/++
  read configuration files<BR>
  - read config files<BR>
  ao_config_files.d
+/
template ConfigIn() {
  private import
    std.algorithm,
    std.array,
    std.container,
    std.exception,
    std.stdio,
    std.file,
    std.path,
    std.range,
    std.regex,
    std.string,
    std.traits,
    std.typecons,
    std.uni,
    std.utf,
    std.conv : to;
  import std.file;
  final string ConfigIn(C,E)(C conf_sdl, E env) {
    string dot_pwd = chainPath(to!string(env["pwd"]), ".sisu").array;
    string underscore_pwd = chainPath(to!string(env["pwd"]), "_sisu").array;
    string dot_home = chainPath(to!string(env["home"]), ".sisu").array;
    string[] possible_config_path_locations = [
      dot_pwd,
      underscore_pwd,
      dot_home,
      "/etc/sisu"
    ];
    string config_file_str;
    foreach(pth; possible_config_path_locations) {
      auto conf_file = format(
        "%s/%s",
        pth,
        conf_sdl,
      );
      try {
        if (exists(conf_file)) {
          debug(configfile) {
            writeln(conf_file);
          }
          config_file_str = readText(conf_file);
          break;
        }
      }
      catch (ErrnoException ex) {
      }
      catch (FileException ex) {
      }
    }
    return config_file_str;
  }
}
/+

+/
template ConfigSDLang() {
  import sdlang;
  private import
    std.algorithm,
    std.array,
    std.container,
    std.exception,
    std.stdio,
    std.file,
    std.path,
    std.range,
    std.regex,
    std.string,
    std.traits,
    std.typecons,
    std.uni,
    std.utf,
    std.conv : to;
  auto ConfigSDLang(string configuration, string conf_sdl_filename) {
    Tag sdl_root_conf;
    try {
      sdl_root_conf = parseSource(configuration);
    }
    catch(ParseException e) {
      stderr.writeln("SDLang problem with content for ", conf_sdl_filename);
      stderr.writeln(e.msg);
    }
    debug(sdlang) {
      Value output_dir_structure_by = sdl_root_conf.tags["output_dir_structure_by"][0].values[0];
      assert(output_dir_structure_by.type == typeid(string));
      writeln(output_dir_structure_by);
      writeln("conf SDL:");
      writeln(sdl_root_conf.toSDLDocument());
    }
    return sdl_root_conf;
  }
}
/+
+/
template ConfigHub() {
  private import
    std.algorithm,
    std.array,
    std.container,
    std.exception,
    std.stdio,
    std.file,
    std.path,
    std.range,
    std.regex,
    std.string,
    std.traits,
    std.typecons,
    std.uni,
    std.utf,
    std.conv : to;
  
  final auto ConfigHub(C,E)(C conf_sdl, E env) {
    auto configuration = ConfigIn!()(conf_sdl, env);
    auto sdl_root = ConfigSDLang!()(configuration, conf_sdl);
    return sdl_root;
  }
}