Use the max height of the terminal

cmd/ru/main.go

@@ -3,9 +3,12 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
+	"os"
 	"time"
 
 	"git.lattuga.net/blallo/ruspa/tree"
+	"golang.org/x/crypto/ssh/terminal"
 )
 
 type UnitValue struct {
@@ -41,15 +44,38 @@ func (u *UnitValue) Set(value string) error {
 	}
 }
 
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
 func main() {
 	var path string
 	var depth int
 	var root tree.Node
+	var interval time.Duration
 	var unit = &UnitValue{unit: "KB"}
-	flag.StringVar(&path, "path", ".", "Path from where to start the walk from")
-	flag.IntVar(&depth, "depth", 0, "Depth to display")
-	flag.Var(unit, "unit", "Unit in which to report size")
-	flag.Parse()
+	cli := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	cli.IntVar(&depth, "depth", 0, "Depth to display")
+	cli.Var(unit, "unit", "Unit in which to report size")
+	cli.DurationVar(&interval, "interval", 100*time.Millisecond, "The update interval")
+	cli.Usage = func() {
+		fmt.Fprintf(cli.Output(), "Usage:\n%s [opts] [PATH]\n\n  PATH: the root path to start from. Defaults to $PWD.\n\nopts:\n", os.Args[0])
+		cli.PrintDefaults()
+	}
+	cli.Parse(os.Args[1:])
+
+	switch narg := cli.NArg(); narg {
+	case 0:
+		path = "."
+	case 1:
+		path = cli.Args()[0]
+	default:
+		fmt.Fprintln(os.Stderr, "Too many arguments")
+		os.Exit(-1)
+	}
 
 	if depth == 0 || !tree.AnyDirectoryDownThere(path) {
 		root = tree.NewSingle(path)
@@ -57,13 +83,27 @@ func main() {
 		root = tree.NewTop(path)
 	}
 	root.SetUnit(unit.String())
-	go root.Spawn(depth)
+	out := log.New(os.Stdout, "", 0)
 
+	go root.Spawn(depth)
+	_, height, err := terminal.GetSize(int(os.Stdin.Fd()))
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "Could not get terminal size")
+		os.Exit(1)
+	}
+
+	firstRound := true
 	for {
 		select {
-		case <-time.After(500 * time.Millisecond):
-			fmt.Printf("\033[H\033[2J")
-			fmt.Println(root)
+		case <-time.After(interval):
+			if !firstRound {
+				depth := min(root.Depth()+2, height)
+				out.Printf("\r\033[%dA", depth)
+			} else {
+				out.Print("\r\033[A")
+			}
+			out.Print(root)
+			firstRound = false
 			if root.Complete() {
 				return
 			}

tree/dynamic_tree.go

@@ -35,6 +35,7 @@ type Node interface {
 	Level() int
 	Name() string
 	Complete() bool
+	Depth() int
 }
 
 //////////////////////////////
@@ -128,6 +129,14 @@ func (t *Top) Complete() bool {
 	return true
 }
 
+func (t *Top) Depth() int {
+	var depth int
+	for _, child := range t.tree {
+		depth += child.Depth()
+	}
+	return depth
+}
+
 func (t *Top) String() string {
 	var out string
 	var lines []string
@@ -280,6 +289,14 @@ func (i *Intermediate) Complete() bool {
 	return true
 }
 
+func (i *Intermediate) Depth() int {
+	var depth int
+	for _, child := range i.tree {
+		depth += child.Depth()
+	}
+	return depth
+}
+
 func (i *Intermediate) String() string {
 	var lines []string
 	out := fmt.Sprintf("(%s) %s\n", fmtSize(i.Size(), i.GetUnit()), i.Name())
@@ -409,6 +426,10 @@ func (b *Bottom) Complete() bool {
 	return b.complete
 }
 
+func (b *Bottom) Depth() int {
+	return 1
+}
+
 func (b *Bottom) String() string {
 	return fmt.Sprintf("(%s) %s", fmtSize(b.Size(), b.GetUnit()), b.Name())
 }
@@ -476,6 +497,10 @@ func (s *Single) Complete() bool {
 	return s.complete
 }
 
+func (s *Single) Depth() int {
+	return 1
+}
+
 func (s *Single) String() string {
 	return fmt.Sprintf("(%s) %s\n", fmtSize(s.Size(), s.GetUnit()), s.Name())
 }