From 9d56f8eed24550c4d822136c39e3b750a60de8b9 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 24 Aug 2022 12:23:11 +0530
Subject: [PATCH] Use TUI to build a nice password read control

---
 tools/tui/loop.go     | 44 +++++++++++++++++++++
 tools/tui/password.go | 90 +++++++++++++++++++++++++++++++++++++++++++
 tools/tui/signal.go   | 28 ++++++++++++++
 3 files changed, 162 insertions(+)
 create mode 100644 tools/tui/password.go

diff --git a/tools/tui/loop.go b/tools/tui/loop.go
index 57c74dc3a..4a111a7cf 100644
--- a/tools/tui/loop.go
+++ b/tools/tui/loop.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"kitty/tools/tty"
 	"os"
+	"syscall"
 	"time"
 
 	"kitty/tools/utils"
@@ -120,6 +121,32 @@ func CreateLoop() (*Loop, error) {
 	return &l, nil
 }
 
+func (self *Loop) UseAlternateScreen() {
+	self.terminal_options.alternate_screen = true
+}
+
+func (self *Loop) MouseTracking(mt MouseTracking) {
+	self.terminal_options.mouse_tracking = mt
+}
+
+func (self *Loop) DeathSignalName() string {
+	if self.death_signal != SIGNULL {
+		return self.death_signal.String()
+	}
+	return ""
+}
+
+func (self *Loop) KillIfSignalled() {
+	switch self.death_signal {
+	case SIGINT:
+		syscall.Kill(-1, syscall.SIGINT)
+	case SIGTERM:
+		syscall.Kill(-1, syscall.SIGTERM)
+	case SIGHUP:
+		syscall.Kill(-1, syscall.SIGHUP)
+	}
+}
+
 func (self *Loop) Run() (err error) {
 	signal_read_file, signal_write_file, err := os.Pipe()
 	if err != nil {
@@ -229,6 +256,23 @@ func (self *Loop) queue_write_to_tty(data []byte) {
 	self.write_buf = append(self.write_buf, data...)
 }
 
+func (self *Loop) QueueWriteString(data string) {
+	self.queue_write_to_tty([]byte(data))
+}
+
+func (self *Loop) ExitCode() int {
+	return self.exit_code
+}
+
+func (self *Loop) Beep() {
+	self.QueueWriteString("\a")
+}
+
+func (self *Loop) Quit(exit_code int) {
+	self.exit_code = exit_code
+	self.keep_going = false
+}
+
 func (self *Loop) write_to_tty() error {
 	if len(self.write_buf) == 0 || self.controlling_term == nil {
 		return nil
diff --git a/tools/tui/password.go b/tools/tui/password.go
new file mode 100644
index 000000000..2f66e7b0a
--- /dev/null
+++ b/tools/tui/password.go
@@ -0,0 +1,90 @@
+package tui
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/mattn/go-runewidth"
+)
+
+type KilledBySignal struct {
+	Msg        string
+	SignalName string
+}
+
+func (self *KilledBySignal) Error() string { return self.Msg }
+
+var Canceled = errors.New("Canceled by user")
+
+func ReadPassword(prompt string, kill_if_signaled bool) (password string, err error) {
+	loop, err := CreateLoop()
+	shadow := ""
+	if err != nil {
+		return
+	}
+
+	loop.OnText = func(loop *Loop, text string, from_key_event bool, in_bracketed_paste bool) error {
+		old_width := runewidth.StringWidth(password)
+		password += text
+		new_width := runewidth.StringWidth(password)
+		if new_width > old_width {
+			extra := strings.Repeat("*", new_width-old_width)
+			loop.QueueWriteString(extra)
+			shadow += extra
+		}
+		return nil
+	}
+
+	loop.OnKeyEvent = func(loop *Loop, event *KeyEvent) error {
+		if event.MatchesPressOrRepeat("backscape") || event.MatchesPressOrRepeat("delete") {
+			event.Handled = true
+			if len(password) > 0 {
+				old_width := runewidth.StringWidth(password)
+				password = password[:len(password)-1]
+				new_width := runewidth.StringWidth(password)
+				delta := new_width - old_width
+				if delta > 0 {
+					if delta > len(shadow) {
+						delta = len(shadow)
+					}
+					shadow = shadow[:len(shadow)-delta]
+					loop.QueueWriteString(strings.Repeat("\x08\x1b[P", delta))
+				}
+			} else {
+				loop.Beep()
+			}
+		}
+		if event.MatchesPressOrRepeat("enter") || event.MatchesPressOrRepeat("return") {
+			event.Handled = true
+			if password == "" {
+				loop.Quit(1)
+			} else {
+				loop.Quit(0)
+			}
+		}
+		if event.MatchesPressOrRepeat("esc") {
+			event.Handled = true
+			loop.Quit(1)
+			return Canceled
+		}
+		return nil
+	}
+
+	err = loop.Run()
+	if err != nil {
+		return
+	}
+	ds := loop.DeathSignalName()
+	if ds != "" {
+		if kill_if_signaled {
+			loop.KillIfSignalled()
+			return
+		}
+		return "", &KilledBySignal{Msg: fmt.Sprint("Killed by signal: ", ds), SignalName: ds}
+	}
+	if loop.ExitCode() != 0 {
+		password = ""
+	}
+	return password, nil
+}
diff --git a/tools/tui/signal.go b/tools/tui/signal.go
index 8bdbff0e2..e82288b38 100644
--- a/tools/tui/signal.go
+++ b/tools/tui/signal.go
@@ -1,6 +1,7 @@
 package tui
 
 import (
+	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
@@ -21,6 +22,33 @@ const (
 	SIGALRM Signal = 9
 )
 
+func (self *Signal) String() string {
+	switch *self {
+	case SIGNULL:
+		return "SIGNULL"
+	case SIGINT:
+		return "SIGINT"
+	case SIGTERM:
+		return "SIGTERM"
+	case SIGTSTP:
+		return "SIGTSTP"
+	case SIGHUP:
+		return "SIGHUP"
+	case SIGTTIN:
+		return "SIGTTIN"
+	case SIGTTOU:
+		return "SIGTTOU"
+	case SIGUSR1:
+		return "SIGUSR1"
+	case SIGUSR2:
+		return "SIGUSR2"
+	case SIGALRM:
+		return "SIGALRM"
+	default:
+		return fmt.Sprintf("SIG#%s", *self)
+	}
+}
+
 func as_signal(which os.Signal) Signal {
 	switch which {
 	case os.Interrupt: