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// +build windows
package windowsconsole
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"strings"
"unsafe"
ansiterm "github.com/Azure/go-ansiterm"
"github.com/Azure/go-ansiterm/winterm"
)
const (
escapeSequence = ansiterm.KEY_ESC_CSI
)
// ansiReader wraps a standard input file (e.g., os.Stdin) providing ANSI sequence translation.
type ansiReader struct {
file *os.File
fd uintptr
buffer []byte
cbBuffer int
command []byte
}
// NewAnsiReader returns an io.ReadCloser that provides VT100 terminal emulation on top of a
// Windows console input handle.
func NewAnsiReader(nFile int) io.ReadCloser {
file, fd := winterm.GetStdFile(nFile)
return &ansiReader{
file: file,
fd: fd,
command: make([]byte, 0, ansiterm.ANSI_MAX_CMD_LENGTH),
buffer: make([]byte, 0),
}
}
// Close closes the wrapped file.
func (ar *ansiReader) Close() (err error) {
return ar.file.Close()
}
// Fd returns the file descriptor of the wrapped file.
func (ar *ansiReader) Fd() uintptr {
return ar.fd
}
// Read reads up to len(p) bytes of translated input events into p.
func (ar *ansiReader) Read(p []byte) (int, error) {
if len(p) == 0 {
return 0, nil
}
// Previously read bytes exist, read as much as we can and return
if len(ar.buffer) > 0 {
originalLength := len(ar.buffer)
copiedLength := copy(p, ar.buffer)
if copiedLength == originalLength {
ar.buffer = make([]byte, 0, len(p))
} else {
ar.buffer = ar.buffer[copiedLength:]
}
return copiedLength, nil
}
// Read and translate key events
events, err := readInputEvents(ar, len(p))
if err != nil {
return 0, err
} else if len(events) == 0 {
return 0, nil
}
keyBytes := translateKeyEvents(events, []byte(escapeSequence))
// Save excess bytes and right-size keyBytes
if len(keyBytes) > len(p) {
ar.buffer = keyBytes[len(p):]
keyBytes = keyBytes[:len(p)]
} else if len(keyBytes) == 0 {
return 0, nil
}
copiedLength := copy(p, keyBytes)
if copiedLength != len(keyBytes) {
return 0, errors.New("unexpected copy length encountered")
}
return copiedLength, nil
}
// readInputEvents polls until at least one event is available.
func readInputEvents(ar *ansiReader, maxBytes int) ([]winterm.INPUT_RECORD, error) {
// Determine the maximum number of records to retrieve
// -- Cast around the type system to obtain the size of a single INPUT_RECORD.
// unsafe.Sizeof requires an expression vs. a type-reference; the casting
// tricks the type system into believing it has such an expression.
recordSize := int(unsafe.Sizeof(*((*winterm.INPUT_RECORD)(unsafe.Pointer(&maxBytes)))))
countRecords := maxBytes / recordSize
if countRecords > ansiterm.MAX_INPUT_EVENTS {
countRecords = ansiterm.MAX_INPUT_EVENTS
} else if countRecords == 0 {
countRecords = 1
}
// Wait for and read input events
events := make([]winterm.INPUT_RECORD, countRecords)
nEvents := uint32(0)
eventsExist, err := winterm.WaitForSingleObject(ar.fd, winterm.WAIT_INFINITE)
if err != nil {
return nil, err
}
if eventsExist {
err = winterm.ReadConsoleInput(ar.fd, events, &nEvents)
if err != nil {
return nil, err
}
}
// Return a slice restricted to the number of returned records
return events[:nEvents], nil
}
// KeyEvent Translation Helpers
var arrowKeyMapPrefix = map[uint16]string{
winterm.VK_UP: "%s%sA",
winterm.VK_DOWN: "%s%sB",
winterm.VK_RIGHT: "%s%sC",
winterm.VK_LEFT: "%s%sD",
}
var keyMapPrefix = map[uint16]string{
winterm.VK_UP: "\x1B[%sA",
winterm.VK_DOWN: "\x1B[%sB",
winterm.VK_RIGHT: "\x1B[%sC",
winterm.VK_LEFT: "\x1B[%sD",
winterm.VK_HOME: "\x1B[1%s~", // showkey shows ^[[1
winterm.VK_END: "\x1B[4%s~", // showkey shows ^[[4
winterm.VK_INSERT: "\x1B[2%s~",
winterm.VK_DELETE: "\x1B[3%s~",
winterm.VK_PRIOR: "\x1B[5%s~",
winterm.VK_NEXT: "\x1B[6%s~",
winterm.VK_F1: "",
winterm.VK_F2: "",
winterm.VK_F3: "\x1B[13%s~",
winterm.VK_F4: "\x1B[14%s~",
winterm.VK_F5: "\x1B[15%s~",
winterm.VK_F6: "\x1B[17%s~",
winterm.VK_F7: "\x1B[18%s~",
winterm.VK_F8: "\x1B[19%s~",
winterm.VK_F9: "\x1B[20%s~",
winterm.VK_F10: "\x1B[21%s~",
winterm.VK_F11: "\x1B[23%s~",
winterm.VK_F12: "\x1B[24%s~",
}
// translateKeyEvents converts the input events into the appropriate ANSI string.
func translateKeyEvents(events []winterm.INPUT_RECORD, escapeSequence []byte) []byte {
var buffer bytes.Buffer
for _, event := range events {
if event.EventType == winterm.KEY_EVENT && event.KeyEvent.KeyDown != 0 {
buffer.WriteString(keyToString(&event.KeyEvent, escapeSequence))
}
}
return buffer.Bytes()
}
// keyToString maps the given input event record to the corresponding string.
func keyToString(keyEvent *winterm.KEY_EVENT_RECORD, escapeSequence []byte) string {
if keyEvent.UnicodeChar == 0 {
return formatVirtualKey(keyEvent.VirtualKeyCode, keyEvent.ControlKeyState, escapeSequence)
}
_, alt, control := getControlKeys(keyEvent.ControlKeyState)
if control {
// TODO(azlinux): Implement following control sequences
// <Ctrl>-D Signals the end of input from the keyboard; also exits current shell.
// <Ctrl>-H Deletes the first character to the left of the cursor. Also called the ERASE key.
// <Ctrl>-Q Restarts printing after it has been stopped with <Ctrl>-s.
// <Ctrl>-S Suspends printing on the screen (does not stop the program).
// <Ctrl>-U Deletes all characters on the current line. Also called the KILL key.
// <Ctrl>-E Quits current command and creates a core
}
// <Alt>+Key generates ESC N Key
if !control && alt {
return ansiterm.KEY_ESC_N + strings.ToLower(string(keyEvent.UnicodeChar))
}
return string(keyEvent.UnicodeChar)
}
// formatVirtualKey converts a virtual key (e.g., up arrow) into the appropriate ANSI string.
func formatVirtualKey(key uint16, controlState uint32, escapeSequence []byte) string {
shift, alt, control := getControlKeys(controlState)
modifier := getControlKeysModifier(shift, alt, control)
if format, ok := arrowKeyMapPrefix[key]; ok {
return fmt.Sprintf(format, escapeSequence, modifier)
}
if format, ok := keyMapPrefix[key]; ok {
return fmt.Sprintf(format, modifier)
}
return ""
}
// getControlKeys extracts the shift, alt, and ctrl key states.
func getControlKeys(controlState uint32) (shift, alt, control bool) {
shift = 0 != (controlState & winterm.SHIFT_PRESSED)
alt = 0 != (controlState & (winterm.LEFT_ALT_PRESSED | winterm.RIGHT_ALT_PRESSED))
control = 0 != (controlState & (winterm.LEFT_CTRL_PRESSED | winterm.RIGHT_CTRL_PRESSED))
return shift, alt, control
}
// getControlKeysModifier returns the ANSI modifier for the given combination of control keys.
func getControlKeysModifier(shift, alt, control bool) string {
if shift && alt && control {
return ansiterm.KEY_CONTROL_PARAM_8
}
if alt && control {
return ansiterm.KEY_CONTROL_PARAM_7
}
if shift && control {
return ansiterm.KEY_CONTROL_PARAM_6
}
if control {
return ansiterm.KEY_CONTROL_PARAM_5
}
if shift && alt {
return ansiterm.KEY_CONTROL_PARAM_4
}
if alt {
return ansiterm.KEY_CONTROL_PARAM_3
}
if shift {
return ansiterm.KEY_CONTROL_PARAM_2
}
return ""
}
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