split src/devices/input into src/devices/input/{raw,wrap}

src/device/input/wrap/buffered.go

@@ -0,0 +1,101 @@
+package wrap
+
+import (
+	"context"
+	"os"
+	"sync"
+	"time"
+)
+
+type Buffered struct {
+	ctx                context.Context
+	can                context.CancelFunc
+	lock               sync.Mutex
+	keys               map[byte]int64
+	input              Wrap
+	listenInterval     time.Duration
+	expirationInterval time.Duration
+}
+
+func NewBuffered(ctx context.Context, input Wrap) *Buffered {
+	ctx, can := context.WithCancel(ctx)
+	expirationInterval := time.Millisecond * 125
+	if d, err := time.ParseDuration(os.Getenv("WRAP_BUFFERED_STICKY_DURATION")); err == nil {
+		expirationInterval = d
+	}
+	result := &Buffered{
+		input:              input,
+		ctx:                ctx,
+		can:                can,
+		lock:               sync.Mutex{},
+		keys:               map[byte]int64{},
+		listenInterval:     time.Millisecond * 10,
+		expirationInterval: expirationInterval,
+	}
+	go result.listen()
+	return result
+}
+
+func (b *Buffered) listen() {
+	for b.ctx.Err() == nil {
+		buttons := b.input.Read()
+
+		b.lock.Lock()
+		for i := range buttons {
+			if buttons[i].Down {
+				b.keys[buttons[i].Char] = time.Now().UnixNano()
+			} else {
+				b.keys[buttons[i].Char] = 0
+			}
+		}
+		b.lock.Unlock()
+		select {
+		case <-b.ctx.Done():
+		case <-time.After(b.listenInterval):
+		}
+	}
+}
+
+func (b *Buffered) Close() {
+	b.input.Close()
+	b.can()
+}
+
+func (b *Buffered) Read() []Button {
+	for b.ctx.Err() == nil {
+		result := b.read()
+		if len(result) > 0 {
+			return result
+		}
+		select {
+		case <-b.ctx.Done():
+		case <-time.After(b.listenInterval):
+		}
+	}
+	return []Button{}
+}
+
+func (b *Buffered) read() []Button {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	result := make([]Button, 0, len(b.keys))
+	for k, v := range b.keys {
+		isFresh := v > 0
+		isStale := v < 0 && time.Since(time.Unix(0, -1*v)) > b.expirationInterval
+		if isFresh || isStale {
+			result = append(result, Button{Char: k, Down: isFresh})
+		}
+		if isFresh {
+			b.keys[k] = -1 * v
+		}
+	}
+
+	for i := range result {
+		if !result[i].Down {
+			delete(b.keys, result[i].Char)
+		}
+	}
+
+	return result
+}