feat(collections): add a time.Time key codec

collections/codec/correctness_test.go

@@ -2,6 +2,7 @@ package codec_test
 
 import (
 	"testing"
+	"time"
 
 	"cosmossdk.io/collections"
 	"cosmossdk.io/collections/colltest"
@@ -48,4 +49,7 @@ func TestKeyCorrectness(t *testing.T) {
 			collections.Join("hello", "testing"),
 		)
 	})
+	t.Run("time.Time", func(t *testing.T) {
+		colltest.TestKeyCodec(t, collections.TimeKey, time.UnixMilli(time.Now().UnixMilli()).UTC())
+	})
 }

collections/codec/time.go

@@ -0,0 +1,54 @@
+package codec
+
+import (
+	"encoding/binary"
+	"fmt"
+	"time"
+)
+
+var timeSize = 8
+
+type timeKey struct{}
+
+func NewTimeKey() KeyCodec[time.Time] { return timeKey{} }
+
+func (t timeKey) Encode(buffer []byte, key time.Time) (int, error) {
+	if len(buffer) < timeSize {
+		return 0, fmt.Errorf("buffer too small, required at least 8 bytes")
+	}
+	millis := key.UTC().UnixNano() / int64(time.Millisecond)
+	binary.BigEndian.PutUint64(buffer, uint64(millis))
+	return timeSize, nil
+}
+
+func (t timeKey) Decode(buffer []byte) (int, time.Time, error) {
+	if len(buffer) != timeSize {
+		return 0, time.Time{}, fmt.Errorf("invalid time buffer buffer size")
+	}
+	millis := int64(binary.BigEndian.Uint64(buffer))
+	return timeSize, time.UnixMilli(millis).UTC(), nil
+}
+
+func (t timeKey) Size(_ time.Time) int { return timeSize }
+
+func (t timeKey) EncodeJSON(value time.Time) ([]byte, error) { return value.MarshalJSON() }
+
+func (t timeKey) DecodeJSON(b []byte) (time.Time, error) {
+	time := time.Time{}
+	err := time.UnmarshalJSON(b)
+	return time, err
+}
+
+func (t timeKey) Stringify(key time.Time) string { return key.String() }
+func (t timeKey) KeyType() string                { return "sdk/time.Time" }
+func (t timeKey) EncodeNonTerminal(buffer []byte, key time.Time) (int, error) {
+	return t.Encode(buffer, key)
+}
+
+func (t timeKey) DecodeNonTerminal(buffer []byte) (int, time.Time, error) {
+	if len(buffer) < timeSize {
+		return 0, time.Time{}, fmt.Errorf("invalid time buffer size, wanted: %d at least, got: %d", timeSize, len(buffer))
+	}
+	return t.Decode(buffer[:timeSize])
+}
+func (t timeKey) SizeNonTerminal(key time.Time) int { return t.Size(key) }

collections/collections.go

@@ -2,11 +2,10 @@ package collections
 
 import (
 	"context"
+	"cosmossdk.io/collections/codec"
 	"errors"
 	io "io"
 	"math"
-
-	"cosmossdk.io/collections/codec"
 )
 
 var (
@@ -51,6 +50,8 @@ var (
 	// BoolKey can be used to encode booleans. It uses a single byte to represent the boolean.
 	// 0x0 is used to represent false, and 0x1 is used to represent true.
 	BoolKey = codec.NewBoolKey[bool]()
+	// TimeKey can be used to encode time.Time keys. The encoding is done using the UnixMilli
+	TimeKey = codec.NewTimeKey()
 )
 
 // VALUES
@@ -72,6 +73,8 @@ var (
 	StringValue = codec.KeyToValueCodec(StringKey)
 	// BytesValue implements a ValueCodec for bytes.
 	BytesValue = codec.KeyToValueCodec(BytesKey)
+	// TimeValue implements a ValueCodec for time.Time.
+	TimeValue = codec.KeyToValueCodec(TimeKey)
 )
 
 // Collection is the interface that all collections implement. It will eventually