app.go RawHistoryFolder

1package main
2
3import (
4	"context"
5	"flag"
6	"fmt"
7	"os"
8
9	"github.com/bnema/neferbar/internal/app"
10)
11
12const appUsage = `usage: neferbar app [-once] <field>...
13
14Prints fields of the window that has the focus: one line now, then one more
15each time it changes. With several fields, a tab separates them on the line
16(a title never contains a tab). Fields are empty when no window has the focus.
17
18fields:
19  id     the application id, such as com.github.bnema.dumber
20  name   the short form of the id, such as dumber
21  title  the window title, without control characters
22
23flags:
24`
25
26// runApp is "neferbar app <field>": the focused window, for scripts.
27func runApp(ctx context.Context, args []string, display string) error {
28	fs := flag.NewFlagSet("neferbar app", flag.ContinueOnError)
29	once := fs.Bool("once", false, "print the current value and exit")
30	fs.Usage = func() { fmt.Fprint(os.Stderr, appUsage); fs.PrintDefaults() }
31	if err := fs.Parse(args); err != nil {
32		return err
33	}
34	if fs.NArg() == 0 {
35		fs.Usage()
36		return fmt.Errorf("give at least one field: id, name or title")
37	}
38	var picks []func(app.Window) string
39	for _, field := range fs.Args() {
40		switch field {
41		case "id":
42			picks = append(picks, func(w app.Window) string { return app.Clean(w.ID) })
43		case "name":
44			picks = append(picks, func(w app.Window) string { return app.Clean(app.Name(w.ID)) })
45		case "title":
46			picks = append(picks, func(w app.Window) string { return app.Clean(w.Title) })
47		default:
48			return fmt.Errorf("%q is not a field; use id, name or title", field)
49		}
50	}
51	ctx, cancel := context.WithCancel(ctx)
52	defer cancel()
53	return app.Watch(ctx, display, func(w app.Window) error {
54		var line []byte
55		for i, pick := range picks {
56			if i > 0 {
57				line = append(line, '\t')
58			}
59			line = append(line, pick(w)...)
60		}
61		if _, err := os.Stdout.Write(append(line, '\n')); err != nil {
62			return err
63		}
64		if *once {
65			cancel()
66		}
67		return nil
68	})
69}