From 233b44a13f675bc201cf15964aa2e2cfe2c18a2f Mon Sep 17 00:00:00 2001
From: Tnze <cjd001113@outlook.com>
Date: Wed, 26 May 2021 15:02:49 +0800
Subject: [PATCH] Basic SNBT list support

---
 nbt/snbt_decode.go       | 50 +++++++++++++++++++++++++++++++++++++++-
 nbt/snbt_decode_test.go  |  2 +-
 nbt/snbt_scanner.go      |  2 +-
 nbt/snbt_scanner_test.go |  4 ++--
 4 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/nbt/snbt_decode.go b/nbt/snbt_decode.go
index 418e391..f450ff8 100644
--- a/nbt/snbt_decode.go
+++ b/nbt/snbt_decode.go
@@ -1,6 +1,7 @@
 package nbt
 
 import (
+	"bytes"
 	"math"
 	"strconv"
 	"strings"
@@ -31,7 +32,7 @@ func writeValue(e *Encoder, d *decodeState, tagName string) error {
 	case scanBeginCompound:
 		return writeCompound(e, d, tagName)
 	case scanBeginList:
-		panic("not implemented")
+		return writeListOrArray(e, d, tagName)
 	}
 }
 
@@ -105,6 +106,53 @@ func writeCompound(e *Encoder, d *decodeState, tagName string) error {
 	return nil
 }
 
+func writeListOrArray(e *Encoder, d *decodeState, tagName string) error {
+	d.scanWhile(scanSkipSpace)
+	if d.opcode == scanEndValue { // ']', empty TAG_List
+		e.writeTag(TagList, tagName)
+		e.writeInt32(0)
+		return nil
+	}
+
+	start := d.readIndex()
+
+	switch d.opcode {
+	case scanBeginLiteral:
+		d.scanWhile(scanContinue)
+		literal := d.data[start:d.readIndex()]
+		if d.opcode == scanListType { // TAG_X_Array
+			//listType := literal[0]
+			break
+		}
+		if d.opcode != scanListValue { // TAG_List<TAG_String>
+			panic(phasePanicMsg)
+		}
+		// TODO
+		parseLiteral(literal)
+		fallthrough
+	case scanBeginList: // TAG_List<TAG_List>
+		// We don't know the length of the List,
+		// so we read them into a buffer and count.
+		var buf bytes.Buffer
+		e2 := NewEncoder(&buf)
+		var count int
+		for {
+			d.scanWhile(scanSkipSpace)
+			if d.opcode == scanEndValue {
+				break
+			}
+			if d.opcode == scanListValue {
+				// TODO
+				e2.writeInt32(0)
+			}
+		}
+		e.writeListHeader(TagList, tagName, count)
+		e.w.Write(buf.Bytes())
+	case scanBeginCompound: // TAG_List<TAG_Compound>
+	}
+	return nil
+}
+
 // readIndex returns the position of the last byte read.
 func (d *decodeState) readIndex() int {
 	return d.off - 1
diff --git a/nbt/snbt_decode_test.go b/nbt/snbt_decode_test.go
index 2053d80..54e9e54 100644
--- a/nbt/snbt_decode_test.go
+++ b/nbt/snbt_decode_test.go
@@ -8,7 +8,7 @@ import (
 func TestEncoder_WriteSNBT(t *testing.T) {
 	var buf bytes.Buffer
 	e := NewEncoder(&buf)
-	if err := e.WriteSNBT(`{ abc: 123F, def: {}}`); err != nil {
+	if err := e.WriteSNBT(`[1,2,3]`); err != nil {
 		t.Fatal(err)
 	}
 	t.Log(buf.Bytes())
diff --git a/nbt/snbt_scanner.go b/nbt/snbt_scanner.go
index 49cc566..d97e8d2 100644
--- a/nbt/snbt_scanner.go
+++ b/nbt/snbt_scanner.go
@@ -239,7 +239,7 @@ func (s *scanner) stateListOrArray(c byte) int {
 	switch c {
 	case 'B', 'I', 'L':
 		s.step = s.stateListOrArrayT
-		return scanContinue
+		return scanBeginLiteral
 	case ']':
 		return s.stateEndValue(c)
 	default:
diff --git a/nbt/snbt_scanner_test.go b/nbt/snbt_scanner_test.go
index 83b4c9d..5810724 100644
--- a/nbt/snbt_scanner_test.go
+++ b/nbt/snbt_scanner_test.go
@@ -6,10 +6,10 @@ import (
 )
 
 func TestSNBT_checkScanCode(t *testing.T) {
-	t.SkipNow()
+	//t.SkipNow()
 	var s scanner
 	s.reset()
-	for _, c := range []byte(`{ "a b\"c": {}, def: 12345, 'gh"i': 0.123f}`) {
+	for _, c := range []byte(`[I;1,2,3]`) {
 		t.Logf("[%c] - %d", c, s.step(c))
 	}
 	t.Logf("[%c] - %d", ' ', s.eof())