%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2023. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(shell).

-export([start/0, start/1, start/2, server/1, server/2, history/1, results/1]).
-export([get_state/0, get_function/2]).
-export([start_restricted/1, stop_restricted/0]).
-export([local_func/0, local_func/1, local_allowed/3, non_local_allowed/3]).
-export([catch_exception/1, prompt_func/1, strings/1]).
-export([start_interactive/0, start_interactive/1]).
-export([read_and_add_records/5]).
-export([whereis/0]).

-define(LINEMAX, 30).
-define(CHAR_MAX, 60).
-define(DEF_HISTORY, 20).
-define(DEF_RESULTS, 20).
-define(DEF_CATCH_EXCEPTION, false).
-define(DEF_PROMPT_FUNC, default).
-define(DEF_STRINGS, true).

-define(RECORDS, shell_records).

-define(MAXSIZE_HEAPBINARY, 64).
-record(shell_state,{
                     bindings = [],
                     records = [],
                     functions = []
                    }).
%% When used as the fallback restricted shell callback module...
local_allowed(q,[],State) ->
    {true,State};
local_allowed(_,_,State) ->
    {false,State}.

non_local_allowed({init,stop},[],State) ->
    {true,State};
non_local_allowed(_,_,State) ->
    {false,State}.

-spec start_interactive() -> ok | {error, already_started}.
start_interactive() ->
    user_drv:start_shell().
-spec start_interactive(noshell | {module(), atom(), [term()]}) ->
          ok | {error, already_started};
                       ({remote, string()}) ->
          ok | {error, already_started | noconnection};
                       ({node(), {module(), atom(), [term()]}} | {remote, string(), {module(), atom(), [term()]}}) ->
          ok | {error, already_started | noconnection | badfile | nofile | on_load_failure}.
start_interactive({Node, {M, F, A}}) ->
    user_drv:start_shell(#{ initial_shell => {Node, M, F ,A} });
start_interactive(InitialShell) ->
    user_drv:start_shell(#{ initial_shell => InitialShell }).

-spec whereis() -> pid() | undefined.
whereis() ->
    group:whereis_shell().

-spec start() -> pid().

start() ->
    start(false, false).

start(init) ->
    start(false, true);
start(NoCtrlG) ->
    start(NoCtrlG, false).

start(NoCtrlG, StartSync) ->
    _ = code:ensure_loaded(user_default),
    Ancestors = [self() | case get('$ancestors') of
                              undefined -> [];
                              Anc -> Anc
                          end],
    spawn(fun() ->
                  put('$ancestors', Ancestors),
                  server(NoCtrlG, StartSync)
          end).

%% Call this function to start a user restricted shell
%% from a normal shell session.
-spec start_restricted(Module) -> {'error', Reason} when
      Module :: module(),
      Reason :: code:load_error_rsn().

start_restricted(RShMod) when is_atom(RShMod) ->
    case code:ensure_loaded(RShMod) of
        {module,RShMod} ->
            application:set_env(stdlib, restricted_shell, RShMod),
            exit(restricted_shell_started);
        {error,What} = Error ->
            error_logger:error_report(
              lists:flatten(
                io_lib:fwrite(
                  "Restricted shell module ~w not found: ~tp\n",
                  [RShMod,What]))),
            Error
    end.

-spec stop_restricted() -> no_return().

stop_restricted() ->
    application:unset_env(stdlib, restricted_shell),
    exit(restricted_shell_stopped).

-spec server(boolean(), boolean()) -> 'terminated'.

server(NoCtrlG, StartSync) ->
    put(no_control_g, NoCtrlG),
    server(StartSync).


%%% The shell should not start until the system is up and running.
%%% We subscribe with init to get a notification of when.

%%% In older releases we didn't syncronize the shell with init, but let it
%%% start in parallell with other system processes. This was bad since
%%% accessing the shell too early could interfere with the boot procedure.
%%% Still, by means of a flag, we make it possible to start the shell the
%%% old way (for backwards compatibility reasons). This should however not
%%% be used unless for very special reasons necessary.

-spec server(boolean()) -> 'terminated'.

server(StartSync) ->
    case init:get_argument(async_shell_start) of
        {ok,_} ->
            ok;                                 % no sync with init
        _ when not StartSync ->
            ok;
        _ ->
            case init:notify_when_started(self()) of
                started ->
                    ok;
                _ ->
                    init:wait_until_started()
            end
    end,
    %% Our spawner has fixed the process groups.
    Bs = erl_eval:new_bindings(),

    %% Use an Ets table for record definitions. It takes too long to
    %% send a huge term to and from the evaluator. Ets makes it
    %% possible to have thousands of record definitions.
    RT = ets:new(?RECORDS, [public,ordered_set]),
    _ = initiate_records(Bs, RT),
    process_flag(trap_exit, true),
    %% Store function definitions and types in an ets table.
    FT = ets:new(user_functions, [public,ordered_set]),

    %% Check if we're in user restricted mode.
    RShErr =
        case application:get_env(stdlib, restricted_shell) of
            {ok,RShMod} when is_atom(RShMod) ->
                io:fwrite(<<"Restricted ">>, []),
                case code:ensure_loaded(RShMod) of
                    {module,RShMod} ->
                        undefined;
                    {error,What} ->
                        {RShMod,What}
                end;
            {ok, Term} ->
                {Term,not_an_atom};
            undefined ->
                undefined
        end,

    JCL =
        case get(no_control_g) of
            true -> " (type help(). for help)";
            _ -> " (press Ctrl+G to abort, type help(). for help)"
        end,
    DefaultSessionSlogan =
        io_lib:format(<<"Eshell V~s">>, [erlang:system_info(version)]),
    SessionSlogan =
        case application:get_env(stdlib, shell_session_slogan, DefaultSessionSlogan) of
            SloganFun when is_function(SloganFun, 0) ->
                SloganFun();
            Slogan ->
                Slogan
        end,
    try
        io:fwrite("~ts~ts\n",[unicode:characters_to_list(SessionSlogan),JCL])
    catch _:_ ->
            io:fwrite("Warning! The slogan \"~p\" could not be printed.\n",[SessionSlogan])
    end,
    erase(no_control_g),

    case RShErr of
        undefined ->
            ok;
        {RShMod2,What2} ->
            io:fwrite(
                ("Warning! Restricted shell module ~w not found: ~tp.\n"
                 "Only the commands q() and init:stop() will be allowed!\n"),
              [RShMod2,What2]),
            application:set_env(stdlib, restricted_shell, ?MODULE)
    end,

    {History,Results} = check_and_get_history_and_results(),
    server_loop(0, start_eval(Bs, RT, FT, []), Bs, RT, FT, [], History, Results).

server_loop(N0, Eval_0, Bs00, RT, FT, Ds00, History0, Results0) ->
    N = N0 + 1,
    {Eval_1,Bs0,Ds0,Prompt} = prompt(N, Eval_0, Bs00, RT, FT, Ds00),
    {Res,Eval0} = get_command(Prompt, Eval_1, Bs0, RT, FT, Ds0),

    case Res of
        {ok,Es0} ->
            case expand_hist(Es0, N) of
                {ok,Es} ->
                    {V,Eval,Bs,Ds} = shell_cmd(Es, Eval0, Bs0, RT, FT, Ds0, cmd),
                    {History,Results} = check_and_get_history_and_results(),
                    add_cmd(N, Es, V),
                    HB1 = del_cmd(command, N - History, N - History0, false),
                    HB = del_cmd(result, N - Results, N - Results0, HB1),
                    %% The following test makes sure that large binaries
                    %% (outside of the heap) are garbage collected as soon
                    %% as possible.
                    if
                        HB ->
                            garb(self());
                        Results < Results0 ->
                            garb(self());
                        true ->
                            ok
                    end,
                    server_loop(N, Eval, Bs, RT, FT, Ds, History, Results);
                {error,E} ->
                    fwrite_severity(benign, <<"~ts">>, [E]),
                    server_loop(N0, Eval0, Bs0, RT, FT, Ds0, History0, Results0)
            end;
        {error,{Location,Mod,What}} ->
            fwrite_severity(benign, <<"~s: ~ts">>,
                            [pos(Location), Mod:format_error(What)]),
            server_loop(N0, Eval0, Bs0, RT, FT, Ds0, History0, Results0);
        {error,terminated} ->                   %Io process terminated
            exit(Eval0, kill),
            terminated;
        {error,interrupted} ->                  %Io process interrupted us
            exit(Eval0, kill),
            {_,Eval,_,_} = shell_rep(Eval0, Bs0, RT, FT, Ds0),
            server_loop(N0, Eval, Bs0, RT, FT, Ds0, History0, Results0);
        {error,tokens} ->                       %Most probably character > 255
            fwrite_severity(benign, <<"~w: Invalid tokens.">>,
                            [N]),
            server_loop(N0, Eval0, Bs0, RT, FT, Ds0, History0, Results0);
        eof ->
            fwrite_severity(fatal, <<"Terminating erlang (~w)">>, [node()]),
            halt()
    end.

get_command(Prompt, Eval, Bs, RT, FT, Ds) ->
    Ancestors = [self() | get('$ancestors')],
    ResWordFun = fun erl_scan:reserved_word/1,
    Parse =
        fun() ->
                put('$ancestors', Ancestors),
                exit(
                  case
                      io:scan_erl_exprs(group_leader(), Prompt, {1,1},
                                        [text,{reserved_word_fun,ResWordFun}])
                  of
                      {ok,Toks,_EndPos} ->
                          %% NOTE: we can handle function definitions, records and soon type declarations
                          %% but this cannot be handled by the function which only expects erl_parse:abstract_expressions()
                          %% for now just pattern match against those types and pass the string to shell local func.
                          case Toks of
                              [{'-', _}, {atom, _, Atom}|_] ->
                                  SpecialCase = fun(LocalFunc) ->
                                                        FakeLine = begin
                                                                       case erl_parse:parse_form(Toks) of
                                                                           {ok, Def} -> lists:flatten(erl_pp:form(Def));
                                                                           E ->
                                                                            exit(E)
                                                                       end
                                                                   end,
                                                        {done, {ok, FakeResult, _}, _} = erl_scan:tokens(
                                                                                           [], atom_to_list(LocalFunc) ++ "(\""++FakeLine++"\").\n",
                                                                                           {1,1}, [text,{reserved_word_fun,fun erl_scan:reserved_word/1}]),
                                                        erl_eval:extended_parse_exprs(FakeResult)
                                                end,
                                  case Atom of
                                      record -> SpecialCase(rd);
                                      spec -> SpecialCase(ft);
                                      type -> SpecialCase(td)
                                  end;
                              [{atom, _, FunName}, {'(', _}|_] ->
                                  case erl_parse:parse_form(Toks) of
                                      {ok, FunDef} ->
                                          case {edlin_expand:shell_default_or_bif(atom_to_list(FunName)), shell:local_func(FunName)} of
                                              {"user_defined", false} ->
                                                  FakeLine =reconstruct(FunDef, FunName),
                                                  {done, {ok, FakeResult, _}, _} = erl_scan:tokens(
                                                                                     [], "fd("++ atom_to_list(FunName) ++ ", " ++ FakeLine ++ ").\n",
                                                                                     {1,1}, [text,{reserved_word_fun,fun erl_scan:reserved_word/1}]),
                                                  erl_eval:extended_parse_exprs(FakeResult);
                                              _ -> erl_eval:extended_parse_exprs(Toks)
                                          end;
                                      _ -> erl_eval:extended_parse_exprs(Toks)
                                  end;
                              _ ->
                                  erl_eval:extended_parse_exprs(Toks)
                          end;
                      {eof,_EndPos} ->
                          eof;
                      {error,ErrorInfo,_EndPos} ->
                          %% Skip the rest of the line:
                          Opts = io:getopts(),
                          TmpOpts = lists:keyreplace(echo, 1, Opts,
                                                     {echo, false}),
                          _ = io:setopts(TmpOpts),
                          _ = io:get_line(''),
                          _ = io:setopts(Opts),
                          {error,ErrorInfo};
                      Else ->
                          Else
                  end
                 )
        end,
    Pid = spawn_link(Parse),
    get_command1(Pid, Eval, Bs, RT, FT, Ds).

reconstruct(Fun, Name) ->
    lists:flatten(erl_pp:expr(reconstruct1(Fun, Name))).
reconstruct1({function, Anno, Name, Arity, Clauses}, Name) ->
    {named_fun, Anno, 'RecursiveFuncVar', reconstruct1(Clauses, Name, Arity)}.
reconstruct1([{call, Anno, {atom, Anno1, Name}, Args}|Body], Name, Arity) when length(Args) =:= Arity ->
    [{call, Anno, {var, Anno1, 'RecursiveFuncVar'}, reconstruct1(Args, Name, Arity)}| reconstruct1(Body, Name, Arity)];
reconstruct1([{call, Anno, {atom, Anno1, Name}, Args}|Body], Name, Arity) -> % arity not the same
    [{call, Anno, {remote, Anno1, {atom, Anno1, shell_default}, {atom, Anno1, Name}}, reconstruct1(Args, Name, Arity)}|
     reconstruct1(Body, Name, Arity)];
reconstruct1([{call, Anno, {atom, Anno1, Fun}, Args}|Body], Name, Arity) -> % Name not the same
    case {edlin_expand:shell_default_or_bif(atom_to_list(Fun)), shell:local_func(Fun)} of
        {"user_defined", false} ->
            [{call, Anno, {remote, Anno1, {atom, Anno1, shell_default}, {atom, Anno1, Fun}}, reconstruct1(Args, Name, Arity)}|
             reconstruct1(Body, Name, Arity)];
        {"shell_default", false} ->
            [{call, Anno, {remote, Anno1, {atom, Anno1, shell_default}, {atom, Anno1, Fun}}, reconstruct1(Args, Name, Arity)}| reconstruct1(Body, Name, Arity)];
        {"erlang", false} ->
            [{call, Anno, {remote, Anno1, {atom, Anno1, erlang}, {atom, Anno1, Fun}}, reconstruct1(Args, Name, Arity)}| reconstruct1(Body, Name, Arity)];
        {_, true} ->
            [{call, Anno, {atom, Anno1, Fun}, reconstruct1(Args, Name, Arity)}| reconstruct1(Body, Name, Arity)]
    end;
reconstruct1([E|Body], Name, Arity) when is_tuple(E) ->
    [list_to_tuple(reconstruct1(tuple_to_list(E), Name, Arity))|reconstruct1(Body, Name, Arity)];
reconstruct1([E|Body], Name, Arity) when is_list(E) ->
    [reconstruct1(E, Name, Arity)|reconstruct1(Body, Name, Arity)];
reconstruct1([E|Body], Name, Arity) ->
    [E|reconstruct1(Body, Name, Arity)];
reconstruct1([], _, _) -> [].

get_command1(Pid, Eval, Bs, RT, FT, Ds) ->
    receive
        {shell_state, From} ->
            From ! {shell_state, Bs, RT, FT},
            get_command1(Pid, Eval, Bs, RT, FT, Ds);
        {'EXIT', Pid, Res} ->
            {Res, Eval};
        {'EXIT', Eval, {Reason,Stacktrace}} ->
            report_exception(error, {Reason,Stacktrace}, RT),
            get_command1(Pid, start_eval(Bs, RT, FT, Ds), Bs, RT, FT, Ds);
        {'EXIT', Eval, Reason} ->
            report_exception(error, {Reason,[]}, RT),
            get_command1(Pid, start_eval(Bs, RT, FT, Ds), Bs, RT, FT, Ds)
    end.

prompt(N, Eval0, Bs0, RT, FT, Ds0) ->
    case get_prompt_func() of
        {M,F} ->
            A = erl_anno:new(1),
            L = {cons,A,{tuple,A,[{atom,A,history},{integer,A,N}]},{nil,A}},
            C = {call,A,{remote,A,{atom,A,M},{atom,A,F}},[L]},
            {V,Eval,Bs,Ds} = shell_cmd([C], Eval0, Bs0, RT, FT, Ds0, pmt),
            {Eval,Bs,Ds,case V of
                            {pmt,Val} ->
                                Val;
                            _ ->
                                bad_prompt_func({M,F}),
                                default_prompt(N)
                        end};
        default ->
            {Eval0,Bs0,Ds0,default_prompt(N)}
    end.

get_prompt_func() ->
    case application:get_env(stdlib, shell_prompt_func, default) of
        {M,F}=PromptFunc when is_atom(M), is_atom(F) ->
            PromptFunc;
        default=Default ->
            Default;
        Term ->
            bad_prompt_func(Term),
            default
    end.

bad_prompt_func(M) ->
    fwrite_severity(benign, "Bad prompt function: ~tp", [M]).

default_prompt(N) ->
    %% Don't bother flattening the list irrespective of what the
    %% I/O-protocol states.
    case is_alive() of
        true  -> io_lib:format(<<"(~s)~w> ">>, [node(), N]);
        false -> io_lib:format(<<"~w> ">>, [N])
    end.

%% expand_hist(Expressions, CommandNumber)
%%  Preprocess the expression list replacing all history list commands
%%  with their expansions.

expand_hist(Es, C) ->
    catch {ok,expand_exprs(Es, C)}.

expand_exprs([E|Es], C) ->
    [expand_expr(E, C)|expand_exprs(Es, C)];
expand_exprs([], _C) ->
    [].

expand_expr({cons,A,H,T}, C) ->
    {cons,A,expand_expr(H, C),expand_expr(T, C)};
expand_expr({lc,A,E,Qs}, C) ->
    {lc,A,expand_expr(E, C),expand_quals(Qs, C)};
expand_expr({bc,A,E,Qs}, C) ->
    {bc,A,expand_expr(E, C),expand_quals(Qs, C)};
expand_expr({tuple,A,Elts}, C) ->
    {tuple,A,expand_exprs(Elts, C)};
expand_expr({map,A,Es}, C) ->
    {map,A,expand_exprs(Es, C)};
expand_expr({map,A,Arg,Es}, C) ->
    {map,A,expand_expr(Arg, C),expand_exprs(Es, C)};
expand_expr({map_field_assoc,A,K,V}, C) ->
    {map_field_assoc,A,expand_expr(K, C),expand_expr(V, C)};
expand_expr({map_field_exact,A,K,V}, C) ->
    {map_field_exact,A,expand_expr(K, C),expand_expr(V, C)};
expand_expr({record_index,A,Name,F}, C) ->
    {record_index,A,Name,expand_expr(F, C)};
expand_expr({record,A,Name,Is}, C) ->
    {record,A,Name,expand_fields(Is, C)};
expand_expr({record_field,A,R,Name,F}, C) ->
    {record_field,A,expand_expr(R, C),Name,expand_expr(F, C)};
expand_expr({record,A,R,Name,Ups}, C) ->
    {record,A,expand_expr(R, C),Name,expand_fields(Ups, C)};
expand_expr({record_field,A,R,F}, C) ->         %This is really illegal!
    {record_field,A,expand_expr(R, C),expand_expr(F, C)};
expand_expr({block,A,Es}, C) ->
    {block,A,expand_exprs(Es, C)};
expand_expr({'if',A,Cs}, C) ->
    {'if',A,expand_cs(Cs, C)};
expand_expr({'case',A,E,Cs}, C) ->
    {'case',A,expand_expr(E, C),expand_cs(Cs, C)};
expand_expr({'try',A,Es,Scs,Ccs,As}, C) ->
    {'try',A,expand_exprs(Es, C),expand_cs(Scs, C),
     expand_cs(Ccs, C),expand_exprs(As, C)};
expand_expr({'receive',A,Cs}, C) ->
    {'receive',A,expand_cs(Cs, C)};
expand_expr({'receive',A,Cs,To,ToEs}, C) ->
    {'receive',A,expand_cs(Cs, C), expand_expr(To, C), expand_exprs(ToEs, C)};
expand_expr({call,A,{atom,_,e},[N]}, C) ->
    case get_cmd(N, C) of
        {undefined,_,_} ->
            no_command(N);
        {[Ce],_V,_CommandN} ->
            Ce;
        {Ces,_V,_CommandN} when is_list(Ces) ->
            {block,A,Ces}
    end;
expand_expr({call,CA,{atom,VA,v},[N]}, C) ->
    case get_cmd(N, C) of
        {undefined,_,_} ->
            no_command(N);
        {Ces,_V,CommandN} when is_list(Ces) ->
            {call,CA,{atom,VA,v},[{integer,VA,CommandN}]}
    end;
expand_expr({call,A,F,Args}, C) ->
    {call,A,expand_expr(F, C),expand_exprs(Args, C)};
expand_expr({'catch',A,E}, C) ->
    {'catch',A,expand_expr(E, C)};
expand_expr({match,A,Lhs,Rhs}, C) ->
    {match,A,Lhs,expand_expr(Rhs, C)};
expand_expr({op,A,Op,Arg}, C) ->
    {op,A,Op,expand_expr(Arg, C)};
expand_expr({op,A,Op,Larg,Rarg}, C) ->
    {op,A,Op,expand_expr(Larg, C),expand_expr(Rarg, C)};
expand_expr({remote,A,M,F}, C) ->
    {remote,A,expand_expr(M, C),expand_expr(F, C)};
expand_expr({'fun',A,{clauses,Cs}}, C) ->
    {'fun',A,{clauses,expand_exprs(Cs, C)}};
expand_expr({named_fun,A,Name,Cs}, C) ->
    {named_fun,A,Name,expand_exprs(Cs, C)};
expand_expr({clause,A,H,G,B}, C) ->
    %% Could expand H and G, but then erl_eval has to be changed as well.
    {clause,A,H, G, expand_exprs(B, C)};
expand_expr({bin,A,Fs}, C) ->
    {bin,A,expand_bin_elements(Fs, C)};
                                                %expand_expr({'-'})
expand_expr(E, _C) ->    % Constants.
    E.

expand_cs([{clause,A,P,G,B}|Cs], C) ->
    [{clause,A,P,G,expand_exprs(B, C)}|expand_cs(Cs, C)];
expand_cs([], _C) ->
    [].

expand_fields([{record_field,A,F,V}|Fs], C) ->
    [{record_field,A,expand_expr(F, C),expand_expr(V, C)}|
     expand_fields(Fs, C)];
expand_fields([], _C) -> [].

expand_quals([{generate,A,P,E}|Qs], C) ->
    [{generate,A,P,expand_expr(E, C)}|expand_quals(Qs, C)];
expand_quals([{b_generate,A,P,E}|Qs], C) ->
    [{b_generate,A,P,expand_expr(E, C)}|expand_quals(Qs, C)];
expand_quals([E|Qs], C) ->
    [expand_expr(E, C)|expand_quals(Qs, C)];
expand_quals([], _C) -> [].

expand_bin_elements([], _C) ->
    [];
expand_bin_elements([{bin_element,A,E,Sz,Ts}|Fs], C) ->
    [{bin_element,A,expand_expr(E, C),Sz,Ts}|expand_bin_elements(Fs, C)].

no_command(N) ->
    throw({error,
           io_lib:fwrite(<<"~ts: command not found">>,
                         [erl_pp:expr(N, enc())])}).

%% add_cmd(Number, Expressions, Value)
%% get_cmd(Number, CurrentCommand)
%% del_cmd(Number, NewN, OldN, HasBin0) -> bool()

add_cmd(N, Es, V) ->
    put({command,N}, Es),
    put({result,N}, V).

getc(N) ->
    {get({command,N}), get({result,N}), N}.

get_cmd(Num, C) ->
    case catch erl_eval:expr(Num, erl_eval:new_bindings()) of
        {value,N,_} when N < 0 -> getc(C+N);
        {value,N,_} -> getc(N);
        _Other -> {undefined,undefined,undefined}
    end.

del_cmd(_Type, N, N0, HasBin) when N < N0 ->
    HasBin;
del_cmd(Type, N, N0, HasBin0) ->
    T = erase({Type,N}),
    HasBin = HasBin0 orelse has_binary(T),
    del_cmd(Type, N-1, N0, HasBin).

has_binary(T) ->
    try has_bin(T), false
    catch true=Thrown -> Thrown
    end.

has_bin(T) when is_tuple(T) ->
    has_bin(T, tuple_size(T));
has_bin([E | Es]) ->
    has_bin(E),
    has_bin(Es);
has_bin(B) when byte_size(B) > ?MAXSIZE_HEAPBINARY ->
    throw(true);
has_bin(T) ->
    T.

has_bin(T, 0) ->
    T;
has_bin(T, I) ->
    has_bin(element(I, T)),
    has_bin(T, I - 1).

get_state() ->
    whereis() ! {shell_state, self()},
    receive
        {shell_state, Bs, RT, FT} ->
            #shell_state{bindings = Bs, records = ets:tab2list(RT), functions = ets:tab2list(FT)}
    end.

get_function(Func, Arity) ->
    {shell_state, _Bs, _RT, FT} = get_state(),
    try
        {value, {_, Fun}} = lists:keysearch({function, {shell_default,Func,Arity}}, 1, FT),
        Fun
    catch _:_ ->
        undefined
    end.

%% shell_cmd(Sequence, Evaluator, Bindings, RecordTable, Dictionary, What)
%% shell_rep(Evaluator, Bindings, RecordTable, Dictionary) ->
%%      {Value,Evaluator,Bindings,Dictionary}
%%  Send a command to the evaluator and wait for the reply. Start a new
%%  evaluator if necessary.
%%  What = pmt | cmd. When evaluating a prompt ('pmt') the evaluated value
%%  must not be displayed, and it has to be returned.

shell_cmd(Es, Eval, Bs, RT, FT, Ds, W) ->
    Eval ! {shell_cmd,self(),{eval,Es}, W},
    shell_rep(Eval, Bs, RT, FT, Ds).

shell_rep(Ev, Bs0, RT, FT, Ds0) ->
    receive
        {shell_rep,Ev,{value,V,Bs,Ds}} ->
            {V,Ev,Bs,Ds};
        {shell_rep,Ev,{command_error,{Location,M,Error}}} ->
            fwrite_severity(benign, <<"~s: ~ts">>,
                            [pos(Location), M:format_error(Error)]),
            {{'EXIT',Error},Ev,Bs0,Ds0};
        {shell_req,Ev,{get_cmd,N}} ->
            Ev ! {shell_rep,self(),getc(N)},
            shell_rep(Ev, Bs0, RT, FT, Ds0);
        {shell_req,Ev,get_cmd} ->
            Ev ! {shell_rep,self(),get()},
            shell_rep(Ev, Bs0, RT, FT, Ds0);
        {shell_req,Ev,exit} ->
            Ev ! {shell_rep,self(),exit},
            exit(normal);
        {shell_req,Ev,{update_dict,Ds}} ->      % Update dictionary
            Ev ! {shell_rep,self(),ok},
            shell_rep(Ev, Bs0, RT, FT, Ds);
        {shell_state, From} ->
            From ! {shell_state, Bs0, RT, FT},
            shell_rep(Ev, Bs0, RT, FT, Ds0);
        {ev_exit,{Ev,Class,Reason0}} ->         % It has exited unnaturally
            receive {'EXIT',Ev,normal} -> ok end,
            report_exception(Class, Reason0, RT),
            Reason = nocatch(Class, Reason0),
            {{'EXIT',Reason},start_eval(Bs0, RT, FT, Ds0), Bs0, Ds0};
        {ev_caught,{Ev,Class,Reason0}} ->       % catch_exception is in effect
            report_exception(Class, benign, Reason0, RT),
            Reason = nocatch(Class, Reason0),
            {{'EXIT',Reason},Ev,Bs0,Ds0};
        {'EXIT',_Id,interrupt} ->               % Someone interrupted us
            exit(Ev, kill),
            shell_rep(Ev, Bs0, RT, FT, Ds0);
        {'EXIT',Ev,{Reason,Stacktrace}} ->
            report_exception(exit, {Reason,Stacktrace}, RT),
            {{'EXIT',Reason},start_eval(Bs0, RT, FT, Ds0), Bs0, Ds0};
        {'EXIT',Ev,Reason} ->
            report_exception(exit, {Reason,[]}, RT),
            {{'EXIT',Reason},start_eval(Bs0, RT, FT, Ds0), Bs0, Ds0};
        {'EXIT',_Id,R} ->
            exit(Ev, R),
            exit(R);
        _Other ->                               % Ignore everything else
            io:format("Throwing ~p~n", [_Other]),
            shell_rep(Ev, Bs0, RT, FT, Ds0)
    end.

nocatch(throw, {Term,Stack}) ->
    {{nocatch,Term},Stack};
nocatch(error, Reason) ->
    Reason;
nocatch(exit, Reason) ->
    Reason.

report_exception(Class, Reason, RT) ->
    report_exception(Class, serious, Reason, RT).

report_exception(Class, Severity, {Reason,Stacktrace}, RT) ->
    Tag = severity_tag(Severity),
    I = iolist_size(Tag) + 1,
    PF = fun(Term, I1) -> pp(Term, I1, RT) end,
    SF = fun(M, _F, _A) -> (M =:= erl_eval) or (M =:= ?MODULE) end,
    Enc = encoding(),
    Str = erl_error:format_exception(I, Class, Reason, Stacktrace, SF, PF, Enc),
    io:requests([{put_chars, latin1, Tag},
                 {put_chars, unicode, Str},
                 nl]).

start_eval(Bs, RT, FT, Ds) ->
    Self = self(),
    Ancestors = [self() | get('$ancestors')],
    Eval = spawn_link(fun() ->
                              put('$ancestors', Ancestors),
                              evaluator(Self, Bs, RT, FT, Ds)
                      end),
    put(evaluator, Eval),
    Eval.

%% evaluator(Shell, Bindings, RecordTable, ProcessDictionary)
%%  Evaluate expressions from the shell. Use the "old" variable bindings
%%  and dictionary.

evaluator(Shell, Bs, RT, FT, Ds) ->
    init_dict(Ds),
    case application:get_env(stdlib, restricted_shell) of
        undefined ->
            eval_loop(Shell, Bs, RT, FT);
        {ok,RShMod} ->
            case get(restricted_shell_state) of
                undefined -> put(restricted_shell_state, []);
                _ -> ok
            end,
            put(restricted_expr_state, []),
            restricted_eval_loop(Shell, Bs, RT, FT, RShMod)
    end.

eval_loop(Shell, Bs0, RT, FT) ->
    receive
        {shell_cmd,Shell,{eval,Es},W} ->
            Ef = {value,
                  fun(MForFun, As) -> apply_fun(MForFun, As, Shell) end},
            Lf = local_func_handler(Shell, RT, FT, Ef),
            Bs = eval_exprs(Es, Shell, Bs0, RT, Lf, Ef, W),
            eval_loop(Shell, Bs, RT, FT)
    end.

restricted_eval_loop(Shell, Bs0, RT, FT, RShMod) ->
    receive
        {shell_cmd,Shell,{eval,Es}, W} ->
            {LFH,NLFH} = restrict_handlers(RShMod, Shell, RT,  FT),
            put(restricted_expr_state, []),
            Bs = eval_exprs(Es, Shell, Bs0, RT, {eval,LFH}, {value,NLFH}, W),
            restricted_eval_loop(Shell, Bs, RT, FT, RShMod)
    end.

eval_exprs(Es, Shell, Bs0, RT, Lf, Ef, W) ->
    try
        {R,Bs2} = exprs(Es, Bs0, RT, Lf, Ef, W),
        Shell ! {shell_rep,self(),R},
        Bs2
    catch
        exit:normal ->
            exit(normal);
        Class:Reason:Stacktrace ->
            M = {self(),Class,{Reason,Stacktrace}},
            case do_catch(Class, Reason) of
                true ->
                    Shell ! {ev_caught,M},
                    Bs0;
                false ->
                    %% We don't want the ERROR REPORT generated by the
                    %% emulator. Note: exit(kill) needs nothing special.
                    {links,LPs} = process_info(self(), links),
                    ER = nocatch(Class, {Reason,Stacktrace}),
                    lists:foreach(fun(P) -> exit(P, ER) end, LPs--[Shell]),
                    Shell ! {ev_exit,M},
                    exit(normal)
            end
    end.

do_catch(exit, restricted_shell_stopped) ->
    false;
do_catch(exit, restricted_shell_started) ->
    false;
do_catch(_Class, _Reason) ->
    case application:get_env(stdlib, shell_catch_exception, false) of
        true ->
            true;
        _ ->
            false
    end.

exprs(Es, Bs0, RT, Lf, Ef, W) ->
    exprs(Es, Bs0, RT, Lf, Ef, Bs0, W).

exprs([E0|Es], Bs1, RT, Lf, Ef, Bs0, W) ->
    UsedRecords = used_record_defs(E0, RT),
    RBs = record_bindings(UsedRecords, Bs1),
    case check_command(prep_check([E0]), RBs) of
        ok ->
            E1 = expand_records(UsedRecords, E0),
            {value,V0,Bs2} = expr(E1, Bs1, Lf, Ef),
            Bs = orddict:from_list([VV || {X,_}=VV <- erl_eval:bindings(Bs2),
                                          not is_expand_variable(X)]),
            if
                Es =:= [] ->
                    VS = pp(V0, 1, RT),
                    case W of
                        cmd -> io:requests([{put_chars, unicode, VS}, nl]);
                        pmt -> ok
                    end,
                    %% Don't send the result back if it will be
                    %% discarded anyway.
                    V = if
                            W =:= pmt ->
                                {W,V0};
                            true -> case result_will_be_saved() of
                                        true -> V0;
                                        false ->
                                            erlang:garbage_collect(),
                                            ignored
                                    end
                        end,
                    {{value,V,Bs,get()},Bs};
                true ->
                    exprs(Es, Bs, RT, Lf, Ef, Bs0, W)
            end;
        {error,Error} ->
            {{command_error,Error},Bs0}
    end.

is_expand_variable(V) ->
    case catch atom_to_list(V) of
        "rec" ++ _Integer -> true;
        _ -> false
    end.

result_will_be_saved() ->
    case get_history_and_results() of
        {_, 0} -> false;
        _ -> true
    end.

used_record_defs(E, RT) ->
    %% Be careful to return a list where used records come before
    %% records that use them. The linter wants them ordered that way.
    UR = case used_records(E, [], RT, []) of
             [] ->
                 [];
             L0 ->
                 L1 = lists:zip(L0, lists:seq(1, length(L0))),
                 L2 = lists:keysort(2, lists:ukeysort(1, L1)),
                 [R || {R, _} <- L2]
         end,
    record_defs(RT, UR).

used_records(E, U0, RT, Skip) ->
    case used_records(E) of
        {name,Name,E1} ->
            U = case lists:member(Name, Skip) of
                    true ->
                        U0;
                    false ->
                        R = ets:lookup(RT, Name),
                        used_records(R, [Name | U0], RT, [Name | Skip])
                end,
            used_records(E1, U, RT, Skip);
        {expr,[E1 | Es]} ->
            used_records(Es, used_records(E1, U0, RT, Skip), RT, Skip);
        _ ->
            U0
    end.

used_records({record_index,_,Name,F}) ->
    {name, Name, F};
used_records({record,_,Name,Is}) ->
    {name, Name, Is};
used_records({record_field,_,R,Name,F}) ->
    {name, Name, [R | F]};
used_records({record,_,R,Name,Ups}) ->
    {name, Name, [R | Ups]};
used_records({record_field,_,R,F}) -> % illegal
    {expr, [R | F]};
used_records({call,_,{atom,_,record},[A,{atom,_,Name}]}) ->
    {name, Name, A};
used_records({call,_,{atom,_,is_record},[A,{atom,_,Name}]}) ->
    {name, Name, A};
used_records({call,_,{remote,_,{atom,_,erlang},{atom,_,is_record}},
              [A,{atom,_,Name}]}) ->
    {name, Name, A};
used_records({call,_,{atom,_,record_info},[A,{atom,_,Name}]}) ->
    {name, Name, A};
used_records({call,A,{tuple,_,[M,F]},As}) ->
    used_records({call,A,{remote,A,M,F},As});
used_records({type,_,record,[{atom,_,Name}|Fs]}) ->
    {name, Name, Fs};
used_records(T) when is_tuple(T) ->
    {expr, tuple_to_list(T)};
used_records(E) ->
    {expr, E}.

fwrite_severity(Severity, S, As) ->
    io:fwrite(<<"~ts\n">>, [format_severity(Severity, S, As)]).

format_severity(Severity, S, As) ->
    add_severity(Severity, io_lib:fwrite(S, As)).

add_severity(Severity, S) ->
    [severity_tag(Severity), S].

severity_tag(fatal)   -> <<"*** ">>;
severity_tag(serious) -> <<"** ">>;
severity_tag(benign)  -> <<"* ">>.

restrict_handlers(RShMod, Shell, RT, FT) ->
    { fun(F,As,Binds) ->
              local_allowed(F, As, RShMod, Binds, Shell, RT, FT)
      end,
      fun(MF,As) ->
              non_local_allowed(MF, As, RShMod, Shell)
      end }.

-define(BAD_RETURN(M, F, V),
        try erlang:error(reason)
        catch _:_:S -> erlang:raise(exit, {restricted_shell_bad_return,V},
                                    [{M,F,3} | S])
        end).

local_allowed(F, As, RShMod, Bs, Shell, RT,  FT) when is_atom(F) ->
    {LFH,NLFH} = restrict_handlers(RShMod, Shell, RT, FT),
    case not_restricted(F, As) of % Not restricted is the same as builtin.
                                                % variable and record manipulations local
                                                % to the shell process. Those are never
                                                % restricted.
        true ->
            local_func(F, As, Bs, Shell, RT, FT, {eval,LFH}, {value,NLFH});
        false ->
            {AsEv,Bs1} = expr_list(As, Bs, {eval,LFH}, {value,NLFH}),
            case RShMod:local_allowed(F, AsEv, {get(restricted_shell_state),
                                                get(restricted_expr_state)}) of
                {Result,{RShShSt,RShExprSt}} ->
                    put(restricted_shell_state, RShShSt),
                    put(restricted_expr_state, RShExprSt),
                    if not Result ->
                            shell_req(Shell, {update_dict,get()}),
                            exit({restricted_shell_disallowed,{F,AsEv}});
                       true -> % This is never a builtin,
                                                % those are handled above.
                            non_builtin_local_func(F,AsEv,Bs1, FT)
                    end;
                Unexpected ->  % The user supplied non conforming module
                    ?BAD_RETURN(RShMod, local_allowed, Unexpected)
            end
    end.

non_local_allowed(MForFun, As, RShMod, Shell) ->
    case RShMod:non_local_allowed(MForFun, As, {get(restricted_shell_state),
                                                get(restricted_expr_state)}) of
        {Result,{RShShSt,RShExprSt}} ->
            put(restricted_shell_state, RShShSt),
            put(restricted_expr_state, RShExprSt),
            case Result of
                false ->
                    shell_req(Shell, {update_dict,get()}),
                    exit({restricted_shell_disallowed,{MForFun,As}});
                {redirect, NewMForFun, NewAs} ->
                    apply_fun(NewMForFun, NewAs, Shell);
                _ ->
                    apply_fun(MForFun, As, Shell)
            end;
        Unexpected ->  % The user supplied non conforming module
            ?BAD_RETURN(RShMod, non_local_allowed, Unexpected)
    end.

%% The commands implemented in shell should not be checked if allowed
%% This *has* to correspond to the function local_func/7!
%% (especially true for f/1, the argument must not be evaluated).
not_restricted(f, []) ->
    true;
not_restricted(f, [_]) ->
    true;
not_restricted(h, []) ->
    true;
not_restricted(b, []) ->
    true;
not_restricted(history, [_]) ->
    true;
not_restricted(results, [_]) ->
    true;
not_restricted(catch_exception, [_]) ->
    true;
not_restricted(exit, []) ->
    true;
not_restricted(fl, []) ->
    true;
not_restricted(fd, [_]) ->
    true;
not_restricted(ft, [_]) ->
    true;
not_restricted(td, [_]) ->
    true;
not_restricted(rd, [_]) ->
    true;
not_restricted(rd, [_,_]) ->
    true;
not_restricted(rf, []) ->
    true;
not_restricted(rf, [_]) ->
    true;
not_restricted(rl, []) ->
    true;
not_restricted(rl, [_]) ->
    true;
not_restricted(rp, [_]) ->
    true;
not_restricted(rr, [_]) ->
    true;
not_restricted(rr, [_,_]) ->
    true;
not_restricted(rr, [_,_,_]) ->
    true;
not_restricted(_, _) ->
    false.

%% When erlang:garbage_collect() is called from the shell,
%% the shell process process that spawned the evaluating
%% process is garbage collected as well.
%% To garbage collect the evaluating process only the command
%% garbage_collect(self()). can be used.
apply_fun({erlang,garbage_collect}, [], Shell) ->
    garb(Shell);
apply_fun({M,F}, As, _Shell) ->
    apply(M, F, As);
apply_fun(MForFun, As, _Shell) ->
    apply(MForFun, As).

prep_check({call,Anno,{atom,_,f},[{var,_,_Name}]}) ->
    %% Do not emit a warning for f(V) when V is unbound.
    {atom,Anno,ok};
prep_check({value,_CommandN,_Val}) ->
    %% erl_lint cannot handle the history expansion {value,_,_}.
    {atom,a0(),ok};
prep_check(T) when is_tuple(T) ->
    list_to_tuple(prep_check(tuple_to_list(T)));
prep_check([E | Es]) ->
    [prep_check(E) | prep_check(Es)];
prep_check(E) ->
    E.

expand_records([], E0) ->
    E0;
expand_records(UsedRecords, E0) ->
    RecordDefs = [Def || {_Name,Def} <- UsedRecords],
    A = erl_anno:new(1),
    E = prep_rec(E0),
    Forms0 = RecordDefs ++ [{function,A,foo,0,[{clause,A,[],[],[E]}]}],
    Forms = erl_expand_records:module(Forms0, [strict_record_tests]),
    {function,A,foo,0,[{clause,A,[],[],[NE]}]} = lists:last(Forms),
    prep_rec(NE).

prep_rec({value,_CommandN,_V}=Value) ->
    %% erl_expand_records cannot handle the history expansion {value,_,_}.
    {atom,Value,ok};
prep_rec({atom,{value,_CommandN,_V}=Value,ok}) ->
    %% Undo the effect of the previous clause...
    Value;
prep_rec(T) when is_tuple(T) -> list_to_tuple(prep_rec(tuple_to_list(T)));
prep_rec([E | Es]) -> [prep_rec(E) | prep_rec(Es)];
prep_rec(E) -> E.

init_dict([{K,V}|Ds]) ->
    put(K, V),
    init_dict(Ds);
init_dict([]) -> true.

%% local_func(Function, Args, Bindings, Shell, RecordTable,
%%            LocalFuncHandler, ExternalFuncHandler) -> {value,Val,Bs}
%%  Evaluate local functions, including shell commands.
%%
%% Note that the predicate not_restricted/2 has to correspond to what's
%% handled internally - it should return 'true' for all local functions
%% handled in this module (i.e. those that are not eventually handled by
%% non_builtin_local_func/3 (user_default/shell_default).
local_func() -> [v,h,b,f,fl,rd,rf,rl,rp,rr,history,results,catch_exception].
local_func(Func) ->
    lists:member(Func, local_func()).
local_func(v, [{integer,_,V}], Bs, Shell, _RT, _FT, _Lf, _Ef) ->
    %% This command is validated and expanded prior.
    {_Ces,Value,_N} = shell_req(Shell, {get_cmd, V}),
    {value,Value,Bs};
local_func(h, [], Bs, Shell, RT, _FT, _Lf, _Ef) ->
    Cs = shell_req(Shell, get_cmd),
    Cs1 = lists:filter(fun({{command, _},_}) -> true;
                          ({{result, _},_}) -> true;
                          (_) -> false
                       end,
                       Cs),
    Cs2 = lists:map(fun({{T, N}, V}) -> {{N, T}, V} end,
                    Cs1),
    Cs3 = lists:keysort(1, Cs2),
    {value,list_commands(Cs3, RT),Bs};
local_func(b, [], Bs, _Shell, RT, _FT, _Lf, _Ef) ->
    {value,list_bindings(erl_eval:bindings(Bs), RT),Bs};
local_func(f, [], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    {value,ok,erl_eval:new_bindings()};
local_func(f, [{var,_,Name}], Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    {value,ok,erl_eval:del_binding(Name, Bs)};
local_func(f, [_Other], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell,f,1}]);
local_func(fl, [], Bs, _Shell, _RT, FT, _Lf, _Ef) ->
    {value, ets:tab2list(FT), Bs};
local_func(fd, [{atom,_,FunName}, FunExpr], Bs, _Shell, _RT, FT, _Lf, _Ef) ->
    {value, Fun, []} = erl_eval:expr(FunExpr, []),
    {arity, Arity} = erlang:fun_info(Fun, arity),
    ets:insert(FT, [{{function, {shell_default, FunName, Arity}}, Fun}]),
    {value, ok, Bs};
local_func(fd, [_], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell, fd, 1}]);
local_func(ft, [{string, _, TypeDef}], Bs, _Shell, _RT, FT, _Lf, _Ef) ->
    case erl_scan:tokens([], TypeDef, {1,1}, [text,{reserved_word_fun,fun erl_scan:reserved_word/1}]) of
        {done, {ok, Toks, _}, _} ->
            case erl_parse:parse_form(Toks) of
                {ok, {attribute,_,spec,{{FunName, Arity},_}}=AttrForm} ->
                    ets:insert(FT, [{{function_type, {shell_default, FunName, Arity}}, AttrForm}]),
                    {value, ok, Bs};
                {error,{_Location,M,ErrDesc}} ->
                    ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
                    exit(lists:flatten(ErrStr))
            end;
        {done, {error,{_Location, M, ErrDesc}, _}, _} ->
            ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
            exit(lists:flatten(ErrStr))
    end;
local_func(ft, [_], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell, ft, 1}]);
local_func(td, [{string, _, TypeDef}], Bs, _Shell, _RT, FT, _Lf, _Ef) ->
    case erl_scan:tokens([], TypeDef, {1,1}, [text,{reserved_word_fun,fun erl_scan:reserved_word/1}]) of
        {done, {ok, Toks, _}, _} ->
            case erl_parse:parse_form(Toks) of
                {ok, {attribute,_,type,{TypeName, _, _}}=AttrForm} ->
                    ets:insert(FT, [{{type, TypeName}, AttrForm}]),
                    {value, ok, Bs};
                {error,{_Location,M,ErrDesc}} ->
                    ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
                    exit(lists:flatten(ErrStr))
            end;
        {done, {error,{_Location, M, ErrDesc}, _}, _} ->
            ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
            exit(lists:flatten(ErrStr))
    end;
local_func(td, [_], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell, td, 1}]);
local_func(rd, [{string, _, TypeDef}], Bs, _Shell, RT, _FT, _Lf, _Ef) ->
    case erl_scan:tokens([], TypeDef, {1,1}, [text,{reserved_word_fun,fun erl_scan:reserved_word/1}]) of
        {done, {ok, Toks, _}, _} ->
            case erl_parse:parse_form(Toks) of
                {ok,{attribute,_,_,_}=AttrForm} ->
                    [_] = add_records([AttrForm], Bs, RT),
                    {value,ok,Bs};
                {error,{_Location,M,ErrDesc}} ->
                    ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
                    exit(lists:flatten(ErrStr))
            end;
        {done, {error,{_Location, M, ErrDesc}, _}, _}  ->
            ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
            exit(lists:flatten(ErrStr))
    end;
local_func(rd, [_], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell, rd, 1}]);
local_func(rd, [{atom,_,RecName0},RecDef0], Bs, _Shell, RT, _FT, _Lf, _Ef) ->
    RecDef = expand_value(RecDef0),
    RDs = lists:flatten(erl_pp:expr(RecDef)),
    RecName = io_lib:write_atom_as_latin1(RecName0),
    Attr = lists:concat(["-record(", RecName, ",", RDs, ")."]),
    {ok, Tokens, _} = erl_scan:string(Attr),
    case erl_parse:parse_form(Tokens) of
        {ok,AttrForm} ->
            [RN] = add_records([AttrForm], Bs, RT),
            {value,RN,Bs};
        {error,{_Location,M,ErrDesc}} ->
            ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
            exit(lists:flatten(ErrStr))
    end;
local_func(rd, [_,_], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell,rd,2}]);
local_func(rf, [], Bs, _Shell, RT, _FT, _Lf, _Ef) ->
    true = ets:delete_all_objects(RT),
    {value,initiate_records(Bs, RT),Bs};
local_func(rf, [A], Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[Recs],Bs} = expr_list([A], Bs0, Lf, Ef),
    if '_' =:= Recs ->
            true = ets:delete_all_objects(RT);
       true ->
            lists:foreach(fun(Name) -> true = ets:delete(RT, Name)
                          end, listify(Recs))
    end,
    {value,ok,Bs};
local_func(rl, [], Bs, _Shell, RT, _FT, _Lf, _Ef) ->
    {value,list_records(ets:tab2list(RT)),Bs};
local_func(rl, [A], Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[Recs],Bs} = expr_list([A], Bs0, Lf, Ef),
    {value,list_records(record_defs(RT, listify(Recs))),Bs};
local_func(rp, [A], Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[V],Bs} = expr_list([A], Bs0, Lf, Ef),
    Cs = pp(V, _Column=1, _Depth=-1, RT),
    io:requests([{put_chars, unicode, Cs}, nl]),
    {value,ok,Bs};
local_func(rr, [A], Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[File],Bs} = expr_list([A], Bs0, Lf, Ef),
    {value,read_and_add_records(File, '_', [], Bs, RT),Bs};
local_func(rr, [_,_]=As0, Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[File,Sel],Bs} = expr_list(As0, Bs0, Lf, Ef),
    {value,read_and_add_records(File, Sel, [], Bs, RT),Bs};
local_func(rr, [_,_,_]=As0, Bs0, _Shell, RT, _FT, Lf, Ef) ->
    {[File,Sel,Options],Bs} = expr_list(As0, Bs0, Lf, Ef),
    {value,read_and_add_records(File, Sel, Options, Bs, RT),Bs};
local_func(history, [{integer,_,N}], Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    {value,history(N),Bs};
local_func(history, [_Other], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell,history,1}]);
local_func(results, [{integer,_,N}], Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    {value,results(N),Bs};
local_func(results, [_Other], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell,results,1}]);
local_func(catch_exception, [{atom,_,Bool}], Bs, _Shell, _RT, _FT, _Lf, _Ef)
  when Bool; not Bool ->
    {value,catch_exception(Bool),Bs};
local_func(catch_exception, [_Other], _Bs, _Shell, _RT, _FT, _Lf, _Ef) ->
    erlang:raise(error, function_clause, [{shell,catch_exception,1}]);
local_func(exit, [], _Bs, Shell, _RT, _FT, _Lf, _Ef) ->
    shell_req(Shell, exit),                     %This terminates us
    exit(normal);
local_func(F, As0, Bs0, _Shell, _RT, FT, Lf, Ef) when is_atom(F) ->
    {As,Bs} = expr_list(As0, Bs0, Lf, Ef),
    non_builtin_local_func(F,As,Bs, FT).

non_builtin_local_func(F,As,Bs, FT) ->
    Arity = length(As),
    case erlang:function_exported(user_default, F, Arity) of
        true ->
            {eval,erlang:make_fun(user_default, F, Arity),As,Bs};
        false ->
            shell_default(F,As,Bs, FT)
    end.

shell_default(F,As,Bs, FT) ->
    M = shell_default,
    A = length(As),
    case code:ensure_loaded(M) of
        {module, _} ->
            case erlang:function_exported(M,F,A) of
                true ->
                    {eval,erlang:make_fun(M, F, A),As,Bs};
                false ->
                    shell_default_local_func(F,As, Bs, FT)
            end;
        {error, _} ->
            shell_default_local_func(F,As, Bs, FT)
    end.

shell_default_local_func(F, As, Bs, FT) ->
    case ets:lookup(FT, {function, {shell_default, F, length(As)}}) of
        [] -> shell_undef(F, length(As));
        [{_, Fun}] -> {eval, Fun, As, Bs}
    end.

shell_undef(F,A) ->
    erlang:error({shell_undef,F,A,[]}).

local_func_handler(Shell, RT, FT, Ef) ->
    H = fun(Lf) ->
                fun(F, As, Bs) ->
                        local_func(F, As, Bs, Shell, RT, FT, {eval,Lf(Lf)}, Ef)
                end
        end,
    {eval,H(H)}.

record_print_fun(RT) ->
    fun(Tag, NoFields) ->
            case ets:lookup(RT, Tag) of
                [{_,{attribute,_,record,{Tag,Fields}}}]
                  when length(Fields) =:= NoFields ->
                    record_fields(Fields);
                _ ->
                    no
            end
    end.

record_fields([{record_field,_,{atom,_,Field}} | Fs]) ->
    [Field | record_fields(Fs)];
record_fields([{record_field,_,{atom,_,Field},_} | Fs]) ->
    [Field | record_fields(Fs)];
record_fields([{typed_record_field,Field,_Type} | Fs]) ->
    record_fields([Field | Fs]);
record_fields([]) ->
    [].

initiate_records(Bs, RT) ->
    RNs1 = init_rec(shell_default, Bs, RT),
    RNs2 = case code:is_loaded(user_default) of
               {file,_File} ->
                   init_rec(user_default, Bs, RT);
               false ->
                   []
           end,
    lists:usort(RNs1 ++ RNs2).

init_rec(Module, Bs, RT) ->
    case read_records(Module, []) of
        RAs when is_list(RAs) ->
            case catch add_records(RAs, Bs, RT) of
                {'EXIT',_} ->
                    [];
                RNs ->
                    RNs
            end;
        _Error ->
            []
    end.

read_and_add_records(File, Selected, Options, Bs, RT) ->
    case read_records(File, Selected, Options) of
        RAs when is_list(RAs) ->
            add_records(RAs, Bs, RT);
        Error ->
            Error
    end.

read_records(File, Selected, Options) ->
    case read_records(File, listify(Options)) of
        Error when is_tuple(Error) ->
            Error;
        RAs when Selected =:= '_' ->
            RAs;
        RAs ->
            Sel = listify(Selected),
            [RA || {attribute,_,_,{Name,_}}=RA <- RAs,
                   lists:member(Name, Sel)]
    end.

add_records(RAs, Bs0, RT) ->
    %% TODO store File name to support type completion
    Recs = [{Name,D} || {attribute,_,_,{Name,_}}=D <- RAs],
    Bs1 = record_bindings(Recs, Bs0),
    case check_command([], Bs1) of
        {error,{_Location,M,ErrDesc}} ->
            %% A source file that has not been compiled.
            ErrStr = io_lib:fwrite(<<"~ts">>, [M:format_error(ErrDesc)]),
            exit(lists:flatten(ErrStr));
        ok ->
            true = ets:insert(RT, Recs),
            lists:usort([Name || {Name,_} <- Recs])
    end.

listify(L) when is_list(L) ->
    L;
listify(E) ->
    [E].

check_command(Es, Bs) ->
    erl_eval:check_command(Es, Bs).

expr(E, Bs, Lf, Ef) ->
    erl_eval:expr(E, Bs, Lf, Ef).

expr_list(Es, Bs, Lf, Ef) ->
    erl_eval:expr_list(Es, Bs, Lf, Ef).

%% Note that a sequence number is used here to make sure that if a
%% record is used by another record, then the first record is parsed
%% before the second record. (erl_eval:check_command() calls the
%% linter which needs the records in a proper order.)
record_bindings([], Bs) ->
    Bs;
record_bindings(Recs0, Bs0) ->
    {Recs1, _} = lists:mapfoldl(fun ({Name,Def}, I) -> {{Name,I,Def},I+1}
                                end, 0, Recs0),
    Recs2 = lists:keysort(2, lists:ukeysort(1, Recs1)),
    lists:foldl(fun ({Name,I,Def}, Bs) ->
                        erl_eval:add_binding({record,I,Name}, Def, Bs)
                end, Bs0, Recs2).

%%% Read record information from file(s)

read_records(FileOrModule, Opts0) ->
    Opts = lists:delete(report_warnings, Opts0),
    case find_file(FileOrModule) of
        {beam, Beam, File} ->
            read_records_from_beam(Beam, File);
        {files,[File]} ->
            read_file_records(File, Opts);
        {files,Files} ->
            lists:flatmap(fun(File) ->
                                  case read_file_records(File, Opts) of
                                      RAs when is_list(RAs) -> RAs;
                                      _ -> []
                                  end
                          end, Files);
        Error ->
            Error
    end.

-include_lib("kernel/include/file.hrl").

find_file(Mod) when is_atom(Mod) ->
    case code:which(Mod) of
        File when is_list(File) ->
            %% Special cases:
            %% - Modules not in the code path (loaded with code:load_abs/1):
            %%   code:get_object_code/1 only searches in the code path
            %%   but code:which/1 finds all loaded modules
            %% - File can also be a file in an archive,
            %%   beam_lib:chunks/2 cannot handle such paths but
            %%   erl_prim_loader:get_file/1 can
            case erl_prim_loader:get_file(File) of
                {ok, Beam, _} ->
                    {beam, Beam, File};
                error ->
                    {error, nofile}
            end;
        preloaded ->
            {_M, Beam, File} = code:get_object_code(Mod),
            {beam, Beam, File};
        _Else -> % non_existing, interpreted, cover_compiled
            {error,nofile}
    end;
find_file(File) ->
    case catch filelib:wildcard(File) of
        {'EXIT',_} ->
            {error,invalid_filename};
        Files ->
            {files,Files}
    end.

read_file_records(File, Opts) ->
    case filename:extension(File) of
        ".beam" ->
            read_records_from_beam(File, File);
        _ ->
            parse_file(File, Opts)
    end.

read_records_from_beam(Beam, File) ->
    case beam_lib:chunks(Beam, [abstract_code,"CInf"]) of
        {ok,{_Mod,[{abstract_code,{Version,Forms}},{"CInf",CB}]}} ->
            case record_attrs(Forms) of
                [] when Version =:= raw_abstract_v1 ->
                    [];
                [] ->
                    %% If the version is raw_X, then this test
                    %% is unnecessary.
                    try_source(File, CB);
                Records ->
                    Records
            end;
        {ok,{_Mod,[{abstract_code,no_abstract_code},{"CInf",CB}]}} ->
            try_source(File, CB);
        Error ->
            %% Could be that the "Abst" chunk is missing (pre R6).
            Error
    end.

%% This is how the debugger searches for source files. See int.erl.
try_source(Beam, RawCB) ->
    EbinDir = filename:dirname(Beam),
    CB = binary_to_term(RawCB),
    Os = proplists:get_value(options,CB, []),
    Src0 = filename:rootname(Beam) ++ ".erl",
    Src1 = filename:join([filename:dirname(EbinDir), "src",
                          filename:basename(Src0)]),
    Src2 = proplists:get_value(source, CB, []),
    try_sources([Src0,Src1,Src2], Os).

try_sources([], _) ->
    {error, nofile};
try_sources([Src|Rest], Os) ->
    case is_file(Src) of
        true -> parse_file(Src, Os);
        false -> try_sources(Rest, Os)
    end.

is_file(Name) ->
    case filelib:is_file(Name) of
        true ->
            not filelib:is_dir(Name);
        false ->
            false
    end.

parse_file(File, Opts) ->
    Cwd = ".",
    Dir = filename:dirname(File),
    IncludePath = [Cwd,Dir|inc_paths(Opts)],
    case epp:parse_file(File, IncludePath, pre_defs(Opts)) of
        {ok,Forms} ->
            record_attrs(Forms);
        Error ->
            Error
    end.

pre_defs([{d,M,V}|Opts]) ->
    [{M,V}|pre_defs(Opts)];
pre_defs([{d,M}|Opts]) ->
    [M|pre_defs(Opts)];
pre_defs([_|Opts]) ->
    pre_defs(Opts);
pre_defs([]) -> [].

inc_paths(Opts) ->
    [P || {i,P} <- Opts, is_list(P)].

record_attrs(Forms) ->
    [A || A = {attribute,_,record,_D} <- Forms].

%%% End of reading record information from file(s)

shell_req(Shell, Req) ->
    Shell ! {shell_req,self(),Req},
    receive
        {shell_rep,Shell,Rep} -> Rep
    end.

list_commands([{{N,command},Es0}, {{N,result}, V} |Ds], RT) ->
    Es = prep_list_commands(Es0),
    VS = pp(V, 4, RT),
    Ns = io_lib:fwrite(<<"~w: ">>, [N]),
    I = iolist_size(Ns),
    io:requests([{put_chars, latin1, Ns},
                 {format,<<"~ts\n">>,[erl_pp:exprs(Es, I, enc())]},
                 {format,<<"-> ">>,[]},
                 {put_chars, unicode, VS},
                 nl]),
    list_commands(Ds, RT);
list_commands([{{N,command},Es0} |Ds], RT) ->
    Es = prep_list_commands(Es0),
    Ns = io_lib:fwrite(<<"~w: ">>, [N]),
    I = iolist_size(Ns),
    io:requests([{put_chars, latin1, Ns},
                 {format,<<"~ts\n">>,[erl_pp:exprs(Es, I, enc())]}]),
    list_commands(Ds, RT);
list_commands([_D|Ds], RT) ->
    list_commands(Ds, RT);
list_commands([], _RT) -> ok.

list_bindings([{Name,Val}|Bs], RT) ->
    case erl_eval:fun_data(Val) of
        {fun_data,_FBs,FCs0} ->
            FCs = expand_value(FCs0), % looks nicer
            A = a0(),
            F = {'fun',A,{clauses,FCs}},
            M = {match,A,{var,A,Name},F},
            io:fwrite(<<"~ts\n">>, [erl_pp:expr(M, enc())]);
        {named_fun_data,_FBs,FName,FCs0} ->
            FCs = expand_value(FCs0), % looks nicer
            A = a0(),
            F = {named_fun,A,FName,FCs},
            M = {match,A,{var,A,Name},F},
            io:fwrite(<<"~ts\n">>, [erl_pp:expr(M, enc())]);
        false ->
            Namel = io_lib:fwrite(<<"~s = ">>, [Name]),
            Nl = iolist_size(Namel)+1,
            ValS = pp(Val, Nl, RT),
            io:requests([{put_chars, latin1, Namel},
                         {put_chars, unicode, ValS},
                         nl])
    end,
    list_bindings(Bs, RT);
list_bindings([], _RT) ->
    ok.

list_records(Records) ->
    lists:foreach(fun({_Name,Attr}) ->
                          io:fwrite(<<"~ts">>, [erl_pp:attribute(Attr, enc())])
                  end, Records).

record_defs(RT, Names) ->
    lists:flatmap(fun(Name) -> ets:lookup(RT, Name)
                  end, Names).

expand_value(E) ->
    substitute_v1(fun({value,CommandN,V}) -> try_abstract(V, CommandN)
                  end, E).

%% There is no abstract representation of funs.
try_abstract(V, CommandN) ->
    try erl_parse:abstract(V)
    catch
        _:_ ->
            A = a0(),
            {call,A,{atom,A,v},[{integer,A,CommandN}]}
    end.

%% Rather than listing possibly huge results the calls to v/1 are shown.
prep_list_commands(E) ->
    A = a0(),
    substitute_v1(fun({value,Anno,_V}) ->
                          CommandN = erl_anno:line(Anno),
                          {call,A,{atom,A,v},[{integer,A,CommandN}]}
                  end, E).

substitute_v1(F, {value,_,_}=Value) ->
    F(Value);
substitute_v1(F, T) when is_tuple(T) ->
    list_to_tuple(substitute_v1(F, tuple_to_list(T)));
substitute_v1(F, [E | Es]) ->
    [substitute_v1(F, E) | substitute_v1(F, Es)];
substitute_v1(_F, E) ->
    E.

a0() ->
    erl_anno:new(0).

pos({Line,Col}) ->
    io_lib:format("~w:~w", [Line,Col]);
pos(Line) ->
    io_lib:format("~w", [Line]).

check_and_get_history_and_results() ->
    check_env(shell_history_length),
    check_env(shell_saved_results),
    get_history_and_results().

get_history_and_results() ->
    History = get_env(shell_history_length, ?DEF_HISTORY),
    Results = get_env(shell_saved_results, ?DEF_RESULTS),
    {History, erlang:min(Results, History)}.

pp(V, I, RT) ->
    pp(V, I, _Depth=?LINEMAX, RT).

pp(V, I, D, RT) ->
    Strings = application:get_env(stdlib, shell_strings, true) =/= false,
    io_lib_pretty:print(V, ([{column, I}, {line_length, columns()},
                             {depth, D}, {line_max_chars, ?CHAR_MAX},
                             {strings, Strings},
                             {record_print_fun, record_print_fun(RT)}]
                            ++ enc())).

columns() ->
    case io:columns() of
        {ok,N} -> N;
        _ -> 80
    end.

encoding() ->
    [{encoding, Encoding}] = enc(),
    Encoding.

enc() ->
    case lists:keyfind(encoding, 1, io:getopts()) of
        false -> [{encoding,latin1}]; % should never happen
        Enc -> [Enc]
    end.

garb(Shell) ->
    erlang:garbage_collect(Shell),
    catch erlang:garbage_collect(whereis(user)),
    catch erlang:garbage_collect(group_leader()),
    erlang:garbage_collect().

get_env(V, Def) ->
    case application:get_env(stdlib, V, Def) of
        Val when is_integer(Val), Val >= 0 ->
            Val;
        _ ->
            Def
    end.

check_env(V) ->
    case application:get_env(stdlib, V, 0) of
        Val when is_integer(Val), Val >= 0 ->
            ok;
        Val ->
            Txt = io_lib:fwrite
                    ("Invalid value of STDLIB configuration parameter"
                     "~tw: ~tp\n", [V, Val]),
            error_logger:info_report(lists:flatten(Txt))
    end.

set_env(App, Name, Val, Default) ->
    Prev = case application:get_env(App, Name) of
               undefined ->
                   Default;
               {ok, Old} ->
                   Old
           end,
    application_controller:set_env(App, Name, Val),
    Prev.

-spec history(N) -> non_neg_integer() when
      N :: non_neg_integer().

history(L) when is_integer(L), L >= 0 ->
    set_env(stdlib, shell_history_length, L, ?DEF_HISTORY).

-spec results(N) -> non_neg_integer() when
      N :: non_neg_integer().

results(L) when is_integer(L), L >= 0 ->
    set_env(stdlib, shell_saved_results, L, ?DEF_RESULTS).

-spec catch_exception(Bool) -> boolean() when
      Bool :: boolean().

catch_exception(Bool) ->
        set_env(stdlib, shell_catch_exception, Bool, ?DEF_CATCH_EXCEPTION).

-spec prompt_func(PromptFunc) -> PromptFunc2 when
      PromptFunc :: 'default' | {module(),atom()},
      PromptFunc2 :: 'default' | {module(),atom()}.

prompt_func(PromptFunc) ->
    set_env(stdlib, shell_prompt_func, PromptFunc, ?DEF_PROMPT_FUNC).

-spec strings(Strings) -> Strings2 when
      Strings :: boolean(),
      Strings2 :: boolean().

strings(Strings) ->
    set_env(stdlib, shell_strings, Strings, ?DEF_STRINGS).
