-module(hessianDecode).

-include("hessian.hrl").

-export([decode/2]).
%%-export([init/0]).

%%-record(decoding_state,{type_pool = dict:new(), reference_pool = dict:new()}).
-record(decoding_state,{type_pool = dict:new(), reference_pool = dict:new(),obj_define_no=0}).
%---------------------------------------------------------------------------
% Decoding
%---------------------------------------------------------------------------
decode_str(Rest, 0, R) ->
	{list_to_binary(xmerl_ucs:to_utf8(lists:reverse(R))), Rest}; 
decode_str(<<C/utf8, Rest/binary>>, N, R) ->
	decode_str(Rest, N-1, [C|R]).

% Call
decode(<<$H,?M,?m,$C,Bin/binary>>, State) ->
	{Rest, Function, _State} = decode(Bin,State),
	{Rest2, Count, __State} = decode(Rest,_State),
	case decode(list, Rest2,Count,[], __State) of
		{error, Encoded} ->
			{error, Encoded};
		{not_found, Hash} ->
			{not_found, Hash};    
		{_Rest, Arguments, _NewState} ->
			[Function, Arguments]
	end;
% Fault
decode(<<$H,?M,?m,$F,
		 Rest/binary>>, State) ->
	{_Rest,#map{dict=Dict},_State} = decode(Rest, State),
	{ok, Message} = dict:find(<<"message">>, Dict),
	{error, Message};
% Reply
decode(<<$H,?M,?m,$R,Args/binary>>, State) ->
	case decode(Args,[], State) of
		{<<>>, Decoded,_State} ->
			TypeSet = get_type_set(_State),
			case Decoded of
				[Value] ->
					{Value,TypeSet};
				[H|T] ->
					{[H|T],TypeSet}
			end;
		{error, Encoded} ->
			{error, Encoded}
	end;
% Binaries
decode(<<16#20,Rest/binary>>, State) -> {Rest, <<>>, State};
decode(<<Len:8/unsigned,Rest/binary>>, State) when Len =< 16#2f, 16#20 < Len ->
	_Len = Len - 16#20,
	<<Bin:_Len/binary,_Rest/binary>> = Rest,
	{_Rest, Bin, State};
decode(<<$B,Len:16/unsigned,Bin:Len/binary,Rest/binary>>, State) -> {Rest, Bin, State};
decode(<<$b,Rest/binary>>,State) -> decode(<<$b,Rest/binary>>, [], State);
%% Booleans
decode(<<$T,Rest/binary>>, State) -> {Rest, true, State};
decode(<<$F,Rest/binary>>, State) -> {Rest, false, State};
%% Dates
decode(<<16#4a,Date:64/unsigned,Rest/binary>>, State) ->
	MegaSecs = Date div ?MegaSeconds,
	Secs = (Date - MegaSecs * ?MegaSeconds) div ?Seconds,
	MicroSecs = (Date - MegaSecs * ?MegaSeconds - Secs * ?Seconds) * ?MicroSeconds,
	{Rest, {MegaSecs, Secs, MicroSecs}, State};
decode(<<16#4b,Date:32/unsigned,Rest/binary>>, State) ->
	MegaSecs = (Date * 60000) div ?MegaSeconds,
	Secs = (Date * 60000 - MegaSecs * ?MegaSeconds) div ?Seconds,
	{Rest, {MegaSecs, Secs, 0}, State};
%% Doubles
decode(<<16#5b,Rest/binary>>, State)-> {Rest, 0.0, State};
decode(<<16#5c,Rest/binary>>, State)-> {Rest, 1.0, State};
decode(<<16#5d,Int:8/signed,Rest/binary>>, State)-> {Rest, float(Int), State};
decode(<<16#5e,Int:16/signed,Rest/binary>>, State)-> {Rest, float(Int), State};
decode(<<16#5f,Int:32/signed,Rest/binary>>, State)->
	<<Double:64/float>> = <<Int:32,0,0,0,0>>,
	{Rest, Double, State};
decode(<<$D,Double:64/float,Rest/binary>>, State)-> {Rest, Double, State};
%% Ints
decode(<<$I,Int:32/signed,Rest/binary>>, State)-> {Rest, Int, State};
decode(<<Int:8,Rest/binary>>, State) when Int >= 16#80, Int =< 16#bf -> {Rest, Int - 16#90, State};
decode(<<B2:8,B1:8,B0:8,Rest/binary>>, State) when B2 >= 16#d0, B2 =< 16#d7 -> {Rest, ((B2 - 16#d4) bsl 16) + (B1 bsl 8) + B0, State};
decode(<<B1:8,B0:8,Rest/binary>>, State) when B1 >= 16#c0, B1 =< 16#cf -> {Rest, ((B1 - 16#c8) bsl 8) + B0, State};
%% Longs
decode(<<$L,Long:64/signed,Rest/binary>>, State)-> {Rest, Long, State};
decode(<<16#59,Long:32/signed,Rest/binary>>, State) -> {Rest, Long, State};
decode(<<Long:8,Rest/binary>>, State) when Long >= 16#d8, Long =< 16#ef -> {Rest, Long - 16#e0, State};
decode(<<B2:8,B1:8,B0:8,Rest/binary>>, State) when B2 >= 16#38, B2 =< 16#3f -> {Rest, ((B2 - 16#3c) bsl 16) + (B1 bsl 8) + B0, State};
decode(<<B1:8,B0:8,Rest/binary>>, State) when B1 >= 16#f0, B1 =< 16#ff -> {Rest, ((B1 - 16#f8) bsl 8) + B0, State};
%% Strings
decode(<<0,Rest/binary>>, State) -> {Rest, <<>>, State};
decode(<<Len:8,Rest/binary>>, State) when Len < 32 -> 
	{String, NewRest} = decode_str(Rest, Len, []),
	{NewRest, String, State};
decode(<<B1:8,B0:8,Rest/binary>>, State) when B1 =< 16#33,B1 >= 16#30 -> 
	Len = ((B1 - 16#30) bsl 8) + B0,
	{String, NewRest} = decode_str(Rest, Len, []),
	{NewRest, String, State};
decode(<<$S,Len:16/unsigned,Rest/binary>>, State) -> 
	{String, NewRest} = decode_str(Rest, Len, []),
	{NewRest, String, State};
decode(<<$R,Rest/binary>>, State) -> decode(<<$R,Rest/binary>>,[], State);
%% Nulls
decode(<<$N,Rest/binary>>, State) -> {Rest, undefined, State};
%% References
decode(<<$Q,Bin/binary>>, State)-> 
	{Rest, IntRef, _State} = decode(Bin,State),
	{Rest, {ref, IntRef}, _State};
%% Maps
decode(<<$M,Map/binary>>, State) -> 
	{Rest,Type,_State} = decode(Map, State),
	{_Refnum,__State} = visit(#type_def{foreign_type = map},_State),
	{_Rest,Dict, NewState} = decode(map, Rest, dict:new(), __State),
	{_Rest,#map{refNo=_Refnum,type=Type,dict=Dict},NewState};
decode(<<$H,Map/binary>>, State) -> 
	{_Refnum,_State} = visit(#type_def{foreign_type = map},State),
	{_Rest,Dict, NewState} = decode(map, Map, dict:new(), _State),
	{_Rest,#map{refNo=_Refnum,dict=Dict},NewState};
%% Lists
% 'V' type int value*   # fixed-length list
decode(<<$V,Bin/binary>>, State) -> 
	{Rest1,_Type,_State1} = decode(Bin,State),
	{_Refnum,__State} = visit(#type_def{foreign_type = list},_State1),
	{Rest2,Len,_State2} = decode(Rest1,__State),
	{NewRest,List,NewState} = decode(list, Rest2, Len, [], _State2),
	{NewRest,#list{refNo=_Refnum,len=Len,type=_Type,values=List},NewState};
% 'X' int value*        # fixed-length untyped list
decode(<<$X,Bin/binary>>, State) ->
	{Rest1,Len,_State} = decode(Bin,State),
	{_Refnum,__State} = visit(#type_def{foreign_type = list},_State),
	{NewRest,List,NewState} = decode(list, Rest1, Len, [], __State),
	{NewRest,#list{refNo=_Refnum,len=Len,values=List},NewState};
% [x70-77] type value*  # fixed-length typed list
decode(<<H:5,Len:3,Bin/binary>>, State) when H == 14 ->
	{Rest1,_Type,_State} = decode(Bin,State),
	{_Refnum,__State} = visit(#type_def{foreign_type = list},_State),
	{NewRest,List,NewState} = decode(list, Rest1, Len, [], __State),
	{NewRest,#list{refNo=_Refnum,len=Len,type=_Type,values=List},NewState};
% [x78-7f] value*       # fixed-length untyped list
decode(<<H:5,Len:3,Bin/binary>>, State) when H == 15 ->
	{_Refnum,_State} = visit(#type_def{foreign_type = list},State),
	{NewRest,List,NewState} = decode(list, Bin, Len, [], _State),
	{NewRest,#list{refNo=_Refnum,len=Len,values=List},NewState};
% 'U' type value* 'Z'   # variable-length list
decode(<<$U,Bin/binary>>, State) ->
	{Rest1,_Type,_State} = decode(Bin,State),
	{_Refnum,__State} = visit(#type_def{foreign_type = list},_State),
	{NewRest,List,NewState} = decode(list, Rest1, [], __State),
	{NewRest,#list{refNo=_Refnum,type=_Type,values=List},NewState};
% 'W' value* 'Z'        # variable-length untyped list
decode(<<$W,Bin/binary>>, State) ->
	{_Refnum,_State} = visit(#type_def{foreign_type = list},State),
	{NewRest,List,NewState} = decode(list, Bin, [], _State),
	{NewRest,#list{refNo=_Refnum,values=List},NewState};
decode(<<$C,Bin/binary>>, State0) ->
	{Rest1,Type,State1} = decode(Bin,State0), %% Rest1 剩余字节码, Type 对象类型
	{Rest, TypeDef, State} = decode(type_definition,Type,Rest1,State1),
	NewState = type_decoding:hash_store(TypeDef,State),
	decode(Rest,NewState);
decode(<<$O,Bin/binary>>, State) ->
	{Rest,Ref,_State} = decode(Bin, State),
	case type_decoding:hash_lookup(Ref, _State) of
		{not_found, Ref} ->
			{Rest, {not_found, Ref}, _State};
		ForeignView ->
			#type_def{fieldnames = ForeignFieldNames} = ForeignView,
			{_Refnum,__State} = type_decoding:visit(ForeignView,_State),
			Count = count_fields(ForeignView),
			case decode(field, Rest, Count,[], __State) of
				{not_found,Hash} ->
					{not_found,Hash};
				{_Rest,FieldValues, NewState} ->
					Object = type_decoding:project_native_view(ForeignFieldNames,FieldValues,ForeignView),
%%					{_Rest, #object{refNo=_Refnum, typeRef=Ref,values=Object}, NewState}
					{_Rest, Object, NewState}
			end
	end;      
decode(<<H:4,Ref:4,Rest/binary>>, _State) when H == 6 ->
	case type_decoding:hash_lookup(Ref, _State) of
		{not_found, Ref} ->
			{Rest, {not_found, Ref}, _State};
		ForeignView ->
			#type_def{fieldnames = ForeignFieldNames} = ForeignView,
			{_Refnum,__State} = visit(ForeignView,_State),
			Count = count_fields(ForeignView),
			case decode(field, Rest, Count,[], __State) of
				{not_found,Hash} ->
					{not_found,Hash};
				{_Rest,FieldValues, NewState} ->
					Object = type_decoding:project_native_view(ForeignFieldNames,FieldValues,ForeignView),
					%%{_Rest, #object{refNo =_Refnum, typeRef=Ref,values=Object}, NewState}
					{_Rest, Object, NewState}
			end
	end;
%% Anything else
decode(<<Unexpected/binary>>, State) ->
	{error, hessianEncode:encode(fault, <<"ProtocolException">>, unexpected_byte_sequence, Unexpected, State) }.
decode(<<$b,Len:16/unsigned,Bin:Len/binary,$b,Rest/binary>>, Acc, State) ->
	decode(<<$b,Rest/binary>>,Acc ++ [Bin], State);
decode(<<$b,Len:16/unsigned,Bin:Len/binary,$B,Rest/binary>>, Acc, State) ->
	_Acc = Acc ++ [Bin],
	{_Rest,_Bin, State} = decode(<<$B,Rest/binary>>, State),
	{_Rest, list_to_binary(_Acc ++ [_Bin]), State};
decode(<<$R,Len:16/unsigned,Rest/binary>>,Acc, State) ->
	{_String, NewRest} = decode_str(Rest, Len, []),
	<<H:8,_/binary>> = NewRest,
	case H of 
		$R -> decode(NewRest,list_to_binary([Acc|[_String]]), State);
		$S -> {_Rest,_Bin, _State} = decode(NewRest, State),
			  _Acc2 =[Acc |[_String]],
			  {_Rest, list_to_binary(_Acc2 ++ [_Bin]), _State}
	end;
decode(<<>>, List, State) -> {<<>>, List, State};
decode(<<$Z>>, List, State) -> {<<>>, List, State};
decode(Args, List, State) ->
	case decode(Args,State) of
		{Rest,{ref, Ref}, _State} ->
			decode(Rest, List ++ [{ref, Ref}] , _State);
		{Rest, [H|T], _State} ->
			decode(Rest, List ++ [H|T], _State);
		{Rest, Result, _State} ->
			decode(Rest, List ++ [Result], _State);
		{error, Encoded} ->
			{error, Encoded}
	end.
decode(map, <<$Z>>, Dict, State) -> {<<>>,Dict, State};
decode(map, <<$Z,Rest/binary>>, Dict, State) -> {Rest,Dict, State};
decode(map, Bin, Dict, State) ->
	{_Rest, Key, _State} = decode(Bin, State),
	case decode(_Rest, _State) of
		{Rest, {ref, Ref}, __State} ->
			%Value = lists:nth(Ref + 1, List),
			Value = Ref,
			decode(map, Rest, dict:store(Key, {ref, Value}, Dict), __State);
		{Rest, Value, __State} ->
			decode(map, Rest, dict:store(Key, Value, Dict), __State)
	end;
decode(list, <<>>, List, State) -> {<<>>,lists:reverse(List), State};
decode(list, <<$Z>>, List, State) -> {<<>>,lists:reverse(List), State};
decode(list, <<$Z,Rest/binary>>, List, State) -> {Rest, lists:reverse(List), State};
decode(list, Bin, List, State) ->
	case decode(Bin, State) of
		{error, Encoded} ->
			{error, Encoded};
		{not_found,Hash} ->
			{not_found, Hash};    
		{_Rest, {not_found, Hash}, _State} ->
			{not_found, Hash};    
		{Rest, Value, _State} ->
            decode(list, Rest, [Value|List], _State)
	end;
decode(type_definition, ForeignType, Bin, State) ->
	{Rest,Count, _State} = decode(Bin, State),
	{NewRest,FieldNames, NewState} = decode(field, Rest, Count, [], _State),
	%% change 用回之前的 build_foreign_view NewState 不变
	{TypeDef,NewState2} = type_decoding:build_foreign_view(ForeignType,FieldNames,NewState),
	{NewRest, TypeDef, NewState2}.
decode(list, Bin, 0, List, State) -> {Bin, lists:reverse(List), State};
decode(list, Bin, Len, List, State) ->
    case decode(Bin, State) of
        {error, Encoded} ->
            {error, Encoded};
        {not_found,Hash} ->
            {not_found, Hash};    
        {_Rest, {not_found, Hash}, _State} ->
            {not_found, Hash};    
        {Rest, Value, _State} ->
            decode(list, Rest, Len - 1, [Value|List], _State)
    end;
decode(field, Rest, 0, Acc, State) -> {Rest, Acc, State};
decode(field, <<$Z,Rest/binary>>, _Count, Acc, State) -> {Rest, Acc, State};
decode(field, Bin, Count, Acc, State) ->
	{Rest,Field, _State} = decode(Bin, State),
	case Field of
		{not_found,Hash} ->
			{not_found,Hash};
		_ ->
			decode(field, Rest, Count - 1, Acc ++ [Field], _State)
	end.

get_type_set(#decoding_state{type_pool = Pool}) ->
	case dict:to_list(Pool) of 
		[] -> [];
		Data -> [Value || {_Key,Value} <- Data]
	end.

build_foreign_view(ForeignType,FieldNames,State) ->
	ForeignView = FieldNames,
	#decoding_state{type_pool = OldPool} = State,
	Native = dict:size(OldPool),
	NewPool = dict:store(Native, 
						 #type_def{native_type = Native,
								   foreign_type = ForeignType,
								   fieldnames = ForeignView}, 
						 OldPool),
	{
	 #type_def{native_type = Native,
			   foreign_type = ForeignType,
			   fieldnames = ForeignView},
	 State#decoding_state{type_pool = NewPool}
	}.

project_native_view(ForeignView,ForeignData,
                    #type_def{native_type = _NativeType, foreign_type = _ForeignType, fieldnames = NativeView}) ->
    AsDict = dict:from_list(lists:zip(ForeignView,ForeignData)),
    NativeData = [dict:fetch(Key,AsDict) || Key <- NativeView],
	NativeData.

visit(TypeDef, State = #decoding_state{reference_pool = OldPool}) ->
    Size = dict:size(OldPool),
    NewPool = dict:store(Size, TypeDef, OldPool),
    {Size,State#decoding_state{reference_pool = NewPool}}.

%%hash_lookup(Hash,_State) ->
%%    init(false),
%%    case ets:lookup(hashes, Hash) of
%%        [] ->
%%            {not_found, Hash};
%%        [{Hash,TypeDef}] ->
%%            TypeDef
%%    end.

%%hash_store(TypeDef = #type_def{native_type = Hash}, State) ->
%%    init(false),
%%    ets:insert(hashes,{Hash,TypeDef}),
%%    State.
%%
%%init() -> init(true).
%%
%%init(Delete) when is_boolean(Delete) ->
%%    case ets:info(hashes) of
%%        undefined ->
%%            ets:new(hashes,[public,named_table]);
%%        _ ->
%%            if
%%                Delete ->
%%                    ets:delete(hashes),
%%                    ets:new(hashes,[public,named_table]);
%%                true ->
%%                    ok
%%            end
%%    end,
%%    #decoding_state{}.

count_fields(#type_def{fieldnames = FieldNames}) -> length(FieldNames).