'use client'

import { useState } from 'react'
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
import { Badge } from '@/components/ui/badge'
import { Button } from '@/components/ui/button'
import { Checkbox } from '@/components/ui/checkbox'
import { formatCurrency } from '@/lib/utils'
import {
  Building2,
  Calendar,
  FileText,
  CheckCircle,
  AlertCircle,
  XCircle,
  ArrowRight,
  BarChart3,
  Info,
} from 'lucide-react'
import type { ImportPreview, ParseIssue } from '@/lib/import/types'

interface SIEPreviewStepProps {
  preview: ImportPreview
  issues: ParseIssue[]
  missingAccounts: { number: string; name: string }[]
  onCreateAccounts: () => Promise<void>
  isCreatingAccounts: boolean
  onContinue: () => void
  onBack: () => void
}

export default function SIEPreviewStep({
  preview,
  issues,
  missingAccounts,
  onCreateAccounts,
  isCreatingAccounts,
  onContinue,
  onBack,
}: SIEPreviewStepProps) {
  const errors = issues.filter((i) => i.severity === 'error')
  const warnings = issues.filter((i) => i.severity === 'warning')

  // Opening-balance imbalance. The importer plugs any diff > 0.01 to 2099, but a
  // diff under ~1 SEK is genuine öresavrundning. Anything larger is a real
  // imbalance (incomplete export: missing liabilities / unappropriated prior-year
  // result) that would silently book a bogus amount to 2099. Mirrors the importer's
  // own `fileImbalance > 1.00` "serious" threshold (lib/import/sie-import.ts).
  const ibDiff = Math.round((preview.trialBalance.totalDebit - preview.trialBalance.totalCredit) * 100) / 100
  const significantImbalance = !preview.trialBalance.isBalanced && Math.abs(ibDiff) > 1
  const [ackImbalance, setAckImbalance] = useState(false)

  // Only block on actual parsing errors, not unmapped accounts
  // (users need to proceed to mapping step to fix unmapped accounts).
  // A significant IB imbalance is a soft block: the user must acknowledge it.
  const hasBlockingErrors = errors.length > 0
  const blockContinue = hasBlockingErrors || (significantImbalance && !ackImbalance)

  return (
    <div className="space-y-6">
      {/* Company info */}
      <Card>
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            <Building2 className="h-5 w-5" />
            Företagsinformation
          </CardTitle>
          <CardDescription>Information från SIE-filen</CardDescription>
        </CardHeader>
        <CardContent>
          <div className="grid gap-4 md:grid-cols-2">
            <div>
              <p className="text-sm text-muted-foreground">Företagsnamn</p>
              <p className="font-medium">{preview.companyName || 'Ej angivet'}</p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Organisationsnummer</p>
              <p className="font-medium">{preview.orgNumber || 'Ej angivet'}</p>
            </div>
          </div>
        </CardContent>
      </Card>

      {/* Fiscal year */}
      <Card>
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            <Calendar className="h-5 w-5" />
            Räkenskapsår
          </CardTitle>
        </CardHeader>
        <CardContent>
          <div className="flex items-center gap-4">
            <div>
              <p className="text-sm text-muted-foreground">Start</p>
              <p className="font-medium">
                {preview.fiscalYearStart ?? 'Okänt'}
              </p>
            </div>
            <ArrowRight className="h-4 w-4 text-muted-foreground" />
            <div>
              <p className="text-sm text-muted-foreground">Slut</p>
              <p className="font-medium">
                {preview.fiscalYearEnd ?? 'Okänt'}
              </p>
            </div>
          </div>
        </CardContent>
      </Card>

      {/* Statistics */}
      <div className="grid grid-cols-2 gap-4 md:grid-cols-4">
        <Card>
          <CardContent className="pt-6">
            <div className="flex items-center gap-2 text-muted-foreground mb-1">
              <FileText className="h-4 w-4" />
              <span className="text-sm">Konton</span>
            </div>
            <p className="text-2xl font-display tabular-nums">{preview.accountCount}</p>
          </CardContent>
        </Card>

        <Card>
          <CardContent className="pt-6">
            <div className="flex items-center gap-2 text-muted-foreground mb-1">
              <BarChart3 className="h-4 w-4" />
              <span className="text-sm">Verifikationer</span>
            </div>
            <p className="text-2xl font-display tabular-nums">{preview.voucherCount}</p>
          </CardContent>
        </Card>

        <Card>
          <CardContent className="pt-6">
            <div className="flex items-center gap-2 text-muted-foreground mb-1">
              <span className="text-sm">Transaktionsrader</span>
            </div>
            <p className="text-2xl font-display tabular-nums">{preview.transactionLineCount}</p>
          </CardContent>
        </Card>

        <Card>
          <CardContent className="pt-6">
            <div className="flex items-center gap-2 text-muted-foreground mb-1">
              <span className="text-sm">IB Summa</span>
            </div>
            <p className="text-2xl font-display tabular-nums">{formatCurrency(preview.openingBalanceTotal)}</p>
          </CardContent>
        </Card>
      </div>

      {/* Trial balance check */}
      <Card className={preview.trialBalance.isBalanced ? 'border-success/50' : 'border-warning/50'}>
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            {preview.trialBalance.isBalanced ? (
              <CheckCircle className="h-5 w-5 text-success" />
            ) : (
              <AlertCircle className="h-5 w-5 text-warning" />
            )}
            Balansräkning (IB)
          </CardTitle>
        </CardHeader>
        <CardContent>
          <div className="grid gap-4 md:grid-cols-3">
            <div>
              <p className="text-sm text-muted-foreground">Total debet</p>
              <p className="font-medium">{formatCurrency(preview.trialBalance.totalDebit)}</p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Total kredit</p>
              <p className="font-medium">{formatCurrency(preview.trialBalance.totalCredit)}</p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Status</p>
              {preview.trialBalance.isBalanced ? (
                <Badge variant="success">Balanserar</Badge>
              ) : (
                <Badge variant="secondary">
                  Diff: {formatCurrency(ibDiff)}
                </Badge>
              )}
            </div>
          </div>

          {/* Significant imbalance: explain + require acknowledgement before continuing */}
          {significantImbalance && (
            <div className="mt-4 space-y-3 rounded-lg border border-warning/40 bg-warning/5 px-4 py-3">
              <div className="flex items-start gap-2 text-sm">
                <AlertCircle className="h-4 w-4 text-warning mt-0.5 flex-shrink-0" />
                <div className="space-y-1">
                  <p className="font-medium text-warning">
                    Ingående balanser balanserar inte ({formatCurrency(Math.abs(ibDiff))})
                  </p>
                  <p className="text-muted-foreground">
                    Det betyder oftast att exporten från ditt bokföringssystem är ofullständig:
                    t.ex. att skulder saknas eller att föregående års resultat inte är disponerat.
                    Om du fortsätter bokförs differensen på konto 2099 (Årets resultat), vilket
                    nästan alltid blir fel. Vi rekommenderar att du rättar exporten i källsystemet
                    och laddar upp filen på nytt.
                  </p>
                </div>
              </div>
              <label className="flex items-start gap-2 text-sm cursor-pointer">
                <Checkbox
                  checked={ackImbalance}
                  onCheckedChange={(v) => setAckImbalance(v === true)}
                  className="mt-0.5"
                />
                <span className="text-muted-foreground">
                  Jag förstår att differensen bokförs på 2099 och vill fortsätta ändå.
                </span>
              </label>
            </div>
          )}
        </CardContent>
      </Card>

      {/* Mapping status */}
      <Card
        className={
          preview.mappingStatus.unmapped > 0
            ? 'border-destructive/50'
            : preview.mappingStatus.lowConfidence > 0
            ? 'border-warning/50'
            : 'border-success/50'
        }
      >
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            {preview.mappingStatus.unmapped > 0 ? (
              <XCircle className="h-5 w-5 text-destructive" />
            ) : preview.mappingStatus.lowConfidence > 0 ? (
              <AlertCircle className="h-5 w-5 text-warning" />
            ) : (
              <CheckCircle className="h-5 w-5 text-success" />
            )}
            Kontomappning
          </CardTitle>
          <CardDescription>
            Hur väl kunde kontona i filen matchas mot din kontoplan
          </CardDescription>
        </CardHeader>
        <CardContent>
          <div className="grid grid-cols-2 gap-4 md:grid-cols-4">
            <div>
              <p className="text-sm text-muted-foreground">Totalt</p>
              <p className="font-medium">{preview.mappingStatus.total}</p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Mappade</p>
              <p className="font-medium text-success">{preview.mappingStatus.mapped}</p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Ej mappade</p>
              <p className={`font-medium ${preview.mappingStatus.unmapped > 0 ? 'text-destructive' : ''}`}>
                {preview.mappingStatus.unmapped}
              </p>
            </div>
            <div>
              <p className="text-sm text-muted-foreground">Osäkra</p>
              <p className={`font-medium ${preview.mappingStatus.lowConfidence > 0 ? 'text-warning' : ''}`}>
                {preview.mappingStatus.lowConfidence}
              </p>
            </div>
          </div>
        </CardContent>
      </Card>

      {/* Excluded system accounts info */}
      {preview.excludedSystemAccounts.length > 0 && (
        <div className="flex items-start gap-2 rounded-lg border bg-muted/50 px-4 py-3 text-sm text-muted-foreground">
          <Info className="h-4 w-4 mt-0.5 flex-shrink-0" />
          <span>
            {preview.excludedSystemAccounts.length} internt systemkonto från källsystemet exkluderades ({preview.excludedSystemAccounts.map((a) => a.number).join(', ')}), inte bokföringskonton
          </span>
        </div>
      )}

      {/* Create missing accounts */}
      {missingAccounts.length > 0 ? (
        <Card className="border-primary/50">
          <CardHeader>
            <CardTitle className="flex items-center gap-2">
              <FileText className="h-5 w-5 text-primary" />
              Skapa saknade konton
            </CardTitle>
            <CardDescription>
              {missingAccounts.length} konton från SIE-filen finns inte i din kontoplan ännu.
              Klicka nedan för att skapa dem: de kopplas sedan automatiskt i nästa steg.
            </CardDescription>
          </CardHeader>
          <CardContent>
            <div className="space-y-4">
              <div className="max-h-32 overflow-y-auto text-sm space-y-1">
                {missingAccounts.slice(0, 10).map((acc) => (
                  <div key={acc.number} className="flex gap-2 text-muted-foreground">
                    <span className="font-mono">{acc.number}</span>
                    <span>{acc.name}</span>
                  </div>
                ))}
                {missingAccounts.length > 10 && (
                  <div className="text-muted-foreground">
                    ... och {missingAccounts.length - 10} till
                  </div>
                )}
              </div>
              <Button
                onClick={onCreateAccounts}
                disabled={isCreatingAccounts}
                className="w-full"
              >
                {isCreatingAccounts ? (
                  <>Skapar konton...</>
                ) : (
                  <>Skapa {missingAccounts.length} konton</>
                )}
              </Button>
            </div>
          </CardContent>
        </Card>
      ) : preview.mappingStatus.mapped === preview.mappingStatus.total && preview.mappingStatus.total > 0 && (
        <div className="flex items-center gap-2 rounded-lg border border-success/50 bg-success/5 px-4 py-3 text-sm">
          <CheckCircle className="h-4 w-4 text-success flex-shrink-0" />
          <span>Alla konton skapade och automatiskt kopplade</span>
        </div>
      )}

      {/* Errors */}
      {errors.length > 0 && (
        <Card className="border-destructive/50">
          <CardHeader>
            <CardTitle className="flex items-center gap-2">
              <XCircle className="h-5 w-5 text-destructive" />
              Tolkningsfel ({errors.length})
            </CardTitle>
            <CardDescription>
              Dessa fel hittades under tolkningen av SIE-filen och kan påverka importresultatet.
            </CardDescription>
          </CardHeader>
          <CardContent>
            <div className="space-y-2 max-h-48 overflow-y-auto">
              {errors.map((issue, i) => (
                <div key={`error-${i}`} className="text-sm flex gap-2 text-destructive">
                  <XCircle className="h-4 w-4 flex-shrink-0 mt-0.5" />
                  <span>
                    <span className="font-mono text-xs opacity-70">Rad {issue.line}</span>{' '}
                    {issue.message}
                  </span>
                </div>
              ))}
            </div>
          </CardContent>
        </Card>
      )}

      {/* Warnings */}
      {warnings.length > 0 && (
        <Card className="border-warning/50">
          <CardHeader>
            <CardTitle className="flex items-center gap-2">
              <AlertCircle className="h-5 w-5 text-warning" />
              Varningar ({warnings.length})
            </CardTitle>
            <CardDescription>
              Dessa varningar blockerar inte importen men bör granskas.
            </CardDescription>
          </CardHeader>
          <CardContent>
            <div className="space-y-2 max-h-48 overflow-y-auto">
              {warnings.map((issue, i) => (
                <div key={`warning-${i}`} className="text-sm flex gap-2 text-warning">
                  <AlertCircle className="h-4 w-4 flex-shrink-0 mt-0.5" />
                  <span>
                    <span className="font-mono text-xs opacity-70">Rad {issue.line}</span>{' '}
                    {issue.message}
                  </span>
                </div>
              ))}
            </div>
          </CardContent>
        </Card>
      )}

      {/* Actions */}
      <div className="flex flex-col-reverse gap-3 sm:flex-row sm:justify-between">
        <Button variant="outline" className="min-h-11" onClick={onBack}>
          Tillbaka
        </Button>
        <Button className="min-h-11" onClick={onContinue} disabled={blockContinue}>
          {preview.mappingStatus.lowConfidence > 0 || preview.mappingStatus.unmapped > 0
            ? 'Granska mappningar'
            : 'Fortsätt'}
          <ArrowRight className="ml-2 h-4 w-4" />
        </Button>
      </div>
    </div>
  )
}