'use client'

import { useEffect, useMemo, useState } from 'react'
import { createClient } from '@/lib/supabase/client'

// `createClient()` returns a fresh object on every call, so we keep the
// instance creation inside the effect: listing it as a dep would re-fire
// the fetch on every render and create an infinite loop.
import { Button } from '@/components/ui/button'
import { Input } from '@/components/ui/input'
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription } from '@/components/ui/dialog'
import { useCompany } from '@/contexts/CompanyContext'
import { formatCurrency, formatDate } from '@/lib/utils'
import { Loader2, Search, ArrowDownRight } from 'lucide-react'

interface BankTransaction {
  id: string
  date: string
  description: string
  amount: number
  currency: string
}

interface BankTransactionPickerProps {
  open: boolean
  onOpenChange: (open: boolean) => void
  /** Invoice total in invoice currency. Used to rank transactions by amount proximity. */
  targetAmount: number
  /** Invoice currency. Used to filter the candidate list when set. */
  targetCurrency: string
  onPick: (transactionId: string) => void
}

/**
 * Lightweight picker for unmatched outgoing bank transactions. Used by
 * `/supplier-invoices/new` when the user wants to register an invoice and
 * mark it paid against a specific bank transaction in one go.
 *
 * Filters: negative amount, no journal entry, no supplier_invoice link.
 * Ranks by absolute amount-difference vs `targetAmount`.
 */
export default function BankTransactionPicker({
  open,
  onOpenChange,
  targetAmount,
  targetCurrency,
  onPick,
}: BankTransactionPickerProps) {
  const { company } = useCompany()
  const [transactions, setTransactions] = useState<BankTransaction[]>([])
  const [isLoading, setIsLoading] = useState(false)
  const [searchTerm, setSearchTerm] = useState('')

  useEffect(() => {
    if (!open || !company) return
    let cancelled = false
    const supabase = createClient()

    ;(async () => {
      setIsLoading(true)
      // No strict currency filter: the bank transaction that pays a
      // foreign-currency invoice is almost always in the company's domestic
      // currency (e.g. SEK bank account paying a USD invoice). The user
      // would see "no matches" if we filtered to the invoice currency.
      // Cross-currency amount diff is hidden in the row below so the user
      // isn't shown a misleading "Diff X kr" against a USD target.
      const { data, error } = await supabase
        .from('transactions')
        .select('id, date, description, amount, currency')
        .eq('company_id', company.id)
        .lt('amount', 0)
        .is('journal_entry_id', null)
        .is('supplier_invoice_id', null)
        .is('invoice_id', null)
        .order('date', { ascending: false })
        .limit(200)

      if (!cancelled) {
        if (!error) setTransactions(data || [])
        setIsLoading(false)
      }
    })()

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

  const filtered = useMemo(() => {
    const term = searchTerm.trim().toLowerCase()
    const matches = transactions.filter((t) =>
      term === '' ? true : (t.description || '').toLowerCase().includes(term),
    )
    // Rank by amount proximity only when currencies match: comparing a USD
    // target to a SEK transaction numerically would produce a meaningless
    // ranking. Cross-currency rows fall back to date-desc order.
    return matches.sort((a, b) => {
      const aSame = a.currency === targetCurrency
      const bSame = b.currency === targetCurrency
      if (aSame !== bSame) return aSame ? -1 : 1
      if (!aSame) return 0
      const da = Math.abs(Math.abs(a.amount) - targetAmount)
      const db = Math.abs(Math.abs(b.amount) - targetAmount)
      return da - db
    })
  }, [transactions, searchTerm, targetAmount, targetCurrency])

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent className="sm:max-w-2xl max-h-[90vh] flex flex-col">
        <DialogHeader>
          <DialogTitle>Välj banktransaktion</DialogTitle>
          <DialogDescription>
            Välj den utgående banktransaktion som motsvarar denna faktura. Fakturan registreras och markeras som betald i ett steg.
          </DialogDescription>
        </DialogHeader>

        <div className="relative">
          <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
          <Input
            autoFocus
            placeholder="Sök på beskrivning..."
            value={searchTerm}
            onChange={(e) => setSearchTerm(e.target.value)}
            className="pl-10"
          />
        </div>

        <div className="flex-1 overflow-y-auto space-y-2 -mx-1 px-1">
          {isLoading ? (
            <div className="flex items-center justify-center py-12 text-sm text-muted-foreground">
              <Loader2 className="h-4 w-4 animate-spin mr-2" />
              Laddar transaktioner…
            </div>
          ) : filtered.length === 0 ? (
            <div className="flex flex-col items-center justify-center py-12 text-sm text-muted-foreground">
              <ArrowDownRight className="h-8 w-8 mb-2" />
              {transactions.length === 0
                ? 'Inga okategoriserade utgifts­transaktioner hittades.'
                : `Inga transaktioner matchar "${searchTerm}".`}
            </div>
          ) : (
            filtered.map((tx) => {
              const sameCurrency = tx.currency === targetCurrency
              const absAmount = Math.abs(tx.amount)
              const diff = sameCurrency ? Math.abs(absAmount - targetAmount) : null
              const isExact = diff != null && diff < 0.01
              return (
                <button
                  key={tx.id}
                  type="button"
                  onClick={() => onPick(tx.id)}
                  className="w-full text-left rounded-lg border p-3 hover:border-primary/50 hover:bg-muted/30 transition-colors"
                >
                  <div className="flex items-start justify-between gap-3">
                    <div className="min-w-0">
                      <p className="font-medium truncate">{tx.description}</p>
                      <p className="text-xs text-muted-foreground">{formatDate(tx.date)}</p>
                    </div>
                    <div className="text-right shrink-0">
                      <p className="font-mono font-medium tabular-nums text-destructive">
                        {formatCurrency(tx.amount, tx.currency)}
                      </p>
                      {isExact ? (
                        <p className="text-xs text-success">Belopp matchar</p>
                      ) : diff != null && targetAmount > 0 ? (
                        <p className="text-xs text-muted-foreground">
                          Diff {formatCurrency(diff, tx.currency)}
                        </p>
                      ) : !sameCurrency ? (
                        <p className="text-xs text-muted-foreground">
                          Annan valuta
                        </p>
                      ) : null}
                    </div>
                  </div>
                </button>
              )
            })
          )}
        </div>

        <div className="flex justify-end pt-2">
          <Button variant="outline" onClick={() => onOpenChange(false)}>
            Avbryt
          </Button>
        </div>
      </DialogContent>
    </Dialog>
  )
}