with Agpl.Interfaces.C.Types;

package body Agpl.Random is

   Internal : Object;

   procedure Gsl_Init;
   pragma Import (C, Gsl_Init, "agpl__random__gsl_init");

   procedure Gsl_Reset;
   pragma Import (C, Gsl_Reset, "agpl__random__gsl_reset");

   procedure Gsl_Reset_Seed (Seed : Integer);
   pragma Import (C, Gsl_Reset_Seed, "agpl__random__gsl_reset_seed");

   function Gsl_Gaussian (Sigma : Interfaces.C.Types.Double)
                          return  Interfaces.C.Types.Double;
   pragma Import (C, Gsl_Gaussian, "agpl__random__gsl_gaussian");

   ------------------
   -- Open_Uniform --
   ------------------

   function Open_Uniform return Open_Uniformly_Distributed is
   begin
      return Internal.Open_Uniform;
   end Open_Uniform;

   -------------
   -- Uniform --
   -------------

   function Uniform return Uniformly_Distributed is
   begin
      return Internal.Uniform;
   end Uniform;

   --------------
   -- Gaussian --
   --------------

   function Gaussian (Sigma : Float) return Float is
   begin
      return Internal.Gaussian (Sigma);
   end Gaussian;

   ----------------------
   -- Uniform_Discrete --
   ----------------------

   function Uniform_Discrete return Discrete is
      Min : constant Integer := Discrete'Pos (Discrete'First);
      Max : constant Integer := Discrete'Pos (Discrete'Last);
   begin
      return Discrete'Val (Get_Integer (Min, Max));
   end Uniform_Discrete;

   ---------------
   -- Get_Float --
   ---------------

   function Get_Float (Min, Max : in Float) return Float is
   begin
      return Uniform * (Max - Min) + Min;
   end Get_Float;

   ---------------
   -- Get_Float --
   ---------------

   function Get_Float (This     : in Object;
                       Min, Max : in Float) return Float
   is
   begin
      return This.Uniform * (Max - Min) + Min;
   end Get_Float;

   -----------------
   -- Get_Integer --
   -----------------

   function Get_Integer (Min, Max : in Integer) return Integer is
   begin
      return Internal.Get_Integer (Min, Max);
   end Get_Integer;

   -----------
   -- Reset --
   -----------

   procedure Reset (Initiator : in Integer) is
   begin
      Internal.Reset (Initiator);
   end Reset;

   -----------
   -- Reset --
   -----------

   procedure Reset (This : in out Object) is
   begin
      Ada.Numerics.Float_Random.Reset (This.Gen);
      Gsl_Reset;
   end Reset;

   -----------
   -- Reset --
   -----------

   procedure Reset (This : in out Object; Initiator : in Integer) is
   begin
      Ada.Numerics.Float_Random.Reset (This.Gen, Initiator);
      Gsl_Reset_Seed (Initiator);
   end Reset;

   -------------
   -- Uniform --
   -------------

   function Uniform (This : in Object) return Uniformly_Distributed is
   begin
      return Ada.Numerics.Float_Random.Random (This.Gen);
   end Uniform;

   --------------
   -- Gaussian --
   --------------

   function Gaussian (This : in Object; Sigma : Float) return Float is
      pragma Unreferenced (This);
   begin
      return Float (Gsl_Gaussian (Interfaces.C.Types.Double (Sigma)));
   end Gaussian;

   -----------------
   -- Get_Integer --
   -----------------

   function Get_Integer
     (This     : in Object;
      Min, Max : in Integer)
      return Integer
   is
   begin
      if Max < Min then
         return Max;
      else
         return Integer'Min
           (Integer (Float'Floor (This.Get_Float (Float (Min), Float (Max + 1)))),
            Max);
      end if;
   end Get_Integer;

   ---------------------
   -- Discrete_Random --
   ---------------------

   function Discrete_Random (This : in Object) return Discrete is
      pragma Unreferenced (This);
      Min : constant Integer := Discrete'Pos (Discrete'First);
      Max : constant Integer := Discrete'Pos (Discrete'Last);
   begin
      return Discrete'Val (Get_Integer (Min, Max));
   end Discrete_Random;

   ------------------
   -- Open_Uniform --
   ------------------

   function Open_Uniform (This : in Object) return Open_Uniformly_Distributed is
   begin
      return Float'Min (Ada.Numerics.Float_Random.Random (This.Gen),
                        Open_Uniformly_Distributed'Last);
   end Open_Uniform;

   ---------------
   -- Flip_Coin --
   ---------------

   function Flip_Coin return Boolean is
   begin
      return Get_Integer (0, 1) = 1;
   end Flip_Coin;

begin
   Gsl_Init;
   Internal.Reset;
end Agpl.Random;