//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2020 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    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 Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

#ifndef OPENVPN_APPLE_MACLIFE_H
#define OPENVPN_APPLE_MACLIFE_H

#include <string>
#include <sstream>

#include <thread>

#include <openvpn/log/logthread.hpp>
#include <openvpn/apple/cf/cftimer.hpp>
#include <openvpn/apple/cf/cfhelper.hpp>
#include <openvpn/apple/cf/cfrunloop.hpp>
#include <openvpn/apple/reachable.hpp>
#include <openvpn/client/clilife.hpp>
#include <openvpn/apple/macsleep.hpp>
#include <openvpn/apple/scdynstore.hpp>

namespace openvpn {
  class MacLifeCycle : public ClientLifeCycle, MacSleep, ReachabilityTracker
  {
  public:
    OPENVPN_EXCEPTION(mac_lifecycle_error);

    MacLifeCycle()
      : ReachabilityTracker(true, false),
	nc(nullptr),
	thread(nullptr),
	paused(false)
    {
    }

    virtual ~MacLifeCycle()
    {
      stop_thread();
    }

    virtual bool network_available()
    {
      return net_up();
    }

    virtual void start(NotifyCallback* nc_arg)
    {
      if (!thread && nc_arg)
	{
	  nc = nc_arg;
	  thread = new std::thread(&MacLifeCycle::thread_func, this);
	}
    }

    virtual void stop()
    {
      stop_thread();
    }

  private:
    struct State
    {
      State()
	: net_up(false),
	  sleep(false)
      {
      }

      State(bool net_up_arg, const std::string& iface_arg, bool sleep_arg)
	: net_up(net_up_arg),
	  iface(iface_arg),
	  sleep(sleep_arg)
      {
      }

      bool operator==(const State& other) const
      {
	return net_up == other.net_up && iface == other.iface && sleep == other.sleep;
      }

      bool operator!=(const State& other) const
      {
	return !operator==(other);
      }

      std::string to_string() const
      {
	std::ostringstream os;
	os << "[net_up=" << net_up << " iface=" << iface << " sleep=" << sleep << ']';
	return os.str();
      }

      bool net_up;
      std::string iface;
      bool sleep;
    };

    void stop_thread()
    {
      if (thread)
	{
	  if (runloop.defined())
	    CFRunLoopStop(runloop());
	  thread->join();
	  delete thread;
	  thread = nullptr;
	}
    }

    void thread_func()
    {
      runloop.reset(CFRunLoopGetCurrent(), CF::GET);
      Log::Context logctx(logwrap);
      try {
	// set up dynamic store query object
	dstore.reset(SCDynamicStoreCreate(kCFAllocatorDefault,
					  CFSTR("OpenVPN_MacLifeCycle"),
					  nullptr,
					  nullptr));

	// init state
	state = State(net_up(), primary_interface(), false);
	prev_state = state;
	paused = false;

	// enable sleep/wakeup notifications
	mac_sleep_start();

	// enable network reachability notifications
	reachability_tracker_schedule();

	// enable interface change notifications
	iface_watch();

	// process event loop until CFRunLoopStop is called from parent thread
	CFRunLoopRun();
      }
      catch (const std::exception& e)
	{
	  OPENVPN_LOG("MacLifeCycle exception: " << e.what());
	}

      // cleanup
      cancel_action_timer();
      mac_sleep_stop();
      reachability_tracker_cancel();
      dstore.reset();
    }

    std::string primary_interface()
    {
      CF::Dict dict(CF::DynamicStoreCopyDict(dstore, "State:/Network/Global/IPv4"));
      return CF::dict_get_str(dict, "PrimaryInterface");
    }

    bool net_up()
    {
      ReachabilityViaInternet r;
      return ReachabilityViaInternet::status_from_flags(r.flags()) != ReachabilityInterface::NotReachable;
    }

    void iface_watch()
    {
      SCDynamicStoreContext context = {0, this, nullptr, nullptr, nullptr};
      CF::DynamicStore ds(SCDynamicStoreCreate(kCFAllocatorDefault,
					       CFSTR("OpenVPN_MacLifeCycle_iface_watch"),
					       iface_watch_callback_static,
					       &context));
      if (!ds.defined())
	throw mac_lifecycle_error("SCDynamicStoreCreate");
      CF::MutableArray watched_keys(CF::mutable_array());
      CF::array_append_str(watched_keys, "State:/Network/Global/IPv4");
      //CF::array_append_str(watched_keys, "State:/Network/Global/IPv6");
      if (!watched_keys.defined())
	throw mac_lifecycle_error("watched_keys is undefined");
      if (!SCDynamicStoreSetNotificationKeys(ds(),
					     watched_keys(),
					     nullptr))
	throw mac_lifecycle_error("SCDynamicStoreSetNotificationKeys failed");
      CF::RunLoopSource rls(SCDynamicStoreCreateRunLoopSource(kCFAllocatorDefault, ds(), 0));
      if (!rls.defined())
	throw mac_lifecycle_error("SCDynamicStoreCreateRunLoopSource failed");
      CFRunLoopAddSource(CFRunLoopGetCurrent(), rls(), kCFRunLoopDefaultMode);
    }

    static void iface_watch_callback_static(SCDynamicStoreRef store, CFArrayRef changedKeys, void *arg)
    {
      MacLifeCycle *self = (MacLifeCycle *)arg;
      self->iface_watch_callback(store, changedKeys);
    }

    void iface_watch_callback(SCDynamicStoreRef store, CFArrayRef changedKeys)
    {
      state.iface = primary_interface();
      OPENVPN_LOG("MacLifeCycle NET_IFACE " << state.iface);
      schedule_action_timer(1);
    }

    virtual void notify_sleep()
    {
      OPENVPN_LOG("MacLifeCycle SLEEP");
      state.sleep = true;
      schedule_action_timer(0);
    }

    virtual void notify_wakeup()
    {
      OPENVPN_LOG("MacLifeCycle WAKEUP");
      state.sleep = false;
      schedule_action_timer(1);
    }

    virtual void reachability_tracker_event(const ReachabilityBase& rb, SCNetworkReachabilityFlags flags)
    {
      if (rb.vtype() == ReachabilityBase::Internet)
	{
	  const ReachabilityBase::Status status = rb.vstatus(flags);
	  state.net_up = (status != ReachabilityInterface::NotReachable);
	  OPENVPN_LOG("MacLifeCycle NET_STATE " << state.net_up << " status=" << ReachabilityBase::render_status(status) << " flags=" << ReachabilityBase::render_flags(flags));
	  schedule_action_timer(1);
	}
    }

    void schedule_action_timer(const int seconds)
    {
      cancel_action_timer();
      if (seconds)
	{
	  CFRunLoopTimerContext context = { 0, this, nullptr, nullptr, nullptr };
	  action_timer.reset(CFRunLoopTimerCreate(kCFAllocatorDefault, CFAbsoluteTimeGetCurrent() + seconds, 0, 0, 0, action_timer_callback_static, &context));
	  if (action_timer.defined())
	    CFRunLoopAddTimer(CFRunLoopGetCurrent(), action_timer(), kCFRunLoopCommonModes);
	  else
	    OPENVPN_LOG("MacLifeCycle::schedule_action_timer: failed to create timer");
	}
      else
	action_timer_callback(nullptr);
    }

    void cancel_action_timer()
    {
      if (action_timer.defined())
	{
	  CFRunLoopTimerInvalidate(action_timer());
	  action_timer.reset(nullptr);
	}
    }

    static void action_timer_callback_static(CFRunLoopTimerRef timer, void *info)
    {
      MacLifeCycle* self = (MacLifeCycle*)info;
      self->action_timer_callback(timer);
    }

    void action_timer_callback(CFRunLoopTimerRef timer)
    {
      try {
	if (state != prev_state)
	  {
	    OPENVPN_LOG("MacLifeCycle ACTION pause=" << paused << " state=" << state.to_string() << " prev=" << prev_state.to_string());
	    if (paused)
	      {
		if (!state.sleep && state.net_up)
		  {
		    nc->cln_resume();
		    paused = false;
		  }
	      }
	    else
	      {
		if (state.sleep)
		  {
		    nc->cln_pause("sleep");
		    paused = true;
		  }
		else if (!state.net_up)
		  {
		    nc->cln_pause("network-unavailable");
		    paused = true;
		  }
		else
		  {
		    if (state.iface != prev_state.iface)
		      nc->cln_reconnect(0);
		  }
	      }
	    prev_state = state;
	  }
      }
      catch (const std::exception& e)
	{
	  OPENVPN_LOG("MacLifeCycle::action_timer_callback exception: " << e.what());
	}
    }

    NotifyCallback* nc;
    std::thread* thread;
    CF::RunLoop runloop;           // run loop in thread
    CF::DynamicStore dstore;
    State state;
    State prev_state;
    bool paused;
    CF::Timer action_timer;
    Log::Context::Wrapper logwrap; // used to carry forward the log context from parent thread
  };
}

#endif