adding to git.i0t.app

internal/ipc/ipc.go

@@ -0,0 +1,75 @@
+// Package ipc defines the tiny control protocol shared by the daemon (server)
+// and the CLI/TUI (clients). Messages are newline-delimited JSON over a unix
+// socket, so switching layouts or reading status never requires restarting
+// the video wall.
+package ipc
+
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"net"
+	"os"
+	"path/filepath"
+	"strconv"
+	"time"
+)
+
+// Request is a command sent to the daemon.
+type Request struct {
+	Cmd  string `json:"cmd"`            // "status" | "reload" | "set-layout"
+	Name string `json:"name,omitempty"` // layout name for set-layout
+}
+
+// SlotStatus reports one grid cell's state.
+type SlotStatus struct {
+	Slot    int    `json:"slot"`
+	Camera  string `json:"camera"`
+	PID     int    `json:"pid"`
+	Running bool   `json:"running"`
+	Healthy bool   `json:"healthy"`
+}
+
+// Response is the daemon's reply.
+type Response struct {
+	OK           bool         `json:"ok"`
+	Error        string       `json:"error,omitempty"`
+	ActiveLayout string       `json:"active_layout,omitempty"`
+	Slots        []SlotStatus `json:"slots,omitempty"`
+}
+
+// SocketPath returns the control socket path inside the runtime dir.
+func SocketPath() string {
+	return filepath.Join(RunDir(), "control.sock")
+}
+
+// RunDir is the per-user runtime directory for sockets, created on demand.
+func RunDir() string {
+	base := os.Getenv("XDG_RUNTIME_DIR")
+	if base == "" {
+		base = filepath.Join(os.TempDir(), "rtsp-streamer-"+strconv.Itoa(os.Getuid()))
+	} else {
+		base = filepath.Join(base, "rtsp-streamer")
+	}
+	return base
+}
+
+// Send dials the daemon, sends one request, and returns the reply.
+func Send(req Request) (*Response, error) {
+	conn, err := net.DialTimeout("unix", SocketPath(), 3*time.Second)
+	if err != nil {
+		return nil, fmt.Errorf("cannot reach daemon (is it running?): %w", err)
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(5 * time.Second))
+
+	enc := json.NewEncoder(conn)
+	if err := enc.Encode(req); err != nil {
+		return nil, err
+	}
+	var resp Response
+	if err := json.NewDecoder(bufio.NewReader(conn)).Decode(&resp); err != nil {
+		return nil, err
+	}
+	return &resp, nil
+}