Start work on config watcher kitten

go.mod

@@ -20,6 +20,7 @@ require (
 	github.com/kovidgoyal/imaging v1.8.21
 	github.com/nwaples/rardecode/v2 v2.2.2
 	github.com/seancfoley/ipaddress-go v1.7.1
+	github.com/sgtdi/fswatcher v1.2.0
 	github.com/shirou/gopsutil/v4 v4.26.3
 	github.com/ulikunitz/xz v0.5.15
 	github.com/zeebo/xxh3 v1.1.0

go.sum

@@ -52,6 +52,8 @@ github.com/seancfoley/bintree v1.3.1 h1:cqmmQK7Jm4aw8gna0bP+huu5leVOgHGSJBEpUx3E
 github.com/seancfoley/bintree v1.3.1/go.mod h1:hIUabL8OFYyFVTQ6azeajbopogQc2l5C/hiXMcemWNU=
 github.com/seancfoley/ipaddress-go v1.7.1 h1:fDWryS+L8iaaH5RxIKbY0xB5Z+Zxk8xoXLN4S4eAPdQ=
 github.com/seancfoley/ipaddress-go v1.7.1/go.mod h1:TQRZgv+9jdvzHmKoPGBMxyiaVmoI0rYpfEk8Q/sL/Iw=
+github.com/sgtdi/fswatcher v1.2.0 h1:uSJuMc3/Eo/vaPnZWpJ42EFYb5j38cZENmkszOV0yhw=
+github.com/sgtdi/fswatcher v1.2.0/go.mod h1:smzXnaqu0SYJQNIwGLLkvRkpH4RdEACB7avMSsSaqjQ=
 github.com/shirou/gopsutil/v4 v4.26.3 h1:2ESdQt90yU3oXF/CdOlRCJxrP+Am1aBYubTMTfxJ1qc=
 github.com/shirou/gopsutil/v4 v4.26.3/go.mod h1:LZ6ewCSkBqUpvSOf+LsTGnRinC6iaNUNMGBtDkJBaLQ=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=

tools/cmd/tool/main.go

@@ -134,6 +134,7 @@ func KittyToolEntryPoints(root *cli.Command) {
 			return confirm_and_run_exe(args)
 		},
 	})
+	// __watch_conf__
 
 	// __convert_image__
 	images.ConvertEntryPoint(root)

tools/config/api.go

@@ -39,9 +39,10 @@ type ConfigLine struct {
 }
 
 type ConfigParser struct {
-	LineHandler     func(key, val string) error
-	CommentsHandler func(line string) error
-	SourceHandler   func(text, path string)
+	LineHandler      func(key, val string) error
+	CommentsHandler  func(line string) error
+	SourceHandler    func(text, path string)
+	AllIncludedFiles *utils.Set[string]
 
 	bad_lines     []ConfigLine
 	seen_includes map[string]bool
@@ -111,11 +112,16 @@ func ExpandVars(x string) string {
 	})
 }
 
+const OverridesFileName = "<overrides>"
+
 func (self *ConfigParser) parse(scanner Scanner, name, base_path_for_includes string, depth int) error {
 	if self.seen_includes[name] { // avoid include loops
 		return nil
 	}
 	self.seen_includes[name] = true
+	if self.AllIncludedFiles != nil && name != OverridesFileName {
+		self.AllIncludedFiles.Add(name)
+	}
 
 	recurse := func(r io.Reader, nname, base_path_for_includes string) error {
 		if depth > 32 {

tools/watch/api.go

@@ -0,0 +1,144 @@
+package watch
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/sgtdi/fswatcher"
+	"golang.org/x/sys/unix"
+
+	"github.com/kovidgoyal/kitty/tools/cli"
+	"github.com/kovidgoyal/kitty/tools/config"
+	"github.com/kovidgoyal/kitty/tools/utils"
+)
+
+var _ = fmt.Print
+
+// watch_dir starts fswatcher in a background goroutine and pipes events to a custom channel.
+func watch_dir(ctx context.Context, path string, debounce time.Duration, eventChan chan<- fswatcher.WatchEvent) error {
+	w, err := fswatcher.New(
+		fswatcher.WithPath(path),
+		fswatcher.WithCooldown(debounce),
+	)
+	if err != nil {
+		return err
+	}
+	go w.Watch(ctx)
+	go func() {
+		for event := range w.Events() {
+			eventChan <- event
+		}
+	}()
+	return nil
+}
+
+type config_file_collection struct {
+	mutex         sync.Mutex
+	config_paths  []string
+	dirs_to_watch []string
+}
+
+func (cfc *config_file_collection) get_list_of_config_files() *utils.Set[string] {
+	cp := config.ConfigParser{
+		AllIncludedFiles: utils.NewSet[string](), LineHandler: func(k, v string) error { return nil }}
+	cp.ParseFiles(cfc.config_paths...)
+	for _, path := range cfc.config_paths {
+		path = filepath.Clean(path)
+		cp.AllIncludedFiles.Add(path)
+		for _, q := range []string{"dark-theme.auto.conf", "light-theme.auto.conf", "no-preference-theme.auto.conf"} {
+			q = filepath.Join(filepath.Dir(path), q)
+			cp.AllIncludedFiles.Add(filepath.Clean(q))
+		}
+	}
+	return cp.AllIncludedFiles
+}
+
+func (cfc *config_file_collection) EventIsSignificant(ev fswatcher.WatchEvent) bool {
+	cfc.mutex.Lock()
+	defer cfc.mutex.Unlock()
+	conf_files := cfc.get_list_of_config_files()
+	q := filepath.Clean(ev.Path)
+	return conf_files.Has(q)
+}
+
+func watch_for_kitty_config_changes(action func() error, debounce_time time.Duration, config_paths []string) error {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	event_chan := make(chan fswatcher.WatchEvent)
+	dirs := utils.NewSet[string](len(config_paths))
+	for _, path := range config_paths {
+		if parent := filepath.Dir(path); parent != "" && parent != "." && parent != "/" {
+			dirs.Add(path)
+		}
+	}
+	if dirs.Len() == 0 {
+		return fmt.Errorf("No directories to watch provided")
+	}
+	cfc := config_file_collection{config_paths: config_paths, dirs_to_watch: dirs.AsSlice()}
+
+	filtered_action := func(ev fswatcher.WatchEvent) error {
+		if cfc.EventIsSignificant(ev) {
+			return action()
+		}
+		return nil
+	}
+	for _, path := range cfc.dirs_to_watch {
+		if err := watch_dir(ctx, path, debounce_time, event_chan); err != nil {
+			return err
+		}
+	}
+	stdinClosed := make(chan struct{})
+	go func() {
+		scanner := bufio.NewScanner(os.Stdin)
+		for scanner.Scan() {
+		}
+		close(stdinClosed)
+	}()
+	for {
+		select {
+		case event := <-event_chan:
+			if err := filtered_action(event); err != nil {
+				fmt.Fprintf(os.Stderr, "failed to signal kitty in event: %s with error: %s\n", event, err)
+			}
+		case <-stdinClosed:
+			return nil
+		}
+	}
+}
+
+func signal_kitty_to_reload_config(kitty_pid int) error {
+	return unix.Kill(kitty_pid, unix.SIGUSR1)
+}
+
+func EntryPoint(root *cli.Command) {
+	root.AddSubCommand(&cli.Command{
+		Name:            "__watch_conf__",
+		Hidden:          true,
+		OnlyArgsAllowed: true,
+		Run: func(cmd *cli.Command, args []string) (rc int, err error) {
+			if len(args) < 3 {
+				return 1, fmt.Errorf("Usage: __watch_conf__ kitty_pid debounce_time_ms config_paths...")
+			}
+			kitty_pid, err := strconv.Atoi(args[0])
+			if err != nil {
+				return 1, err
+			}
+			debounce_time_ms, err := strconv.ParseUint(args[1], 10, 64)
+			if err != nil {
+				return 1, err
+			}
+			if err = watch_for_kitty_config_changes(
+				func() error { return signal_kitty_to_reload_config(kitty_pid) },
+				time.Millisecond*time.Duration(debounce_time_ms), args[2:]); err != nil {
+				return 1, err
+			}
+			return 0, nil
+		},
+	})
+}