'use client'

import { ENABLED_EXTENSION_IDS } from '@/lib/extensions/_generated/enabled-extensions'
import React, { useState, useEffect, useCallback } from 'react'
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
import { Button } from '@/components/ui/button'
import { Badge } from '@/components/ui/badge'
import {
  AlertCircle,
  CheckCircle2,
  Download,
  ExternalLink,
  Gavel,
  Link2,
  Link2Off,
  Loader2,
  FileCheck,
  Lock,
  Unlock,
  Send,
  ShieldAlert,
  Trash2,
} from 'lucide-react'
import type { VatDeclarationRutor, VatPeriodType } from '@/types'
import { formatRedovisare, formatRedovisningsperiod } from '@/lib/skatteverket/format'
import {
  runVatDeclarationChecks,
  type VatDeclarationCheck,
} from '@/lib/reports/vat-declaration-checks'
import type { RcBasisGap } from '@/lib/reports/rc-basis-gaps'
import { formatDate } from '@/lib/utils'
import { useCapability } from '@/contexts/CompanyContext'
import { CAPABILITY } from '@/lib/entitlements/keys'
import { UpgradeNote } from '@/components/billing/UpgradeNote'

interface SkatteverketStatus {
  connected: boolean
  expired?: boolean
  canRefresh?: boolean
  scope?: string
  expiresAt?: string
}

/**
 * Codes from /lib/api-client.ts's SkatteverketAuthError that mean "the user
 * needs to reconnect with BankID before this action can succeed". When the API
 * returns one of these codes we flip the local status.expired flag so the
 * "Session utgången" badge + "Förnya session" button surface, even if the
 * upstream /status endpoint hasn't reflected the change yet.
 */
const AUTH_RECONNECT_CODES = new Set([
  'NOT_CONNECTED',
  'SESSION_EXPIRED',
  'REFRESH_EXHAUSTED',
  'TOKEN_REVOKED',
  'TOKEN_CORRUPTED',
  'MISSING_SCOPE',
])

// Shape per Skatteverket Momsdeklaration v1.0.24 RAML
// (kontrollResultat.resultat[].{kod, status, beskrivning})
interface KontrollResult {
  kod: string
  status: 'ERROR' | 'WARNING'
  beskrivning: string
}

interface SkatteverketPanelProps {
  periodType: VatPeriodType
  year: number
  period: number
  hasData: boolean
  /**
   * Calculated rutor for the current period. Used to run local pre-flight
   * checks before Skatteverket sees the payload: SKV only validates internal
   * arithmetic consistency, so we have to catch "ruta 30-32 present but
   * 20-24 empty" locally before letting the user submit.
   */
  rutor?: VatDeclarationRutor | null
}

function formatAmount(amount: number): string {
  return amount.toLocaleString('sv-SE', { minimumFractionDigits: 2, maximumFractionDigits: 2 })
}

const SKV_ENABLED = ENABLED_EXTENSION_IDS.has('skatteverket')

export function SkatteverketPanel(props: SkatteverketPanelProps) {
  if (!SKV_ENABLED) return null
  return <SkatteverketPanelInner {...props} />
}

function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: SkatteverketPanelProps) {
  const hasSkvCapability = useCapability(CAPABILITY.skatteverket)
  const [status, setStatus] = useState<SkatteverketStatus | null>(null)
  const [loading, setLoading] = useState(true)
  const [actionLoading, setActionLoading] = useState<string | null>(null)
  const [error, setError] = useState<string | null>(null)
  const [success, setSuccess] = useState<string | null>(null)
  const [kontroller, setKontroller] = useState<KontrollResult[]>([])
  const [signeringslank, setSigneringslank] = useState<string | null>(null)
  const [submitted, setSubmitted] = useState<{
    kvittensnummer?: string
    tidpunkt?: string
  } | null>(null)

  // Local sanity checks against the calculated declaration, run before any
  // SKV call. SKV's "OK" only confirms arithmetic: these checks confirm
  // the declaration looks plausible (no orphaned RC output, no missing
  // basis, no summaMoms drift).
  const localChecks: VatDeclarationCheck[] = rutor ? runVatDeclarationChecks(rutor) : []
  const localErrors = localChecks.filter((c) => c.status === 'ERROR')
  const localBlocked = localErrors.length > 0

  // Per-voucher RC basis gap detection: fetched whenever a RC_BASIS_MISSING
  // warning fires so we can show the user exactly which verifikationer are
  // missing the basbelopp pair and offer a one-click correction.
  const hasRcBasisWarning = localChecks.some((c) => c.code === 'RC_BASIS_MISSING')
  const [gaps, setGaps] = useState<RcBasisGap[]>([])
  const [gapsLoading, setGapsLoading] = useState(false)
  const [fixingId, setFixingId] = useState<string | null>(null)
  const [gapSelections, setGapSelections] = useState<
    Record<string, { supplierType: 'eu_business' | 'non_eu_business' | 'swedish_business'; supplyType: 'service' | 'goods' }>
  >({})

  useEffect(() => {
    if (!hasRcBasisWarning) {
      setGaps([])
      return
    }
    let cancelled = false
    setGapsLoading(true)
    fetch(
      `/api/reports/vat-declaration/rc-basis-gaps?periodType=${periodType}&year=${year}&period=${period}`,
    )
      .then((r) => r.json())
      .then((j) => {
        if (cancelled) return
        setGaps(j?.data?.gaps || [])
      })
      .catch(() => {
        if (cancelled) return
        setGaps([])
      })
      .finally(() => {
        if (cancelled) return
        setGapsLoading(false)
      })
    return () => {
      cancelled = true
    }
  }, [hasRcBasisWarning, periodType, year, period])

  const handleFixGap = async (gap: RcBasisGap) => {
    const sel = gapSelections[gap.entryId] ?? { supplierType: 'eu_business', supplyType: 'service' as const }
    setFixingId(gap.entryId)
    setError(null)
    try {
      const res = await fetch('/api/reports/vat-declaration/rc-basis-gaps/fix', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          entryId: gap.entryId,
          supplierType: sel.supplierType,
          supplyType: sel.supplyType,
        }),
      })
      const result = await res.json()
      if (!res.ok) {
        setError(result?.error || 'Kunde inte korrigera verifikationen')
      } else {
        setGaps((prev) => prev.filter((g) => g.entryId !== gap.entryId))
        setSuccess(
          `Verifikation ${gap.voucherSeries}-${gap.voucherNumber} korrigerad. Storno + ny verifikation skapad. Ladda om sidan för att uppdatera rutorna.`,
        )
      }
    } catch {
      setError('Kunde inte korrigera verifikationen')
    } finally {
      setFixingId(null)
    }
  }

  /**
   * Apply an API JSON error result. When the error indicates the SKV session
   * has expired/been revoked/lost scope, immediately reflect that in the
   * local status so the "Förnya session" CTA appears next to the message:
   * the user shouldn't have to wait for /status to catch up.
   */
  const applyApiError = useCallback((result: { error?: string; code?: string } | null) => {
    if (!result?.error) return false
    setError(result.error)
    if (result.code && AUTH_RECONNECT_CODES.has(result.code)) {
      setStatus((prev) => prev ? { ...prev, expired: true } : prev)
    }
    return true
  }, [])

  const fetchStatus = useCallback(async () => {
    try {
      const res = await fetch('/api/extensions/ext/skatteverket/status')
      if (res.ok) {
        const data = await res.json()
        setStatus(data)
      }
    } catch {
      // Extension might not be enabled
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => {
    fetchStatus()

    // Check URL params for OAuth callback results
    const params = new URLSearchParams(window.location.search)
    if (params.get('skv_connected') === 'true') {
      setSuccess('Ansluten till Skatteverket')
      fetchStatus()
      // Clean URL
      const url = new URL(window.location.href)
      url.searchParams.delete('skv_connected')
      window.history.replaceState({}, '', url.toString())
    }
    const skvError = params.get('skv_error')
    if (skvError) {
      setError(decodeURIComponent(skvError))
      const url = new URL(window.location.href)
      url.searchParams.delete('skv_error')
      window.history.replaceState({}, '', url.toString())
    }
  }, [fetchStatus])

  const handleConnect = () => {
    // return_to brings the user back to the momsdeklaration after the BankID
    // round-trip; the authorize route's default otherwise lands on the report
    // library. The callback appends skv_connected/skv_error itself.
    window.location.href =
      '/api/extensions/ext/skatteverket/authorize?return_to=' +
      encodeURIComponent('/reports/vat-declaration')
  }

  const handleDisconnect = async () => {
    setActionLoading('disconnect')
    setError(null)
    try {
      const res = await fetch('/api/extensions/ext/skatteverket/disconnect', {
        method: 'POST',
      })
      if (res.ok) {
        setStatus({ connected: false })
        setSuccess(null)
        setKontroller([])
        setSigneringslank(null)
        setSubmitted(null)
      }
    } catch {
      setError('Kunde inte koppla bort')
    } finally {
      setActionLoading(null)
    }
  }

  const handleValidate = async () => {
    if (localBlocked) {
      setError(
        'Lokala kontroller hittade fel i bokföringen. Åtgärda dessa innan ' +
        'du skickar till Skatteverket.',
      )
      return
    }
    setActionLoading('validate')
    setError(null)
    setKontroller([])
    try {
      const res = await fetch('/api/extensions/ext/skatteverket/declaration/validate', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ periodType, year, period }),
      })
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else {
        const controls: KontrollResult[] = result.data?.kontrollResultat?.resultat || []
        setKontroller(controls)
        if (controls.length === 0) {
          // SKV's OK only confirms arithmetic: it does NOT confirm that the
          // declaration is materially correct. We say so explicitly so the
          // user doesn't read this as a green light for actual filing.
          setSuccess(
            'Skatteverket har inga tekniska invändningar mot deklarationen. ' +
            'Kontrollera siffrorna i förhandsgranskningen innan du skickar in.',
          )
        } else {
          const errors = controls.filter(k => k.status === 'ERROR')
          if (errors.length > 0) {
            setError(`${errors.length} valideringsfel hittades`)
          } else {
            setSuccess('Skatteverket har inga tekniska invändningar (med varningar)')
          }
        }
      }
    } catch {
      setError('Kunde inte validera deklarationen')
    } finally {
      setActionLoading(null)
    }
  }

  const handleSaveDraft = async () => {
    if (localBlocked) {
      setError(
        'Lokala kontroller hittade fel i bokföringen. Åtgärda dessa innan ' +
        'du sparar utkastet hos Skatteverket.',
      )
      return
    }
    setActionLoading('draft')
    setError(null)
    try {
      const res = await fetch('/api/extensions/ext/skatteverket/declaration/draft', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ periodType, year, period }),
      })
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else {
        const controls: KontrollResult[] = result.data?.kontrollResultat?.resultat || []
        setKontroller(controls)
        const errors = controls.filter(k => k.status === 'ERROR')
        if (errors.length === 0) {
          setSuccess('Utkast sparat i Eget utrymme hos Skatteverket')
        } else {
          setError(`Utkastet sparades men har ${errors.length} valideringsfel`)
        }
      }
    } catch {
      setError('Kunde inte spara utkast')
    } finally {
      setActionLoading(null)
    }
  }

  const handleLock = async () => {
    setActionLoading('lock')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/lock?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`,
        { method: 'PUT' }
      )
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else if (result.data?.signeringsLank) {
        setSigneringslank(result.data.signeringsLank)
        setSuccess('Utkastet är låst. Öppna signeringslänken för att signera med BankID.')
      }
    } catch {
      setError('Kunde inte låsa utkastet')
    } finally {
      setActionLoading(null)
    }
  }

  const handleUnlock = async () => {
    setActionLoading('unlock')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/lock?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`,
        { method: 'DELETE' }
      )
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else {
        setSigneringslank(null)
        setSuccess('Utkastet har låsts upp')
      }
    } catch {
      setError('Kunde inte låsa upp utkastet')
    } finally {
      setActionLoading(null)
    }
  }

  const handleCheckSubmitted = async () => {
    setActionLoading('check')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/submitted?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`
      )
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else if (result.data) {
        setSubmitted(result.data)
        setSuccess('Deklarationen har lämnats in')
      } else {
        setSuccess('Ingen inlämnad deklaration hittades för denna period')
      }
    } catch {
      setError('Kunde inte kontrollera inlämningsstatus')
    } finally {
      setActionLoading(null)
    }
  }

  const handleDeleteDraft = async () => {
    setActionLoading('delete')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/draft?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`,
        { method: 'DELETE' }
      )
      if (res.status === 204 || res.ok) {
        setKontroller([])
        setSigneringslank(null)
        setSuccess('Utkastet har raderats från Eget utrymme')
      } else {
        const result = await res.json().catch(() => ({}))
        if (!applyApiError(result)) {
          setError(`Kunde inte radera utkast (${res.status})`)
        }
      }
    } catch {
      setError('Kunde inte radera utkast')
    } finally {
      setActionLoading(null)
    }
  }

  const handleFetchDraft = async () => {
    setActionLoading('fetchDraft')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/draft?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`
      )
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else if (!result.data) {
        setSuccess('Inget sparat utkast hittades för perioden')
      } else {
        const locked = result.data?.locked ? ' (låst)' : ''
        const summa = result.data?.momsuppgift?.summaMoms
        const summaLabel = summa !== undefined ? `, summaMoms = ${formatAmount(summa)}` : ''
        setSuccess(`Sparat utkast hittades${locked}${summaLabel}`)
      }
    } catch {
      setError('Kunde inte hämta utkast')
    } finally {
      setActionLoading(null)
    }
  }

  const handleFetchDecided = async () => {
    setActionLoading('fetchDecided')
    setError(null)
    try {
      const res = await fetch(
        `/api/extensions/ext/skatteverket/declaration/decided?redovisare=${encodeURIComponent(
          await getRedovisare()
        )}&redovisningsperiod=${getRedovisningsperiod()}`
      )
      const result = await res.json()
      if (applyApiError(result)) {
        // surfaced + status updated; nothing more to do
      } else if (!result.data) {
        setSuccess('Inget beslut hittades för perioden')
      } else {
        const tid = result.data?.beslutadTidpunkt
        const tidLabel = tid ? ` (beslutad ${new Date(tid).toLocaleDateString('sv-SE')})` : ''
        setSuccess(`Beslut hittades${tidLabel}`)
      }
    } catch {
      setError('Kunde inte hämta beslutade uppgifter')
    } finally {
      setActionLoading(null)
    }
  }

  // Helper to get redovisare from settings
  const getRedovisare = async (): Promise<string> => {
    const res = await fetch('/api/settings')
    const { data } = await res.json()
    if (!data?.org_number) throw new Error('Organisationsnummer saknas')
    return formatRedovisare(data.org_number, data.entity_type)
  }

  const getRedovisningsperiod = (): string => {
    return formatRedovisningsperiod(periodType, year, period)
  }

  if (loading) {
    return (
      <Card>
        <CardContent className="p-6 flex items-center gap-2 text-muted-foreground">
          <Loader2 className="h-4 w-4 animate-spin" />
          Kontrollerar Skatteverket-anslutning...
        </CardContent>
      </Card>
    )
  }

  // Paywall: direct API submission is the paid convenience; manual filing at
  // skatteverket.se stays free and is described in the card above this panel.
  // Rendered BEFORE the connected check so a company that connected during
  // trial sees the upsell instead of action buttons that would 403.
  if (!hasSkvCapability) {
    return (
      <Card>
        <CardHeader>
          <CardTitle className="text-lg flex items-center gap-2">
            <FileCheck className="h-5 w-5" />
            Skicka direkt till Skatteverket (valfritt)
          </CardTitle>
        </CardHeader>
        <CardContent className="space-y-4">
          <p className="text-sm text-muted-foreground">
            Deklarationen är redan klar att lämnas in manuellt hos Skatteverket
            (se ovan). Med ett abonnemang kan du ansluta med BankID och skicka
            den direkt härifrån, samt validera, spara utkast och signera.
          </p>
          <UpgradeNote>
            Direktinlämning till Skatteverket kräver ett abonnemang.
          </UpgradeNote>
        </CardContent>
      </Card>
    )
  }

  // Not connected. The momsdeklaration is already complete and can be filed
  // manually at skatteverket.se with no connection (see the manual-filing card
  // rendered above this panel). Connecting is an optional convenience for
  // submitting directly from Accounted, so frame it that way: users must not
  // read the connection as a prerequisite for producing or filing the report.
  if (!status?.connected) {
    return (
      <Card>
        <CardHeader>
          <CardTitle className="text-lg flex items-center gap-2">
            <FileCheck className="h-5 w-5" />
            Skicka direkt till Skatteverket (valfritt)
          </CardTitle>
        </CardHeader>
        <CardContent className="space-y-4">
          {error && (
            <div className="flex items-start gap-2 text-sm text-destructive bg-destructive/5 rounded-lg p-3">
              <AlertCircle className="h-4 w-4 mt-0.5 shrink-0" />
              <span>{error}</span>
            </div>
          )}
          <p className="text-sm text-muted-foreground">
            Deklarationen är redan klar att lämnas in manuellt hos Skatteverket
            (se ovan). Vill du slippa skriva in siffrorna själv kan du ansluta med
            BankID och skicka den direkt härifrån, samt validera, spara utkast och
            signera.
          </p>
          <Button onClick={handleConnect} className="gap-2">
            <Link2 className="h-4 w-4" />
            Anslut med BankID
          </Button>
        </CardContent>
      </Card>
    )
  }

  // Connected: show actions
  const hasErrors = kontroller.some(k => k.status === 'ERROR')
  const hasWarnings = kontroller.some(k => k.status === 'WARNING')

  return (
    <Card>
      <CardHeader>
        <div className="flex items-center justify-between">
          <CardTitle className="text-lg flex items-center gap-2">
            <FileCheck className="h-5 w-5" />
            Skicka till Skatteverket
          </CardTitle>
          <div className="flex items-center gap-2">
            <Badge variant="success" className="gap-1">
              <CheckCircle2 className="h-3 w-3" />
              Ansluten
            </Badge>
            {status.expired && (
              <>
                <Badge variant="destructive" className="gap-1">
                  <AlertCircle className="h-3 w-3" />
                  Session utgången
                </Badge>
                <Button
                  size="sm"
                  variant="outline"
                  onClick={handleConnect}
                  className="gap-1.5 h-7"
                >
                  <Link2 className="h-3.5 w-3.5" />
                  Förnya session
                </Button>
              </>
            )}
          </div>
        </div>
      </CardHeader>
      <CardContent className="space-y-4">
        {/* Messages */}
        {error && (
          <div className="flex items-start gap-2 text-sm text-destructive bg-destructive/5 rounded-lg p-3">
            <AlertCircle className="h-4 w-4 mt-0.5 shrink-0" />
            <span>{error}</span>
          </div>
        )}
        {success && !error && (
          <div className="flex items-start gap-2 text-sm text-success bg-success/5 rounded-lg p-3">
            <CheckCircle2 className="h-4 w-4 mt-0.5 shrink-0" />
            <span>{success}</span>
          </div>
        )}

        {/* Local pre-flight check results: surfaced separately from SKV's
            kontroller so the user knows these are Accounted's own sanity checks,
            not Skatteverket's. ERRORs block the submit/validate buttons. */}
        {localChecks.length > 0 && (
          <div className="space-y-1.5">
            <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide">
              Lokala kontroller
            </p>
            {localChecks.map((c, i) => (
              <div
                key={`${c.code}-${i}`}
                className={`flex items-start gap-2 text-sm rounded-lg p-3 ${
                  c.status === 'ERROR'
                    ? 'bg-destructive/5 text-destructive'
                    : 'bg-amber-50 text-amber-800 dark:bg-amber-950/30 dark:text-amber-200'
                }`}
              >
                {c.status === 'ERROR' ? (
                  <ShieldAlert className="h-4 w-4 mt-0.5 shrink-0" />
                ) : (
                  <AlertCircle className="h-4 w-4 mt-0.5 shrink-0" />
                )}
                <div>
                  <span className="font-mono text-xs mr-1.5">{c.code}</span>
                  {c.message}
                </div>
              </div>
            ))}
          </div>
        )}

        {/* Per-voucher RC basis gaps: concrete list of verifikationer that
            triggered RC_BASIS_MISSING, with a one-click korrigera action. */}
        {hasRcBasisWarning && (
          <div className="space-y-2">
            <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide">
              Verifikationer som saknar basbelopp
            </p>
            {gapsLoading ? (
              <div className="text-sm text-muted-foreground flex items-center gap-2">
                <Loader2 className="h-3.5 w-3.5 animate-spin" />
                Söker berörda verifikationer...
              </div>
            ) : gaps.length === 0 ? (
              <p className="text-sm text-muted-foreground">
                Inga verifikationer hittades. Bristen kan ligga utanför perioden
                eller i bokföring som inte är posted.
              </p>
            ) : (
              <div className="space-y-2">
                {gaps.map((gap) => {
                  const sel = gapSelections[gap.entryId] ?? {
                    supplierType: 'eu_business' as const,
                    supplyType: 'service' as const,
                  }
                  return (
                    <div
                      key={gap.entryId}
                      className="rounded-lg border bg-card p-3 space-y-2"
                    >
                      <div className="flex items-start justify-between gap-3">
                        <div className="min-w-0">
                          <p className="text-sm font-medium">
                            Verifikation {gap.voucherSeries}-{gap.voucherNumber}
                            <span className="text-muted-foreground font-normal">
                              {' · '}
                              {formatDate(gap.entryDate)}
                            </span>
                          </p>
                          <p className="text-sm text-muted-foreground truncate">
                            {gap.description}
                          </p>
                          <p className="text-xs text-muted-foreground mt-1 tabular-nums">
                            {gap.rcOutputAccount} har{' '}
                            {gap.rcOutputAmount.toLocaleString('sv-SE', {
                              minimumFractionDigits: 2,
                              maximumFractionDigits: 2,
                            })}{' '}
                            kr fiktiv moms: saknar basbelopp{' '}
                            {gap.expectedBasisAmount.toLocaleString('sv-SE', {
                              minimumFractionDigits: 2,
                              maximumFractionDigits: 2,
                            })}{' '}
                            kr
                          </p>
                        </div>
                      </div>
                      <div className="flex flex-wrap items-center gap-2">
                        <select
                          className="text-xs border rounded px-2 py-1 bg-background"
                          value={sel.supplierType}
                          onChange={(e) => {
                            const next = e.target.value as typeof sel.supplierType
                            setGapSelections((prev) => ({
                              ...prev,
                              [gap.entryId]: {
                                supplierType: next,
                                // Non-EU + goods is import VAT, not RC: coerce back
                                // to service so the user can't submit an invalid combo.
                                supplyType: next === 'non_eu_business' ? 'service' : sel.supplyType,
                              },
                            }))
                          }}
                          disabled={fixingId === gap.entryId}
                        >
                          <option value="eu_business">EU-leverantör</option>
                          <option value="non_eu_business">Utanför EU</option>
                          <option value="swedish_business">Svensk RC</option>
                        </select>
                        <select
                          className="text-xs border rounded px-2 py-1 bg-background"
                          value={sel.supplyType}
                          onChange={(e) =>
                            setGapSelections((prev) => ({
                              ...prev,
                              [gap.entryId]: {
                                ...sel,
                                supplyType: e.target.value as typeof sel.supplyType,
                              },
                            }))
                          }
                          disabled={fixingId === gap.entryId}
                        >
                          <option value="service">Tjänst</option>
                          {/* Non-EU goods is import VAT, not reverse charge: hide the
                              option for that combination so the fix endpoint never
                              has to reject it. */}
                          {sel.supplierType !== 'non_eu_business' && (
                            <option value="goods">Vara</option>
                          )}
                        </select>
                        <Button
                          variant="outline"
                          size="sm"
                          onClick={() => handleFixGap(gap)}
                          disabled={fixingId !== null}
                          className="gap-1.5 h-7"
                        >
                          {fixingId === gap.entryId ? (
                            <Loader2 className="h-3 w-3 animate-spin" />
                          ) : (
                            <CheckCircle2 className="h-3 w-3" />
                          )}
                          Korrigera
                        </Button>
                      </div>
                    </div>
                  )
                })}
              </div>
            )}
          </div>
        )}

        {/* Validation results from Skatteverket */}
        {kontroller.length > 0 && (
          <div className="space-y-1.5">
            <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide">
              Skatteverkets valideringsresultat
            </p>
            {kontroller.map((k, i) => (
              <div
                key={`${k.kod}-${i}`}
                className={`flex items-start gap-2 text-sm rounded-lg p-3 ${
                  k.status === 'ERROR'
                    ? 'bg-destructive/5 text-destructive'
                    : 'bg-amber-50 text-amber-800 dark:bg-amber-950/30 dark:text-amber-200'
                }`}
              >
                {k.status === 'ERROR' ? (
                  <ShieldAlert className="h-4 w-4 mt-0.5 shrink-0" />
                ) : (
                  <AlertCircle className="h-4 w-4 mt-0.5 shrink-0" />
                )}
                <div>
                  <span className="font-mono text-xs mr-1.5">{k.kod}</span>
                  {k.beskrivning}
                </div>
              </div>
            ))}
          </div>
        )}

        {/* Submitted confirmation */}
        {submitted && (
          <div className="rounded-lg border p-3 space-y-1">
            <p className="text-sm font-medium flex items-center gap-1.5">
              <CheckCircle2 className="h-4 w-4 text-success" />
              Inlämnad
            </p>
            {submitted.kvittensnummer && (
              <p className="text-xs text-muted-foreground">
                Kvittensnummer: <span className="font-mono">{submitted.kvittensnummer}</span>
              </p>
            )}
            {submitted.tidpunkt && (
              <p className="text-xs text-muted-foreground">
                Tidpunkt: {new Date(submitted.tidpunkt).toLocaleString('sv-SE')}
              </p>
            )}
          </div>
        )}

        {/* Signing link */}
        {signeringslank && (
          <div className="rounded-lg border border-success/30 bg-success/5 p-3 space-y-2">
            <p className="text-sm font-medium">Utkastet är låst och redo att signeras</p>
            <p className="text-xs text-muted-foreground">
              Öppna länken nedan och signera med BankID på Skatteverkets sida.
            </p>
            <Button
              variant="outline"
              size="sm"
              className="gap-1.5"
              onClick={() => window.open(signeringslank, '_blank')}
            >
              <ExternalLink className="h-3.5 w-3.5" />
              Öppna signeringssidan
            </Button>
          </div>
        )}

        {/* Forward-lifecycle buttons */}
        <div className="flex flex-wrap gap-2 pt-1">
          <Button
            variant="outline"
            size="sm"
            onClick={handleValidate}
            disabled={!hasData || localBlocked || actionLoading !== null}
            className="gap-1.5"
            title={localBlocked ? 'Åtgärda lokala kontrollfel innan validering' : undefined}
          >
            {actionLoading === 'validate' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <FileCheck className="h-3.5 w-3.5" />
            )}
            Validera
          </Button>

          <Button
            variant="outline"
            size="sm"
            onClick={handleSaveDraft}
            disabled={!hasData || localBlocked || actionLoading !== null}
            className="gap-1.5"
            title={localBlocked ? 'Åtgärda lokala kontrollfel innan inlämning' : undefined}
          >
            {actionLoading === 'draft' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Send className="h-3.5 w-3.5" />
            )}
            Spara utkast
          </Button>

          <Button
            size="sm"
            onClick={handleLock}
            disabled={!hasData || hasErrors || actionLoading !== null}
            className="gap-1.5"
            title={hasErrors ? 'Valideringsfel måste åtgärdas först' : ''}
          >
            {actionLoading === 'lock' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Lock className="h-3.5 w-3.5" />
            )}
            Lås och signera
          </Button>
        </div>

        {/* Read-only fetches from Skatteverket. */}
        <div className="flex flex-wrap gap-2">
          <Button
            variant="ghost"
            size="sm"
            onClick={handleFetchDraft}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground"
            title="Hämta sparat utkast från Eget utrymme"
          >
            {actionLoading === 'fetchDraft' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Download className="h-3.5 w-3.5" />
            )}
            Hämta utkast
          </Button>

          <Button
            variant="ghost"
            size="sm"
            onClick={handleCheckSubmitted}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground"
            title="Kontrollera om en signerad deklaration har lämnats in"
          >
            {actionLoading === 'check' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <CheckCircle2 className="h-3.5 w-3.5" />
            )}
            Kontrollera inlämning
          </Button>

          <Button
            variant="ghost"
            size="sm"
            onClick={handleFetchDecided}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground"
            title="Hämta Skatteverkets beslut för perioden"
          >
            {actionLoading === 'fetchDecided' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Gavel className="h-3.5 w-3.5" />
            )}
            Hämta beslut
          </Button>
        </div>

        {/* Recovery / cleanup buttons. Always visible when connected so
           the user can back out of a locked or stale draft state without
           depending on local UI state surviving a reload. SKV returns
           404/409 if the action isn't applicable; we surface that as an
           error message rather than hiding the button. */}
        <div className="flex flex-wrap gap-2">
          <Button
            variant="outline"
            size="sm"
            onClick={handleUnlock}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground"
            title="Lås upp en låst period så att utkastet kan ändras eller raderas"
          >
            {actionLoading === 'unlock' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Unlock className="h-3.5 w-3.5" />
            )}
            Lås upp
          </Button>

          <Button
            variant="outline"
            size="sm"
            onClick={handleDeleteDraft}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground"
            title="Radera sparat utkast från Skatteverkets Eget utrymme"
          >
            {actionLoading === 'delete' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Trash2 className="h-3.5 w-3.5" />
            )}
            Radera utkast
          </Button>
        </div>

        {/* Disconnect */}
        <div className="pt-2 border-t">
          <Button
            variant="ghost"
            size="sm"
            onClick={handleDisconnect}
            disabled={actionLoading !== null}
            className="gap-1.5 text-muted-foreground hover:text-destructive"
          >
            {actionLoading === 'disconnect' ? (
              <Loader2 className="h-3.5 w-3.5 animate-spin" />
            ) : (
              <Link2Off className="h-3.5 w-3.5" />
            )}
            Koppla bort Skatteverket
          </Button>
        </div>
      </CardContent>
    </Card>
  )
}