Add DowngradeLevelChunkPacket

legacyver/all.go

@@ -1,7 +1,20 @@
 package legacyver
 
 import (
+	"fmt"
+	"sync"
+
+	"github.com/akmalfairuz/legacy-version/internal/chunk"
+	"github.com/akmalfairuz/legacy-version/mapping"
 	"github.com/sandertv/gophertunnel/minecraft"
+	"github.com/sandertv/gophertunnel/minecraft/protocol/packet"
+)
+
+var (
+	EnableChunkTranslation = true
+
+	blockTranslatorsMu sync.RWMutex
+	blockTranslators   map[int32]BlockTranslator
 )
 
 // All returns a slice of all legacy protocol versions that are supported. dragonflyMapping
@@ -24,3 +37,37 @@ func All(dragonflyMapping bool) []minecraft.Protocol {
 		New649(dragonflyMapping),
 	}
 }
+
+// lookupOrCreateBlockTranslator looks up a block translator for the given protocol version.
+func lookupOrCreateBlockTranslator(protocolVersion, blockVersion int32, blockStateData []byte) BlockTranslator {
+	blockTranslatorsMu.RLock()
+	if translator, ok := blockTranslators[protocolVersion]; ok {
+		blockTranslatorsMu.RUnlock()
+		return translator
+	}
+	blockTranslatorsMu.RUnlock()
+
+	blockTranslatorsMu.Lock()
+	defer blockTranslatorsMu.Unlock()
+
+	if translator, ok := blockTranslators[protocolVersion]; ok {
+		return translator
+	}
+
+	blockMapping := mapping.NewBlockMapping(blockStateData)
+	ret := NewBlockTranslator(blockMapping, blockMappingLatest, chunk.NewNetworkPersistentEncoding(blockMapping, blockVersion), chunk.NewBlockPaletteEncoding(blockMapping, blockVersion), false)
+	blockTranslators[protocolVersion] = ret
+	return ret
+}
+
+// DowngradeLevelChunkPacket downgrades the given level chunk packet to the specified protocol version.
+func DowngradeLevelChunkPacket(protocolVersion int32, pk *packet.LevelChunk) error {
+	blockTranslatorsMu.RLock()
+	translator, ok := blockTranslators[protocolVersion]
+	blockTranslatorsMu.RUnlock()
+	if !ok {
+		return fmt.Errorf("no block translator found for protocol version %d", protocolVersion)
+	}
+
+	return translator.DowngradeLevelChunk(pk)
+}