sway/client.go

package sway

import (
	"encoding/binary"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"sync"
)

// Client is a single connection to a sway socket.
// All requests are synchronized in order to be thread-safe.
// That means they are processed in incoming order.
// If you want to be truly concurrent, use multiple clients
// connected to the same sway socket path.
// Subscriptions are the exception: They use their own socket connection
// so other requests are still possible.
// Subscription connections get closed as soon as the provided context is done.
// Use Client.Close after all requests are processed
// to close the connection to the socket.
// Client.Close does not handle subscriptions.
type Client struct {
	sync.Mutex

	socket string
	conn   net.Conn
}

// GetDefaultClient returns a sway client for the current seat.
// It determines the current seat by the SWAYSOCK environment variable
func GetDefaultClient() (*Client, error) {
	socket, ok := os.LookupEnv("SWAYSOCK")
	if !ok {
		return nil, errors.New("could not find sway socket. is $SWAYSOCK set properly?")
	}

	return GetClientBySocket(socket)
}

// GetClientBySocket returns a sway client for the provided socket.
func GetClientBySocket(socket string) (*Client, error) {
	conn, err := net.Dial("unix", socket)
	if err != nil {
		return nil, err
	}

	return &Client{
		socket: socket,
		conn:   conn,
	}, nil
}

// Close closes the socket connection.
// All requests will return errors after calling Close
func (c *Client) Close() error {
	c.Lock()
	defer c.Unlock()

	return c.conn.Close()
}

func sendMessage[T any](client *Client, messageType uint32, payload string) (T, error) {
	client.Lock()
	defer client.Unlock()

	if _, err := fmt.Fprint(client.conn, "i3-ipc"); err != nil {
		return *new(T), err
	}

	if err := binary.Write(client.conn, binary.LittleEndian, uint32(len(payload))); err != nil {
		return *new(T), err
	}

	if err := binary.Write(client.conn, binary.LittleEndian, messageType); err != nil {
		return *new(T), err
	}

	if _, err := fmt.Fprint(client.conn, payload); err != nil {
		return *new(T), err
	}

	if _, err := client.conn.Read(make([]byte, 6)); err != nil {
		return *new(T), err
	}

	var length uint32
	if err := binary.Read(client.conn, binary.LittleEndian, &length); err != nil {
		return *new(T), err
	}

	var responseType uint32
	if err := binary.Read(client.conn, binary.LittleEndian, &responseType); err != nil {
		return *new(T), err
	}

	// io.Copy(os.Stdout, client.conn)
	// return *new(T), nil

	result := new(T)
	if err := json.NewDecoder(io.LimitReader(client.conn, int64(length))).Decode(result); err != nil {
		return *new(T), err
	}

	return *result, nil
}