terminal_probe.go RawHistoryFolder

1package client
2
3import (
4	"context"
5	"time"
6
7	"github.com/bnema/vev-vt/protocol/terminalquery"
8
9	"github.com/bnema/vev/internal/ports"
10)
11
12// terminalCapabilityProbeTimeout bounds the outer-terminal capability probe.
13// DA1 answers first on any terminal, so a real terminal finishes far sooner.
14const terminalCapabilityProbeTimeout = 150 * time.Millisecond
15
16// terminalCapabilities is what the outer terminal declared to the probe.
17type terminalCapabilities struct {
18	KittyGraphics bool
19	KittyKeyboard bool
20}
21
22// probeTerminalCapabilities performs one bounded probe of the outer terminal
23// through the lifecycle's only input pump. It must run before any other
24// consumer claims input. Probe responses are removed; every unrelated byte is
25// kept, in order, for the next consumer.
26func probeTerminalCapabilities(ctx context.Context, terminal ports.Terminal, clock ports.Clock, input *terminalInputPump) terminalCapabilities {
27	if input == nil || supervisorNil(terminal) || supervisorNil(clock) {
28		return terminalCapabilities{}
29	}
30	consumer, ok := input.tryClaim()
31	if !ok {
32		return terminalCapabilities{}
33	}
34	defer input.revoke(consumer)
35
36	query := terminalquery.KittyGraphicsQuery + terminalquery.KittyKeyboardQuery + terminalquery.DeviceAttributesQuery
37	if _, err := terminal.Out().Write([]byte(query)); err != nil {
38		return terminalCapabilities{}
39	}
40	if err := terminal.Flush(); err != nil {
41		return terminalCapabilities{}
42	}
43
44	probe := &terminalquery.Probe{}
45	var replay []byte
46	timer := clock.NewTimer(terminalCapabilityProbeTimeout)
47	defer timer.Stop()
48	// DA1 is the FIFO sentinel: once it arrives, the answers to the earlier
49	// queries are definitive.
50wait:
51	for !probe.DA1() {
52		select {
53		case <-ctx.Done():
54			break wait
55		case <-timer.C():
56			break wait
57		case <-input.readyFor(consumer):
58			result, ok := input.take(ctx, consumer)
59			if !ok {
60				if ctx.Err() != nil {
61					break wait
62				}
63				continue
64			}
65			replay = append(replay, probe.Feed(result.data)...)
66			input.ack(consumer)
67			if result.err != nil {
68				break wait
69			}
70		}
71	}
72	replay = append(replay, probe.Finish()...)
73	// Preserve before revoke so the next consumer reads these bytes before any
74	// later terminal read.
75	input.preserveResidual(consumer, replay)
76	if !probe.DA1() {
77		return terminalCapabilities{}
78	}
79	return terminalCapabilities{KittyGraphics: probe.KittyGraphics(), KittyKeyboard: probe.KittyKeyboard()}
80}