import { areMoneyDTOEqual } from "@erp/core";
import { useMoney, usePercentage, useQuantity } from "@erp/core/hooks";
import * as React from "react";
import { UseFormReturn } from "react-hook-form";
import { CustomerInvoiceFormData, CustomerInvoiceItemFormData } from "../../schemas";

/**
 * Hook que recalcula automáticamente los totales de cada línea
 * y los totales generales de la factura cuando cambian los valores relevantes.
 */
export function useInvoiceAutoRecalc(form: UseFormReturn<CustomerInvoiceFormData>) {
  const {
    watch,
    setValue,
    getValues,
    formState: { isDirty, isLoading, isSubmitting },
  } = form;

  const moneyHelper = useMoney();
  const qtyHelper = useQuantity();
  const pctHelper = usePercentage();

  // Cálculo de una línea
  const calculateItemTotals = React.useCallback(
    (item: CustomerInvoiceItemFormData) => {
      if (!item) {
        const zero = moneyHelper.fromNumber(0);
        return {
          subtotalDTO: zero,
          discountAmountDTO: zero,
          taxableBaseDTO: zero,
          taxesDTO: zero,
          totalDTO: zero,
        };
      }

      // Subtotal = unit_amount × quantity
      const subtotalDTO = moneyHelper.multiply(item.unit_amount, qtyHelper.toNumber(item.quantity));

      // Descuento = subtotal × (discount_percentage / 100)
      const discountDTO = moneyHelper.percentage(
        subtotalDTO,
        pctHelper.toNumber(item.discount_percentage)
      );

      // Base imponible = subtotal − descuento
      const taxableBaseDTO = moneyHelper.sub(subtotalDTO, discountDTO);

      // Impuestos (placeholder: se integrará con tax catalog)
      const taxesDTO = moneyHelper.fromNumber(0);

      // Total = base imponible + impuestos
      const totalDTO = moneyHelper.add(taxableBaseDTO, taxesDTO);

      return {
        subtotalDTO,
        discountAmountDTO: discountDTO,
        taxableBaseDTO,
        taxesDTO,
        totalDTO,
      };
    },
    [moneyHelper, qtyHelper, pctHelper]
  );

  // Cálculo de los totales de la factura a partir de los conceptos
  const calculateInvoiceTotals = React.useCallback(
    (items: CustomerInvoiceItemFormData[]) => {
      let subtotalDTO = moneyHelper.fromNumber(0);
      let discountTotalDTO = moneyHelper.fromNumber(0);
      let taxableBaseDTO = moneyHelper.fromNumber(0);
      let taxesDTO = moneyHelper.fromNumber(0);
      let totalDTO = moneyHelper.fromNumber(0);

      for (const item of items) {
        const t = calculateItemTotals(item);
        subtotalDTO = moneyHelper.add(subtotalDTO, t.subtotalDTO);
        discountTotalDTO = moneyHelper.add(discountTotalDTO, t.discountAmountDTO);
        taxableBaseDTO = moneyHelper.add(taxableBaseDTO, t.taxableBaseDTO);
        taxesDTO = moneyHelper.add(taxesDTO, t.taxesDTO);
        totalDTO = moneyHelper.add(totalDTO, t.totalDTO);
      }

      return {
        subtotalDTO,
        discountTotalDTO,
        taxableBaseDTO,
        taxesDTO,
        totalDTO,
      };
    },
    [moneyHelper, calculateItemTotals]
  );

  // Suscribirse a cambios del formulario
  React.useEffect(() => {
    if (!isDirty || isLoading || isSubmitting) {
      return;
    }

    const subscription = watch((formData, { name, type }) => {
      if (!formData?.items?.length) return;

      // 1. Si cambia una línea completa (add/remove/move)
      if (name === "items" && type === "change") {
        formData.items.forEach((item, i) => {
          if (!item) return;

          const typedItem = item as CustomerInvoiceItemFormData;
          const totals = calculateItemTotals(typedItem);
          const current = getValues(`items.${i}.total_amount`);

          if (!areMoneyDTOEqual(current, totals.totalDTO)) {
            setValue(`items.${i}.total_amount`, totals.totalDTO, {
              shouldDirty: true,
              shouldValidate: false,
            });
          }
        });

        // Recalcular importes totales de la factura y
        // actualizar valores calculados.
        const typedItems = formData.items as CustomerInvoiceItemFormData[];
        const totalsGlobal = calculateInvoiceTotals(typedItems);

        setValue("subtotal_amount", totalsGlobal.subtotalDTO);
        setValue("discount_amount", totalsGlobal.discountTotalDTO);
        setValue("taxable_amount", totalsGlobal.taxableBaseDTO);
        setValue("taxes_amount", totalsGlobal.taxesDTO);
        setValue("total_amount", totalsGlobal.totalDTO);
      }

      // 2. Si cambia un campo dentro de un concepto
      if (name?.startsWith("items.") && type === "change") {
        const index = Number(name.split(".")[1]);
        const fieldName = name.split(".")[2];

        if (["quantity", "unit_amount", "discount_percentage"].includes(fieldName)) {
          const typedItem = formData.items[index] as CustomerInvoiceItemFormData;
          if (!typedItem) return;

          // Recalcular línea
          const totals = calculateItemTotals(typedItem);
          const current = getValues(`items.${index}.total_amount`);

          if (!areMoneyDTOEqual(current, totals.totalDTO)) {
            setValue(`items.${index}.total_amount`, totals.totalDTO, {
              shouldDirty: true,
              shouldValidate: false,
            });
          }

          // Recalcular importes totales de la factura y
          // actualizar valores calculados.
          const typedItems = formData.items as CustomerInvoiceItemFormData[];
          const totalsGlobal = calculateInvoiceTotals(typedItems);

          setValue("subtotal_amount", totalsGlobal.subtotalDTO);
          setValue("discount_amount", totalsGlobal.discountTotalDTO);
          setValue("taxable_amount", totalsGlobal.taxableBaseDTO);
          setValue("taxes_amount", totalsGlobal.taxesDTO);
          setValue("total_amount", totalsGlobal.totalDTO);
        }
      }
    });

    return () => subscription.unsubscribe();
  }, [
    watch,
    isDirty,
    isLoading,
    isSubmitting,
    setValue,
    getValues,
    calculateItemTotals,
    calculateInvoiceTotals,
  ]);
}