// Skonto wird an der Bankzuordnung gespeichert (cashDiscountAmount, gleiches Vorzeichen wie amount).
// Zahlbetrag und Skonto gleichen den Beleg gemeinsam aus; der Bankumsatz selbst enthält nur amount.

export const CASH_DISCOUNT_RATES = ["19", "7", "0"] as const

export const DEFAULT_CASH_DISCOUNT_ACCOUNTS = {
    received: { "19": "3736", "7": "3731", "0": "3730" },
    granted: { "19": "8736", "7": "8731", "0": "8730" },
}

export const getAllocationCashDiscount = (allocation: any) => Number(allocation?.cashDiscountAmount || 0)

export const getAllocationSettledAmount = (allocation: any) =>
    Number(allocation?.amount || 0) + getAllocationCashDiscount(allocation)

export const sumSettledAllocations = (allocations: any[] = []) =>
    (allocations || []).reduce((sum, allocation) => sum + getAllocationSettledAmount(allocation), 0)

export const hasCashDiscount = (allocation: any) =>
    !allocation?.archived && Array.isArray(allocation?.cashDiscountSplit) && allocation.cashDiscountSplit.length > 0

// Steuerkorrektur nach § 17 UStG im Zeitraum der Zahlung.
// Ausgangsbelege mindern die Umsatzsteuer, Eingangsbelege die Vorsteuer (Vorzeichen aus der Zahlung).
export function getCashDiscountTaxBreakdown(allocation: any) {
    const output = { net19: 0, tax19: 0, net7: 0, tax7: 0, net0: 0 }
    const input = { ...output }
    if (!hasCashDiscount(allocation)) return { output, input }

    const isOutgoing = Boolean(allocation.createddocument || allocation.cd_id)
    const target = isOutgoing ? output : input
    const sign = isOutgoing ? -1 : 1

    for (const item of allocation.cashDiscountSplit) {
        const net = Number(item?.net || 0) * sign
        const tax = Number(item?.tax || 0) * sign
        if (Number(item?.rate) === 19) {
            target.net19 += net
            target.tax19 += tax
        } else if (Number(item?.rate) === 7) {
            target.net7 += net
            target.tax7 += tax
        } else {
            target.net0 += net
        }
    }
    return { output, input }
}

export const resolveCashDiscountAccounts = (config: any) => {
    const result = {
        received: { ...DEFAULT_CASH_DISCOUNT_ACCOUNTS.received },
        granted: { ...DEFAULT_CASH_DISCOUNT_ACCOUNTS.granted },
    }
    for (const side of ["received", "granted"] as const) {
        for (const rate of CASH_DISCOUNT_RATES) {
            const value = config?.[side]?.[rate]
            if (value !== undefined && value !== null && String(value).trim()) result[side][rate] = String(value).trim()
        }
    }
    return result
}

// ---------------------------------------------------------------------------
// Skonto-Bedingungen auf Belegen (gleiche Logik wie backend/src/modules/cash-discount.ts)
// ---------------------------------------------------------------------------

const roundMoney = (value: number) => Number(value.toFixed(2))
const formatEuro = (value: number) => new Intl.NumberFormat("de-DE", { style: "currency", currency: "EUR" }).format(value)
const formatGermanDate = (value: string) => {
    const [year, month, day] = value.split("-")
    return `${day}.${month}.${year}`
}

const addDays = (date: any, days: number) => {
    if (!date) return null
    const iso = typeof date === "string" ? date.slice(0, 10) : new Date(date?.toISOString?.() || date).toISOString().slice(0, 10)
    const parsed = new Date(`${iso}T00:00:00Z`)
    if (Number.isNaN(parsed.getTime())) return null
    parsed.setUTCDate(parsed.getUTCDate() + days)
    return parsed.toISOString().slice(0, 10)
}

export function buildCashDiscountTerms({ percent, days, documentDate, dueDate, amount }: any) {
    const normalizedPercent = Number(percent)
    if (!Number.isFinite(normalizedPercent) || normalizedPercent <= 0 || !Number.isFinite(Number(amount)) || !Number(amount)) return null
    const normalizedDays = days === null || days === undefined || days === "" ? null : Number(days)
    const computedDueDate = dueDate
        ? String(dueDate).slice(0, 10)
        : normalizedDays !== null && Number.isFinite(normalizedDays) ? addDays(documentDate, normalizedDays) : null
    const discount = roundMoney(Number(amount) * normalizedPercent / 100)
    return {
        percent: normalizedPercent,
        days: normalizedDays !== null && Number.isFinite(normalizedDays) ? normalizedDays : null,
        dueDate: computedDueDate,
        discount,
        payable: roundMoney(Number(amount) - discount),
    }
}

export function formatCashDiscountText(terms: any) {
    if (!terms) return ""
    const percent = String(terms.percent).replace(".", ",")
    const deadline = terms.dueDate
        ? `bis zum ${formatGermanDate(terms.dueDate)}`
        : terms.days !== null ? `innerhalb von ${terms.days} Tagen` : "bei sofortiger Zahlung"
    return `Bei Zahlung ${deadline} gewähren wir ${percent} % Skonto (${formatEuro(Math.abs(terms.discount))}), Zahlbetrag ${formatEuro(Math.abs(terms.payable))}.`
}

export function getCashDiscountTemplateContext(terms: any) {
    if (!terms) return {}
    return {
        skonto_prozent: String(terms.percent).replace(".", ","),
        skonto_tage: terms.days,
        skonto_datum: terms.dueDate ? formatGermanDate(terms.dueDate) : null,
        skonto_betrag: formatEuro(Math.abs(terms.discount)),
        zahlbetrag_mit_skonto: formatEuro(Math.abs(terms.payable)),
        skonto_hinweis: formatCashDiscountText(terms),
    }
}

export function appendCashDiscountText(renderedText: string, template: string | null | undefined, terms: any) {
    if (!terms || /skonto_/i.test(String(template || ""))) return renderedText
    const sentence = formatCashDiscountText(terms)
    return renderedText ? `${sentence}\n\n${renderedText}` : sentence
}

// Liegt eine Zahlung innerhalb der Skontofrist und passt sie zum Betrag abzüglich Skonto?
export function matchCashDiscountPayment({ open, payment, percent, dueDate, paymentDate }: any) {
    const openAmount = Math.abs(Number(open || 0))
    const paid = Math.abs(Number(payment || 0))
    const rate = Number(percent || 0)
    if (!openAmount || !paid || !(rate > 0)) return null
    if (dueDate && paymentDate && String(paymentDate).slice(0, 10) > String(dueDate).slice(0, 10)) return null
    const expected = roundMoney(openAmount * (1 - rate / 100))
    if (Math.abs(expected - paid) > 0.05) return null
    return { discount: roundMoney(openAmount - paid), percent: rate }
}

// Nettowirkung von Skonto für die BWA: gewährter Skonto mindert Erlöse, erhaltener Skonto den Aufwand.
// Vorzeichen: Erlösminderung positiv; Aufwand im Vorzeichen der Eingangsbelege (Ausgaben positiv).
export function getCashDiscountNetTotals(allocations: any[] = []) {
    let grantedNet = 0
    let receivedNet = 0
    let receivedGross = 0
    for (const allocation of allocations || []) {
        if (!hasCashDiscount(allocation)) continue
        const isOutgoing = Boolean(allocation.createddocument || allocation.cd_id)
        for (const item of allocation.cashDiscountSplit) {
            if (isOutgoing) grantedNet += Number(item?.net || 0)
            else {
                receivedNet += Number(item?.net || 0)
                receivedGross += Number(item?.gross || 0)
            }
        }
    }
    return {
        grantedNet: roundMoney(grantedNet),
        // Eingangsbelege: Zahlungen (und damit Skonto) sind negativ, Aufwand wird positiv geführt.
        receivedNet: roundMoney(-receivedNet),
        receivedGross: roundMoney(-receivedGross),
    }
}