85 lines
2.9 KiB
TypeScript
85 lines
2.9 KiB
TypeScript
/**
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* useDocumentTotals
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*
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* Pure calculation hook for invoice-style documents (invoices, bills, estimates,
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* credit notes, vendor credits, etc.).
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*
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* Inputs
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* ────────────────────────────────────────────────────────────────────────────
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* lineItems – flat array of all items (parts + services + expenses)
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* discountType – 'no' | 'line_item_level' | 'transaction_level'
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* discountAmount – used when discountType === 'transaction_level'
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* taxRate – percentage (e.g. 15 for 15 %). Undefined → no tax.
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*
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* Calculation order
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* ────────────────────────────────────────────────────────────────────────────
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* 1. subTotal = Σ (qty × rate)
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* 2. lineItemDiscount = Σ discount_amount (only when discountType === 'line_item_level')
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* 3. transactionDiscount = discountAmount (only when discountType === 'transaction_level')
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* 4. totalDiscount = lineItemDiscount + transactionDiscount
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* 5. afterDiscount = subTotal - totalDiscount
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* 6. taxAmount = afterDiscount × (taxRate / 100)
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* 7. total = afterDiscount + taxAmount
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*/
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export type DocumentLineItem = {
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quantity: number
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rate: number
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discount_amount?: number
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}
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export type UseDocumentTotalsInput = {
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lineItems: DocumentLineItem[]
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discountType?: string | null
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discountAmount?: number
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taxRate?: number
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}
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export type DocumentTotals = {
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subTotal: number
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lineItemDiscount: number
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transactionDiscount: number
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totalDiscount: number
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afterDiscount: number
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taxAmount: number
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total: number
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hasLineItems: boolean
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}
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export function useDocumentTotals({
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lineItems,
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discountType,
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discountAmount,
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taxRate,
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}: UseDocumentTotalsInput): DocumentTotals {
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const subTotal = lineItems.reduce((sum, item) => {
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const qty = Number(item.quantity) || 0
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const rate = Number(item.rate) || 0
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return sum + qty * rate
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}, 0)
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const lineItemDiscount =
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discountType === "line_item_level"
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? lineItems.reduce((sum, item) => sum + (Number(item.discount_amount) || 0), 0)
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: 0
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const transactionDiscount =
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discountType === "transaction_level" ? Number(discountAmount) || 0 : 0
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const totalDiscount = lineItemDiscount + transactionDiscount
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const afterDiscount = Math.max(0, subTotal - totalDiscount)
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const taxAmount = taxRate ? afterDiscount * (taxRate / 100) : 0
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const total = afterDiscount + taxAmount
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return {
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subTotal,
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lineItemDiscount,
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transactionDiscount,
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totalDiscount,
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afterDiscount,
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taxAmount,
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total,
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hasLineItems: lineItems.length > 0,
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}
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}
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