script_info_dummy.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "../stdafx.h"
#include <squirrel.h>
 
#include "../string_func.h"
#include "../strings_func.h"
#include "../core/format.hpp"
 
#include "../safeguards.h"
 
/* The reason this exists in C++, is that a user can trash their ai/ or game/ dir,
 *  leaving no Scripts available. The complexity to solve this is insane, and
 *  therefore the alternative is used, and make sure there is always a Script
 *  available, no matter what the situation is. By defining it in C++, there
 *  is simply no way a user can delete it, and therefore safe to use. It has
 *  to be noted that this Script is complete invisible for the user, and impossible
 *  to select manual. It is a fail-over in case no Scripts are available.
 */

void Script_CreateDummyInfo(HSQUIRRELVM vm, std::string_view type, std::string_view dir)
{
  std::string dummy_script = fmt::format(
      "class Dummy{0} extends {0}Info {{\n"
      "function GetAuthor()      {{ return \"OpenTTD Developers Team\"; }}\n"
      "function GetName()        {{ return \"Dummy{0}\"; }}\n"
      "function GetShortName()   {{ return \"DUMM\"; }}\n"
      "function GetDescription() {{ return \"A Dummy {0} that is loaded when your {1}/ dir is empty\"; }}\n"
      "function GetVersion()     {{ return 1; }}\n"
      "function GetDate()        {{ return \"2008-07-26\"; }}\n"
      "function CreateInstance() {{ return \"Dummy{0}\"; }}\n"
      "}} RegisterDummy{0}(Dummy{0}());\n", type, dir);
 
  sq_pushroottable(vm);
 
  /* Load and run the script */
  if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script, "dummy", SQTrue))) {
    sq_push(vm, -2);
    if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
      sq_pop(vm, 1);
      return;
    }
  }
  NOT_REACHED();
}

static std::vector<std::string> EscapeQuotesAndSlashesAndSplitOnNewLines(const std::string &message)
{
  std::vector<std::string> messages;
 
  std::string safe_message;
  for (auto c : message) {
    if (c == '\n') {
      messages.emplace_back(std::move(safe_message));
      safe_message.clear(); // std::move leaves safe_message in a "valid but unspecified state" according to the specification.
      continue;
    }
 
    if (c == '"' || c == '\\') safe_message.push_back('\\');
    safe_message.push_back(c);
  }
  messages.emplace_back(std::move(safe_message));
  return messages;
}

void Script_CreateDummy(HSQUIRRELVM vm, StringID string, std::string_view type)
{
  /* We want to translate the error message.
   * We do this in three steps:
   * 1) We get the error message, escape quotes and slashes, and split on
   *    newlines because Log.Error terminates passed strings at newlines.
   */
  std::string error_message = GetString(string);
  std::vector<std::string> messages = EscapeQuotesAndSlashesAndSplitOnNewLines(error_message);
 
  /* 2) We construct the AI's code. This is done by merging a header, body and footer */
  std::string dummy_script;
  /* Just a rough ballpark estimate. */
  dummy_script.reserve(error_message.size() + 128 + 64 * messages.size());
 
  format_append(dummy_script, "class Dummy{0} extends {0}Controller {{\n  function Start()\n  {{\n", type);
  for (std::string &message : messages) {
    format_append(dummy_script, "    {}Log.Error(\"{}\");\n", type, message);
  }
  dummy_script += "  }\n}\n";
 
  /* 3) Finally we load and run the script */
  sq_pushroottable(vm);
  if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script, "dummy", SQTrue))) {
    sq_push(vm, -2);
    if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
      sq_pop(vm, 1);
      return;
    }
  }
  NOT_REACHED();
}