// NewUser tracks a new authenticated user and saves its details in the state
func NewUser(st *state.State, username, macaroon string, discharges []string) (*UserState, error) {
	var authStateData AuthState

	err := st.Get("auth", &authStateData)
	if err == state.ErrNoState {
		authStateData = AuthState{}
	} else if err != nil {
		return nil, err
	}

	sort.Strings(discharges)
	authStateData.LastID++
	authenticatedUser := UserState{
		ID:              authStateData.LastID,
		Username:        username,
		Macaroon:        macaroon,
		Discharges:      discharges,
		StoreMacaroon:   macaroon,
		StoreDischarges: discharges,
	}
	authStateData.Users = append(authStateData.Users, authenticatedUser)

	st.Set("auth", authStateData)

	return &authenticatedUser, nil
}

// allLocalSnapInfos returns the information about the all current snaps and their SnapStates.
func allLocalSnapInfos(st *state.State) ([]aboutSnap, error) {
	st.Lock()
	defer st.Unlock()

	snapStates, err := snapstate.All(st)
	if err != nil {
		return nil, err
	}

	about := make([]aboutSnap, 0, len(snapStates))

	var firstErr error
	for name, snapState := range snapStates {
		info, err := snap.ReadInfo(name, snapState.Current())
		if err != nil {
			// XXX: aggregate instead?
			if firstErr == nil {
				firstErr = err
			}
			continue
		}
		about = append(about, aboutSnap{info, snapState})
	}

	return about, firstErr
}

// CheckMacaroon returns the UserState for the given macaroon/discharges credentials
func CheckMacaroon(st *state.State, macaroon string, discharges []string) (*UserState, error) {
	var authStateData AuthState
	err := st.Get("auth", &authStateData)
	if err != nil {
		return nil, ErrInvalidAuth
	}

NextUser:
	for _, user := range authStateData.Users {
		if user.Macaroon != macaroon {
			continue
		}
		if len(user.Discharges) != len(discharges) {
			continue
		}
		// sort discharges (stored users' discharges are already sorted)
		sort.Strings(discharges)
		for i, d := range user.Discharges {
			if d != discharges[i] {
				continue NextUser
			}
		}
		return &user, nil
	}
	return nil, ErrInvalidAuth
}

// Disconnect returns a set of tasks for  disconnecting an interface.
func Disconnect(s *state.State, plugSnap, plugName, slotSnap, slotName string) (*state.TaskSet, error) {
	// TODO: Remove the intent-to-connect from the state so that we no longer
	// automatically try to reconnect on reboot.
	summary := fmt.Sprintf(i18n.G("Disconnect %s:%s from %s:%s"),
		plugSnap, plugName, slotSnap, slotName)
	task := s.NewTask("disconnect", summary)
	task.Set("slot", interfaces.SlotRef{Snap: slotSnap, Name: slotName})
	task.Set("plug", interfaces.PlugRef{Snap: plugSnap, Name: plugName})
	return state.NewTaskSet(task), nil
}

// Connect returns a set of tasks for connecting an interface.
//
func Connect(s *state.State, plugSnap, plugName, slotSnap, slotName string) (*state.TaskSet, error) {
	// TODO: Store the intent-to-connect in the state so that we automatically
	// try to reconnect on reboot (reconnection can fail or can connect with
	// different parameters so we cannot store the actual connection details).
	summary := fmt.Sprintf(i18n.G("Connect %s:%s to %s:%s"),
		plugSnap, plugName, slotSnap, slotName)
	task := s.NewTask("connect", summary)
	task.Set("slot", interfaces.SlotRef{Snap: slotSnap, Name: slotName})
	task.Set("plug", interfaces.PlugRef{Snap: plugSnap, Name: plugName})
	return state.NewTaskSet(task), nil
}

func getConns(st *state.State) (map[string]connState, error) {
	// Get information about connections from the state
	var conns map[string]connState
	err := st.Get("conns", &conns)
	if err != nil && err != state.ErrNoState {
		return nil, fmt.Errorf("cannot obtain data about existing connections: %s", err)
	}
	if conns == nil {
		conns = make(map[string]connState)
	}
	return conns, nil
}

// User returns a user from the state given its ID
func User(st *state.State, id int) (*UserState, error) {
	var authStateData AuthState

	err := st.Get("auth", &authStateData)
	if err != nil {
		return nil, err
	}

	for _, user := range authStateData.Users {
		if user.ID == id {
			return &user, nil
		}
	}
	return nil, fmt.Errorf("invalid user")
}

// All retrieves return a map from name to SnapState for all current snaps in the system state.
func All(s *state.State) (map[string]*SnapState, error) {
	// XXX: result is a map because sideloaded snaps carry no name
	// atm in their sideinfos
	var stateMap map[string]*SnapState
	if err := s.Get("snaps", &stateMap); err != nil && err != state.ErrNoState {
		return nil, err
	}
	curStates := make(map[string]*SnapState, len(stateMap))
	for snapName, snapState := range stateMap {
		if snapState.Current() != nil {
			curStates[snapName] = snapState
		}
	}
	return curStates, nil
}

func checkChangeConflict(s *state.State, snapName string) error {
	for _, task := range s.Tasks() {
		k := task.Kind()
		chg := task.Change()
		if (k == "link-snap" || k == "unlink-snap") && (chg == nil || !chg.Status().Ready()) {
			ss, err := TaskSnapSetup(task)
			if err != nil {
				return fmt.Errorf("internal error: cannot obtain snap setup from task: %s", task.Summary())
			}
			if ss.Name == snapName {
				return fmt.Errorf("snap %q has changes in progress", snapName)
			}
		}
	}
	return nil
}

// Get retrieves the SnapState of the given snap.
func Get(s *state.State, name string, snapst *SnapState) error {
	var snaps map[string]*json.RawMessage
	err := s.Get("snaps", &snaps)
	if err != nil {
		return err
	}
	raw, ok := snaps[name]
	if !ok {
		return state.ErrNoState
	}
	err = json.Unmarshal([]byte(*raw), &snapst)
	if err != nil {
		return fmt.Errorf("cannot unmarshal snap state: %v", err)
	}
	return nil
}

// ActiveInfos returns information about all active snaps.
func ActiveInfos(s *state.State) ([]*snap.Info, error) {
	var stateMap map[string]*SnapState
	var infos []*snap.Info
	if err := s.Get("snaps", &stateMap); err != nil && err != state.ErrNoState {
		return nil, err
	}
	for snapName, snapState := range stateMap {
		if !snapState.Active {
			continue
		}
		snapInfo, err := readInfo(snapName, snapState.Current())
		if err != nil {
			logger.Noticef("cannot retrieve info for snap %q: %s", snapName, err)
			continue
		}
		infos = append(infos, snapInfo)
	}
	return infos, nil
}

// Set sets the SnapState of the given snap, overwriting any earlier state.
func Set(s *state.State, name string, snapst *SnapState) {
	var snaps map[string]*json.RawMessage
	err := s.Get("snaps", &snaps)
	if err != nil && err != state.ErrNoState {
		panic("internal error: cannot unmarshal snaps state: " + err.Error())
	}
	if snaps == nil {
		snaps = make(map[string]*json.RawMessage)
	}
	if snapst == nil || (len(snapst.Sequence) == 0 && snapst.Candidate == nil) {
		delete(snaps, name)
	} else {
		data, err := json.Marshal(snapst)
		if err != nil {
			panic("internal error: cannot marshal snap state: " + err.Error())
		}
		raw := json.RawMessage(data)
		snaps[name] = &raw
	}
	s.Set("snaps", snaps)
}

// RemoveUser removes a user from the state given its ID
func RemoveUser(st *state.State, userID int) error {
	var authStateData AuthState

	err := st.Get("auth", &authStateData)
	if err != nil {
		return err
	}

	for i := range authStateData.Users {
		if authStateData.Users[i].ID == userID {
			// delete without preserving order
			n := len(authStateData.Users) - 1
			authStateData.Users[i] = authStateData.Users[n]
			authStateData.Users[n] = UserState{}
			authStateData.Users = authStateData.Users[:n]
			st.Set("auth", authStateData)
			return nil
		}
	}

	return fmt.Errorf("invalid user")
}

// localSnapInfo returns the information about the current snap for the given name plus the SnapState with the active flag and other snap revisions.
func localSnapInfo(st *state.State, name string) (info *snap.Info, active bool, err error) {
	st.Lock()
	defer st.Unlock()

	var snapst snapstate.SnapState
	err = snapstate.Get(st, name, &snapst)
	if err != nil && err != state.ErrNoState {
		return nil, false, fmt.Errorf("cannot consult state: %v", err)
	}

	cur := snapst.Current()
	if cur == nil {
		return nil, false, nil
	}

	info, err = snap.ReadInfo(name, cur)
	if err != nil {
		return nil, false, fmt.Errorf("cannot read snap details: %v", err)
	}

	return info, snapst.Active, nil
}

func verifyInstallUpdateTasks(c *C, curActive bool, ts *state.TaskSet, st *state.State) {
	i := 0
	n := 5
	if curActive {
		n++
	}
	c.Assert(ts.Tasks(), HasLen, n)
	// all tasks are accounted
	c.Assert(st.Tasks(), HasLen, n)
	c.Assert(ts.Tasks()[i].Kind(), Equals, "download-snap")
	i++
	c.Assert(ts.Tasks()[i].Kind(), Equals, "mount-snap")
	i++
	if curActive {
		c.Assert(ts.Tasks()[i].Kind(), Equals, "unlink-current-snap")
		i++
	}
	c.Assert(ts.Tasks()[i].Kind(), Equals, "copy-snap-data")
	i++
	c.Assert(ts.Tasks()[i].Kind(), Equals, "setup-profiles")
	i++
	c.Assert(ts.Tasks()[i].Kind(), Equals, "link-snap")
}

func newRunnerManager(s *state.State) *runnerManager {
	rm := &runnerManager{
		runner: state.NewTaskRunner(s),
	}

	rm.runner.AddHandler("runMgr1", func(t *state.Task, _ *tomb.Tomb) error {
		s := t.State()
		s.Lock()
		defer s.Unlock()
		s.Set("runMgr1Mark", 1)
		return nil
	}, nil)
	rm.runner.AddHandler("runMgr2", func(t *state.Task, _ *tomb.Tomb) error {
		s := t.State()
		s.Lock()
		defer s.Unlock()
		s.Set("runMgr2Mark", 1)
		return nil
	}, nil)
	rm.runner.AddHandler("runMgrEnsureBefore", func(t *state.Task, _ *tomb.Tomb) error {
		s := t.State()
		s.Lock()
		defer s.Unlock()
		s.EnsureBefore(20 * time.Millisecond)
		return nil
	}, nil)

	return rm
}

func doInstall(s *state.State, curActive bool, snapName, snapPath, channel string, userID int, flags snappy.InstallFlags) (*state.TaskSet, error) {
	if err := checkChangeConflict(s, snapName); err != nil {
		return nil, err
	}

	if snapPath == "" && channel == "" {
		channel = "stable"
	}

	var prepare *state.Task
	ss := SnapSetup{
		Channel: channel,
		UserID:  userID,
		Flags:   int(flags),
	}
	ss.Name = snapName
	ss.SnapPath = snapPath
	if snapPath != "" {
		prepare = s.NewTask("prepare-snap", fmt.Sprintf(i18n.G("Prepare snap %q"), snapPath))
	} else {
		prepare = s.NewTask("download-snap", fmt.Sprintf(i18n.G("Download snap %q from channel %q"), snapName, channel))
	}
	prepare.Set("snap-setup", ss)

	tasks := []*state.Task{prepare}
	addTask := func(t *state.Task) {
		t.Set("snap-setup-task", prepare.ID())
		tasks = append(tasks, t)
	}

	// mount
	mount := s.NewTask("mount-snap", fmt.Sprintf(i18n.G("Mount snap %q"), snapName))
	addTask(mount)
	mount.WaitFor(prepare)
	precopy := mount

	if curActive {
		// unlink-current-snap (will stop services for copy-data)
		unlink := s.NewTask("unlink-current-snap", fmt.Sprintf(i18n.G("Make current revision for snap %q unavailable"), snapName))
		addTask(unlink)
		unlink.WaitFor(mount)
		precopy = unlink
	}

	// copy-data (needs stopped services by unlink)
	copyData := s.NewTask("copy-snap-data", fmt.Sprintf(i18n.G("Copy snap %q data"), snapName))
	addTask(copyData)
	copyData.WaitFor(precopy)

	// security
	setupSecurity := s.NewTask("setup-profiles", fmt.Sprintf(i18n.G("Setup snap %q security profiles"), snapName))
	addTask(setupSecurity)
	setupSecurity.WaitFor(copyData)

	// finalize (wrappers+current symlink)
	linkSnap := s.NewTask("link-snap", fmt.Sprintf(i18n.G("Make snap %q available to the system"), snapName))
	addTask(linkSnap)
	linkSnap.WaitFor(setupSecurity)

	return state.NewTaskSet(tasks...), nil
}

// Remove returns a set of tasks for removing snap.
// Note that the state must be locked by the caller.
func Remove(s *state.State, name string, flags snappy.RemoveFlags) (*state.TaskSet, error) {
	if err := checkChangeConflict(s, name); err != nil {
		return nil, err
	}

	var snapst SnapState
	err := Get(s, name, &snapst)
	if err != nil && err != state.ErrNoState {
		return nil, err
	}

	cur := snapst.Current()
	if cur == nil {
		return nil, fmt.Errorf("cannot find snap %q", name)
	}

	revision := snapst.Current().Revision
	active := snapst.Active

	info, err := Info(s, name, revision)
	if err != nil {
		return nil, err
	}

	ss := SnapSetup{
		Name:     name,
		Revision: revision,
		Flags:    int(flags),
	}

	// check if this is something that can be removed
	if !backend.CanRemove(info, active) {
		return nil, fmt.Errorf("snap %q is not removable", ss.Name)
	}

	// trigger remove

	discardSnap := s.NewTask("discard-snap", fmt.Sprintf(i18n.G("Remove snap %q from the system"), name))
	discardSnap.Set("snap-setup", ss)

	discardSnapID := discardSnap.ID()
	tasks := ([]*state.Task)(nil)
	var chain *state.Task
	addNext := func(t *state.Task) {
		if chain != nil {
			t.WaitFor(chain)
		}
		if t.ID() != discardSnapID {
			t.Set("snap-setup-task", discardSnapID)
		}
		tasks = append(tasks, t)
		chain = t
	}

	if active {
		unlink := s.NewTask("unlink-snap", fmt.Sprintf(i18n.G("Make snap %q unavailable to the system"), name))

		addNext(unlink)
	}

	removeSecurity := s.NewTask("remove-profiles", fmt.Sprintf(i18n.G("Remove security profile for snap %q"), name))
	addNext(removeSecurity)

	clearData := s.NewTask("clear-snap", fmt.Sprintf(i18n.G("Remove data for snap %q"), name))
	addNext(clearData)

	addNext(discardSnap)

	if len(snapst.Sequence) == 1 {
		discardConns := s.NewTask("discard-conns", fmt.Sprintf(i18n.G("Discard interface connections for snap %q"), name))
		addNext(discardConns)
	}

	return state.NewTaskSet(tasks...), nil
}

func setConns(st *state.State, conns map[string]connState) {
	st.Set("conns", conns)
}