attachment_echo.go RawHistoryFolder

1package client
2
3import (
4	"fmt"
5	"time"
6
7	"github.com/bnema/vev/internal/domain"
8	"github.com/bnema/vev/internal/ports"
9	"github.com/bnema/vev/internal/protocol"
10)
11
12// echoTickInterval re-culls pending guesses while a timing trigger may still
13// fire without output, as mosh's PredictionEngine::wait_time.
14const echoTickInterval = 50 * time.Millisecond
15
16// attachmentEcho connects the prediction engine to one attached loop: it feeds
17// sent input and applied output to the engine and writes the guesses through
18// the foreground. It is nil when the attachment does not predict (local
19// attachments, scripted foregrounds, echo.predict = never), and every method
20// is a no-op on nil.
21type attachmentEcho struct {
22	predictor *echoPredictor
23	out       attachmentPredictionForeground
24	clock     ports.Clock
25	tick      ports.Timer
26}
27
28func newAttachmentEcho(w *sessionAttachmentWorker, fg AttachmentForeground) *attachmentEcho {
29	if w.cfg.Request.Local || w.cfg.EchoPredict == domain.EchoPredictNever {
30		return nil
31	}
32	out, ok := fg.(attachmentPredictionForeground)
33	if !ok {
34		return nil
35	}
36	return &attachmentEcho{predictor: newEchoPredictor(w.cfg.EchoPredict), out: out, clock: w.cfg.Clock}
37}
38
39// seed mirrors output written before the loop started (the initial frame).
40func (e *attachmentEcho) seed(output protocol.Output) {
41	if e == nil {
42		return
43	}
44	e.predictor.applyOutput(output, e.clock.Now())
45}
46
47// input records one session Input sent with seq.
48func (e *attachmentEcho) input(seq uint64, data []byte) error {
49	if e == nil {
50		return nil
51	}
52	e.predictor.input(seq, data, e.clock.Now())
53	return e.draw()
54}
55
56// output mirrors one Output after the foreground wrote it.
57func (e *attachmentEcho) output(output protocol.Output) error {
58	if e == nil {
59		return nil
60	}
61	e.predictor.applyOutput(output, e.clock.Now())
62	return e.draw()
63}
64
65// resized handles a terminal resize. A new size makes the daemon repaint
66// everything, so the guesses are simply forgotten. The same size brings no
67// repaint, so drawn guesses are erased from the mirror instead.
68func (e *attachmentEcho) resized(size domain.Size) error {
69	if e == nil {
70		return nil
71	}
72	screen := e.predictor.screen
73	if size.Cols != screen.Columns() || size.Rows != screen.Rows() {
74		e.predictor.forget()
75		return nil
76	}
77	e.predictor.reset()
78	return e.draw()
79}
80
81// tickC fires while a pending guess waits on a timing trigger.
82func (e *attachmentEcho) tickC() <-chan time.Time {
83	if e == nil || e.tick == nil {
84		return nil
85	}
86	return e.tick.C()
87}
88
89func (e *attachmentEcho) ticked() error {
90	if e == nil {
91		return nil
92	}
93	e.tick = nil
94	e.predictor.cull(e.clock.Now())
95	return e.draw()
96}
97
98func (e *attachmentEcho) close() {
99	if e != nil && e.tick != nil {
100		e.tick.Stop()
101		e.tick = nil
102	}
103}
104
105func (e *attachmentEcho) draw() error {
106	defer e.armTick()
107	data := e.predictor.render()
108	if len(data) == 0 {
109		return nil
110	}
111	written, err := e.out.writePrediction(data)
112	if err != nil {
113		return fmt.Errorf("writing predicted echo: %w", err)
114	}
115	if !written {
116		// An overlay owns the terminal: its box covers the guesses and the
117		// daemon repaints everything once it closes.
118		e.predictor.forget()
119	}
120	return nil
121}
122
123func (e *attachmentEcho) armTick() {
124	if e.tick != nil || !e.predictor.needsTick() {
125		return
126	}
127	e.tick = e.clock.NewTimer(echoTickInterval)
128}