// JavaScript Document
function calculate()
{
	var tax_year = $('#taxyear').val();
	var list_price = to_num($('#listprice').val());
	var extras = to_num($('#extras').val());
	var capital_contribution = to_num($('#cont_costs').val());		
	var private_amount = to_num($('#private_amount').val());
	var fuel_type = $('#fuel_type').val();						
	var co2_emission = to_num($('#co2_emissions').val());					
	var engine_capacity = $('#engine_capacity').val();			
	var reg_date = $('#date_registered').val();				
	var private_amount = to_amount($('#private_amount').val());		
	var pay_employer = $("input[name='employer_pays']:checked").val();	
	var yearVal = 12; // this would be used to reset based on the year to calulate co2 %	
	var rate = $('#tax_rate').val();
	var total_value = 0;
	var start_dd = to_num($('#start_dd').val());
	var start_mm = to_num($('#start_mm').val());
	var start_yy = to_num($('#start_yy').val());
	var end_dd = to_num($('#end_dd').val());
	var end_mm = to_num($('#end_mm').val());
	var end_yy = to_num($('#end_yy').val());
	var whole_year = $("input[name='all_year']:checked").val();
	var unavl_days = to_num($("input[name='unavl_days']").val());
	var un_period = $("input[name='un_period']:checked").val();
	
	//Taxable Rate
	var tax_rate;
	//Car Benefit
	var car_benefit;	
	// Fuel Benefit
	var fuel_benefit;	
	// Total Benefit
	var total_benefit;
	
	var form = document.car_calc;
	
	var res = true;
	var date_msg = new Array();
	var message = "Please check the following errors:\n\n";
	
	
	if(tax_year == 0)
	{
		message += " - Please select a tax year.\n\n";
		res = false;
	}
	if(list_price == 0)
	{
		message += " - Please provide list price of the car\n\n";
		res = false;
	}
	if(list_price > 80000)
	{
		message +=" - Your car valule can only be upto 80,000\n\n";
		res = false;
	}
	if(reg_date == "")
	{
		message += " - Please select the registration date\n\n";
		res = false;
	}
	if(fuel_type == "")
	{
		message += " - Please select the fuel type\n\n";
		res = false;
	}
	
	if(reg_date == "Pre98" && $('#no_co2:checked').val() == null){
		message += " - Before 1998 there was only pre-defined catogeries for engine\n    sizes so please tick the box and select an engine size\n\n";
		res = false;
	}
	if(co2_emission == 0 && $('#no_co2:checked').val() == null)
	{
		message += " - Please provide the CO2 Emission value\n\n";
		res = false;		
	}
	if(engine_capacity == "" && $('#no_co2').attr('checked'))
	{
		message += " - Please choose the Engine Capacity\n\n";
		res = false;				
	}
	if(whole_year == null || whole_year == undefined){
		message += " - Please select if the car was available for the whole tax year\n\n";
		res = false;
	}
	if(whole_year == "no")
	{
		
		// check the start is ok..
		date_msg = is_date_ok(start_dd,start_mm,start_yy,tax_year);
		if(date_msg[0] == true)
		{
			// then check the end part of the date. 
		   date_msg = is_date_ok(end_dd,end_mm,end_yy,tax_year);
		   if(date_msg[0] == false)
		   {
			   message += date_msg[1];
			   res = false;
		   }
		}
		else
		{
			message += date_msg[1];
			res = false;
		}
		if(un_period == null || un_period == undefined){
		message += " - Please select whether the car was anavailable for more than 30 days.\n\n";
		res = false;
		}
		if((unavl_days<30) && (un_period == "yes")){
		message += " - You can only claim for any period that the car was unavailable for 30 or more consecutive days.\n\n";
		res = false;	
		}
	}
	
	if (res == false)
	{
		alert(message);
		return false;
	}
	
	//If CO2 value was not entered, set to zero
	if(co2_emission == 0 || $("#no_co2").is(":checked") || fuel_type == "E") co2_emission = 0;
	//If Capital Contribution value was not entered, set to zero or > than 5000, default to 5000.
	if (capital_contribution == '') capital_contribution = 0;
	else if(capital_contribution > 5000) captial_contribution = 5000;
	//If Extras value was not entered, set to zero
	if (extras == '')extras = 0;
	
	
	// calculate total taxable value of the car:	
	list_price += extras;
	total_value = list_price - capital_contribution;
	// check if total taxable value is greater than 80k if so, make it to max accepted value. 
	if(total_value > 80,000) total_value = 80,000;
	
	
	// calculating the appropriate % 
	
	if(reg_date == "Post98" && co2_emission > 0)
	{
		if (co2_emission != 0)
		{
			if(co2_emission > 124)
			{
				co2_emission=Math.floor(co2_emission / 5) * 5;					
			}
			
			//Ensure CO2 value within defined range
			switch(tax_year)
			{
				case '2010':
				case '2009':				
								if(co2_emission < 121)
								{
									co2_emission = 110;
								}
								if (co2_emission > 120 && co2_emission < 135) 
								{
									co2_emission=135;									
								}
								if (co2_emission>235) 
								{
									co2_emission=235;
								}
								yearVal = 12;
								break;
				
				
								
				case '2008':	
				case '2007':	
				case '2006':	
								if (co2_emission<140) 
								{
									co2_emission=140 ;
								}
								if (co2_emission>240) 
								{
									co2_emission=240;
								}
								yearVal = 13;
								break;
				case '2005':
								if (co2_emission<145) 
								{
									co2_emission=145 ;
								}
								if (co2_emission>245) 
								{
									co2Emission=245;
								}
								yearVal = 14;
								break;
				case '2004':
								if (co2_emission<155) 
								{
									co2_emission=155 ;
								}
								if (co2_emission>255) 
								{
									co2_emission=255;
								}
								yearVal = 16;
								break;
			}
			
			
			//Calculate tax_rate value
			tax_rate = Math.floor(co2_emission/5) - yearVal;			       		

			// Adjust tax_rate based on fuel types
			if (co2_emission != 0) 
			{				
				switch(fuel_type)
				{
					case 'D':
							//If Diesel, increase tax_rate percentage by 3
							tax_rate = tax_rate + 3;
							break;
					case 'H':							
							if(tax_year >2006)tax_rate = tax_rate - 3;
							else tax_rate = tax_rate - 2;
							break;
					case 'E85':
							if(tax_year>2009)tax_rate = tax_rate - 2;
							break;
				}
				//make sure that tax_rate is in the allowed range
				/*if (tax_rate<10) tax_rate=15; */
				if (tax_rate>35) tax_rate=35; 
			}
			// for 2009/10 year calculation to have tax_value defined as below:
			else if(fuel_type == "P" || fuel_type == "D" || fuel_type == "H" && co2_emission >= 120)
			{
				// should set default tax value for the all possible types for values = 120. 				
			}
	
		}		
		
	}
	else if(reg_date == "Post98" && co2_emission == 0)
	{
		if (engine_capacity == "1") { tax_rate=15; }

		if (engine_capacity == "2") { tax_rate=25; }

		if (engine_capacity == "3" || engine_capacity == "4") { tax_rate=35; }	
		if(fuel_type == "E")
		{
			tax_rate = 9;
		}
		else if(fuel_type == "H")
		{
			tax_rate = tax_rate - 3;
		}
	}
	else if(reg_date == "Pre98" && co2_emission == 0)
	{
		if (engine_capacity == "1") { tax_rate=15; }

		if (engine_capacity == "2") { tax_rate=22; }

		if (engine_capacity == "3" || engine_capacity == "4") { tax_rate=32; }		

		if(fuel_type == "E")
		{
			tax_rate = 15;
		}
		
								
	}	


	// calculate the results:
	
	tax_rate = tax_rate/100;
	
	car_benefit = Math.floor(tax_rate * total_value);
	// check whether the car was available whole year, if not do the calc for the available period.
	if(whole_year == "no")
	{
		// calculate the total days that the car was unavailable
		// need to minus month by 1 because in javascript the month is calculated from 0-11 not 1-12
		var standard_day = 1000*60*60*24;
		var start_date = new Date(start_yy,(start_mm-1),start_dd);
		var end_date = new Date(end_yy,(end_mm-1),end_dd);		
		var total_days = Math.ceil((end_date.getTime() - start_date.getTime())/standard_day);
		if(unavl_days == "" || unavl_days == 0) unavl_days = 0;
		total_days += Math.round(unavl_days);
		total_days = 365 - total_days;
		car_benefit = car_benefit - Math.ceil((car_benefit * (total_days/365)));
	}
	
	car_benefit = car_benefit - private_amount;
	
	// if employer pays for the priave use for fuel , then calculate it.
	if(pay_employer == "yes")
	{
		if(tax_year >= 2009)
		{
			fuel_benefit = Math.ceil(16900 * tax_rate);
		}
		else
		{
			fuel_benefit = Math.ceil(14400 * tax_rate);
		}
		if(whole_year == "no")
		{
			fuel_benefit = fuel_benefit - Math.ceil(fuel_benefit*(total_days/365));
		}
	}
	else
	{
		fuel_benefit = 0;
	}
	//alert(tax_year +" "+ tax_rate);
	form.car_benefit.value = to_amount(car_benefit);
	form.fuel_benefit.value = to_amount(fuel_benefit);
	form.cb_per.value = to_amount(car_benefit*rate);	
	form.fb_per.value = to_amount(fuel_benefit*rate);
	form.tr_per.value = to_amount(tax_rate*100);
	
} // function ends here.. 

function is_date_ok(iDate,iMonth,iYear,year)
{
	 var data = new Array();
	 var message = "";
	 var res = true;
	 //checking to ensure the entries are digits
     if (iYear == 0 || iMonth == 0 || iDate == 0 || iYear < 2000 || iMonth < 1 ||
        iMonth > 12 || iDate < 1 || iDate > 31) {
		 data[0] = false;
         data[1] = " - Please put a date in the start/end date boxes\n    in dd/mm/yyyy format\n\n";         
     }	 
	 
	 else
	 {
		 var chkdate = iDate+"/"+iMonth+"/"+iYear; 
		 var datUser = new Date(iYear,iMonth,iDate);
		 data = check_date(chkdate);
		 if(data[0] == true)
		 {
			var datNow = new Date(year,04,05);
			var datLimit = new Date(year - 1,04,06);
			if ((datUser.getTime() - datLimit.getTime()) < 0 || (datUser.getTime() - datNow.getTime()) > 0)
			{
				  data[0] = false;
				  data[1] = " -Start & End dates should be\n\n between 6th April " + (year - 1) + " and 5th April " + year + "\n\n";				  
			}
		 }
	 }
	 return data;		 
}