/************************************************************************************    
   VERSION:  1.0

   PROGRAM:  Calculator implementing the Time-Money Equation created by
             Professor Ian Walker of Warwick University:

             V=(W((100-t)/100))/C

             Where V is an hour's value
             W is a person's hourly wage
             t is the tax rate
             C is the local cost of living

        BY:  TheDollarRule.com

     NOTES:  Incorporates 2007 US Income Tax rates and Cost of Living indices

        Released under a creative commons Attribution-ShareAlike 3.0 license:
        (http://creativecommons.org/licenses/by-sa/3.0/)

        Please credit TheDollarRule.com in any derivative work.

        You are free:
         * to Share - to copy, distribute and transmit the work
         * to Remix - to adapt the work

        Under the following conditions:
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         * Share Alike. If you alter, transform, or build upon this work, you
           may distribute the resulting work only under the same, similar or a 
           compatible license.

        For any reuse or distribution, you must make clear to others the license 
        terms of this work. The best way to do this is with a link to the web page:
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        Any of the above conditions can be waived if you get permission from the 
        copyright holder.


        Nothing in this license impairs or restricts the author's moral rights.
***********************************************************************************/

function annual2hourly (salary) {
    return (salary / 2080);
}

function hourly2annual (salary) {
    return salary * 2080;
}


function calculate() {
   var Wobj = document.getElementById('W');
   var annual_Wobj = document.getElementById('annual_W');
   var W;

   var Cobj = document.getElementById('C');
   var other_Cobj = document.getElementById('other_C');
   var C;

   var t = document.getElementById('t').value;
   var V = document.getElementById('V');

   // annual overrides hourly salary
   if (annual_Wobj.value && Wobj.value || ! Wobj.value) {

       W = annual2hourly(annual_Wobj.value);
       Wobj.value = W;
   }   
   else {
       W = Wobj.value;
   }

   if (other_Cobj.value && Cobj.value) {
       C = other_Cobj.value
   }
   else {
      C = Cobj.value;
   }
   var Cscale = 0.01;

   var result = (W * (100 - t) / (C * Cscale) ) / 100;

   V.value = result;
}

// Based on 2007 US Tax rates
function set_tax_bracket (salary) {
    var status = document.getElementById('file_status').value;
    var rate;

    if (status == "single") {
       if (salary <= 7825) {
           rate = 10;
       }
       else if (salary > 7825 && salary <= 31850) {
           rate = 15;
       }
       else if (salary > 31850 && salary <= 77100) {
           rate = 25;
       }
       else if (salary > 77100 && salary <= 160850) {
           rate = 28;
       }
       else if (salary > 160850 && salary <= 349700) {
           rate = 33;
       }
       else if (salary > 349700) {
           rate = 35;
       }
    }
    else if (status == "married_sep") {
       if (salary <= 7825) {
           rate = 10;
       }
       else if (salary > 7825 && salary <= 31850) {
           rate = 15;
       }
       else if (salary > 31850 && salary <= 64250) {
           rate = 25;
       }
       else if (salary > 64250 && salary <= 97925) {
           rate = 28;
       }
       else if (salary > 97925 && salary <= 174850) {
           rate = 33;
       }
       else if (salary > 174850) {
           rate = 35;
       }
    }
    else if (status == "married_joint") {
       if (salary <= 15650) {
           rate = 10;
       }
       else if (salary > 15650 && salary <= 63700) {
           rate = 15;
       }
       else if (salary > 63700 && salary <= 128500) {
           rate = 25;
       }
       else if (salary > 128500 && salary <= 195850) {
           rate = 28;
       }
       else if (salary > 195850 && salary <= 349700) {
           rate = 33;
       }
       else if (salary > 349700) {
           rate = 35;
       }
    }
    else if (status == "head") {
       if (salary <= 11200) {
           rate = 10;
       }
       else if (salary > 11200 && salary <= 42650) {
           rate = 15;
       }
       else if (salary > 42650 && salary <= 110100) {
           rate = 25;
       }
       else if (salary > 110100 && salary <= 178350) {
           rate = 28;
       }
       else if (salary > 178350 && salary <= 349700) {
           rate = 33;
       }
       else if (salary > 349700) {
           rate = 35;
       }
    }

    document.getElementById('t').value = rate;
}

function set_tax_bracket_hourly (hourly) {
    var annual = hourly2annual(hourly);
    document.getElementById('annual_W').value = annual;
    set_tax_bracket(annual);
}

function empty_c () {
   document.getElementById('other_C').value = "";
}