sync

packages/client/tui/input/driver.go

@@ -0,0 +1,192 @@
+//nolint:unused,revive,nolintlint
+package input
+
+import (
+	"bytes"
+	"io"
+	"unicode/utf8"
+
+	"github.com/muesli/cancelreader"
+)
+
+// Logger is a simple logger interface.
+type Logger interface {
+	Printf(format string, v ...any)
+}
+
+// win32InputState is a state machine for parsing key events from the Windows
+// Console API into escape sequences and utf8 runes, and keeps track of the last
+// control key state to determine modifier key changes. It also keeps track of
+// the last mouse button state and window size changes to determine which mouse
+// buttons were released and to prevent multiple size events from firing.
+type win32InputState struct {
+	ansiBuf                    [256]byte
+	ansiIdx                    int
+	utf16Buf                   [2]rune
+	utf16Half                  bool
+	lastCks                    uint32 // the last control key state for the previous event
+	lastMouseBtns              uint32 // the last mouse button state for the previous event
+	lastWinsizeX, lastWinsizeY int16  // the last window size for the previous event to prevent multiple size events from firing
+}
+
+// Reader represents an input event reader. It reads input events and parses
+// escape sequences from the terminal input buffer and translates them into
+// human‑readable events.
+type Reader struct {
+	rd         cancelreader.CancelReader
+	table      map[string]Key // table is a lookup table for key sequences.
+	term       string         // $TERM
+	paste      []byte         // bracketed paste buffer; nil when disabled
+	buf        [256]byte      // read buffer
+	partialSeq []byte         // holds incomplete escape sequences
+	keyState   win32InputState
+	parser     Parser
+	logger     Logger
+}
+
+// NewReader returns a new input event reader.
+func NewReader(r io.Reader, termType string, flags int) (*Reader, error) {
+	d := new(Reader)
+	cr, err := newCancelreader(r, flags)
+	if err != nil {
+		return nil, err
+	}
+
+	d.rd = cr
+	d.table = buildKeysTable(flags, termType)
+	d.term = termType
+	d.parser.flags = flags
+	return d, nil
+}
+
+// SetLogger sets a logger for the reader.
+func (d *Reader) SetLogger(l Logger) { d.logger = l }
+
+// Read implements io.Reader.
+func (d *Reader) Read(p []byte) (int, error) { return d.rd.Read(p) }
+
+// Cancel cancels the underlying reader.
+func (d *Reader) Cancel() bool { return d.rd.Cancel() }
+
+// Close closes the underlying reader.
+func (d *Reader) Close() error { return d.rd.Close() }
+
+func (d *Reader) readEvents() ([]Event, error) {
+	nb, err := d.rd.Read(d.buf[:])
+	if err != nil {
+		return nil, err
+	}
+
+	var events []Event
+
+	// Combine any partial sequence from previous read with new data.
+	var buf []byte
+	if len(d.partialSeq) > 0 {
+		buf = make([]byte, len(d.partialSeq)+nb)
+		copy(buf, d.partialSeq)
+		copy(buf[len(d.partialSeq):], d.buf[:nb])
+		d.partialSeq = nil
+	} else {
+		buf = d.buf[:nb]
+	}
+
+	// Fast path: direct lookup for simple escape sequences.
+	if bytes.HasPrefix(buf, []byte{0x1b}) {
+		if k, ok := d.table[string(buf)]; ok {
+			if d.logger != nil {
+				d.logger.Printf("input: %q", buf)
+			}
+			events = append(events, KeyPressEvent(k))
+			return events, nil
+		}
+	}
+
+	var i int
+	for i < len(buf) {
+		consumed, ev := d.parser.parseSequence(buf[i:])
+		if d.logger != nil && consumed > 0 {
+			d.logger.Printf("input: %q", buf[i:i+consumed])
+		}
+
+		// Incomplete sequence – store remainder and exit.
+		if consumed == 0 && ev == nil {
+			rem := len(buf) - i
+			if rem > 0 {
+				d.partialSeq = make([]byte, rem)
+				copy(d.partialSeq, buf[i:])
+			}
+			break
+		}
+
+		// Handle bracketed paste specially so we don’t emit a paste event for
+		// every byte.
+		if d.paste != nil {
+			if _, ok := ev.(PasteEndEvent); !ok {
+				d.paste = append(d.paste, buf[i])
+				i++
+				continue
+			}
+		}
+
+		switch ev.(type) {
+		case PasteStartEvent:
+			d.paste = []byte{}
+		case PasteEndEvent:
+			var paste []rune
+			for len(d.paste) > 0 {
+				r, w := utf8.DecodeRune(d.paste)
+				if r != utf8.RuneError {
+					paste = append(paste, r)
+				}
+				d.paste = d.paste[w:]
+			}
+			d.paste = nil
+			events = append(events, PasteEvent(paste))
+		case nil:
+			i++
+			continue
+		}
+
+		if mevs, ok := ev.(MultiEvent); ok {
+			events = append(events, []Event(mevs)...)
+		} else {
+			events = append(events, ev)
+		}
+		i += consumed
+	}
+
+	// Collapse bursts of wheel/motion events into a single event each.
+	events = coalesceMouseEvents(events)
+	return events, nil
+}
+
+// coalesceMouseEvents reduces the volume of MouseWheelEvent and MouseMotionEvent
+// objects that arrive in rapid succession by keeping only the most recent
+// event in each contiguous run.
+func coalesceMouseEvents(in []Event) []Event {
+	if len(in) < 2 {
+		return in
+	}
+
+	out := make([]Event, 0, len(in))
+	for _, ev := range in {
+		switch ev.(type) {
+		case MouseWheelEvent:
+			if len(out) > 0 {
+				if _, ok := out[len(out)-1].(MouseWheelEvent); ok {
+					out[len(out)-1] = ev // replace previous wheel event
+					continue
+				}
+			}
+		case MouseMotionEvent:
+			if len(out) > 0 {
+				if _, ok := out[len(out)-1].(MouseMotionEvent); ok {
+					out[len(out)-1] = ev // replace previous motion event
+					continue
+				}
+			}
+		}
+		out = append(out, ev)
+	}
+	return out
+}