document.addEventListener("DOMContentLoaded", function () {

    function getVal(id) {
        return parseFloat(document.getElementsByName(id)[0].value) || 0;
    }

    function setVal(id, value) {
        document.getElementsByName(id)[0].value = Number(value).toFixed(2);
    }

    window.calculate = function () {

        // Base Values
        let gross_total_income = getVal("gross_total_income");
        let disallowance_14a = getVal("disallowance_14a");
        let disallowance_37 = getVal("disallowance_37");

        // Deductions
        let d80_business = getVal("deduction_80ia_business");
        let deduction_sec37 = getVal("deduction_sec37_disallowance");
        let deduction_80g = getVal("deduction_80g");

        // Total Deduction
        let total_deductions = d80_business + deduction_sec37;

        // Net Taxable Income
        let net_taxable_income =
            (gross_total_income + disallowance_14a + disallowance_37)
            - total_deductions
            - deduction_80g;

        setVal("net_taxable_income", net_taxable_income);

        // Tax @ 30%
        let tax_30_percent = net_taxable_income * 0.30;
        setVal("tax_30_percent", tax_30_percent);

        // Surcharge @ 12%
        let surcharge_12 = tax_30_percent * 0.12;
        setVal("surcharge_12", surcharge_12);

        // Education Cess @ 3%
        let edu_cess_3 = (tax_30_percent + surcharge_12) * 0.03;
        setVal("edu_cess_3", edu_cess_3);

        // Total Tax Payable
        let total_tax_payable = tax_30_percent + surcharge_12 + edu_cess_3;
        setVal("total_tax_payable", total_tax_payable);

        // MAT, Interest
        let mat_credit = getVal("mat_credit");
        let interest_234c = getVal("interest_234c");

        let total_tax = total_tax_payable + mat_credit + interest_234c;
        setVal("total_tax", total_tax);

        // Advance, TDS, TCS
        let advance_tax = getVal("advance_tax");
        let tds = getVal("tds");
        let tcs = getVal("tcs");

        let tax_on_assessment = advance_tax + tds + tcs;
        setVal("tax_on_assessment", tax_on_assessment);

        // Refund / Payablesss
        let refund = total_tax - tax_on_assessment;
        setVal("refund", refund);
    };
});