'use client'

import { useState, useEffect, useCallback } from 'react'
import { useRouter } from 'next/navigation'
import { useTranslations } from 'next-intl'
import { Badge } from '@/components/ui/badge'
import { Button } from '@/components/ui/button'
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription } from '@/components/ui/dialog'
import { useToast } from '@/components/ui/use-toast'
import { ToastAction } from '@/components/ui/toast'
import { formatCurrency, formatDate } from '@/lib/utils'
import { linkDocuments, formatFailedDocumentNames } from '@/lib/documents/link-documents'
import { ArrowUpRight, ArrowDownRight, Check, Paperclip, ChevronDown, ChevronUp, AlertTriangle } from 'lucide-react'
import { getDefaultAccountForCategory } from '@/lib/bookkeeping/category-mapping'
import { isCounterpartyTemplateId } from '@/lib/bookkeeping/counterparty-templates'
import { getVatRate } from '@/lib/bookkeeping/vat-entries'
import type { ReviewTemplate } from '@/lib/transactions/quick-review-defaults'
import { resolveExplicitVat } from '@/lib/transactions/quick-review-defaults'
import { resolveSekAmount } from '@/lib/bookkeeping/currency-utils'
import { formatAccountWithName } from '@/lib/bookkeeping/client-account-names'
import JournalEntryPreview from './JournalEntryPreview'
import AccountCombobox from '@/components/bookkeeping/AccountCombobox'
import LineDimensionFields from '@/components/dimensions/LineDimensionFields'
import DocumentUploadZone from '@/components/bookkeeping/DocumentUploadZone'
import DocumentViewerPane from '@/components/bookkeeping/DocumentViewerPane'
import type { UploadedFile } from '@/components/bookkeeping/DocumentUploadZone'
import VatTreatmentSelect from './VatTreatmentSelect'
import { VAT_TREATMENT_OPTIONS } from './transaction-types'
import type { TransactionWithInvoice } from './transaction-types'
import type { TransactionCategory, VatTreatment, BASAccount, EntityType, LinePatternEntry } from '@/types'
import { getErrorMessage as getUserErrorMessage } from '@/lib/errors/get-error-message'

interface QuickReviewDialogProps {
  open: boolean
  onOpenChange: (open: boolean) => void
  transaction: TransactionWithInvoice | null
  category: TransactionCategory | null
  categoryLabel: string
  /** Empty string when there is no sensible default: never undefined. */
  defaultAccount: string
  defaultVat: VatTreatment | 'none'
  entityType?: EntityType
  template?: ReviewTemplate | null
  templateId?: string
  counterpartyLinePattern?: LinePatternEntry[] | null
  /**
   * Learned bag from the counterparty template (default_dimensions): prefills
   * the picker so the user sees, and can change, what the booking will be
   * tagged with.
   */
  counterpartyDefaultDimensions?: Record<string, string> | null
  onConfirm: (
    id: string,
    category: TransactionCategory,
    vatTreatment: VatTreatment | undefined,
    accountOverride: string | undefined,
    templateId?: string,
    dimensions?: Record<string, string>
  ) => Promise<string | null>
  onChangeTemplate?: () => void
}

export default function QuickReviewDialog({
  open,
  onOpenChange,
  transaction,
  category,
  categoryLabel,
  defaultAccount,
  defaultVat,
  entityType,
  template,
  templateId,
  counterpartyLinePattern,
  counterpartyDefaultDimensions,
  onConfirm,
  onChangeTemplate,
}: QuickReviewDialogProps) {
  const t = useTranslations('tx_quick_review')
  const tCat = useTranslations('tx_categories')
  const { toast } = useToast()
  const router = useRouter()
  // `?? ''` is deliberate belt-and-braces: the prop is a required string, but
  // a caller that hands over a template-shaped object missing debit_account
  // used to make this undefined and take the whole page down on the
  // .startsWith() below. An empty account disables the confirm button; it
  // never throws.
  const [accountOverride, setAccountOverride] = useState(defaultAccount ?? '')
  const [vatTreatment, setVatTreatment] = useState<VatTreatment | 'none'>(defaultVat)
  const [accounts, setAccounts] = useState<BASAccount[]>([])
  const [isProcessing, setIsProcessing] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [uploadedFiles, setUploadedFiles] = useState<UploadedFile[]>([])
  const [showUploadZone, setShowUploadZone] = useState(false)
  const [showVatDropdown, setShowVatDropdown] = useState(false)
  // Mirror of `transaction` so we can patch in a freshly-fetched SEK conversion
  // before the user confirms: the verifikation must always be in SEK and the
  // engine reads these fields straight off the transaction row.
  const [enrichedTx, setEnrichedTx] = useState<TransactionWithInvoice | null>(transaction)
  const [rateLoading, setRateLoading] = useState(false)
  const [rateError, setRateError] = useState<string | null>(null)
  // Dimension tagging (kostnadsställe/projekt): the picker renders only when
  // company_settings.dimensions_enabled, same gate as BulkBookDialog. Seeded
  // from the counterparty template's learned bag so the user sees what the
  // booking will carry and can change it.
  const [dimensionsEnabled, setDimensionsEnabled] = useState(false)
  const [dims, setDims] = useState<Record<string, string>>(
    () => ({ ...(counterpartyDefaultDimensions ?? {}) }),
  )

  const preAttachedDocumentId = transaction?.document_id ?? null

  // Handle account changes: clear VAT for liability/equity accounts (class 2)
  const handleAccountChange = useCallback((account: string) => {
    setAccountOverride(account ?? '')
    if (account?.startsWith('2')) {
      setVatTreatment('none')
    }
  }, [])

  // Fetch accounts on mount
  useEffect(() => {
    async function fetchAccounts() {
      try {
        const res = await fetch('/api/bookkeeping/accounts')
        const { data } = await res.json()
        if (data) {
          setAccounts(data)
        }
      } catch {
        // Non-critical
      }
    }
    fetchAccounts()
  }, [])

  // Reset local mirror whenever the underlying transaction changes (the parent
  // reuses the dialog instance across rows).
  useEffect(() => {
    setEnrichedTx(transaction)
    setRateError(null)
    setDims({ ...(counterpartyDefaultDimensions ?? {}) })
    // Re-seeding on counterpartyDefaultDimensions alone would clobber in-
    // flight edits; the bag only changes together with the transaction.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [transaction])

  // Company settings gate the dimension affordance (dimensions_enabled).
  // Fetched once per open; on failure the picker simply stays hidden.
  useEffect(() => {
    if (!open) return
    let cancelled = false
    fetch('/api/settings')
      .then((r) => r.json())
      .then(({ data }) => {
        if (!cancelled) setDimensionsEnabled(data?.dimensions_enabled === true)
      })
      .catch(() => {
        if (!cancelled) setDimensionsEnabled(false)
      })
    return () => { cancelled = true }
  }, [open])

  // Backfill the SEK conversion on demand. resolveSekAmount silently falls
  // back to the raw foreign amount when amount_sek/exchange_rate are null,
  // which means the user would see misleading "kr" values in the verifikation
  // and the engine would post the wrong number to the books.
  useEffect(() => {
    if (!open || !transaction) return
    const needsRate =
      !!transaction.currency &&
      transaction.currency !== 'SEK' &&
      (transaction.amount_sek == null || transaction.exchange_rate == null)
    if (!needsRate) return

    let cancelled = false
    setRateLoading(true)
    setRateError(null)
    ;(async () => {
      try {
        const res = await fetch(`/api/transactions/${transaction.id}/refresh-exchange-rate`, {
          method: 'POST',
        })
        const json = await res.json()
        if (cancelled) return
        if (!res.ok) {
          setRateError(getUserErrorMessage(json?.error) || t('exchange_rate_fetch_failed'))
          return
        }
        if (json?.data) {
          setEnrichedTx({ ...json.data, ...{
            potential_invoice: transaction.potential_invoice,
            potential_supplier_invoice: transaction.potential_supplier_invoice,
          } })
        }
      } catch {
        if (!cancelled) setRateError(t('exchange_rate_fetch_failed'))
      } finally {
        if (!cancelled) setRateLoading(false)
      }
    })()

    return () => {
      cancelled = true
    }
  }, [open, transaction, t])

  if (!transaction || !category) return null

  const tx = enrichedTx ?? transaction
  const isIncome = tx.amount > 0
  // Keyed off the template ID, not off the presence of a line pattern: a
  // *learned* counterparty (one business line, no pattern) is still booked
  // server-side from counterparty_template_id, so its accounts and VAT come
  // from the stored template. Deciding this from counterparties that happen
  // to have a multi-line pattern made single-line ones fall through to the
  // category branch, which previewed the wrong accounts and offered an
  // account/VAT editor whose values the categorize route discards.
  const isCounterpartyTemplate = !!template?.id && isCounterpartyTemplateId(template.id)
  const hasCounterpartyPattern = !!(counterpartyLinePattern && counterpartyLinePattern.length > 0)
  const isTemplateBooking = !!templateId || isCounterpartyTemplate
  const isLiabilityAccount = accountOverride?.startsWith('2') ?? false
  // For non-SEK transactions, the verifikation and the headline must show
  // the SEK-converted total: the mall/category booking always posts in SEK.
  const sekAmount = resolveSekAmount(
    tx.amount,
    tx.amount_sek,
    tx.currency,
    tx.exchange_rate
  )
  const isForeign = !!(tx.currency && tx.currency !== 'SEK')
  const sekConversionMissing = isForeign && (tx.amount_sek == null || tx.exchange_rate == null)

  // Dimensions carried by the counterparty template's line pattern (dimensions
  // PR7). Business lines may each carry a {sie_dim_no: code} bag: merge them
  // into one compact display label ("KS01 · P001", dim-number order). This is
  // display-only: booking applies the pattern's bags server-side.
  const patternDims: Record<string, string> = {}
  for (const line of counterpartyLinePattern ?? []) {
    if (line.dimensions) Object.assign(patternDims, line.dimensions)
  }
  const patternDimsLabel = Object.entries(patternDims)
    .filter(([, code]) => code)
    .sort(([a], [b]) => Number(a) - Number(b))
    .map(([, code]) => code)
    .join(' · ')

  async function handleConfirm() {
    if (!category || !transaction) return

    setIsProcessing(true)
    setError(null)
    try {
      // 'none' as the seeded default stays off the wire (server derives, no
      // VAT line); 'none' as a user deviation goes as explicit 'exempt'. The
      // old unconditional collapse re-derived the default server-side and
      // booked 25% moms against an explicit "Ingen moms" while the preview
      // showed none. See resolveExplicitVat.
      const resolvedVat = resolveExplicitVat(vatTreatment, defaultVat)
      const catDefault = getDefaultAccountForCategory(category)
      const override = accountOverride && accountOverride !== catDefault
        ? accountOverride
        : undefined

      // Cleared combobox values leave empty strings behind; strip them so an
      // untouched picker sends no bag at all (learned template bags then apply
      // server-side unchanged).
      const cleanedDims = Object.fromEntries(
        Object.entries(dims).filter(([, code]) => code && code.trim().length > 0),
      )
      const journalEntryId = await onConfirm(
        transaction.id,
        category,
        resolvedVat,
        override,
        templateId,
        Object.keys(cleanedDims).length > 0 ? cleanedDims : undefined,
      )

      // Attach the uploaded underlag to the verifikat the booking just created.
      // BFL 5 kap 7 § requires the verifikation to reference its underlag and
      // BFL 7 kap requires that underlag to be archived with it; the verifikat
      // is already committed here, so a failed link can only be reported, not
      // undone. The parent's "Bokförd" toast must not be the last word when a
      // receipt never made it onto the books.
      if (journalEntryId && uploadedFiles.length > 0) {
        const targets = uploadedFiles
          .filter((f) => f.status === 'uploaded' && f.id)
          .map((f) => ({ documentId: f.id as string, fileName: f.fileName }))
        const { failed } = await linkDocuments(targets, journalEntryId)
        if (failed.length > 0) {
          toast({
            title: t('doc_link_failed_booked_title'),
            description: t('doc_link_failed_booked_description', {
              count: failed.length,
              files: formatFailedDocumentNames(failed),
            }),
            variant: 'destructive',
            action: (
              <ToastAction
                altText={t('doc_link_open_entry')}
                onClick={() => router.push(`/bookkeeping/${journalEntryId}`)}
              >
                {t('doc_link_open_entry')}
              </ToastAction>
            ),
          })
          // By this point the parent has already closed the dialog (onConfirm
          // resolved before linkDocuments did), so this component's file state
          // is invisible either way: the toast above, with its open-entry
          // action, is the user's actual pointer to the underlag that did not
          // attach. The early return just skips the redundant cleanup below.
          return
        }
      }

      setUploadedFiles([])
      setShowUploadZone(false)
    } catch {
      setError(t('generic_error'))
    } finally {
      // Always reset isProcessing: without this, an onConfirm that resolves
      // with null (e.g. server returned a structured 4xx error like
      // ACCOUNTS_NOT_IN_CHART) leaves the dialog frozen because the
      // <Dialog onOpenChange> below disables backdrop/ESC while processing.
      setIsProcessing(false)
    }
  }

  return (
    <Dialog open={open} onOpenChange={isProcessing ? undefined : (o) => {
      if (!o) {
        setUploadedFiles([])
        setShowUploadZone(false)
      }
      onOpenChange(o)
    }}>
      <DialogContent className={preAttachedDocumentId ? 'max-w-6xl max-h-[90vh] overflow-y-auto' : 'max-w-md sm:max-w-lg max-h-[85vh] overflow-y-auto'}>
        <DialogHeader>
          <DialogTitle>{t('title')}</DialogTitle>
          <DialogDescription>
            {isTemplateBooking ? t('description_template') : t('description_default')}
          </DialogDescription>
        </DialogHeader>

        {/* When a document is pre-attached, show it side-by-side (receipt left,
            review right). With no document the wrappers use display:contents so
            the dialog collapses to the original single-column layout. */}
        <div className={preAttachedDocumentId ? 'grid grid-cols-1 gap-6 lg:grid-cols-[minmax(0,1fr)_minmax(0,520px)]' : 'contents'}>
          {preAttachedDocumentId && (
            <div className="h-[45vh] lg:sticky lg:top-0 lg:h-[72vh] lg:self-start">
              <DocumentViewerPane documentId={preAttachedDocumentId} className="h-full" />
            </div>
          )}
          <div className={preAttachedDocumentId ? 'space-y-4' : 'contents'}>

        {/* Transaction summary */}
        <div className="flex items-center gap-3 rounded-lg border p-3">
          <div
            className={`h-9 w-9 rounded-full flex items-center justify-center flex-shrink-0 ${isIncome ? 'text-success' : 'text-destructive'}`}
          >
            {isIncome ? (
              <ArrowUpRight className="h-4 w-4" />
            ) : (
              <ArrowDownRight className="h-4 w-4" />
            )}
          </div>
          <div className="flex-1 min-w-0">
            <p className="font-medium text-sm break-all">{tx.description}</p>
            <p className="text-xs text-muted-foreground">{formatDate(tx.date)}</p>
          </div>
          <div className="text-right flex-shrink-0">
            {isForeign ? (
              <>
                <p className={`font-medium text-sm tabular-nums ${isIncome ? 'text-success' : ''}`}>
                  {isIncome ? '+' : ''}
                  {formatCurrency(tx.amount, tx.currency)}
                </p>
                <p className="text-xs text-muted-foreground tabular-nums">
                  {rateLoading || sekConversionMissing
                    ? t('amount_loading')
                    : t('amount_approx', { sign: isIncome ? '+' : '', sek: formatCurrency(sekAmount, 'SEK') })}
                </p>
              </>
            ) : (
              <p className={`font-medium text-sm tabular-nums ${isIncome ? 'text-success' : ''}`}>
                {isIncome ? '+' : ''}
                {formatCurrency(sekAmount, 'SEK')}
              </p>
            )}
          </div>
        </div>

        {isForeign && tx.exchange_rate != null && tx.exchange_rate_date && !sekConversionMissing && (
          <p className="text-xs text-muted-foreground -mt-1">
            {t('rate_footnote', {
              rate: formatCurrency(tx.exchange_rate, 'SEK'),
              currency: tx.currency,
              date: formatDate(tx.exchange_rate_date),
            })}
          </p>
        )}

        {rateError && (
          <div className="rounded-lg border border-destructive/30 bg-destructive/[0.05] px-3 py-2">
            <p className="text-xs text-destructive leading-snug">{rateError}</p>
          </div>
        )}

        {/* Template or Category */}
        <div>
          <label className="text-sm font-medium text-muted-foreground">
            {isCounterpartyTemplate ? t('label_counterparty_template') : template ? t('label_template') : t('label_category')}
          </label>
          <div className="mt-1 flex items-center gap-2">
            <span className="text-sm font-medium text-foreground">
              {template ? template.name_sv : categoryLabel}
            </span>
            {patternDimsLabel && (
              <Badge variant="secondary" className="font-mono tabular-nums">
                {patternDimsLabel}
              </Badge>
            )}
            {onChangeTemplate && !hasCounterpartyPattern && (
              <button
                type="button"
                className="text-xs text-primary hover:underline"
                onClick={onChangeTemplate}
              >
                {t('change_template')}
              </button>
            )}
          </div>
          {/* Only when there IS a single debit/credit pair to show: a
              multi-line counterparty pattern has none, and a template that
              never carried accounts would render "D:  → K: ". */}
          {!hasCounterpartyPattern && template?.debit_account && template?.credit_account && (
            <p className="mt-1.5 text-xs font-mono text-muted-foreground">
              D: {formatAccountWithName(template.debit_account)} → K: {formatAccountWithName(template.credit_account)}
            </p>
          )}
        </div>

        {/* Template special rules */}
        {template?.special_rules_sv && (
          <div className="rounded-lg border border-warning/30 bg-warning/[0.03] px-3 py-2">
            <p className="text-xs text-warning-foreground leading-snug">
              {template.special_rules_sv}
            </p>
          </div>
        )}

        {/* Deductibility note */}
        {template?.deductibility_note_sv && (
          <div className="rounded-lg border border-primary/20 bg-primary/[0.03] px-3 py-2">
            <p className="text-xs text-foreground leading-snug">
              {template.deductibility_note_sv}
            </p>
          </div>
        )}

        {/* Reverse charge warning */}
        {template?.requires_vat_registration_data && (
          <div className="rounded-lg border border-warning/30 bg-warning/[0.03] px-3 py-2">
            <div className="flex items-start gap-2">
              <AlertTriangle className="h-3.5 w-3.5 text-warning-foreground flex-shrink-0 mt-0.5" />
              <p className="text-xs text-warning-foreground leading-snug">
                {t('reverse_charge_warning')}
              </p>
            </div>
          </div>
        )}

        {/* Journal entry preview: hidden until we have a SEK conversion;
            otherwise we'd render a verifikation in the wrong currency. */}
        {!sekConversionMissing && !rateLoading && (
          <JournalEntryPreview
            amount={tx.amount}
            amountSek={sekAmount}
            {...(hasCounterpartyPattern
              ? { linePattern: counterpartyLinePattern ?? undefined }
              : isTemplateBooking && template?.debit_account && template?.credit_account
                ? {
                    templateDebitAccount: template.debit_account,
                    templateCreditAccount: template.credit_account,
                    // A counterparty template carries a treatment but no rate,
                    // and its legacy booking path emits an input-VAT leg from
                    // that treatment only (no basbelopp pair), so it gets the
                    // rate alone: passing the treatment too would preview
                    // reverse-charge lines the engine never books.
                    templateVatRate: isCounterpartyTemplate
                      ? (template.vat_treatment ? getVatRate(template.vat_treatment) : 0)
                      : template.vat_rate,
                    ...(isCounterpartyTemplate
                      ? {}
                      : {
                          templateVatTreatment: template.vat_treatment,
                          templateSupplierType: template.reverse_charge_supplier_type,
                        }),
                  }
                : { category, vatTreatment: isLiabilityAccount ? 'none' : vatTreatment, accountOverride, entityType }
            )}
          />
        )}

        {/* Account & VAT: hidden for template bookings (accounts defined by the template) */}
        {!isTemplateBooking && (
          <>
            <div>
              <label className="text-sm font-medium text-muted-foreground">{t('label_account')}</label>
              <div className="mt-1">
                <AccountCombobox
                  value={accountOverride}
                  accounts={accounts}
                  onChange={handleAccountChange}
                />
              </div>
            </div>

            <div>
              <label className="text-sm font-medium text-muted-foreground">{t('label_vat_treatment')}</label>
              <div className="mt-1">
                {isLiabilityAccount ? (
                  <p className="text-sm text-muted-foreground">
                    {t('no_vat_liability_account')}
                  </p>
                ) : showVatDropdown ? (
                  <VatTreatmentSelect
                    value={vatTreatment}
                    onValueChange={setVatTreatment}
                  />
                ) : (
                  <p className="text-sm">
                    {(() => {
                      const opt = VAT_TREATMENT_OPTIONS.find(o => o.value === vatTreatment)
                      return opt ? tCat(opt.labelKey) : t('no_vat_default')
                    })()}
                    {' '}
                    <button
                      type="button"
                      className="text-xs text-primary hover:underline"
                      onClick={() => setShowVatDropdown(true)}
                    >
                      {t('change')}
                    </button>
                  </p>
                )}
              </div>
            </div>
          </>
        )}

        {/* Dimension tags (kostnadsställe/projekt): rendered for category,
            library-template and legacy counterparty bookings. Multi-line
            counterparty patterns are excluded: their per-line bags are
            authoritative server-side and an edit here would be ignored. */}
        {dimensionsEnabled && !hasCounterpartyPattern && (
          <div>
            <label className="text-sm font-medium text-muted-foreground">{t('label_dimensions')}</label>
            <div className="mt-1">
              <LineDimensionFields
                dimensions={dims}
                onChange={(sieDimNo, code) => {
                  setDims((prev) => {
                    const next = { ...prev }
                    if (code) next[sieDimNo] = code
                    else delete next[sieDimNo]
                    return next
                  })
                }}
                inputClassName="h-8"
              />
            </div>
          </div>
        )}

        {/* No pre-attached document: let the user upload one. (When a document
            IS pre-attached it's shown in the left preview column instead.) */}
        {!preAttachedDocumentId && (
          <div className="rounded-lg border">
            <button
              type="button"
              onClick={() => setShowUploadZone(!showUploadZone)}
              className="flex items-center justify-between w-full px-3 py-2.5 text-sm hover:bg-muted/50 transition-colors"
            >
              <div className="flex items-center gap-2">
                <Paperclip className="h-4 w-4 text-muted-foreground" />
                <span className="font-medium">{t('doc_label')}</span>
                {uploadedFiles.filter((f) => f.status === 'uploaded').length > 0 && (
                  <span className="text-xs text-muted-foreground">
                    {t('doc_attached_count', { count: uploadedFiles.filter((f) => f.status === 'uploaded').length })}
                  </span>
                )}
              </div>
              {showUploadZone ? (
                <ChevronUp className="h-4 w-4 text-muted-foreground" />
              ) : (
                <ChevronDown className="h-4 w-4 text-muted-foreground" />
              )}
            </button>
            {showUploadZone && (
              <div className="px-3 pb-3">
                <DocumentUploadZone
                  files={uploadedFiles}
                  onFilesChange={setUploadedFiles}
                  compact
                />
              </div>
            )}
          </div>
        )}

        {error && (
          <div className="p-3 rounded-lg bg-destructive/10 text-destructive text-sm">
            {error}
          </div>
        )}

        {/* Actions */}
        <div className="flex gap-2 pt-2">
          <Button
            variant="outline"
            className="flex-1"
            onClick={() => onOpenChange(false)}
            disabled={isProcessing}
          >
            {t('cancel')}
          </Button>
          <Button
            className="flex-1"
            onClick={handleConfirm}
            disabled={
              isProcessing ||
              (!isTemplateBooking && !accountOverride) ||
              rateLoading ||
              sekConversionMissing
            }
          >
            <Check className="mr-2 h-4 w-4" />
            {isProcessing ? t('booking') : rateLoading ? t('fetching_rate') : t('book')}
          </Button>
        </div>
          </div>
        </div>
      </DialogContent>
    </Dialog>
  )
}