package hackers_git

import (
	"inotify"
	"os"
	"path/filepath"
	"sd_daemon/logger"
	"sd_daemon/lsb"
)

const (
	in_CHILD_ADD = inotify.IN_CREATE | inotify.IN_MOVED_TO
	in_CHILD_DEL = inotify.IN_DELETE | inotify.IN_MOVED_FROM
	in_CHILD_MOD = inotify.IN_CLOSE_WRITE | inotify.IN_MOVED_TO
	in_CHILD_ANY = in_CHILD_ADD | in_CHILD_DEL | in_CHILD_MOD

	in_DIR_INVALID = inotify.IN_MOVE_SELF | inotify.IN_DELETE_SELF
	in_DIR         = inotify.IN_ONLYDIR | in_DIR_INVALID
)

func (o *Hackers) watchHomedir(uid int32) {
	wd, err := o.in_fd.AddWatch(o.users[uid].passwd.HomeDir, in_DIR|in_CHILD_ANY)
	if err == nil {
		oldwd, found := o.in_uid2wd[uid]
		if found && oldwd != wd {
			o.unwatchHomedir(oldwd)
		}
		o.in_uid2wd[uid] = wd
		o.in_wd2uid[wd] = uid
	} else {
		delete(o.in_uid2wd, uid)
		logger.Info("could not watch: %s", o.users[uid].passwd.HomeDir)
	}
}
func (o *Hackers) unwatchHomedir(wd inotify.Cint) {
	err := o.in_fd.RmWatch(wd)
	if err != nil {
		logger.Warning("could not remove watch: %v", wd)
		return
	}
	uid := o.in_wd2uid[wd]
	delete(o.in_wd2uid, wd)
	delete(o.in_uid2wd, uid)
}

func NewHackers(config Config) *Hackers {
	o := Hackers{
		cfg: config,
	}
	err := o.reload()
	if err != nil {
		return nil
	}
	go o.worker()
	return &o
}

func (o *Hackers) close() {
	if o.in_fd != nil {
		o.in_fd.Close()
		o.in_fd = nil
	}
	o.in_wd_home = -1
	o.in_wd_yaml = -1
	o.users = make(map[int32]user, 0)
	o.in_uid2wd = make(map[int32]inotify.Cint, 0)
	o.in_wd2uid = make(map[inotify.Cint]int32, 0)
}

func (o *Hackers) reload() (err error) {
	o.close()
	o.in_fd, err = inotify.InotifyInit()                                    ; if err != nil { return }
	o.in_wd_home, err = o.in_fd.AddWatch("/home"      , in_DIR|in_CHILD_ADD); if err != nil { return }
	o.in_wd_yaml, err = o.in_fd.AddWatch(o.cfg.Yamldir, in_DIR|in_CHILD_ANY); if err != nil { return }

	filenames, err := filepath.Glob(o.cfg.Yamldir + "/*.yml")
	o.users = make(map[int32]user, len(filenames))
	o.in_uid2wd = make(map[int32]inotify.Cint, len(filenames))
	o.in_wd2uid = make(map[inotify.Cint]int32, len(filenames))
	for _, filename := range filenames {
		logger.Info("Loading yaml file: %s", filename)
		user, err := load_user_yaml(filename)
		if err == nil {
			o.users[user.passwd.UID] = user
			logger.Info("... success")
			o.watchHomedir(user.passwd.UID)
			o.passwords[user.passwd.UID] = load_user_password(user.passwd.HomeDir + "/.password")
		} else {
			logger.Info("... error: %v", err)
		}
	}

	err = nil
	return
}

func (o *Hackers) worker_handle_user_add(user user) {
	o.lock.Lock()
	defer o.lock.Unlock()

	o.users[user.passwd.UID] = user
	o.watchHomedir(user.passwd.UID)
	o.passwords[user.passwd.UID] = load_user_password(user.passwd.HomeDir + "/.password")
}

func (o *Hackers) worker_handle_user_del(uid int32) {
	o.lock.Lock()
	defer o.lock.Unlock()

	wd, found := o.in_uid2wd[uid]
	if found {
		o.unwatchHomedir(wd)
	}
	delete(o.users, uid)
}

func (o *Hackers) worker_watch_homedirs() {
	for uid, _ := range o.users {
		o.watchHomedir(uid)
	}
}

func (o *Hackers) worker_handle_passwd(uid int32) {
	o.lock.Lock()
	defer o.lock.Unlock()

	o.passwords[uid] = load_user_password(o.users[uid].passwd.HomeDir + "/.password")
}

func worker_error(format string, a ...interface{}) {
	logger.Err(format, a)
	os.Exit(int(lsb.EXIT_FAILURE))
}

func (o *Hackers) worker() {
	err := os.Chdir(o.cfg.Yamldir)
	if err != nil {
		worker_error("failed to load %q: %v", o.cfg.Yamldir, err)
	}
	for event, err := o.in_fd.Read(); err == nil; event, err = o.in_fd.Read() {
		switch event.Wd {
		case o.in_wd_yaml:
			// handle updates to yaml files
			if event.Mask&in_DIR_INVALID != 0 {
				err := o.Reload()
				if err != nil {
					worker_error("failed to reload hackers.git yaml directory: %v", err)

				}
				err = os.Chdir(o.cfg.Yamldir)
				if err != nil {
					worker_error("failed to load %q: %v", o.cfg.Yamldir, err)
				}
			} else if event.Mask&in_CHILD_ANY != 0 {
				filename := o.cfg.Yamldir + "/" + *event.Name
				logger.Info("Loading yaml file: %s", filename)
				user, err := load_user_yaml(filename)
				if err == nil {
					// User added/updated
					logger.Info("... success")
					o.worker_handle_user_add(user)
				} else if user.passwd.UID >= 0 {
					// User became invalid
					logger.Info("... error: %v", err)
					o.worker_handle_user_del(user.passwd.UID)
				}
			} else {
				panic("recieved non-subscribed inotify event from kernel")
			}
		case o.in_wd_home:
			if event.Mask&in_DIR_INVALID != 0 {
				err := o.Reload()
				if err != nil {
					panic(err)
				}
			} else if event.Mask&inotify.IN_ISDIR != 0 {
				// handle added home directory
				o.worker_watch_homedirs()
			}
		default:
			// handle a change to someone's password
			if event.Mask&in_DIR_INVALID != 0 {
				o.unwatchHomedir(event.Wd)
				o.worker_watch_homedirs()
			} else if *event.Name == ".password" {
				o.worker_handle_passwd(o.in_wd2uid[event.Wd])
			}
		}
	}
	panic("not reached")
}