--Calculates the heat index based on temperature in degrees
--fahrenheit and percent of relative humidity.
--Heat index formula taken from
--Http://Www.Usatoday.Com/Weather/Whicalc.htm
--Written By: Ralph W. Reid
--Last Modified: February 26, 2005
--This is the second version of this program.  The first version
--produced a warning during compilation due to the use of unchecked
--conversion of a character into an integer (different sizes).  This
--version of this program produces no such warning during compilation
--while using gnat 3.3.4 on a Slackware Linux 10.1 system with
--kernel 2.4.29.
--This source code is freeware.  Give credit/blame as appropriate.
--No warranties apply.
--Simple compile: gnatmake hi_ada

with Ada.Command_Line;
with Ada.Exceptions;
with Ada.Io_Exceptions;
with Ada.Text_Io;
use Ada.Text_Io;
with Ada.Float_Text_Io;
use Ada.Float_Text_Io;

function Hi_Ada return Natural is

function Atof (workstr : in String) return Float is
--Returns a floating point value of the workstr parameter.  The
--returned value is undefined if workstr contains invalid characters.

   --define a float array to define floating point digit values
   type Floatarray is array (0 .. 9) of Float;

   --variable definitions
   I : Natural range 1 .. (workstr'length + 1) := 1;
   Keep_Working : Boolean := TRUE;
   Multiplier : Float := 0.1;
   Negative : Boolean := FALSE;
   Result : Float := 0.0;
   Values : Floatarray := (0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0);
   Workchar : Character := ' ';
   Zerochar : Integer := Character'Pos ('0');

begin
   --deal with an empty string
   if (Workstr'Length = 0) then
      return 0.0;
   end if;

   --get past any initial white space
   Workchar := Workstr (I);
   while (workchar <= ' '  and  I <= Workstr'length)  loop
      I := I + 1;
      if (I <= Workstr'Length) then
         Workchar := Workstr (I);
      end if;
   end loop;

   --handle any numeric negation
   while (workchar = '-'  and  I <= Workstr'Length)  loop
     if Negative = FALSE then
        Negative := TRUE;
     else
        Negative := FALSE;
     end if;
     I := I + 1;
      if (I <= Workstr'Length) then
         Workchar := Workstr (I);
      end if;
   end loop;

   --perform the whole number digit conversions
   while (I <= Workstr'Length
          and workchar >= '0'
          and  workchar <= '9')
   loop
      Result := Result * 10.0;
      Result := Result + Values (Character'Pos (workchar) - zerochar);
      I:= I + 1;
      if (I <= Workstr'Length) then
         Workchar := Workstr (I);
      end if;
   end loop;

   --deal with fractional part of number if needed
   if (workchar = '.') then
      I := I + 1;
      if (I <= Workstr'Length) then
         Workchar := Workstr (I);
      end if;
      while (I <= Workstr'Length
             and Workchar >= '0'
             and Workchar <= '9')
      loop
         result := result + multiplier * Values (Character'Pos (workchar) - zerochar);
         Multiplier := Multiplier * 0.1;
         I := I + 1;
         if (I <= Workstr'Length) then
            Workchar := Workstr (I);
         end if;
      end loop;
   end if;

   --negate the result if necessary
   if Negative then
      Result := -1.0 * Result;
   end if;

   --return the final result
   return Result;
end Atof;

----------------------------------------------------------------------

function Calc_Heat_Index (Temp : in float; Humidity : in float)
                         return float is
--This function returns the heat index based on temperature in degrees
--fahrenheit and percentage of relative humidity.  The temperature and
--relative humidity values are expected to be within valid ranges.

begin
   return (-42.379
    + (2.04901523 * Temp)
    + (10.14333127 * Humidity)
    - (0.22475541 * Temp * Humidity)
    - (6.83783 * 0.001 * (Temp * temp))
    - (5.481717 * 0.01 * (Humidity * Humidity))
    + (1.22874 * 0.001 * (Temp * temp) * Humidity)
    + (8.5282 * 0.0001 * temp * (Humidity * humidity))
    - (1.99 * 0.000001 * (Temp * temp) * (Humidity * humidity)));
end Calc_Heat_Index;

----------------------------------------------------------------------

--mainline code

   --temperature range is from about absolute 0 to near plasma?
   Lowtemp : Float := -279.4;
   Hightemp : Float := 3000.0;
   --relative humidity is from 0.0 to 100.0 percent
   Lowhumidity : Float := 0.0;
   Highhumidity : Float := 100.0;

   temp : Float range lowtemp .. hightemp := 0.0;
   humidity : Float range lowhumidity .. highhumidity := 0.0;
   result : Float range lowtemp .. Float'last := 0.0;

begin
   if Ada.Command_Line.Argument_Count = 0 then
      Put_Line ("Program for calculating heat index");
      Put_Line ("Written in Ada95 by: Ralph W. Reid");
      Put_Line ("Last Modified: February 26, 2005");
      New_Line;
      Put_Line ("No command line arguments found.");
      Put_Line ("In the future, fahrenheit degrees and relative");
      Put_Line ("humidity can be passed on the command line if");
      Put_Line ("desired.");
      New_Line (2);

      Put ("Temp in degrees fahrenheit (");
      Put (lowtemp, 0, 0, 0);
      Put (" through ");
      Put (hightemp, 0, 0, 0);
      Put_Line ("):");
      Get (Temp);
      Put ("Relative humidity percentage (");
      Put (Lowhumidity, 0, 0, 0);
      Put (" through ");
      Put (Highhumidity, 0, 0, 0);
      Put_Line ("):");
      Get (Humidity);
      New_Line;
   else if Ada.Command_Line.Argument_Count = 1 then
      Temp := atof (Ada.Command_Line.Argument (1));
      Put ("Relative humidity percentage (");
      Put (Lowhumidity, 0, 0, 0);
      Put (" through ");
      Put (Highhumidity, 0, 0, 0);
      Put_Line ("):");
      Get (Humidity);
      New_Line;
   else
      Temp := Atof (Ada.Command_Line.Argument (1));
      Humidity := Atof (Ada.Command_Line.Argument (2));
   end if;
   end if;

   --calculate the heat index
    result := Calc_Heat_Index (temp, humidity);

  Put ("The heat index is ");
  Put (Result, 0, 0, 0);
  Put_Line (" degrees fahrenheit.");

  --return a no-error condition
  return 0;
end Hi_Ada;