termcap.go

package tea

import (
	"bytes"
	"encoding/hex"
	"strings"
)

// requestCapabilityMsg is an internal message that requests the terminal to
// send its Termcap/Terminfo response.
type requestCapabilityMsg string

// RequestCapability is a command that requests the terminal to send its
// Termcap/Terminfo response for the given capability.
func RequestCapability(s string) Cmd {
	return func() Msg {
		return requestCapabilityMsg(s)
	}
}

// CapabilityMsg represents a Termcap/Terminfo response event. Termcap
// responses are generated by the terminal in response to RequestTermcap
// (XTGETTCAP) requests.
//
// See: https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Operating-System-Commands
type CapabilityMsg string

func parseTermcap(data []byte) CapabilityMsg {
	// XTGETTCAP
	if len(data) == 0 {
		return CapabilityMsg("")
	}

	var tc strings.Builder
	split := bytes.Split(data, []byte{';'})
	for _, s := range split {
		parts := bytes.SplitN(s, []byte{'='}, 2)
		if len(parts) == 0 {
			return CapabilityMsg("")
		}

		name, err := hex.DecodeString(string(parts[0]))
		if err != nil || len(name) == 0 {
			continue
		}

		var value []byte
		if len(parts) > 1 {
			value, err = hex.DecodeString(string(parts[1]))
			if err != nil {
				continue
			}
		}

		if tc.Len() > 0 {
			tc.WriteByte(';')
		}
		tc.WriteString(string(name))
		if len(value) > 0 {
			tc.WriteByte('=')
			tc.WriteString(string(value))
		}
	}

	return CapabilityMsg(tc.String())
}