refactor: windows: clean up, tidy and improve windows key handling

This fixes a bunch of issues on Windows bringing improvements and
reliability to the implementation. It replacing the existing key events
hack with a key state that keeps track of previous key events to parse
the incoming ANSI escape sequences. It also decodes unicode utf16 pairs
at the parser level instead of the driver level.

Related: #1126

driver.go

@@ -31,6 +31,10 @@ type driver struct {
 	// multiple size events from firing.
 	lastWinsizeEventX, lastWinsizeEventY int16 // nolint: unused
 
+	// keyState keeps track of the current Windows Console API key events state.
+	// It is used to decode ANSI escape sequences and utf16 sequences.
+	keyState win32KeyState // nolint:unused
+
 	flags int // control the behavior of the driver.
 }
 

driver_windows.go

@@ -6,9 +6,7 @@ package tea
 import (
 	"errors"
 	"fmt"
-	"unicode/utf16"
 
-	"github.com/charmbracelet/x/ansi"
 	xwindows "github.com/charmbracelet/x/windows"
 	"golang.org/x/sys/windows"
 )
@@ -36,140 +34,33 @@ func (d *driver) handleConInput(
 
 	// read up to 256 events, this is to allow for sequences events reported as
 	// key events.
-	var events [256]xwindows.InputRecord
+	var events [numEvents]xwindows.InputRecord
 	_, err := finput(cc.conin, events[:])
 	if err != nil {
 		return nil, fmt.Errorf("read coninput events: %w", err)
 	}
 
 	var evs []Msg
 	for _, event := range events {
-		if e := parseConInputEvent(event, &d.prevMouseState, &d.lastWinsizeEventX, &d.lastWinsizeEventY); e != nil {
+		if e := parseConInputEvent(event, &d.keyState, &d.prevMouseState, &d.lastWinsizeEventX, &d.lastWinsizeEventY); e != nil {
 			evs = append(evs, e)
-		}
-	}
-
-	return d.detectConInputQuerySequences(evs), nil
-}
-
-// Using ConInput API, Windows Terminal responds to sequence query events with
-// KEY_EVENT_RECORDs so we need to collect them and parse them as a single
-// sequence.
-// Is this a hack?
-func (d *driver) detectConInputQuerySequences(events []Msg) []Msg {
-	var newEvents []Msg
-	start, end := -1, -1
-
-loop:
-	for i, e := range events {
-		switch e := e.(type) {
-		case KeyPressMsg:
-			switch e.Code {
-			case ansi.ESC, ansi.CSI, ansi.OSC, ansi.DCS, ansi.APC:
-				// start of a sequence
-				if start == -1 {
-					start = i
-				}
+			if event.EventType == xwindows.KEY_EVENT {
+				k := event.KeyEvent()
+				evs = append(evs, printLineMessage{keyEventString(k.VirtualKeyCode, k.VirtualScanCode, k.Char, k.KeyDown, k.ControlKeyState, k.RepeatCount)})
 			}
-		default:
-			break loop
-		}
-		end = i
-	}
-
-	if start == -1 || end <= start {
-		return events
-	}
-
-	var seq []byte
-	for i := start; i <= end; i++ {
-		switch e := events[i].(type) {
-		case KeyPressMsg:
-			seq = append(seq, byte(e.Code))
-		}
-	}
-
-	n, seqevent := parseSequence(seq)
-	switch seqevent.(type) {
-	case UnknownMsg:
-		// We're not interested in unknown events
-	default:
-		if start+n > len(events) {
-			return events
 		}
-		newEvents = events[:start]
-		newEvents = append(newEvents, seqevent)
-		newEvents = append(newEvents, events[start+n:]...)
-		return d.detectConInputQuerySequences(newEvents)
 	}
 
-	return events
+	return evs, nil
 }
 
-func parseConInputEvent(event xwindows.InputRecord, buttonState *uint32, windowSizeX, windowSizeY *int16) Msg {
+func parseConInputEvent(event xwindows.InputRecord, keyState *win32KeyState, buttonState *uint32, windowSizeX, windowSizeY *int16) Msg {
 	switch event.EventType {
 	case xwindows.KEY_EVENT:
 		kevent := event.KeyEvent()
-		event := parseWin32InputKeyEvent(kevent.VirtualKeyCode, kevent.VirtualScanCode,
+		return parseWin32InputKeyEvent(keyState, kevent.VirtualKeyCode, kevent.VirtualScanCode,
 			kevent.Char, kevent.KeyDown, kevent.ControlKeyState, kevent.RepeatCount)
 
-		var key Key
-		switch event := event.(type) {
-		case KeyPressMsg:
-			key = Key(event)
-		case KeyReleaseMsg:
-			key = Key(event)
-		default:
-			return nil
-		}
-
-		// If the key is not printable, return the event as is
-		// (e.g. function keys, arrows, etc.)
-		// Otherwise, try to translate it to a rune based on the active keyboard
-		// layout.
-		if len(key.Text) == 0 {
-			return event
-		}
-
-		// Always use US layout for translation
-		// This is to follow the behavior of the Kitty Keyboard base layout
-		// feature :eye_roll:
-		// https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-language-pack-default-values?view=windows-11
-		const usLayout = 0x409
-
-		// Translate key to rune
-		var keyState [256]byte
-		var utf16Buf [16]uint16
-		const dontChangeKernelKeyboardLayout = 0x4
-		ret := windows.ToUnicodeEx(
-			uint32(kevent.VirtualKeyCode),
-			uint32(kevent.VirtualScanCode),
-			&keyState[0],
-			&utf16Buf[0],
-			int32(len(utf16Buf)),
-			dontChangeKernelKeyboardLayout,
-			usLayout,
-		)
-
-		// -1 indicates a dead key
-		// 0 indicates no translation for this key
-		if ret < 1 {
-			return event
-		}
-
-		runes := utf16.Decode(utf16Buf[:ret])
-		if len(runes) != 1 {
-			// Key doesn't translate to a single rune
-			return event
-		}
-
-		key.BaseCode = runes[0]
-		if kevent.KeyDown {
-			return KeyPressMsg(key)
-		}
-
-		return KeyReleaseMsg(key)
-
 	case xwindows.WINDOW_BUFFER_SIZE_EVENT:
 		wevent := event.WindowBufferSizeEvent()
 		if wevent.Size.X != *windowSizeX || wevent.Size.Y != *windowSizeY {

parse.go

@@ -349,6 +349,7 @@ func parseCsi(b []byte) (int, Msg) {
 		}
 
 		event := parseWin32InputKeyEvent(
+			nil,
 			uint16(csi.Param(0)), //nolint:gosec // Vk wVirtualKeyCode
 			uint16(csi.Param(1)), //nolint:gosec // Sc wVirtualScanCode
 			rune(csi.Param(2)),   // Uc UnicodeChar