1package lipgloss
  2
  3import (
  4	"fmt"
  5	"image/color"
  6	"io"
  7	"strings"
  8	"time"
  9
 10	"github.com/charmbracelet/x/ansi"
 11	"github.com/muesli/cancelreader"
 12)
 13
 14// queryBackgroundColor queries the terminal for the background color.
 15// If the terminal does not support querying the background color, nil is
 16// returned.
 17//
 18// Note: you will need to set the input to raw mode before calling this
 19// function.
 20//
 21//	state, _ := term.MakeRaw(in.Fd())
 22//	defer term.Restore(in.Fd(), state)
 23//
 24// copied from x/term@v0.1.3.
 25func queryBackgroundColor(in io.Reader, out io.Writer) (c color.Color, err error) {
 26	err = queryTerminal(in, out, defaultQueryTimeout,
 27		func(seq string, pa *ansi.Parser) bool {
 28			switch {
 29			case ansi.HasOscPrefix(seq):
 30				switch pa.Command() {
 31				case 11: // OSC 11
 32					parts := strings.Split(string(pa.Data()), ";")
 33					if len(parts) != 2 {
 34						break // invalid, but we still need to parse the next sequence
 35					}
 36					c = ansi.XParseColor(parts[1])
 37				}
 38			case ansi.HasCsiPrefix(seq):
 39				switch pa.Command() {
 40				case ansi.Command('?', 0, 'c'): // DA1
 41					return false
 42				}
 43			}
 44			return true
 45		}, ansi.RequestBackgroundColor+ansi.RequestPrimaryDeviceAttributes)
 46	return
 47}
 48
 49const defaultQueryTimeout = time.Second * 2
 50
 51// queryTerminalFilter is a function that filters input events using a type
 52// switch. If false is returned, the QueryTerminal function will stop reading
 53// input.
 54type queryTerminalFilter func(seq string, pa *ansi.Parser) bool
 55
 56// queryTerminal queries the terminal for support of various features and
 57// returns a list of response events.
 58// Most of the time, you will need to set stdin to raw mode before calling this
 59// function.
 60// Note: This function will block until the terminal responds or the timeout
 61// is reached.
 62// copied from x/term@v0.1.3.
 63func queryTerminal(
 64	in io.Reader,
 65	out io.Writer,
 66	timeout time.Duration,
 67	filter queryTerminalFilter,
 68	query string,
 69) error {
 70	rd, err := cancelreader.NewReader(in)
 71	if err != nil {
 72		return fmt.Errorf("could not create cancel reader: %w", err)
 73	}
 74
 75	defer rd.Close() //nolint: errcheck
 76
 77	done := make(chan struct{}, 1)
 78	defer close(done)
 79	go func() {
 80		select {
 81		case <-done:
 82		case <-time.After(timeout):
 83			rd.Cancel()
 84		}
 85	}()
 86
 87	if _, err := io.WriteString(out, query); err != nil {
 88		return fmt.Errorf("could not write query: %w", err)
 89	}
 90
 91	pa := ansi.GetParser()
 92	defer ansi.PutParser(pa)
 93
 94	var buf [256]byte // 256 bytes should be enough for most responses
 95	for {
 96		n, err := rd.Read(buf[:])
 97		if err != nil {
 98			return fmt.Errorf("could not read from input: %w", err)
 99		}
100
101		var state byte
102		p := buf[:]
103		for n > 0 {
104			seq, _, read, newState := ansi.DecodeSequence(p[:n], state, pa)
105			if !filter(string(seq), pa) {
106				return nil
107			}
108
109			state = newState
110			n -= read
111			p = p[read:]
112		}
113	}
114}