From 10c3b8771eae2432025495e9ad0ab33d5b5c54f4 Mon Sep 17 00:00:00 2001
From: Tnze <cjd001113@outlook.com>
Date: Sun, 19 Dec 2021 09:53:45 +0800
Subject: [PATCH] SingleValuePalette

---
 save/bitstorage.go      |  4 +-
 save/bitstorage_test.go |  2 +-
 save/palette.go         | 98 ++++++++++++++++++++++++++++++++++-------
 server/dimension.go     |  2 +-
 4 files changed, 87 insertions(+), 19 deletions(-)

diff --git a/save/bitstorage.go b/save/bitstorage.go
index 4622d95..4d7a54b 100644
--- a/save/bitstorage.go
+++ b/save/bitstorage.go
@@ -123,8 +123,8 @@ func (b *BitStorage) Len() int {
 	return b.length
 }
 
-// Longs return the underling array of uint64 for encoding/decoding.
-func (b *BitStorage) Longs() []uint64 {
+// Raw return the underling array of uint64 for encoding/decoding.
+func (b *BitStorage) Raw() []uint64 {
 	if b == nil {
 		return []uint64{}
 	}
diff --git a/save/bitstorage_test.go b/save/bitstorage_test.go
index ab1bd93..8896da5 100644
--- a/save/bitstorage_test.go
+++ b/save/bitstorage_test.go
@@ -42,5 +42,5 @@ func ExampleNewBitStorage_heightmaps() {
 	type HeightMaps struct {
 		MotionBlocking []uint64 `nbt:"MOTION_BLOCKING"`
 	}
-	_ = pk.NBT(HeightMaps{bs.Longs()})
+	_ = pk.NBT(HeightMaps{bs.Raw()})
 }
diff --git a/save/palette.go b/save/palette.go
index 6bf90f4..52adb0e 100644
--- a/save/palette.go
+++ b/save/palette.go
@@ -2,6 +2,7 @@ package save
 
 import (
 	"io"
+	"strconv"
 
 	pk "github.com/Tnze/go-mc/net/packet"
 )
@@ -10,7 +11,8 @@ type BlockState interface {
 }
 
 type PaletteContainer struct {
-	maps blockMaps
+	maps   blockMaps
+	config func(p *PaletteContainer, bits byte)
 	palette
 	BitStorage
 }
@@ -21,20 +23,7 @@ func (p *PaletteContainer) ReadFrom(r io.Reader) (n int64, err error) {
 	if err != nil {
 		return
 	}
-	switch bits {
-	case 0:
-		// TODO: SingleValuePalette
-	case 1, 2, 3, 4:
-		p.palette = &linearPalette{
-			onResize: nil,
-			maps:     p.maps,
-			bits:     4,
-		}
-	case 5, 6, 7, 8:
-		// TODO: HashMapPalette
-	default:
-		// TODO: GlobalPalette
-	}
+	p.config(p, byte(bits))
 
 	nn, err := p.palette.ReadFrom(r)
 	n += nn
@@ -50,6 +39,46 @@ func (p *PaletteContainer) ReadFrom(r io.Reader) (n int64, err error) {
 	return n, nil
 }
 
+func createStatesPalette(p *PaletteContainer, bits byte) {
+	switch bits {
+	case 0:
+		p.palette = &singleValuePalette{
+			onResize: nil,
+			maps:     p.maps,
+			v:        nil,
+		}
+	case 1, 2, 3, 4:
+		p.palette = &linearPalette{
+			onResize: nil,
+			maps:     p.maps,
+			bits:     4,
+		}
+	case 5, 6, 7, 8:
+		// TODO: HashMapPalette
+	default:
+		// TODO: GlobalPalette
+	}
+}
+
+func createBiomesPalette(p *PaletteContainer, bits byte) {
+	switch bits {
+	case 0:
+		p.palette = &singleValuePalette{
+			onResize: nil,
+			maps:     p.maps,
+			v:        nil,
+		}
+	case 1, 2, 3:
+		p.palette = &linearPalette{
+			onResize: nil,
+			maps:     p.maps,
+			bits:     4,
+		}
+	default:
+		// TODO: GlobalPalette
+	}
+}
+
 func (p *PaletteContainer) WriteTo(w io.Writer) (n int64, err error) {
 	return pk.Tuple{
 		pk.UnsignedByte(p.bits),
@@ -70,6 +99,45 @@ type blockMaps interface {
 	getValue(id int) (state BlockState)
 }
 
+type singleValuePalette struct {
+	onResize func(n int, v BlockState) int
+	maps     blockMaps
+	v        BlockState
+}
+
+func (s *singleValuePalette) id(v BlockState) int {
+	if s.v == nil {
+		s.v = v
+		return 0
+	}
+	if s.v == v {
+		return 0
+	}
+	// We have 2 values now. At least 1 bit is required.
+	return s.onResize(1, v)
+}
+
+func (s *singleValuePalette) value(i int) BlockState {
+	if s.v != nil && i == 0 {
+		return s.v
+	}
+	panic("singleValuePalette: " + strconv.Itoa(i) + " out of bounds")
+}
+
+func (s *singleValuePalette) ReadFrom(r io.Reader) (n int64, err error) {
+	var i pk.VarInt
+	n, err = i.ReadFrom(r)
+	if err != nil {
+		return
+	}
+	s.v = s.maps.getValue(int(i))
+	return
+}
+
+func (s *singleValuePalette) WriteTo(w io.Writer) (n int64, err error) {
+	return pk.VarInt(s.maps.getID(s.v)).WriteTo(w)
+}
+
 type linearPalette struct {
 	onResize func(n int, v BlockState) int
 	maps     blockMaps
diff --git a/server/dimension.go b/server/dimension.go
index 203931e..c0ff19f 100644
--- a/server/dimension.go
+++ b/server/dimension.go
@@ -37,7 +37,7 @@ func (c *chunkData) WriteTo(w io.Writer) (int64, error) {
 		// Heightmaps
 		pk.NBT(struct {
 			MotionBlocking []uint64 `nbt:"MOTION_BLOCKING"`
-		}{c.HeightMaps.Longs()}),
+		}{c.HeightMaps.Raw()}),
 		pk.ByteArray(c.Data()), // TODO: Chunk Data
 		pk.VarInt(0),           // TODO: Block Entity
 	}.WriteTo(w)