support $INPUT_REMAP_FILE

src/device/input/input.go

@@ -12,7 +12,7 @@ type Input interface {
 
 func New(ctx context.Context) Input {
 	foo := randomCharFromRange('a', 'g')
-	if p, ok := os.LookupEnv("INPUT_RANDOM_WEIGHT_FILE"); ok {
+	if p, ok := os.LookupEnv("INPUT_RANDOM_WEIGHT_FILE"); ok && len(p) > 0 {
 		foo = randomCharFromWeightFile(p)
 	}
 	var result Input = NewRandom(foo)
@@ -22,5 +22,8 @@ func New(ctx context.Context) Input {
 	if os.Getenv("INPUT_BUFFERED") == "true" {
 		result = NewBuffered(ctx, result)
 	}
+	if p, ok := os.LookupEnv("INPUT_REMAP_FILE"); ok && len(p) > 0 {
+		result = NewRemapFromFile(result, p)
+	}
 	return result
 }

src/device/input/input_exported_test.go

@@ -18,6 +18,37 @@ func TestNew(t *testing.T) {
 	}
 }
 
+func TestNewRemapped(t *testing.T) {
+	d := t.TempDir()
+	remap := path.Join(d, "remap")
+	if err := os.WriteFile(remap, []byte(`{"a":"b"}`), os.ModePerm); err != nil {
+		t.Fatal(err)
+	}
+
+	rand := path.Join(d, "rand")
+	if err := os.WriteFile(rand, []byte(`{"a":1}`), os.ModePerm); err != nil {
+		t.Fatal(err)
+	}
+
+	os.Setenv("INPUT_REMAP_FILE", remap)
+	os.Setenv("INPUT_RANDOM_WEIGHT_FILE", rand)
+	t.Cleanup(func() {
+		os.Unsetenv("INPUT_REMAP_FILE")
+		os.Unsetenv("INPUT_RANDOM_WEIGHT_FILE")
+	})
+
+	r := input.New(context.Background())
+	for i := 0; i < 15; i++ {
+		batch := r.Read()
+		for j := range batch {
+			if batch[j].Char != 'b' {
+				t.Errorf("%c", batch[j].Char)
+			}
+			t.Logf("[%d][%d] %c|%v", i, j, batch[j].Char, batch[j].Down)
+		}
+	}
+}
+
 func TestNewBuffered(t *testing.T) {
 	os.Setenv("INPUT_BUFFERED", "true")
 	t.Cleanup(func() {

src/device/input/input_test.go

@@ -6,4 +6,5 @@ func TestInput(t *testing.T) {
 	var _ Input = &Random{}
 	var _ Input = Keyboard{}
 	var _ Input = &Buffered{}
+	var _ Input = Remap{}
 }

src/device/input/remap.go

@@ -0,0 +1,52 @@
+package input
+
+import (
+	"os"
+
+	"github.com/go-yaml/yaml"
+)
+
+type Remap struct {
+	input Input
+	m     map[byte]byte
+}
+
+func NewRemapFromFile(input Input, p string) Remap {
+	b, err := os.ReadFile(p)
+	if err != nil {
+		panic(err)
+	}
+	var m map[string]string
+	if err := yaml.Unmarshal(b, &m); err != nil {
+		panic(err)
+	}
+	remap := map[byte]byte{}
+	for k, v := range m {
+		if len(k) != 1 || len(v) != 1 {
+			panic("remap must be char:char")
+		}
+		remap[k[0]] = v[0]
+	}
+	return NewRemap(input, remap)
+}
+
+func NewRemap(input Input, m map[byte]byte) Remap {
+	return Remap{
+		input: input,
+		m:     m,
+	}
+}
+
+func (re Remap) Close() {
+	re.input.Close()
+}
+
+func (re Remap) Read() []Button {
+	result := re.input.Read()
+	for i := range result {
+		if v, ok := re.m[result[i].Char]; ok {
+			result[i].Char = v
+		}
+	}
+	return result
+}