'use client'

import { useMemo, useState, useCallback } from 'react'
import { Card, CardContent, CardHeader, CardTitle, CardDescription } from '@/components/ui/card'
import { Button } from '@/components/ui/button'
import { Input } from '@/components/ui/input'
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select'
import { Switch } from '@/components/ui/switch'
import { Label } from '@/components/ui/label'
import { Trash2, AlertTriangle, Loader2, RefreshCw } from 'lucide-react'
import { cn } from '@/lib/utils'
import type { CustomerType } from '@/types'
import type { AnnotatedCustomerRow } from '@/lib/import/customers/types'

let idCounter = 0
const newId = () => `cust_row_${++idCounter}_${Date.now()}`

interface EditableCustomerRow extends AnnotatedCustomerRow {
  id: string
}

interface CustomersEditStepProps {
  rows: AnnotatedCustomerRow[]
  onExecute: (rows: AnnotatedCustomerRow[], updateDuplicates: boolean) => void
  onBack: () => void
  isLoading: boolean
  error: string | null
}

const TYPE_LABELS: Record<CustomerType, string> = {
  individual: 'Privatperson',
  swedish_business: 'Svenskt företag eller organisation',
  eu_business: 'EU-företag',
  non_eu_business: 'Utomeuropeiskt företag',
}

export default function CustomersEditStep({
  rows: initialRows,
  onExecute,
  onBack,
  isLoading,
  error,
}: CustomersEditStepProps) {
  const [rows, setRows] = useState<EditableCustomerRow[]>(() =>
    initialRows.map((r) => ({ ...r, id: newId() })),
  )
  const [updateDuplicates, setUpdateDuplicates] = useState(false)

  const liveDuplicateCount = useMemo(
    () => rows.filter((r) => r.duplicate_match !== null).length,
    [rows],
  )

  const newCount = rows.length - liveDuplicateCount

  const hasErrors = useMemo(
    () => rows.some((r) => !r.is_valid),
    [rows],
  )

  const canContinue = rows.length > 0 && !hasErrors && !isLoading

  const updateRow = useCallback((id: string, updates: Partial<EditableCustomerRow>) => {
    setRows((prev) =>
      prev.map((r) => (r.id === id ? { ...r, ...updates } : r)),
    )
  }, [])

  const deleteRow = useCallback((id: string) => {
    setRows((prev) => prev.filter((r) => r.id !== id))
  }, [])

  const handleExecute = () => {
    if (!canContinue) return
    const stripped: AnnotatedCustomerRow[] = rows.map(({ id: _id, ...rest }) => rest)
    onExecute(stripped, updateDuplicates)
  }

  return (
    <Card>
      <CardHeader>
        <CardTitle>Granska kunder</CardTitle>
        <CardDescription>
          Kontrollera att uppgifterna stämmer. Du kan justera namn och kundtyp inline,
          eller ta bort rader. {newCount} ny{newCount === 1 ? '' : 'a'} kund{newCount === 1 ? '' : 'er'} skapas
          {liveDuplicateCount > 0 ? ` och ${liveDuplicateCount} matchar befintliga.` : '.'}
        </CardDescription>
      </CardHeader>
      <CardContent className="space-y-4">
        {/* Duplicate handling banner */}
        {liveDuplicateCount > 0 && (
          <div className="flex items-start gap-3 rounded-lg border border-warning/30 bg-warning/5 px-4 py-3">
            <RefreshCw className="h-4 w-4 text-warning mt-0.5 shrink-0" />
            <div className="flex-1 space-y-2">
              <p className="text-sm">
                <span className="font-medium">{liveDuplicateCount} rader</span> matchar befintliga
                kunder (på orgnummer eller e-post).
              </p>
              <div className="flex items-center gap-3">
                <Switch
                  id="update-duplicates"
                  checked={updateDuplicates}
                  onCheckedChange={setUpdateDuplicates}
                />
                <Label htmlFor="update-duplicates" className="text-sm cursor-pointer">
                  {updateDuplicates
                    ? 'Uppdatera befintliga kunder med ny information'
                    : 'Hoppa över befintliga kunder'}
                </Label>
              </div>
              {updateDuplicates && (
                <p className="text-xs text-muted-foreground">
                  Endast fält med värden i filen skrivs över. Tomma fält i filen lämnar
                  befintliga värden orörda.
                </p>
              )}
            </div>
          </div>
        )}

        {/* Table */}
        <div className="overflow-x-auto rounded-md border">
          <table className="w-full text-sm">
            <thead className="[&_th]:font-medium [&_th]:text-[11px] [&_th]:uppercase [&_th]:tracking-wider [&_th]:text-muted-foreground">
              <tr className="border-b">
                <th className="px-3 py-2 text-left">Namn</th>
                <th className="px-3 py-2 text-left w-44">Kundtyp</th>
                <th className="px-3 py-2 text-left w-36">Orgnr</th>
                <th className="px-3 py-2 text-left">E-post</th>
                <th className="px-3 py-2 text-left w-32">Status</th>
                <th className="px-3 py-2 w-10" />
              </tr>
            </thead>
            <tbody>
              {rows.map((row) => (
                <tr
                  key={row.id}
                  className={cn(
                    'border-b last:border-0',
                    !row.is_valid && 'bg-destructive/5',
                  )}
                >
                  <td className="px-3 py-1.5">
                    <Input
                      value={row.name}
                      onChange={(e) => updateRow(row.id, { name: e.target.value })}
                      className="h-8"
                    />
                  </td>
                  <td className="px-3 py-1.5">
                    <Select
                      value={row.customer_type}
                      onValueChange={(v) => updateRow(row.id, { customer_type: v as CustomerType })}
                    >
                      <SelectTrigger className="h-8">
                        <SelectValue />
                      </SelectTrigger>
                      <SelectContent>
                        {(Object.keys(TYPE_LABELS) as CustomerType[]).map((t) => (
                          <SelectItem key={t} value={t}>
                            {TYPE_LABELS[t]}
                          </SelectItem>
                        ))}
                      </SelectContent>
                    </Select>
                  </td>
                  <td className="px-3 py-1.5 text-muted-foreground tabular-nums">
                    {row.org_number || '—'}
                  </td>
                  <td className="px-3 py-1.5 text-muted-foreground truncate max-w-xs">
                    {row.email || '—'}
                  </td>
                  <td className="px-3 py-1.5">
                    <div className="flex items-center gap-1.5">
                      {!row.is_valid && (
                        <span
                          className="text-destructive shrink-0"
                          title={row.validation_errors.join(', ')}
                        >
                          <AlertTriangle className="h-3.5 w-3.5" />
                        </span>
                      )}
                      {row.duplicate_match ? (
                        <span
                          className={cn(
                            'text-[11px] font-medium px-1.5 py-0.5 rounded',
                            updateDuplicates
                              ? 'bg-warning/15 text-warning'
                              : 'bg-muted text-muted-foreground',
                          )}
                          title={`Matchar ${row.duplicate_match.existing_name} (${row.duplicate_match.matched_by})`}
                        >
                          {updateDuplicates ? 'Uppdateras' : 'Hoppas över'}
                        </span>
                      ) : (
                        <span className="text-[11px] font-medium px-1.5 py-0.5 rounded bg-success/15 text-success">
                          Ny
                        </span>
                      )}
                    </div>
                  </td>
                  <td className="px-3 py-1.5">
                    <Button
                      variant="ghost"
                      size="icon"
                      className="h-7 w-7"
                      onClick={() => deleteRow(row.id)}
                    >
                      <Trash2 className="h-3.5 w-3.5 text-muted-foreground" />
                    </Button>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>

        {hasErrors && (
          <div className="flex items-start gap-3 rounded-lg border border-warning/30 bg-warning/5 px-4 py-3">
            <AlertTriangle className="h-4 w-4 text-warning mt-0.5 shrink-0" />
            <p className="text-sm text-warning">
              Vissa rader har valideringsfel (markerade i rött). Åtgärda eller ta bort dem
              innan du fortsätter.
            </p>
          </div>
        )}

        {error && (
          <div className="flex items-start gap-3 rounded-lg border border-destructive/30 bg-destructive/5 px-4 py-3">
            <AlertTriangle className="h-4 w-4 text-destructive mt-0.5 shrink-0" />
            <p className="text-sm text-destructive">{error}</p>
          </div>
        )}

        <div className="flex justify-between pt-2">
          <Button variant="ghost" onClick={onBack} disabled={isLoading}>
            Tillbaka
          </Button>
          <Button onClick={handleExecute} disabled={!canContinue}>
            {isLoading ? (
              <>
                <Loader2 className="h-4 w-4 animate-spin mr-2" />
                Importerar...
              </>
            ) : (
              `Importera ${rows.length} rad${rows.length === 1 ? '' : 'er'}`
            )}
          </Button>
        </div>
      </CardContent>
    </Card>
  )
}