init basic working program, need to fix command running

go.mod

@@ -0,0 +1,9 @@
+module forge.steck.dev/bryson/listen
+
+go 1.24
+
+require github.com/jessevdk/go-flags v1.6.1
+
+require github.com/fsnotify/fsnotify v1.9.0
+
+require golang.org/x/sys v0.21.0 // indirect

go.sum

@@ -0,0 +1,6 @@
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
+github.com/jessevdk/go-flags v1.6.1 h1:Cvu5U8UGrLay1rZfv/zP7iLpSHGUZ/Ou68T0iX1bBK4=
+github.com/jessevdk/go-flags v1.6.1/go.mod h1:Mk8T1hIAWpOiJiHa9rJASDK2UGWji0EuPGBnNLMooyc=
+golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

main.go

@@ -0,0 +1,162 @@
+package main
+
+import (
+	"fmt"
+	"io/fs"
+	"log"
+	"maps"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+	flags "github.com/jessevdk/go-flags"
+)
+
+const VERSION string = "v0.1.0"
+
+var opts struct {
+	Version   bool     `short:"v" long:"version" description:"Displays version info and exits"`
+	Files     []string `short:"f" long:"file" description:"File(s) to listen to (watch)" value-name:"FILE"`
+	Condition string   `short:"w" long:"when" description:"If multiple files are specified, choose if any file or all files specified are needed to trigger COMMAND" default:"any" choice:"any" choice:"all"`
+	Checksum  bool     `short:"c" long:"checksum" description:"Use checksum to determine when file(s) are changed instead of modification time (only used when -i is specified)"`
+	Interval  string   `short:"i" long:"interval" description:"Use this time interval (ex. 5m30s, 1s) between filesystem checks instead of using kernel events"`
+}
+
+func validateFiles(files []string) error {
+	if len(files) <= 0 {
+		fmt.Println("listen: at least one file (-f) is required")
+		return flags.ErrCommandRequired
+	}
+
+	for _, file := range files {
+		info, err := os.Stat(file)
+		if err != nil {
+			fmt.Printf("listen: %s\n", err)
+			return err
+		}
+
+		if info.IsDir() {
+			fmt.Printf("listen: %s: not a file\n", file)
+			return fs.ErrInvalid
+		}
+
+		_, err = os.Open(file)
+		if err != nil {
+			fmt.Printf("listen: %s\n", err)
+			return err
+		}
+	}
+
+	return nil
+}
+
+func listen(files map[string]bool, condition string, cksum bool, interval string, command []string) {
+	// catch ^C
+	quit := make(chan bool)
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+
+	// main loop
+	if interval == "" {
+		watcher, err := fsnotify.NewWatcher()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		for key := range files {
+			watcher.Add(key)
+		}
+
+		go func() {
+			for {
+				trigger := false
+				select {
+				case event, ok := <-watcher.Events:
+					if !ok {
+						return
+					}
+					fmt.Println(event)
+
+					for key := range files {
+						if event.Has(fsnotify.Write) && event.Name == key {
+							if condition == "any" {
+								trigger = true
+								break
+							}
+							files[key] = true
+						}
+					}
+
+					if condition == "all" {
+						trigger = true
+						for value := range maps.Values(files) {
+							if !value {
+								trigger = false
+								break
+							}
+						}
+					}
+
+				case _, ok := <-watcher.Errors:
+					if !ok {
+						return
+					}
+				}
+
+				if trigger {
+					if len(command) >= 1 {
+						exec.Command(command[0], command[1:]...)
+					} else {
+						quit <- true
+					}
+				}
+			}
+		}()
+
+	} else {
+		go func() {
+			for {
+				fmt.Printf("running")
+				time.Sleep(1 * time.Second)
+			}
+
+		}()
+
+	}
+
+	select {
+	case <-c:
+	case <-quit:
+	}
+
+}
+
+func main() {
+	parser := flags.NewParser(&opts, flags.Default)
+	parser.Usage = "[OPTIONS] -- [COMMAND]"
+	remaining, err := parser.Parse()
+
+	if err == nil {
+		if opts.Version {
+			fmt.Printf("listen %s\n", VERSION)
+		} else if err := validateFiles(opts.Files); err == nil {
+			var filesMap map[string]bool = make(map[string]bool)
+			success := true
+			for _, file := range opts.Files {
+				abs, err := filepath.Abs(file)
+				if err == nil {
+					filesMap[abs] = false
+				} else {
+					success = false
+				}
+			}
+
+			if success {
+				listen(filesMap, opts.Condition, opts.Checksum, opts.Interval, remaining)
+			}
+		}
+	}
+}