-- TCPMUX - This is a trivial, incomplete, and uncompilable implementation of IETF RFC 1078, TCPMUX.
-- Copyright (C) 2024 Prince Trippy <programmer@verisimilitudes.net>.

-- This program is free software: you can redistribute it and/or modify it under the terms of the
-- GNU Affero General Public License version 3 as published by the Free Software Foundation.

-- This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
-- even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-- See the GNU Affero General Public License for more details.

-- You should have received a copy of the GNU Affero General Public License along with this program.
-- If not, see <http://www.gnu.org/licenses/>.

-- This program would require only Ada 1995 support if it could be compiled, but this is irrelevant.

with Ada.Command_Line, Ada.Strings.Fixed, Ada.Strings.Maps.Constants, Ada.Characters.Latin_1;
with Less_Trivial_Trie, Tedious_Control_Package;

procedure TCPMUX is
   package TCP renames Tedious_Control_Package;
   package TCP.House renames Tedious_Control_Package.House;
   package TCP.Guest renames Tedious_Control_Package.Guest;

   type Node;
   type Link is access Node;

   type Service(Name : String) is record
      Spot : TCP.Port;
   end record;

   type Node(Here : Service) is record
      There : Link;
   end record;

   Longest_Service_Name : constant := 64;
   Line_End : constant String := Ada.Characters.Latin_1.CR & Ada.Characters.Latin_1.LF;

   package Trie is new Less_Trivial_Trie(Index_Type => Positive, Domain_Type => Character,
                                         Input_Type => String,   Stored_Type => Link);
   Services : Trie.Trie;
   Outside  : TCP.House.System_Resource(Where => 1);
   First    : aliased Node := (Here => (Name => "HELP", Spot => 1), There => null);
   Final    : Link := access First;
begin
   Trie.Give(Path => First.Here.Name, Tree => Services, What => First'Access);
   declare
      I : Integer := 0;
   begin
      while I < Ada.Command_Line.Argument_Count loop
         declare
            S : String
              := Ada.Strings.Fixed.Translate(Source => Ada.Command_Line.Argument(I),
                                             Mapping => Ada.Strings.Maps.Constants.Upper_Case_Map);
            P : TCP.Port := TCP.Port'Value(Ada.Command_Line.Argument(I + 1));
            L : Link := new Node'(Here => (Name => S, Port => P), There => null);
         begin
            if S'Length > Longest_Service_Name then return; end if;
            Trie.Give(Path => S & Line_End, Tree => Services, What => L);
            Final.all.There := L;
            Final := L;
         end;
         I := I + 2;
      end loop;
   end;
   loop
      declare
         Connection : TCP.Guest.System_Resource;
         Service_ID : String(1 .. Longest_Service_Name);
         Given_Size : Integer;
         ID_Has_Use : Boolean;
         Given_Link : Link;
      begin
         TCP.House.Wait(Connection);
         TCP.Guest.Pull(By => Connection, Data => Service_ID, Length => Given_Size);
         Ada.Strings.Fixed.Translate(Source => Service_ID(1 .. Given_Size),
                                     Mapping => Ada.Strings.Maps.Constants.Upper_Case_Map);
         Trie.Find(Path => Service_ID(1 .. Given_Size), Tree => Services,
                   Seen => ID_Has_Use, Unto => Given_Link);
         if not ID_Has_Use then
            TCP.Guest.Push(By => Connection, Data => "-Service not found." & Line_End);
         else
            if Given_Link.all.Here.Name = "HELP" then
               declare
                  L : Link := First.There;
               begin
                  TCP.Guest.Push(By => Connection, Data => "+TCPMUX HELP:" & Line_End);
                  while L /= null loop
                     TCP.Guest.Push(By => Connection, Data => L.all.Here.Name & Line_End);
                     L := L.all.There;
                  end loop;
               end;
            else
               declare
                  Internal_Connection : TCP.Guest.System_Resource;
               begin
                  TCP.Guest.Call(By => Connection, House => (127, 0, 0, 1),
                                 At_Port => Given_Link.all.Here.Spot);
                  TCP.Guest.Push(By => Connection, Data => "+Service follows:" & Line_End);
                  -- The following is that missing primitive, which prevents me from finishing this.
                  TCP.Fuse(House => Internal_Connection, Guest => Connection);
               exception
                  when others => TCP.Guest.Push(By => Connection,
                                                Data => "-Service uncooperative." & Line_End);
               end;
            end if;
         end if;
      exception
         when others => null;
      end;
   end loop;
exception
   when others => null;
end TCPMUX;
.