(*  Copyright 2004-2013 Sascha Husa, Ian Hinder, Christiane Lechner

    This file is part of Kranc.

    Kranc is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    Kranc 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Kranc; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*)

BeginPackage[
  "CodeGenSymmetries`",
  {"Errors`", "Helpers`", "Kranc`", "CodeGenCactus`", "MapLookup`", "CodeGenKranc`",
   "CodeGenC`"}];

CreateSymmetriesRegistrationSource::usage = "";

Begin["`Private`"];

(* ------------------------------------------------------------------------ 
   Symmetries Registration
   ------------------------------------------------------------------------ *)

(* Symmetries registration spec = {FullName -> "impl::GFname", 
                                    Sym      -> {symX, symY, symZ}} *)

symmetriesBlock[spec_] :=

  Module[{i, KrancDim},

  If[!MatchQ[spec, {FullName -> _String, Sym -> {_,_,_}}],
    ThrowError["symmetriesBlock: Expecting a symmetry registration spec but got ", spec]];

  KrancDim = 3;

  sym = lookup[spec, Sym];

  {Table["sym[" <> ToString[i - 1]   <> "] = " <> 
                   ToString@sym[[i]] <> ";\n", {i, 1, KrancDim}],

  "SetCartSymVN(cctkGH, sym, \"" <> lookup[spec, FullName] <> "\");\n\n"
}
];

(* syms is a list of rules mapping gridfunctions to their symmetry structures *)
calcSymmetry[gf_, syms_] :=
  Module[{},
    If[mapContains[syms, gf],
      Return[lookup[syms,gf]],
      (* FIXME: We are defaulting to scalar symmetries if no information is
         available.  This shouldn't happen, but I am bypassing this check
         temporarily. *)
      Print["WARNING: defaulting to symmetries of a scalar for "<>ToString[gf]];
      Return[{1,1,1}]]];


(* This function guesses the symmetries based on component names as we
   have not been given them *)
calcSymmetry[gf_] := Module[{sym, q, string},

sym = {1, 1, 1};  (* default *)

string = ToString@gf;

While[IntegerQ[q = ToExpression@StringTake[string, -1]], 

Module[{},
    sym[[q]] = -sym[[q]];
    string   = StringDrop[string, -1]
    ]
];
sym
];

(* Compatibility function to be called by KrancThorns because it
   doesn't understand reflection symmetries *)
CreateSymmetriesRegistrationSource[thornName_, implementationName_, GFs_, debug_] :=
  CreateSymmetriesRegistrationSource[thornName, implementationName, GFs, False, debug];



(* Given a symmetries registration structure as defined above, return a
   C CodeGen structure of a source file which will register the symmetries. *)
CreateSymmetriesRegistrationSource[thornName_, implementationName_, GFs_, reflectionSymmetries_, debug_] :=
  Module[{spec, j, lang, tmp},

  If[debug,
      Print["Registering Symmetries for: ", GFs];
    ];

  lang = CodeGenC`SOURCELANGUAGE;
  CodeGenC`SOURCELANGUAGE = "C";

  spec = Table[{FullName -> implementationName <> "::" <> ToString@GFs[[j]],
                Sym      -> If[reflectionSymmetries === False,
                              calcSymmetry[GFs[[j]]],
                              calcSymmetry[GFs[[j]], Union@reflectionSymmetries]]}, {j, 1, Length@GFs}];

  tmp = {FileHeader["C"],

   Map[IncludeFile, 
        {"cctk.h", "cctk_Arguments.h", "cctk_Parameters.h", "Symmetry.h"}],

   DefineCCTKFunction[ thornName <> "_RegisterSymmetries", "void", 
     If[Length[spec] > 0,
     {CommentedBlock["array holding symmetry definitions",

      "CCTK_INT sym[3];\n\n"],

      CommentedBlock["Register symmetries of grid functions",

      Map[symmetriesBlock, spec]]},
     {}]
]
  };

  CodeGenC`SOURCELANGUAGE = lang;

tmp
];


End[];

EndPackage[];