/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2014 Medical Physics Department, CHU of Liege,
 * Belgium
 *
 * This program 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, either version 3 of the
 * License, or (at your option) any later version.
 *
 * In addition, as a special exception, the copyright holders of this
 * program give permission to link the code of its release with the
 * OpenSSL project's "OpenSSL" library (or with modified versions of it
 * that use the same license as the "OpenSSL" library), and distribute
 * the linked executables. You must obey the GNU General Public License
 * in all respects for all of the code used other than "OpenSSL". If you
 * modify file(s) with this exception, you may extend this exception to
 * your version of the file(s), but you are not obligated to do so. If
 * you do not wish to do so, delete this exception statement from your
 * version. If you delete this exception statement from all source files
 * in the program, then also delete it here.
 * 
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "LuaFunctionCall.h"


namespace Orthanc
{
  void LuaFunctionCall::CheckAlreadyExecuted()
  {
    if (isExecuted_)
    {
      throw LuaException("Arguments cannot be pushed after the function is executed");
    }
  }

  LuaFunctionCall::LuaFunctionCall(LuaContext& context,
                                   const char* functionName) : 
    context_(context),
    lock_(context.mutex_),
    isExecuted_(false)
  {
    // Clear the stack to fulfill the invariant
    lua_settop(context_.lua_, 0);
    lua_getglobal(context_.lua_, functionName);
  }

  void LuaFunctionCall::PushString(const std::string& value)
  {
    CheckAlreadyExecuted();
    lua_pushstring(context_.lua_, value.c_str());
  }

  void LuaFunctionCall::PushBoolean(bool value)
  {
    CheckAlreadyExecuted();
    lua_pushboolean(context_.lua_, value);
  }

  void LuaFunctionCall::PushInteger(int value)
  {
    CheckAlreadyExecuted();
    lua_pushinteger(context_.lua_, value);
  }

  void LuaFunctionCall::PushDouble(double value)
  {
    CheckAlreadyExecuted();
    lua_pushnumber(context_.lua_, value);
  }

  void LuaFunctionCall::PushJSON(const Json::Value& value)
  {
    CheckAlreadyExecuted();

    if (value.isString())
    {
      lua_pushstring(context_.lua_, value.asCString());
    }
    else if (value.isDouble())
    {
      lua_pushnumber(context_.lua_, value.asDouble());
    }
    else if (value.isInt())
    {
      lua_pushinteger(context_.lua_, value.asInt());
    }
    else if (value.isUInt())
    {
      lua_pushinteger(context_.lua_, value.asUInt());
    }
    else if (value.isBool())
    {
      lua_pushboolean(context_.lua_, value.asBool());
    }
    else if (value.isNull())
    {
      lua_pushnil(context_.lua_);
    }
    else if (value.isArray())
    {
      lua_newtable(context_.lua_);

      // http://lua-users.org/wiki/SimpleLuaApiExample
      for (Json::Value::ArrayIndex i = 0; i < value.size(); i++)
      {
        // Push the table index (note the "+1" because of Lua conventions)
        lua_pushnumber(context_.lua_, i + 1);

        // Push the value of the cell
        PushJSON(value[i]);

        // Stores the pair in the table
        lua_rawset(context_.lua_, -3);
      }
    }
    else if (value.isObject())
    {
      lua_newtable(context_.lua_);

      Json::Value::Members members = value.getMemberNames();

      for (Json::Value::Members::const_iterator 
             it = members.begin(); it != members.end(); ++it)
      {
        // Push the index of the cell
        lua_pushstring(context_.lua_, it->c_str());

        // Push the value of the cell
        PushJSON(value[*it]);

        // Stores the pair in the table
        lua_rawset(context_.lua_, -3);
      }
    }
    else
    {
      throw LuaException("Unsupported JSON conversion");
    }
  }

  void LuaFunctionCall::Execute(int numOutputs)
  {
    CheckAlreadyExecuted();

    assert(lua_gettop(context_.lua_) >= 1);
    int nargs = lua_gettop(context_.lua_) - 1;
    int error = lua_pcall(context_.lua_, nargs, numOutputs, 0);

    if (error) 
    {
      assert(lua_gettop(context_.lua_) >= 1);
          
      std::string description(lua_tostring(context_.lua_, -1));
      lua_pop(context_.lua_, 1); /* pop error message from the stack */
      throw LuaException(description);
    }

    if (lua_gettop(context_.lua_) < numOutputs)
    {
      throw LuaException("The function does not give the expected number of outputs");
    }

    isExecuted_ = true;
  }

  bool LuaFunctionCall::ExecutePredicate()
  {
    Execute(1);
        
    if (lua_gettop(context_.lua_) == 0)
    {
      throw LuaException("No output was provided by the function");
    }

    if (!lua_isboolean(context_.lua_, 1))
    {
      throw LuaException("The function is not a predicate (only true/false outputs allowed)");
    }

    return lua_toboolean(context_.lua_, 1) != 0;
  }
}