/* Copyright (c) 2010-2020. The SimGrid Team. All rights reserved.          */

/* This program is free software; you can redistribute it and/or modify it
 * under the terms of the license (GNU LGPL) which comes with this package. */

#include "simgrid/Exception.hpp"
#include "xbt/log.h"
#include "xbt/replay.hpp"

#include <boost/algorithm/string.hpp>

XBT_LOG_NEW_DEFAULT_SUBCATEGORY(replay,xbt,"Replay trace reader");

namespace simgrid {
namespace xbt {

std::ifstream* action_fs = nullptr;
std::unordered_map<std::string, action_fun> action_funs;
static std::unordered_map<std::string, std::queue<ReplayAction*>*> action_queues;

static void read_and_trim_line(std::ifstream& fs, std::string* line)
{
  do {
    std::getline(fs, *line);
    boost::trim(*line);
  } while (not fs.eof() && (line->length() == 0 || line->front() == '#'));
  XBT_DEBUG("got from trace: %s", line->c_str());
}

class ReplayReader {
  std::ifstream fs;
  std::string line;

public:
  explicit ReplayReader(const char* filename) : fs(filename, std::ifstream::in)
  {
    XBT_VERB("Prepare to replay file '%s'", filename);
    xbt_assert(fs.is_open(), "Cannot read replay file '%s'", filename);
  }
  ReplayReader(const ReplayReader&) = delete;
  ReplayReader& operator=(const ReplayReader&) = delete;
  bool get(ReplayAction* action);
};

bool ReplayReader::get(ReplayAction* action)
{
  read_and_trim_line(fs, &line);

  boost::split(*action, line, boost::is_any_of(" \t"), boost::token_compress_on);
  return not fs.eof();
}

static ReplayAction* get_action(const char* name)
{
  ReplayAction* action;

  std::queue<ReplayAction*>* myqueue = nullptr;
  if (action_queues.find(std::string(name)) != action_queues.end())
    myqueue = action_queues.at(std::string(name));
  if (myqueue == nullptr || myqueue->empty()) { // Nothing stored for me. Read the file further
    // Read lines until I reach something for me (which breaks in loop body) or end of file reached
    while (true) {
      std::string action_line;
      read_and_trim_line(*action_fs, &action_line);
      if (action_fs->eof())
        break;
      /* we cannot split in place here because we parse&store several lines for the colleagues... */
      action = new ReplayAction();
      boost::split(*action, action_line, boost::is_any_of(" \t"), boost::token_compress_on);

      // if it's for me, I'm done
      std::string evtname = action->front();
      if (evtname.compare(name) == 0) {
        return action;
      } else {
        // Else, I have to store it for the relevant colleague
        std::queue<ReplayAction*>* otherqueue = nullptr;
        auto act                              = action_queues.find(evtname);
        if (act != action_queues.end()) {
          otherqueue = act->second;
        } else { // Damn. Create the queue of that guy
          otherqueue = new std::queue<ReplayAction*>();
          action_queues.insert({evtname, otherqueue});
        }
        otherqueue->push(action);
      }
    }
    // end of file reached while searching in vain for more work
  } else {
    // Get something from my queue and return it
    action = myqueue->front();
    myqueue->pop();
    return action;
  }

  return nullptr;
}

static void handle_action(ReplayAction& action)
{
  XBT_DEBUG("%s replays a %s action", action.at(0).c_str(), action.at(1).c_str());
  action_fun function = action_funs.at(action.at(1));
  try {
    function(action);
  } catch (const Exception& e) {
    action.clear();
    xbt_die("Replay error:\n %s", e.what());
  }
}

/**
 * @ingroup XBT_replay
 * @brief function used internally to actually run the replay
 */
int replay_runner(const char* actor_name, const char* trace_filename)
{
  std::string actor_name_string(actor_name);
  if (simgrid::xbt::action_fs) { // <A unique trace file
    while (true) {
      simgrid::xbt::ReplayAction* evt = simgrid::xbt::get_action(actor_name);
      if (!evt)
        break;
      simgrid::xbt::handle_action(*evt);
      delete evt;
    }
    if (action_queues.find(actor_name_string) != action_queues.end()) {
      delete action_queues.at(actor_name_string);
      action_queues.erase(actor_name_string);
    }
  } else { // Should have got my trace file in argument
    xbt_assert(trace_filename != nullptr);
    simgrid::xbt::ReplayAction evt;
    simgrid::xbt::ReplayReader reader(trace_filename);
    while (reader.get(&evt)) {
      if (evt.front().compare(actor_name) == 0) {
        simgrid::xbt::handle_action(evt);
      } else {
        XBT_WARN("Ignore trace element not for me (target='%s', I am '%s')", evt.front().c_str(), actor_name);
      }
      evt.clear();
    }
  }
  return 0;
}
}
}

/**
 * @ingroup XBT_replay
 * @brief Registers a function to handle a kind of action
 *
 * Registers a function to handle a kind of action
 * This table is then used by @ref simgrid::xbt::replay_runner
 *
 * The argument of the function is the line describing the action, fields separated by spaces.
 *
 * @param action_name the reference name of the action.
 * @param function prototype given by the type: void...(const char** action)
 */
void xbt_replay_action_register(const char* action_name, const action_fun& function)
{
  simgrid::xbt::action_funs[std::string(action_name)] = function;
}

/**
 * @ingroup XBT_replay
 * @brief Get the function that was previously registered to handle a kind of action
 *
 * This can be useful if you want to override and extend an existing action.
 */
action_fun xbt_replay_action_get(const char* action_name)
{
  return simgrid::xbt::action_funs.at(std::string(action_name));
}
