandler'
import { RESEND_COOLDOWN_SECONDS } from '@/context/AuthContext'
import { texts } from '@/texts'
import { convertPersianToEnglish } from '@/helpers'
import useAuth from '@/hooks/useAuth'
import { useSmsOtpAutofill } from '@/hooks/useSmsOtpAutofill'
import { getDefaultPostLoginPath, getSafeInternalRedirect } from '@/lib/authRouting'
import { ANALYTICS_EVENTS, trackAnalyticsEvent } from '@/lib/analytics'
import {
  CheckOtpFormValidation,
  CompleteProfileFormValidation,
  type CompleteProfileFormValues,
  OTP_LENGTH,
  SendOtpFormValidation,
} from '@/validation/auth'

type AuthStep = 'mobile' | 'otp' | 'profile'
type OtpPurpose = 'login' | 'register'

const OTP_EXPIRES_IN_SECONDS = 120

const BLOCK_MESSAGES = {
  ACCOUNT_SUSPENDED: texts.auth.accountSuspended,
  ACCOUNT_DELETED: texts.auth.accountDeleted,
} as const

function apiErrorCode(error: unknown): string | undefined {
  return error && typeof error === 'object' && 'apiCode' in error ? (error as ServiceError).apiCode : undefined
}

function postLoginRedirect(searchParams: URLSearchParams) {
  const explicit = searchParams.get('redirect')
  let fallback = getDefaultPostLoginPath('user')

  try {
    const raw = localStorage.getItem('user')

    if (raw) fallback = getDefaultPostLoginPath((JSON.parse(raw) as { role?: 'user' | 'admin' }).role)
  } catch {
    // Ignore corrupted legacy storage and use the safe consumer home.
  }

  return getSafeInternalRedirect(explicit, fallback)
}

export function useAuthFlow(
  options: {
    redirectTo?: string
    navigateOnSuccess?: boolean
    onAuthenticated?: () => void
    requireTermsAcceptance?: boolean
  } = {}
) {
  const requireTermsAcceptance = options.requireTermsAcceptance ?? true
  const authSource = useRef(options.navigateOnSuccess === false ? 'auth_gate' : 'auth_page')
  const { sendLoginOtp, checkLoginOtp, completeProfile, user } = useAuth()
  const router = useRouter()
  const searchParams = useSearchParams()
  const [loading, setLoading] = useState(false)
  const [step, setStep] = useState<AuthStep>('mobile')
  const [mobile, setMobile] = useState('')
  const [otpTtl, setOtpTtl] = useState(RESEND_COOLDOWN_SECONDS)
  const [resendCodeTime, setResendCodeTime] = useState(0)
  const [accountBlockMessage, setAccountBlockMessage] = useState<string | null>(null)
  const [otpError, setOtpError] = useState<string | null>(null)
  const [otpPurpose, setOtpPurpose] = useState<OtpPurpose | null>(null)
  const [otpReused, setOtpReused] = useState(false)
  const [termsAccepted, setTermsAccepted] = useState(false)
  const [termsError, setTermsError] = useState<string | null>(null)
  const [otpChallenge, setOtpChallenge] = useState(0)

  const sendOtpForm = useForm({ resolver: zodResolver(SendOtpFormValidation), defaultValues: { mobile: '' } })
  const checkOtpForm = useForm({ resolver: zodResolver(CheckOtpFormValidation), defaultValues: { code: '' } })
  const completeProfileForm = useForm({
    resolver: zodResolver(CompleteProfileFormValidation),
    defaultValues: { firstName: '', lastName: '', gender: '', dateOfBirth: '', cityId: '' },
  })

  const applyAutofilledOtp = useCallback(
    (code: string) => {
      const digits = convertPersianToEnglish(code).replace(/\D/g, '').slice(0, OTP_LENGTH)

      if (digits.length !== OTP_LENGTH) return
      checkOtpForm.setValue('code', digits, { shouldDirty: true, shouldValidate: true })
    },
    [checkOtpForm]
  )

  useSmsOtpAutofill(step === 'otp', otpChallenge, applyAutofilledOtp)

  useEffect(() => {
    trackAnalyticsEvent(ANALYTICS_EVENTS.AUTH_OPENED, { source: authSource.current })
  }, [])

  useEffect(() => {
    if (user?.status === 'pending') setStep('profile')
  }, [user?.status])

  useEffect(() => {
    if (step !== 'otp' || resendCodeTime <= 0) return
    const timer = window.setTimeout(() => {
      setResendCodeTime((value) => Math.max(0, value - 1))
    }, 1000)

    return () => {
      window.clearTimeout(timer)
    }
  }, [resendCodeTime, step])

  const sendOtp = useCallback(
    async (data: { mobile: string }) => {
      try {
        setLoading(true)
        setAccountBlockMessage(null)
        const value = convertPersianToEnglish(data.mobile).trim()
        const result = await sendLoginOtp({ mobile: value })
        const alreadySent = result.alreadySent
        // ارسال تازه همان پنجرهٔ ۱۲۰ ثانیه‌ای محصول است؛ اگر بک‌اند کد قبلی را
        // نگه داشته، شمارش معکوس باید باقی‌ماندهٔ واقعی TTL باشد.
        const resendIn = alreadySent ? Math.min(OTP_EXPIRES_IN_SECONDS, Math.max(1, result.expiresIn)) : OTP_EXPIRES_IN_SECONDS
        const isResend = step === 'otp' && mobile === value

        trackAnalyticsEvent(ANALYTICS_EVENTS.OTP_REQUESTED, {
          purpose: result.purpose,
          is_resend: isResend,
          source: authSource.current,
        })

        setMobile(value)
        setOtpPurpose(result.purpose)
        setOtpReused(alreadySent)
        setOtpTtl(resendIn)
        setResendCodeTime(resendIn)
        setOtpError(null)
        if (!isResend) {
          setTermsAccepted(false)
          setTermsError(null)
        }
        setStep('otp')
        setOtpChallenge((value) => value + 1)
        checkOtpForm.reset({ code: '' })
      } catch (error) {
        const code = apiErrorCode(error)

        trackAnalyticsEvent(ANALYTICS_EVENTS.AUTH_FAILED, {
          auth_stage: 'request_otp',
          error_code: code ?? 'unknown',
          source: authSource.current,
        })

        if (code === 'ACCOUNT_SUSPENDED' || code === 'ACCOUNT_DELETED') setAccountBlockMessage(BLOCK_MESSAGES[code])
        else addToast({ title: texts.auth.sendOtpFailed, color: 'danger' })
      } finally {
        setLoading(false)
      }
    },
    [checkOtpForm, mobile, sendLoginOtp, step]
  )

  const checkOtp = useCallback(
    async (data: { code: string }) => {
      if (requireTermsAcceptance && otpPurpose === 'register' && !termsAccepted) {
        const message = texts.auth.termsRequiredMessage

        setTermsError(message)
        addToast({ title: texts.auth.termsRequiredTitle, description: message, color: 'danger' })
        trackAnalyticsEvent(ANALYTICS_EVENTS.AUTH_FAILED, {
          auth_stage: 'terms_acceptance',
          error_code: 'terms_not_accepted',
          source: authSource.current,
        })

        return
      }

      try {
        setLoading(true)
        setOtpError(null)
        setTermsError(null)
        const status = await checkLoginOtp({
          mobile,
          code: convertPersianToEnglish(data.code).trim(),
          // Server stamps terms version itself; client only asserts acceptance.
          ...(otpPurpose === 'register' ? { termsAccepted: true } : {}),
        })

        if (status === 'pending') setStep('profile')
        if (status === 'active') {
          trackAnalyticsEvent(ANALYTICS_EVENTS.LOGIN, { method: 'otp', source: authSource.current })
          addToast({ title: texts.auth.welcome, color: 'success' })
          options.onAuthenticated?.()
          if (options.navigateOnSuccess !== false) router.replace(options.redirectTo ?? postLoginRedirect(searchParams))
        }
      } catch (error) {
        const code = apiErrorCode(error)

        trackAnalyticsEvent(ANALYTICS_EVENTS.AUTH_FAILED, {
          auth_stage: 'verify_otp',
          error_code: code ?? 'unknown',
          source: authSource.current,
        })

        if (code === 'ACCOUNT_SUSPENDED' || code === 'ACCOUNT_DELETED') {
          setAccountBlockMessage(BLOCK_MESSAGES[code])
          setStep('mobile')
        } else if (code === 'OTP_INVALID' || code === 'OTP_EXPIRED') setOtpError(texts.auth.otpInvalidOrExpired)
        else setOtpError(texts.auth.otpVerifyFailed)
      } finally {
        setLoading(false)
      }
    },
    [checkLoginOtp, mobile, options, otpPurpose, requireTermsAcceptance, router, searchParams, termsAccepted]
  )

  const otpCode = checkOtpForm.watch('code')
  const lastAutoSubmittedOtpRef = useRef<string | null>(null)

  // با پر شدن رقم آخر، فرم را خودکار submit کن (دستی و SMS autofill)
  useEffect(() => {
    if (step !== 'otp' || loading) return

    // watch('code') without a typed form can infer as {}; OTP field is always a string at runtime
    const digits = convertPersianToEnglish(typeof otpCode === 'string' ? otpCode : '')
      .replace(/\D/g, '')
      .slice(0, OTP_LENGTH)

    if (digits.length !== OTP_LENGTH) {
      lastAutoSubmittedOtpRef.current = null

      return
    }

    if (lastAutoSubmittedOtpRef.current === digits) return

    lastAutoSubmittedOtpRef.current = digits
    void checkOtpForm.handleSubmit(checkOtp)()
  }, [checkOtp, checkOtpForm, loading, otpCode, step])

  const submitProfile = useCallback(
    async (data: CompleteProfileFormValues) => {
      try {
        setLoading(true)
        await completeProfile({
          firstName: data.firstName.trim(),
          lastName: data.lastName.trim(),
          gender: data.gender,
          dateOfBirth: data.dateOfBirth,
          cityId: Number(data.cityId),
        })
        addToast({ title: texts.auth.welcome, color: 'success' })
        options.onAuthenticated?.()
        if (options.navigateOnSuccess !== false) router.replace(options.redirectTo ?? postLoginRedirect(searchParams))
      } catch {
        trackAnalyticsEvent(ANALYTICS_EVENTS.AUTH_FAILED, {
          auth_stage: 'complete_profile',
          error_code: 'unknown',
          source: authSource.current,
        })
        addToast({ title: texts.auth.profileCompleteFailed, color: 'danger' })
      } finally {
        setLoading(false)
      }
    },
    [completeProfile, options, router, searchParams]
  )

  const resetToMobile = useCallback(() => {
    setStep('mobile')
    setResendCodeTime(0)
    setOtpError(null)
    setOtpPurpose(null)
    setOtpReused(false)
    setTermsAccepted(false)
    setTermsError(null)
  }, [])

  const updateTermsAccepted = useCallback((accepted: boolean) => {
    setTermsAccepted(accepted)
    if (accepted) setTermsError(null)
  }, [])

  return {
    accountBlockMessage,
    checkOtp,
    checkOtpForm,
    completeProfileForm,
    loading,
    mobile,
    isRegistration: otpPurpose === 'register',
    otpError,
    otpReused,
    otpTtl,
    resendCodeTime,
    resetToMobile,
    sendOtp,
    sendOtpForm,
    step,
    submitProfile,
    termsAccepted,
    termsError,
    updateTermsAccepted,
  }
}