/*
 * SystemBackendPosix.cpp
 *
 * Copyright (C) 2008 Matthias Schiffer <matthias@gamezock.de>
 *
 * 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.
 *
 * 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 "SystemBackendPosix.h"

#include <Net/FdManager.h>
#include <Common/ActionManager.h>

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <sstream>

#include <fcntl.h>
#include <signal.h>
#include <spawn.h>
#include <sys/wait.h>
#include <unistd.h>

#define init SystemBackendPosix_LTX_init
#define deinit SystemBackendPosix_LTX_deinit

namespace Mad {
namespace Modules {

SystemBackendPosix *SystemBackendPosix::backend = 0;

std::map<pid_t, boost::function1<void, int> > SystemBackendPosix::processes;
std::map<pid_t, boost::function2<void, int, const std::string&> > SystemBackendPosix::processesWithOutput;
std::map<pid_t, int> SystemBackendPosix::processesWOHandles;
std::map<pid_t, std::string > SystemBackendPosix::processesWOOutput;


void SystemBackendPosix::setChildHandler() {
  struct sigaction action;

  action.sa_handler = childHandler;
  sigemptyset(&action.sa_mask);
  action.sa_flags = 0;

  sigaction(SIGCHLD, &action, 0);
}

SystemBackendPosix::~SystemBackendPosix() {
  struct sigaction action;

  action.sa_handler = SIG_DFL;
  sigemptyset(&action.sa_mask);
  action.sa_flags = 0;

  sigaction(SIGCHLD, &action, 0);
}


void SystemBackendPosix::fsInfoCallback(int, const std::string &output, const boost::function1<void, const std::vector<Common::SystemManager::FSInfo>& > &callback) {
  std::vector<Common::SystemManager::FSInfo> ret;
  std::istringstream stream(output);
  std::string str;

  std::getline(stream, str); // ignore first line

  while(!stream.eof()) {
    std::getline(stream, str);

    char *fsName = new char[str.length()+1];
    char *mountedOn = new char[str.length()+1];

    Common::SystemManager::FSInfo info;

    if(std::sscanf(str.c_str(), "%s %lld %lld %lld %*d%% %s", fsName, &info.total, &info.used, &info.available, mountedOn) == 5) {
      info.fsName = fsName;
      info.mountedOn = mountedOn;

      ret.push_back(info);
    }

    delete [] fsName;
    delete [] mountedOn;
  }

  callback(ret);
}

bool SystemBackendPosix::getFSInfo(const boost::function1<void, const std::vector<Common::SystemManager::FSInfo>& > &callback) {
  std::vector<std::string> argv;

  argv.push_back("/bin/df");
  argv.push_back("-P");
  argv.push_back("-k");

  return execWithOutput(boost::bind(&SystemBackendPosix::fsInfoCallback, this, _1, _2, callback), "/bin/df", argv);
}


void SystemBackendPosix::childHandler(int) {
  int status;
  pid_t pid;

  while((pid = waitpid(-1, &status, WNOHANG)) > 0) {
    std::map<pid_t, boost::function1<void, int> >::iterator it = processes.find(pid);

    if(it != processes.end()) {
      Common::ActionManager::get()->add(boost::bind(it->second, status));
      processes.erase(it);
    }
    else {
      std::map<pid_t, boost::function2<void, int, const std::string&> >::iterator it2 = processesWithOutput.find(pid);

      if(it2 != processesWithOutput.end()) {
        char buffer[1024];
        ssize_t n;
        std::string &output = processesWOOutput[pid];
        int handle = processesWOHandles[pid];

        while((n = read(handle, buffer, sizeof(buffer))) > 0)
          output += std::string(buffer, n);

        //Net::FdManager::get()->unregisterFd(handle);
        //close(handle);

        //Common::ActionManager::get()->add(boost::bind(it2->second, status, output));
        processesWithOutput.erase(it2);
        processesWOHandles.erase(pid);
        processesWOOutput.erase(pid);
      }
    }
  }

  setChildHandler();
}

void SystemBackendPosix::outputHandler(short events, pid_t pid) {
  char buf[1024];

  if(events & POLLIN) {
    sigset_t set, oldset;
    sigemptyset(&set);
    sigaddset(&set, SIGCHLD);
    sigprocmask(SIG_BLOCK, &set, &oldset);

    ssize_t ret;

    std::map<pid_t, int>::iterator handle = processesWOHandles.find(pid);
    if(handle == processesWOHandles.end())
      return;

    while((ret = read(handle->second, buf, sizeof(buf))) > 0)
      processesWOOutput[pid] += std::string(buf, ret);

    sigprocmask(SIG_SETMASK, &oldset, 0);
  }
}

std::pair<char**, char**> SystemBackendPosix::makeArgs(const std::string &filename, const std::vector<std::string> &argv, const std::vector<std::string> &env) {
  char **argvp, **envp;

  if(argv.empty()) {
    argvp = new char*[2];

    argvp[0] = strdup(filename.c_str());
    argvp[1] = 0;
  }
  else {
    argvp = new char*[argv.size() + 1];

    for(size_t s = 0; s < argv.size(); ++s) {
      argvp[s] = strdup(argv[s].c_str());
    }

    argvp[argv.size()] = 0;
  }

  if(env.empty()) {
    envp = environ;
  }
  else {
    envp = new char*[env.size() + 1];

    for(size_t s = 0; s < env.size(); ++s) {
      envp[0] = strdup(env[s].c_str());
    }

    envp[env.size()] = 0;
  }

  return std::make_pair(argvp, envp);
}

void SystemBackendPosix::destroyArgs(std::pair<char**, char**> args) {
  for(char **p = args.first; *p != 0; ++p)
    std::free(*p);

  delete [] args.first;

  if(args.second != environ) {
    for(char **p = args.second; *p != 0; ++p)
      std::free(*p);

    delete [] args.second;
  }
}

bool SystemBackendPosix::exec(const boost::function1<void, int> &resultHandler, const std::string &filename, const std::vector<std::string> &argv, const std::vector<std::string> &env) {
  pid_t pid;
  std::pair<char**, char**> args = makeArgs(filename, argv, env);

  sigset_t set, oldset;
  sigemptyset(&set);
  sigaddset(&set, SIGCHLD);
  sigprocmask(SIG_BLOCK, &set, &oldset);

  bool ret = (posix_spawnp(&pid, filename.c_str(), 0, 0, args.first, args.second) == 0);

  if(ret)
    processes.insert(std::make_pair(pid, resultHandler));

  sigprocmask(SIG_SETMASK, &oldset, 0);

  destroyArgs(args);

  return ret;
}

bool SystemBackendPosix::execWithOutput(const boost::function2<void, int, const std::string&> &resultHandler, const std::string &filename, const std::vector<std::string> &argv, const std::vector<std::string> &env) {
  pid_t pid;
  std::pair<char**, char**> args = makeArgs(filename, argv, env);

  int saveStdout = dup(STDOUT_FILENO);
  int pipeHandles[2];

  pipe(pipeHandles);

  fcntl(pipeHandles[0], F_SETFD, FD_CLOEXEC);

  int flags = fcntl(pipeHandles[0], F_GETFL, 0);
  fcntl(pipeHandles[0], F_SETFL, flags | O_NONBLOCK);

  sigset_t set, oldset;
  sigemptyset(&set);
  sigaddset(&set, SIGCHLD);
  sigprocmask(SIG_BLOCK, &set, &oldset);

  dup2(pipeHandles[1], STDOUT_FILENO); // set the new pipe as stdout
  close(pipeHandles[1]);

  bool ret = (posix_spawnp(&pid, filename.c_str(), 0, 0, args.first, args.second) == 0);

  if(ret) {
    processesWithOutput.insert(std::make_pair(pid, resultHandler));
    processesWOHandles.insert(std::make_pair(pid, pipeHandles[0]));
    processesWOOutput.insert(std::make_pair(pid, std::string()));

    Net::FdManager::get()->registerFd(pipeHandles[0], boost::bind(&SystemBackendPosix::outputHandler, _1, pid), POLLIN);
  }

  dup2(saveStdout, STDOUT_FILENO); // restore old stdout
  close(saveStdout);

  sigprocmask(SIG_SETMASK, &oldset, 0);

  destroyArgs(args);

  return ret;
}

}
}

extern "C" {

void init() {
  Mad::Modules::SystemBackendPosix::registerBackend();
}

void deinit() {
  Mad::Modules::SystemBackendPosix::unregisterBackend();
}

}