with Ada.Text_IO; use Ada.Text_IO;
with Ada.Command_Line;
with Interfaces.C;
with Interfaces.C.Strings;

procedure Client is
   use Interfaces.C;
   use Interfaces.C.Strings;

   subtype U_Long is Unsigned_Long;
   subtype U_Short is Unsigned_Short;
   subtype Ssize_T is Int;
   type Chars_Ptr_Ptr is access all Chars_Ptr;

   AF_INET : constant := 2;
   SOCK_STREAM : constant := 1;
   SOCK_DGRAM : constant := 2;
   INADDR_ANY : constant := 0;

   type In_Addr is record
      S_Addr : U_Long;
   end record;
   pragma Convention (C, In_Addr);

   type In_Addr_Ptr is access all In_Addr;
   type In_Addr_Ptr_Ptr is access all In_Addr_Ptr;

   type Sockaddr_In is record
     Sin_Family : Short;
     Sin_Port : U_Short;
     Sin_Addr : In_Addr;
     Sin_Zero : Char_Array(0..7);
   end record;
   pragma Convention (C, Sockaddr_In);

   type Hostent is record
      H_Name : Chars_Ptr;
      H_Aliases : Chars_Ptr_Ptr;
      H_Addrtype : Int;
      H_Length : Int;
      H_Addr_List : In_Addr_Ptr_Ptr;
   end record;
   pragma Convention (C, Hostent);

   type Hostent_Ptr is access all Hostent;
   type Sockaddr_In_Ptr is access all Sockaddr_In;
   type Int_Ptr is access all Int;

   function Socket(Domain, Socket_Type, Protocol : in Int) return Int;
   pragma Import (C, Socket, "socket");

   function GetHostByName(Name : Chars_Ptr) return Hostent_Ptr;
   pragma Import (C, GetHostByName, "gethostbyname");

   function SendTo(S : Int; Msg : Chars_Ptr; Len : Size_T; Flags : Int; Sa : Sockaddr_In_Ptr; Salen : Int ) return Ssize_t;
   pragma Import (C, SendTo, "sendto");

   function Close(S : Int) return Int;
   pragma Import (C, Close, "close");

   Sock : Int;
   Name : aliased Sockaddr_In;
   Result : Int;
   BufArray : Char_Array := "This is a test! ";
   Buf, HostName : Chars_Ptr;
   Socket_Error : exception;
   Hp : Hostent_Ptr;

begin
   Put_Line("Starting client");

   Sock := Socket(AF_INET, SOCK_DGRAM, 0);
   if Sock < 0 then
      Put_Line("Error opening datagram socket");
      raise Socket_Error;
   end if;

   Put_Line("Getting host information");
   HostName := New_String(Ada.Command_Line.Argument(1));
   hp := GetHostByName(HostName);
   if Hp = null then
      Put_Line("Unknown Host");
      raise Socket_Error;
   end if;
   Free(HostName);

   Put_Line("Setting up Socket Structures");
   Name.Sin_Addr := Hp.H_Addr_List.all.all;
   Name.Sin_Port := U_Short'Value(Ada.Command_Line.Argument(2));
   Put("Using Port : "); Put(U_Short'Image(Name.Sin_Port)); New_Line;

   Name.Sin_Family := AF_INET;


   Put_Line("Sending datagram");
   Buf := New_Char_Array(BufArray);
   Result := SendTo(sock, Buf, StrLen(Buf), 0, Name'Access, Sockaddr_In'Size / CHAR_BIT);
   if Result < 0 then
      Put_Line("Error sending datagram message");
      raise Socket_Error;
   end if;

   Result :=  Close(sock);

end Client;