-module(target_system).
-export([create/1, create/2, install/2]).

%% Note: RelFileName below is the *stem* without trailing .rel,
%% .script etc.
%%

%% create(RelFileName)
%%
create(RelFileName) ->
    create(RelFileName,[]).

create(RelFileName,SystoolsOpts) ->
    RelFile = RelFileName ++ ".rel", 
    Dir = filename:dirname(RelFileName),
    PlainRelFileName = filename:join(Dir,"plain"),
    PlainRelFile = PlainRelFileName ++ ".rel",
    io:fwrite("Reading file: ~ts ...~n", [RelFile]),
    {ok, [RelSpec]} = file:consult(RelFile),
    io:fwrite("Creating file: ~ts from ~ts ...~n",
              [PlainRelFile, RelFile]),
    {release,
     {RelName, RelVsn},
     {erts, ErtsVsn},
     AppVsns} = RelSpec,
    PlainRelSpec = {release, 
                    {RelName, RelVsn},
                    {erts, ErtsVsn},
                    lists:filter(fun({kernel, _}) -> 
                                         true;
                                    ({stdlib, _}) ->
                                         true;
                                    (_) ->
                                         false
                                 end, AppVsns)
                   },
    {ok, Fd} = file:open(PlainRelFile, [write]),
    io:fwrite(Fd, "~p.~n", [PlainRelSpec]),
    file:close(Fd),

    io:fwrite("Making \"~ts.script\" and \"~ts.boot\" files ...~n",
	      [PlainRelFileName,PlainRelFileName]),
    make_script(PlainRelFileName,SystoolsOpts),

    io:fwrite("Making \"~ts.script\" and \"~ts.boot\" files ...~n",
              [RelFileName, RelFileName]),
    make_script(RelFileName,SystoolsOpts),

    TarFileName = RelFileName ++ ".tar.gz",
    io:fwrite("Creating tar file ~ts ...~n", [TarFileName]),
    make_tar(RelFileName,SystoolsOpts),

    TmpDir = filename:join(Dir,"tmp"),
    io:fwrite("Creating directory ~tp ...~n",[TmpDir]),
    file:make_dir(TmpDir), 

    io:fwrite("Extracting ~ts into directory ~ts ...~n", [TarFileName,TmpDir]),
    extract_tar(TarFileName, TmpDir),

    TmpBinDir = filename:join([TmpDir, "bin"]),
    ErtsBinDir = filename:join([TmpDir, "erts-" ++ ErtsVsn, "bin"]),
    io:fwrite("Deleting \"erl\" and \"start\" in directory ~ts ...~n",
              [ErtsBinDir]),
    file:delete(filename:join([ErtsBinDir, "erl"])),
    file:delete(filename:join([ErtsBinDir, "start"])),

    io:fwrite("Creating temporary directory ~ts ...~n", [TmpBinDir]),
    file:make_dir(TmpBinDir),

    io:fwrite("Copying file \"~ts.boot\" to ~ts ...~n",
              [PlainRelFileName, filename:join([TmpBinDir, "start.boot"])]),
    copy_file(PlainRelFileName++".boot",filename:join([TmpBinDir, "start.boot"])),

    io:fwrite("Copying files \"epmd\", \"run_erl\" and \"to_erl\" from \n"
              "~ts to ~ts ...~n",
              [ErtsBinDir, TmpBinDir]),
    copy_file(filename:join([ErtsBinDir, "epmd"]), 
              filename:join([TmpBinDir, "epmd"]), [preserve]),
    copy_file(filename:join([ErtsBinDir, "run_erl"]), 
              filename:join([TmpBinDir, "run_erl"]), [preserve]),
    copy_file(filename:join([ErtsBinDir, "to_erl"]), 
              filename:join([TmpBinDir, "to_erl"]), [preserve]),

    %% This is needed if 'start' script created from 'start.src' shall
    %% be used as it points out this directory as log dir for 'run_erl'
    TmpLogDir = filename:join([TmpDir, "log"]),
    io:fwrite("Creating temporary directory ~ts ...~n", [TmpLogDir]),
    ok = file:make_dir(TmpLogDir),

    StartErlDataFile = filename:join([TmpDir, "releases", "start_erl.data"]),
    io:fwrite("Creating ~ts ...~n", [StartErlDataFile]),
    StartErlData = io_lib:fwrite("~s ~s~n", [ErtsVsn, RelVsn]),
    write_file(StartErlDataFile, StartErlData),
    
    io:fwrite("Recreating tar file ~ts from contents in directory ~ts ...~n",
	      [TarFileName,TmpDir]),
    {ok, Tar} = erl_tar:open(TarFileName, [write, compressed]),
    %% {ok, Cwd} = file:get_cwd(),
    %% file:set_cwd("tmp"),
    ErtsDir = "erts-"++ErtsVsn,
    erl_tar:add(Tar, filename:join(TmpDir,"bin"), "bin", []),
    erl_tar:add(Tar, filename:join(TmpDir,ErtsDir), ErtsDir, []),
    erl_tar:add(Tar, filename:join(TmpDir,"releases"), "releases", []),
    erl_tar:add(Tar, filename:join(TmpDir,"lib"), "lib", []),
    erl_tar:add(Tar, filename:join(TmpDir,"log"), "log", []),
    erl_tar:close(Tar),
    %% file:set_cwd(Cwd),
    io:fwrite("Removing directory ~ts ...~n",[TmpDir]),
    remove_dir_tree(TmpDir),
    ok.


install(RelFileName, RootDir) ->
    TarFile = RelFileName ++ ".tar.gz", 
    io:fwrite("Extracting ~ts ...~n", [TarFile]),
    extract_tar(TarFile, RootDir),
    StartErlDataFile = filename:join([RootDir, "releases", "start_erl.data"]),
    {ok, StartErlData} = read_txt_file(StartErlDataFile),
    [ErlVsn, _RelVsn| _] = string:tokens(StartErlData, " \n"),
    ErtsBinDir = filename:join([RootDir, "erts-" ++ ErlVsn, "bin"]),
    BinDir = filename:join([RootDir, "bin"]),
    io:fwrite("Substituting in erl.src, start.src and start_erl.src to "
              "form erl, start and start_erl ...\n"),
    subst_src_scripts(["erl", "start", "start_erl"], ErtsBinDir, BinDir, 
                      [{"FINAL_ROOTDIR", RootDir}, {"EMU", "beam"}],
                      [preserve]),
    %%! Workaround for pre OTP 17.0: start.src and start_erl.src did
    %%! not have correct permissions, so the above 'preserve' option did not help
    ok = file:change_mode(filename:join(BinDir,"start"),8#0755),
    ok = file:change_mode(filename:join(BinDir,"start_erl"),8#0755),

    io:fwrite("Creating the RELEASES file ...\n"),
    create_RELEASES(RootDir, filename:join([RootDir, "releases",
					    filename:basename(RelFileName)])).

%% LOCALS 

%% make_script(RelFileName,Opts)
%%
make_script(RelFileName,Opts) ->
    systools:make_script(RelFileName, [no_module_tests,
				       {outdir,filename:dirname(RelFileName)}
				       |Opts]).

%% make_tar(RelFileName,Opts)
%%
make_tar(RelFileName,Opts) ->
    RootDir = code:root_dir(),
    systools:make_tar(RelFileName, [{erts, RootDir},
				    {outdir,filename:dirname(RelFileName)}
				    |Opts]).

%% extract_tar(TarFile, DestDir)
%%
extract_tar(TarFile, DestDir) ->
    erl_tar:extract(TarFile, [{cwd, DestDir}, compressed]).

create_RELEASES(DestDir, RelFileName) ->
    release_handler:create_RELEASES(DestDir, RelFileName ++ ".rel").

subst_src_scripts(Scripts, SrcDir, DestDir, Vars, Opts) -> 
    lists:foreach(fun(Script) ->
                          subst_src_script(Script, SrcDir, DestDir, 
                                           Vars, Opts)
                  end, Scripts).

subst_src_script(Script, SrcDir, DestDir, Vars, Opts) -> 
    subst_file(filename:join([SrcDir, Script ++ ".src"]),
               filename:join([DestDir, Script]),
               Vars, Opts).

subst_file(Src, Dest, Vars, Opts) ->
    {ok, Conts} = read_txt_file(Src),
    NConts = subst(Conts, Vars),
    write_file(Dest, NConts),
    case lists:member(preserve, Opts) of
        true ->
            {ok, FileInfo} = file:read_file_info(Src),
            file:write_file_info(Dest, FileInfo);
        false ->
            ok
    end.

%% subst(Str, Vars)
%% Vars = [{Var, Val}]
%% Var = Val = string()
%% Substitute all occurrences of %Var% for Val in Str, using the list
%% of variables in Vars.
%%
subst(Str, Vars) ->
    subst(Str, Vars, []).

subst([$%, C| Rest], Vars, Result) when $A =< C, C =< $Z ->
    subst_var([C| Rest], Vars, Result, []);
subst([$%, C| Rest], Vars, Result) when $a =< C, C =< $z ->
    subst_var([C| Rest], Vars, Result, []);
subst([$%, C| Rest], Vars, Result) when  C == $_ ->
    subst_var([C| Rest], Vars, Result, []);
subst([C| Rest], Vars, Result) ->
    subst(Rest, Vars, [C| Result]);
subst([], _Vars, Result) ->
    lists:reverse(Result).

subst_var([$%| Rest], Vars, Result, VarAcc) ->
    Key = lists:reverse(VarAcc),
    case lists:keysearch(Key, 1, Vars) of
        {value, {Key, Value}} ->
            subst(Rest, Vars, lists:reverse(Value, Result));
        false ->
            subst(Rest, Vars, [$%| VarAcc ++ [$%| Result]])
    end;
subst_var([C| Rest], Vars, Result, VarAcc) ->
    subst_var(Rest, Vars, Result, [C| VarAcc]);
subst_var([], Vars, Result, VarAcc) ->
    subst([], Vars, [VarAcc ++ [$%| Result]]).

copy_file(Src, Dest) ->
    copy_file(Src, Dest, []).

copy_file(Src, Dest, Opts) ->
    {ok,_} = file:copy(Src, Dest),
    case lists:member(preserve, Opts) of
        true ->
            {ok, FileInfo} = file:read_file_info(Src),
            file:write_file_info(Dest, FileInfo);
        false ->
            ok
    end.
       
write_file(FName, Conts) ->
    Enc = file:native_name_encoding(),
    {ok, Fd} = file:open(FName, [write]),
    file:write(Fd, unicode:characters_to_binary(Conts,Enc,Enc)),
    file:close(Fd).

read_txt_file(File) ->
    {ok, Bin} = file:read_file(File),
    {ok, binary_to_list(Bin)}.

remove_dir_tree(Dir) ->
    remove_all_files(".", [Dir]).

remove_all_files(Dir, Files) ->
    lists:foreach(fun(File) ->
                          FilePath = filename:join([Dir, File]),
                          case filelib:is_dir(FilePath) of
                              true ->
                                  {ok, DirFiles} = file:list_dir(FilePath), 
                                  remove_all_files(FilePath, DirFiles),
                                  file:del_dir(FilePath);
                              _ ->
                                  file:delete(FilePath)
                          end
                  end, Files).