#include "library.h"

struct money
{ int pounds, shillings, pennies, farthings; };

     // 4 farthings make a penny
     // 12 pence make a shilling
     // 20 shillings make a pound.   Up until 1971 anyway.

void set(money & x, int l, int s, int d, int f)
{ x.pounds = l;
  x.shillings = s;
  x.pennies = d;
  x.farthings = f; }

double convert(money a)
{ return a.pounds + a.shillings/20.0 + a.pennies/240.0 + a.farthings/960.0; }

void display(money a)
{ if (a.pennies==0 && a.shillings==0 && a.pounds==0 && a.farthings==0)
    write_string("0");
  if (a.pounds > 0)
  { write_char(0x20A4);            // 0x indicates a number written in base 16, hexadecimal
    write_string(a.pounds);        // 0x20A4 is the unicode character code for the pound sign
    if (a.shillings > 0 || a.pennies > 0 || a.farthings > 0)
      write_string(" "); }
  if (a.shillings > 0)
  { write_string(a.shillings);
    write_string("s");
    if (a.pennies > 0 || a.farthings > 0)
      write_string(" "); }
  if (a.pennies > 0)
  { write_string(a.pennies); }
  if (a.farthings>0)
  { write_char(0x00BB+a.farthings); }    // The unicode codes for 1/4, 1/2, 3/4 are 0xBC, 0xBD, 0xBE
  if (a.pennies > 0 || a.farthings > 0)
  { write_string("d"); } }

void fix(money & a)
{ if (a.farthings > 3)
  { a.pennies = a.pennies + a.farthings / 4;
    a.farthings = a.farthings % 4; }
  if (a.pennies > 11)
  { a.shillings = a.shillings + a.pennies / 12;
    a.pennies = a.pennies % 12; }
  if (a.shillings > 19)
  { a.pounds = a.pounds + a.shillings / 20;
    a.shillings = a.shillings % 20; } }

money convert(double pds)
{ money answer;
  set(answer, 0, 0, 0, (int)(pds*960));
  fix(answer);
  return answer; }

money add(money a, money b)
{ money answer;
  set(answer, a.pounds+b.pounds, a.shillings+b.shillings, 
              a.pennies+b.pennies, a.farthings+b.farthings);
  fix(answer);
  return answer; }

money subtract(money a, money b)
{ money answer;
  set(answer, a.pounds-b.pounds, a.shillings-b.shillings, 
              a.pennies-b.pennies, a.farthings-b.farthings);
  fix(answer);
  return answer; }

money multiply(money a, int b)
{ money answer;
  set(answer, a.pounds*b, a.shillings*b, a.pennies*b, a.farthings*b);
  fix(answer);
  return answer; }

void main()
{ make_window(600, 500);
  set_font_size(24);

  money mine, yours;
  set(mine, 3, 7, 11, 1);
  set(yours, 0, 10, 6, 0);

  move_to(100, 100);
  display(mine);

  move_to(100, 200);
  display(yours);

  mine = add(mine, yours);
  move_to(100, 300);
  display(mine);

  mine = multiply(mine, 35);
  move_to(100, 400);
  display(mine); }