Start work on proper TUI support

tools/tui/loop.go

@@ -0,0 +1,135 @@
+package tui
+
+import (
+	"fmt"
+	"io"
+	"kitty/tools/tty"
+	"os"
+	"time"
+)
+
+type TerminalState struct {
+	alternate_screen, grab_mouse bool
+}
+
+type Loop struct {
+	controlling_term *tty.Term
+	keep_going       bool
+	flush_write_buf  bool
+	write_buf        []byte
+}
+
+func CreateLoop() (*Loop, error) {
+	l := Loop{controlling_term: nil}
+	return &l, nil
+}
+
+func (self *Loop) Run() (err error) {
+	signal_read_file, signal_write_file, err := os.Pipe()
+	if err != nil {
+		return err
+	}
+	defer func() {
+		signal_read_file.Close()
+		signal_write_file.Close()
+	}()
+
+	sigchnl := make(chan os.Signal, 256)
+	reset_signals := notify_signals(sigchnl, SIGINT, SIGTERM, SIGTSTP, SIGHUP)
+	defer reset_signals()
+
+	go func() {
+		for {
+			s := <-sigchnl
+			if write_signal(signal_write_file, s) != nil {
+				break
+			}
+		}
+	}()
+
+	controlling_term, err := tty.OpenControllingTerm()
+	if err != nil {
+		return err
+	}
+	self.controlling_term = controlling_term
+	defer func() {
+		self.controlling_term.RestoreAndClose()
+		self.controlling_term = nil
+	}()
+	err = self.controlling_term.ApplyOperations(tty.TCSANOW, tty.SetRaw)
+	if err != nil {
+		return nil
+	}
+
+	var selector Select
+	selector.RegisterRead(int(signal_read_file.Fd()))
+	selector.RegisterRead(controlling_term.Fd())
+
+	self.keep_going = true
+	self.flush_write_buf = true
+
+	defer func() {
+		if self.flush_write_buf {
+			self.flush()
+		}
+	}()
+
+	for self.keep_going {
+		num_ready, err := selector.WaitForever()
+		if err != nil {
+			return fmt.Errorf("Failed to call select() with error: %w", err)
+		}
+		if num_ready == 0 {
+			continue
+		}
+	}
+
+	return nil
+}
+
+func (self *Loop) write() error {
+	if len(self.write_buf) == 0 || self.controlling_term == nil {
+		return nil
+	}
+	n, err := self.controlling_term.Write(self.write_buf)
+	if err != nil {
+		return err
+	}
+	if n == 0 {
+		return io.EOF
+	}
+	remainder := self.write_buf[n:]
+	if len(remainder) > 0 {
+		self.write_buf = self.write_buf[:len(remainder)]
+		copy(self.write_buf, remainder)
+	} else {
+		self.write_buf = self.write_buf[:0]
+	}
+	return nil
+}
+
+func (self *Loop) flush() error {
+	var selector Select
+	if self.controlling_term == nil {
+		return nil
+	}
+	selector.RegisterWrite(self.controlling_term.Fd())
+	deadline := time.Now().Add(2 * time.Second)
+	for len(self.write_buf) > 0 {
+		timeout := deadline.Sub(time.Now())
+		if timeout < 0 {
+			break
+		}
+		num_ready, err := selector.Wait(timeout)
+		if err != nil {
+			return err
+		}
+		if num_ready > 0 && selector.IsReadyToWrite(self.controlling_term.Fd()) {
+			err = self.write()
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}