/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <dirent.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>

#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <iomanip>
#include <memory>
#include <sstream>
#include <string>
#include <vector>

#include <android-base/strings.h>
#include <android-base/logging.h>

#include "common/libs/fs/shared_fd.h"
#include "common/libs/fs/shared_select.h"
#include "common/libs/utils/environment.h"
#include "common/libs/utils/files.h"
#include "common/libs/utils/flag_parser.h"
#include "common/libs/utils/result.h"
#include "host/commands/run_cvd/runner_defs.h"
#include "host/libs/allocd/request.h"
#include "host/libs/allocd/utils.h"
#include "host/libs/config/cuttlefish_config.h"
#include "host/libs/vm_manager/vm_manager.h"

namespace cuttlefish {
namespace {

std::set<std::string> FallbackDirs() {
  std::set<std::string> paths;
  std::string parent_path = StringFromEnv("HOME", ".");
  paths.insert(parent_path + "/cuttlefish_assembly");

  std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(parent_path.c_str()), closedir);
  for (auto entity = readdir(dir.get()); entity != nullptr; entity = readdir(dir.get())) {
    std::string subdir(entity->d_name);
    if (!android::base::StartsWith(subdir, "cuttlefish_runtime.")) {
      continue;
    }
    paths.insert(parent_path + "/" + subdir);
  }
  return paths;
}

std::set<std::string> DirsForInstance(
    const CuttlefishConfig& config,
    const CuttlefishConfig::InstanceSpecific instance) {
  return {
      config.assembly_dir(),
      instance.instance_dir(),
  };
}

// Gets a set of the possible process groups of a previous launch
std::set<pid_t> GetCandidateProcessGroups(const std::set<std::string>& dirs) {
  std::stringstream cmd;
  cmd << "lsof -t 2>/dev/null";
  for (const auto& dir : dirs) {
    cmd << " +D " << dir;
  }
  std::string cmd_str = cmd.str();
  std::shared_ptr<FILE> cmd_out(popen(cmd_str.c_str(), "r"), pclose);
  if (!cmd_out) {
    LOG(ERROR) << "Unable to execute '" << cmd_str << "': " << strerror(errno);
    return {};
  }
  int64_t pid;
  std::set<pid_t> ret{};
  while(fscanf(cmd_out.get(), "%" PRId64, &pid) != EOF) {
    pid_t pgid = getpgid(static_cast<pid_t>(pid));
    if (pgid < 0) {
      LOG(ERROR) << "Unable to get process group of " << pid << ": "
                 << strerror(errno);
      continue;
    }
    ret.insert(pgid);
  }
  // The process group of stop_cvd should not be killed
  ret.erase(getpgrp());
  return ret;
}

int FallBackStop(const std::set<std::string>& dirs) {
  auto exit_code = 1; // Having to fallback is an error

  auto process_groups = GetCandidateProcessGroups(dirs);
  for (auto pgid: process_groups) {
    LOG(INFO) << "Sending SIGKILL to process group " << pgid;
    auto retval = killpg(pgid, SIGKILL);
    if (retval < 0) {
      LOG(ERROR) << "Failed to kill process group " << pgid << ": "
                 << strerror(errno);
      exit_code |= 4;
    }
  }

  return exit_code;
}

Result<void> CleanStopInstance(
    const CuttlefishConfig::InstanceSpecific& instance,
    std::int32_t wait_for_launcher) {
  auto monitor_path = instance.launcher_monitor_socket_path();
  CF_EXPECT(!monitor_path.empty(), "No path to launcher monitor found");

  auto monitor_socket = SharedFD::SocketLocalClient(
      monitor_path.c_str(), false, SOCK_STREAM, wait_for_launcher);
  CF_EXPECT(monitor_socket->IsOpen(),
            "Unable to connect to launcher monitor at "
                << monitor_path << ": " << monitor_socket->StrError());

  auto request = LauncherAction::kStop;
  auto bytes_sent = monitor_socket->Send(&request, sizeof(request), 0);
  CF_EXPECT(bytes_sent >= 0, "Error sending launcher monitor the stop command: "
                                 << monitor_socket->StrError());

  // Perform a select with a timeout to guard against launcher hanging
  SharedFDSet read_set;
  read_set.Set(monitor_socket);
  struct timeval timeout = {wait_for_launcher, 0};
  int selected = Select(&read_set, nullptr, nullptr,
                        wait_for_launcher <= 0 ? nullptr : &timeout);
  CF_EXPECT(selected >= 0, "Failed communication with the launcher monitor: "
                               << strerror(errno));
  CF_EXPECT(selected > 0, "Timeout expired waiting for launcher to respond");

  LauncherResponse response;
  auto bytes_recv = monitor_socket->Recv(&response, sizeof(response), 0);
  CF_EXPECT(bytes_recv >= 0, "Error receiving response from launcher monitor: "
                                 << monitor_socket->StrError());
  CF_EXPECT(response == LauncherResponse::kSuccess,
            "Received '" << static_cast<char>(response)
                         << "' response from launcher monitor");
  LOG(INFO) << "Successfully stopped device " << instance.instance_name()
            << ": " << instance.adb_ip_and_port();
  return {};
}

int StopInstance(const CuttlefishConfig& config,
                 const CuttlefishConfig::InstanceSpecific& instance,
                 std::int32_t wait_for_launcher) {
  auto res = CleanStopInstance(instance, wait_for_launcher);
  if (!res.ok()) {
    LOG(ERROR) << "Clean stop failed: " << res.error();
    return FallBackStop(DirsForInstance(config, instance));
  }
  return 0;
}

/// Send a StopSession request to allocd
void ReleaseAllocdResources(SharedFD allocd_sock, uint32_t session_id) {
  if (!allocd_sock->IsOpen() || session_id == -1) {
    return;
  }
  Json::Value config;
  Json::Value request_list;
  Json::Value req;
  req["request_type"] =
      ReqTyToStr(RequestType::StopSession);
  req["session_id"] = session_id;
  request_list.append(req);
  config["config_request"]["request_list"] = request_list;
  SendJsonMsg(allocd_sock, config);
  auto resp_opt = RecvJsonMsg(allocd_sock);
  if (!resp_opt.has_value()) {
    LOG(ERROR) << "Bad response from allocd";
    return;
  }
  auto resp = resp_opt.value();
  LOG(INFO) << "Stop Session operation: " << resp["config_status"];
}

int StopCvdMain(int argc, char** argv) {
  ::android::base::InitLogging(argv, android::base::StderrLogger);

  std::vector<Flag> flags;

  std::int32_t wait_for_launcher = 5;
  flags.emplace_back(
      GflagsCompatFlag("wait_for_launcher", wait_for_launcher)
          .Help("How many seconds to wait for the launcher to respond to the "
                "status command. A value of zero means wait indefinitely"));
  bool clear_instance_dirs;
  flags.emplace_back(
      GflagsCompatFlag("clear_instance_dirs", clear_instance_dirs)
          .Help("If provided, deletes the instance dir after attempting to "
                "stop each instance."));
  flags.emplace_back(HelpFlag(flags));
  flags.emplace_back(UnexpectedArgumentGuard());
  std::vector<std::string> args =
      ArgsToVec(argc - 1, argv + 1);  // Skip argv[0]
  CHECK(ParseFlags(flags, args)) << "Could not process command line flags.";

  auto config = CuttlefishConfig::Get();
  if (!config) {
    LOG(ERROR) << "Failed to obtain config object";
    return FallBackStop(FallbackDirs());
  }

  int ret = 0;
  for (const auto& instance : config->Instances()) {
    auto session_id = instance.session_id();
    int exit_status = StopInstance(*config, instance, wait_for_launcher);
    if (exit_status == 0 && instance.use_allocd()) {
      // only release session resources if the instance was stopped
      SharedFD allocd_sock =
          SharedFD::SocketLocalClient(kDefaultLocation, false, SOCK_STREAM);
      if (!allocd_sock->IsOpen()) {
        LOG(ERROR) << "Unable to connect to allocd on "
                   << kDefaultLocation << ": "
                   << allocd_sock->StrError();
      }

      ReleaseAllocdResources(allocd_sock, session_id);
    }
    if (clear_instance_dirs) {
      if (DirectoryExists(instance.instance_dir())) {
        LOG(INFO) << "Deleting instance dir " << instance.instance_dir();
        if (!RecursivelyRemoveDirectory(instance.instance_dir())) {
          LOG(ERROR) << "Unable to rmdir " << instance.instance_dir();
        }
      }
    }
    ret |= exit_status;
  }

  return ret;
}

} // namespace
} // namespace cuttlefish

int main(int argc, char** argv) {
  return cuttlefish::StopCvdMain(argc, argv);
}