var assessmentYear = 1;
var ageCategory = 1;

//input listeners
var deductions_80c = document.getElementById("deductions_80c");
deductions_80c.addEventListener('input', function(evt) {
    if (deductions_80c.value > 150000) {
        deductions_80c.value = 150000;
    }
});

var deductions_80ccd1b = document.getElementById("deductions_80ccd1b");
deductions_80ccd1b.addEventListener('input', function(evt) {
    if (deductions_80ccd1b.value > 50000) {
        deductions_80ccd1b.value = 50000;
    }
});

var deductions_80d = document.getElementById("deductions_80d");
deductions_80d.addEventListener('input', function(evt) {
    ageCategory = document.getElementById("ageCategory").value;
    if (ageCategory == 1) {
        if (deductions_80d.value > 75000) {
            deductions_80d.value = 75000;
        }
    } else if (ageCategory == 2 || ageCategory == 3) {
        if (deductions_80d.value > 100000) {
            deductions_80d.value = 100000;
        }
    }
});

var deductions_80g = document.getElementById("deductions_80g");
var deductions_80e = document.getElementById("deductions_80e");

var deductions_80tta = document.getElementById("deductions_80tta");
deductions_80tta.addEventListener('input', function(evt) {
    ageCategory = document.getElementById("ageCategory").value;
    if (ageCategory == 1) {
        if (deductions_80tta.value > 10000) {
            deductions_80tta.value = 10000;
        }
    } else if (ageCategory == 2 || ageCategory == 3) {
        if (deductions_80tta.value > 50000) {
            deductions_80tta.value = 50000;
        }
    }
});


function Calculate() {

    assessmentYear = document.getElementById("assessmentYear").value;
    ageCategory = document.getElementById("ageCategory").value;

    // Income
    var grossSalaryIncome = parseFloat(document.getElementById("gross_salary_income").value);
    var annualIncomeFromOtherSources = parseFloat(document.getElementById("annual_income_from_other_sources").value);
    var annualIncomeFromInterest = parseFloat(document.getElementById("annual_income_from_interest").value);
    var rentalIncome = parseFloat(document.getElementById("rental_income").value);
    var interestPaidOnHomeLoan = parseFloat(document.getElementById("interest_paid_on_home_loan").value);
    var interestPaidOnHomeLoanLetOut = parseFloat(document.getElementById("interest_paid_on_home_loan_let_out").value);

    // Deductions
    var deductions80c = parseFloat(deductions_80c.value);
    var deductions80ccd1b = parseFloat(deductions_80ccd1b.value);
    var deductions80d = parseFloat(deductions_80d.value);
    var deductions80g = parseFloat(deductions_80g.value);
    var deductions80e = parseFloat(deductions_80e.value);
    var deductions80tta = parseFloat(deductions_80tta.value);

    // HRA Exemption
    var basicSalary = parseFloat(document.getElementById("basic_salary").value);
    var dearnessAllowance = parseFloat(document.getElementById("dearness_allowance").value);
    var hra = parseFloat(document.getElementById("hra").value);
    var totalRentPaid = parseFloat(document.getElementById("total_rent_paid").value);
    var metroCity = document.getElementById("metroCity").value;

    if (grossSalaryIncome >= 0 && annualIncomeFromOtherSources >= 0 && annualIncomeFromInterest >= 0 && rentalIncome >= 0 && interestPaidOnHomeLoan >= 0 && interestPaidOnHomeLoanLetOut >= 0 && deductions80c >= 0 && deductions80ccd1b >= 0 && deductions80tta >= 0 && deductions80g >= 0 && deductions80d >= 0 && deductions80e >= 0 && basicSalary >= 0 && dearnessAllowance >= 0 && hra >= 0 && totalRentPaid >= 0) {

        var grossAnnualIncome = grossSalaryIncome + annualIncomeFromOtherSources + annualIncomeFromInterest;
        var municipalTaxes = 0;
        var netAnnualValue = rentalIncome - municipalTaxes;
        var standardDeduction = 30 * netAnnualValue / 100;

        var totalIncome = grossAnnualIncome + (netAnnualValue - standardDeduction - interestPaidOnHomeLoan - interestPaidOnHomeLoanLetOut);

        var defaultStandardDeduction = 0;

        if (assessmentYear == 1) {
            defaultStandardDeduction = 50000;
        } else if (assessmentYear == 2) {
            defaultStandardDeduction = 40000;
        }

        var totalDeduction = defaultStandardDeduction + deductions80c + deductions80ccd1b + deductions80tta + deductions80g + deductions80d + deductions80e;

        var hra2 = 0;

        if (metroCity == 1) {
            hra2 = 50 * basicSalary / 100;
        } else if (metroCity == 2) {
            hra2 = 40 * basicSalary / 100;
        }

        var hra3 = totalRentPaid - (basicSalary / 10) + dearnessAllowance;

        var totalHraExemption = Math.min(hra, hra2, hra3);
        var finalHraAmountToBeTaxed = hra - totalHraExemption;

        totalTaxableIncome = totalIncome - totalDeduction - totalHraExemption;

        var incomeTaxPayable = 0;
        var incomeTaxPayableWithCess = 0;

        var differenceInTax = 0;
        var differenceInTaxableIncome = 0;
        var marginalRelief = 0;

        if (totalTaxableIncome >= 0 && totalTaxableIncome <= 20000000) {
            if (ageCategory == 1) {
                if (totalTaxableIncome <= 250000) {
                    //income tax payable is already set to 0
                } else if (totalTaxableIncome >= 250001 && totalTaxableIncome <= 500000) {
                    incomeTaxPayable = (5 * (totalTaxableIncome - 250000) / 100);
                } else if (totalTaxableIncome >= 500001 && totalTaxableIncome <= 1000000) {
                    incomeTaxPayable = 12500 + (20 * (totalTaxableIncome - 500000) / 100);
                } else if (totalTaxableIncome >= 1000001 && totalTaxableIncome <= 5000000) {
                    incomeTaxPayable = 112500 + (30 * (totalTaxableIncome - 1000000) / 100);
                } else if (totalTaxableIncome >= 5000001 && totalTaxableIncome <= 5200000) {
                    incomeTaxPayable = 112500 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                    differenceInTax = incomeTaxPayable - 1312500;
                    differenceInTaxableIncome = totalTaxableIncome - 5000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 5200001 && totalTaxableIncome <= 10000000) {
                    incomeTaxPayable = 112500 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                } else if (totalTaxableIncome >= 10000001 && incomeTaxPayable <= 10300000) {
                    incomeTaxPayable = 112500 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                    differenceInTax = incomeTaxPayable - 3093750;
                    differenceInTaxableIncome = totalTaxableIncome - 10000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 10300001) {
                    incomeTaxPayable = 112500 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                }
            } else if (ageCategory == 2) {
                if (totalTaxableIncome <= 300000) {
                    //income tax payable is already set to 0
                } else if (totalTaxableIncome >= 300001 && totalTaxableIncome <= 500000) {
                    incomeTaxPayable = (5 * (totalTaxableIncome - 300000) / 100);
                } else if (totalTaxableIncome >= 500001 && totalTaxableIncome <= 1000000) {
                    incomeTaxPayable = 0 + 10000 + (20 * (totalTaxableIncome - 500000) / 100);
                } else if (totalTaxableIncome >= 1000001 && totalTaxableIncome <= 5000000) {
                    incomeTaxPayable = 0 + 10000 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                } else if (totalTaxableIncome >= 5000001 && totalTaxableIncome <= 5200000) {
                    incomeTaxPayable = 0 + 10000 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                    differenceInTax = incomeTaxPayable - 1310000;
                    differenceInTaxableIncome = totalTaxableIncome - 5000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 5200001 && totalTaxableIncome <= 10000000) {
                    incomeTaxPayable = 0 + 10000 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                } else if (totalTaxableIncome >= 10000001 && totalTaxableIncome <= 10300000) {
                    incomeTaxPayable = 0 + 10000 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                    differenceInTax = incomeTaxPayable - 3091000;
                    differenceInTaxableIncome = totalTaxableIncome - 10000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 10300001) {
                    incomeTaxPayable = 0 + 10000 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                }
            } else if (ageCategory == 3) {
                if (totalTaxableIncome <= 500000) {
                    //income tax payable is already set to 0
                } else if (totalTaxableIncome >= 500000 && totalTaxableIncome <= 1000000) {
                    incomeTaxPayable = (20 * (totalTaxableIncome - 500000) / 100);
                } else if (totalTaxableIncome >= 1000001 && totalTaxableIncome <= 5000000) {
                    incomeTaxPayable = 0 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                } else if (totalTaxableIncome >= 5000001 && totalTaxableIncome <= 5200000) {
                    incomeTaxPayable = 0 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                    differenceInTax = incomeTaxPayable - 1300000;
                    differenceInTaxableIncome = totalTaxableIncome - 5000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 5200001 && totalTaxableIncome <= 10000000) {
                    incomeTaxPayable = 0 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.10);
                } else if (totalTaxableIncome >= 10000001 && totalTaxableIncome <= 10300000) {
                    incomeTaxPayable = 0 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                    differenceInTax = incomeTaxPayable - 3080000;
                    differenceInTaxableIncome = totalTaxableIncome - 10000000;
                    marginalRelief = differenceInTax - differenceInTaxableIncome;
                    incomeTaxPayable = incomeTaxPayable - marginalRelief;
                } else if (totalTaxableIncome >= 10300001) {
                    incomeTaxPayable = 0 + 100000 + (30 * (totalTaxableIncome - 1000000) / 100);
                    incomeTaxPayable = incomeTaxPayable + (incomeTaxPayable * 0.15);
                }
            }
            incomeTaxPayableWithCess = incomeTaxPayable + (4 * incomeTaxPayable / 100);

            var showIncomeTaxValue = document.getElementById("show_income_tax_value");
            showIncomeTaxValue.classList.remove("hide");
            var incomeTaxPayableAmount = document.getElementById("income_tax_payable_amount");
            incomeTaxPayableAmount.innerHTML = "Income Tax Payable: Rs. " + incomeTaxPayableWithCess.toLocaleString();
        } else {
            var showIncomeTaxValue = document.getElementById("show_income_tax_value");
            showIncomeTaxValue.classList.remove("hide");
            var incomeTaxPayableAmount = document.getElementById("income_tax_payable_amount");
            incomeTaxPayableAmount.innerHTML = "This calculator can only calculate income tax for taxable income from zero to 2 crores only.";
        }
    } else {
        var showIncomeTaxValue = document.getElementById("show_income_tax_value");
        showIncomeTaxValue.classList.remove("hide");
        var incomeTaxPayableAmount = document.getElementById("income_tax_payable_amount");
        incomeTaxPayableAmount.innerHTML = "Please fill all the details carefully!";
    }
}