swayipc/event.go

package swayipc

import (
	"encoding/json"
	"fmt"
	"reflect"
)

// Event types.
const (
	EvWorkspace       int = 0x80000000
	EvOutput          int = 0x80000001
	EvMode            int = 0x80000002
	EvWindow          int = 0x80000003
	EvBarconfigUpdate int = 0x80000004
	EvBinding         int = 0x80000005
	EvShutdown        int = 0x80000006
	EvTick            int = 0x80000007
	EvBarStateUpdate  int = 0x80000014
	EvInput           int = 0x80000015
)

// Event  is the  subscriber struct,  use this  to tell  swayipc which
// events you want to subscribe.
type Event struct {
	Workspace       bool `json:"workspace"`
	Output          bool `json:"output"`
	Mode            bool `json:"mode"`
	Window          bool `json:"window"`
	BarconfigUpdate bool `json:"barconfig_update"`
	Binding         bool `json:"binding"`
	Shutdown        bool `json:"shutdown"`
	Tick            bool `json:"tick"`
	BarStateUpdate  bool `json:"bar_state_update"`
	Input           bool `json:"input"`
}

// EventWorkspace stores a workspace event response
type EventWorkspace struct {
	Change  string `json:"change"`
	Current *Node  `json:"workspace"`
	Old     *Node  `json:"old"`
}

// EventOutput stores an output event response
type EventOutput struct {
	Change string `json:"change"`
}

// EventMode stores a ode event response
type EventMode struct {
	Change      string `json:"change"`
	PangoMarkup *Node  `json:"pango_markup"`
}

// EventWindow stores a window event response
type EventWindow struct {
	Change    string `json:"change"`
	Container *Node  `json:"container"`
}

// EventBarConfig stores a BarConfig event response
type EventBarConfig struct {
	Change  string   `json:"change"`
	Binding *Binding `json:"binding"`
}

// EventShutdown stores a Shutdown event response
type EventShutdown struct {
	Change string `json:"change"`
}

// EventTick stores a Tick event response
type EventTick struct {
	First   bool   `json:"first"`
	Payload string `json:"payload"`
}

// EventBarState stores a BarState event response
type EventBarState struct {
	ID                string `json:"id"`
	VisibleByModifier bool   `json:"visible_by_modifier"`
}

// EventInput stores an Input event response
type EventInput struct {
	Change string `json:"change"`
	Input  *Input `json:"input"`
}

// Subscribe  allows to  subscribe to  one or  more events.   Fill the
// Event object accordingly.
//
// Returns a response list containing  a response for every subscribed
// event.
func (ipc *SwayIPC) Subscribe(sub *Event) ([]*Response, error) {
	events := eventList(sub)

	jsonpayload, err := json.Marshal(events)
	if err != nil {
		return nil, fmt.Errorf("failed to json marshal event list: %w", err)
	}

	err = ipc.sendHeader(MsgSubscribe, uint32(len(jsonpayload)))
	if err != nil {
		return nil, err
	}

	err = ipc.sendPayload(jsonpayload)
	if err != nil {
		return nil, err
	}

	payload, err := ipc.readResponse()
	if err != nil {
		responses := []*Response{}
		if err := json.Unmarshal(payload.Payload, &responses); err != nil {
			return nil, fmt.Errorf("failed to unmarshal json response: %w", err)
		}

		return responses, err
	}

	// register the subscribed events
	ipc.Events = sub

	return nil, nil
}

// EventLoop starts an event loop.
//
// Once you have subscribed to an event, you need to enter
// an event  loop over the  same running socket connection.  Sway will
// send event payloads for every subscribed event whenever it happens.
//
// You  supply the  loop a  generic callback  function, which  will be
// called every  time an event  occurs. The function will  receive the
// swayipc.RawResponse object for the event.  You need to Unmarshall the
// Payload field yourself.
//
// If your callback function returns  an error, the event loop returns
// with this error and finishes thus.
func (ipc *SwayIPC) EventLoop(callback func(event *RawResponse) error) error {
	for {
		payload, err := ipc.readResponse()
		if err != nil {
			return err
		}

		if err := callback(payload); err != nil {
			return err
		}
	}
}

// eventList returns a list of subscribe events based on given Event objectstrucstruc
func eventList(sub *Event) []string {
	out := []string{}

	subv := reflect.ValueOf(sub).Elem()
	subType := subv.Type()

	for i := range subv.NumField() {
		field := subv.Field(i)
		structField := subType.Field(i)

		value := field.Interface()
		key := structField.Name

		if tag := structField.Tag.Get(`json`); tag != "" {
			key = tag
		}

		if value.(bool) {
			out = append(out, key)
		}
	}

	return out
}