//pagefix.js
//functions to manipulate html file hydrology21.html
//1/25/2009

function rain_calc_array()
{
	//read data
	//find total input volume, avg intensity, avg flow
	//return as array so the calling button can display whichever value is needed
	//returns [avg intensity, total depth, total volume, average flow]
	//Area is same for all rainfalls
		var a=eval($('#area').val());
		var factor=eval($('#areaUnit').val());
		var acre=a/factor;
		var c=eval($('#cFactor').val());
		var duration=eval($('#duration').val());	//minutes
		var Ans=new Array();

	//calculation differs for different rainfall chosen
		var selector=$('#rainfall_selector').val();
	switch (selector)
	{
		case 'SF':
			var R=eval($('#returnPeriod').val());
			//calculate average intensity		
			var sf=new SF_IDF(R);
			var i=sf.intensity(duration);
			//write result
			Ans[0]=i;	//avg intensity in inch/hr
			Ans[1]=i*duration/60;	//total depth in inches
			Ans[2]=Ans[1]*acre;	//total rainfall volume in acre-inch
			Ans[3]=c*(Ans[2]*43560/12)/(duration*60)	//avg flow in cfs
			break;
			
		case 'SCS':
			Ans[1]=eval($('#scs_depth').val());	//total depth in inches
			Ans[0]=Ans[1]/24;	//avg intensity in inch/hr
			Ans[2]=Ans[1]*acre;	//total volume in acre-inch
			Ans[3]=c*Ans[2]*(43560/12)/(duration*60);	//avg flow in cfs
			break;
			
		case 'Constant':
			var i=eval($('#constant_rain').val()); //constant inch/hr
			Ans[0]=i;	//constant inch/hr
			Ans[1]=i*duration/60;	//total depth in inches
			Ans[2]=Ans[1]*acre;	//total rainfall volume in inches
			Ans[3]=c*(Ans[2]*43560/12)/(duration*60)	//avg flow in cfs
			break;
			
		default:	
			alert('default at choose_rainfall_type function');
	}

	return Ans;	//return array
}

function put_volume()
{
	var factor=eval($('#volumeUnit').val());
	var A=new Array();
	A=rain_calc_array();	
	var vol=A[2]*factor;
	$('#volume').val(addCommas(vol.toFixed(3)));
}

function put_rain()
{
		var A=new Array();
		A=rain_calc_array();	
		$('#avgIntensity').val(A[0].toFixed(4)+' in/hr');
		$('#totaldepth').val(A[1].toFixed(4)+' inch');
}


function put_avg_flowrate()
{
		var factor=eval($('#avg_flowrate_unit').val());
		var A=new Array();
		A=rain_calc_array();	
		var flowrate=A[3]*factor;
		$('#avg_flowrate').val(flowrate.toFixed(3));
}

function choose_infiltration_type()
{
	//if horton, no need to alter
	if($('#infiltration_type').val()=='Horton')
	{
		$('#final').removeAttr("disabled");
				$('#decay_k').removeAttr("disabled");
	}
	//if contant, then disable few things
	if($('#infiltration_type').val()=='constant')
	{$('#final').val($('#initial').val())
		$('#final').attr('disabled','disabled');
				$('#decay_k').val(1);
				$('#decay_k').attr('disabled','disabled');
	}
}

function choose_rainfall_type()
{
	//which rainfall to use- sf or scs or constant?
	var selector=$('#rainfall_selector').val();
	switch (selector)
	{
		case 'SF':
				$('#form10').show('slow');
				$('#form15').hide('slow');
				$('#form16').hide('slow');
				$('#duration').attr('value','Tc');
				$('#duration').removeAttr('disabled');
			break;
			
		case 'SCS':
				$('#form10').hide('slow');
				$('#form16').hide('slow');
				$('#form15').show('slow');
				$('#duration').attr('value','1440');	//scs rainfall uses only 24 hour duration
				$('#duration').attr('disabled','disabled');
			break;
		case 'Constant':
				$('#form10').hide('slow');
				$('#form15').hide('slow');
				$('#form16').show('slow');
				$('#duration').attr('value','Tc');
				$('#duration').removeAttr('disabled');
			break;
		default:	
			alert('default at choose_rainfall_type function');
	}
}