refactor(distribution)!: use collections for ValidatorHistoricalRewards state (#16607)

Co-authored-by: unknown unknown <unknown@unknown>

types/collections.go

@@ -1,6 +1,7 @@
 package types
 
 import (
+	"encoding/binary"
 	"fmt"
 	"time"
 
@@ -37,6 +38,12 @@ var (
 	// be used for new storage keys using time. Please use the time KeyCodec
 	// provided in the collections package.
 	TimeKey collcodec.KeyCodec[time.Time] = timeKeyCodec{}
+
+	// LEUint64Key is a collections KeyCodec that encodes uint64 using little endian.
+	// NOTE: it MUST NOT be used by other modules, distribution relies on this only for
+	// state backwards compatibility.
+	// Deprecated: use collections.Uint64Key instead.
+	LEUint64Key collcodec.KeyCodec[uint64] = leUint64Key{}
 )
 
 type addressUnion interface {
@@ -208,3 +215,37 @@ func (t timeKeyCodec) DecodeNonTerminal(buffer []byte) (int, time.Time, error) {
 	return t.Decode(buffer[:timeSize])
 }
 func (t timeKeyCodec) SizeNonTerminal(key time.Time) int { return t.Size(key) }
+
+type leUint64Key struct{}
+
+func (l leUint64Key) Encode(buffer []byte, key uint64) (int, error) {
+	binary.LittleEndian.PutUint64(buffer, key)
+	return 8, nil
+}
+
+func (l leUint64Key) Decode(buffer []byte) (int, uint64, error) {
+	if size := len(buffer); size < 8 {
+		return 0, 0, fmt.Errorf("invalid buffer size, wanted 8 at least got %d", size)
+	}
+	return 8, binary.LittleEndian.Uint64(buffer), nil
+}
+
+func (l leUint64Key) Size(_ uint64) int { return 8 }
+
+func (l leUint64Key) EncodeJSON(value uint64) ([]byte, error) {
+	return collections.Uint64Key.EncodeJSON(value)
+}
+
+func (l leUint64Key) DecodeJSON(b []byte) (uint64, error) { return collections.Uint64Key.DecodeJSON(b) }
+
+func (l leUint64Key) Stringify(key uint64) string { return collections.Uint64Key.Stringify(key) }
+
+func (l leUint64Key) KeyType() string { return "little-endian-uint64" }
+
+func (l leUint64Key) EncodeNonTerminal(buffer []byte, key uint64) (int, error) {
+	return l.Encode(buffer, key)
+}
+
+func (l leUint64Key) DecodeNonTerminal(buffer []byte) (int, uint64, error) { return l.Decode(buffer) }
+
+func (l leUint64Key) SizeNonTerminal(_ uint64) int { return 8 }

types/collections_test.go

@@ -5,6 +5,8 @@ import (
 	"time"
 
 	"cosmossdk.io/collections/colltest"
+	"github.com/stretchr/testify/require"
+	"pgregory.net/rapid"
 )
 
 func TestCollectionsCorrectness(t *testing.T) {
@@ -28,3 +30,14 @@ func TestCollectionsCorrectness(t *testing.T) {
 		colltest.TestKeyCodec(t, TimeKey, time.Time{})
 	})
 }
+
+func TestLEUint64Key(t *testing.T) {
+	t.Run("conformance", rapid.MakeCheck(func(r *rapid.T) {
+		colltest.TestKeyCodec(t, LEUint64Key, rapid.Uint64().Draw(r, "uint64"))
+	}))
+
+	t.Run("buffer too small", func(t *testing.T) {
+		_, _, err := LEUint64Key.Decode([]byte{0})
+		require.ErrorContains(t, err, "invalid buffer size")
+	})
+}