From 704b440d5ac4ded3014b1a56ab7774965a29aa96 Mon Sep 17 00:00:00 2001
From: Milan Suman <>
Date: Thu, 4 Aug 2022 00:01:12 +0530
Subject: [PATCH] lib/nbt: Add tag classes

---
 src/lib/nbt.cpp          | 55 +++++++++++++++++++++++++++++++++++++---
 src/lib/nbt.hpp          | 26 +++++++++++++++++++
 src/test/nbt_helpers.cpp | 11 ++++++++
 3 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/src/lib/nbt.cpp b/src/lib/nbt.cpp
index 427c109..7ef557b 100644
--- a/src/lib/nbt.cpp
+++ b/src/lib/nbt.cpp
@@ -149,9 +149,6 @@ namespace NBT {
             return ErrorOr<std::vector<int8_t>>(result);
         }
 
-        // Maybe use a struct that holds decoded (de-Java-fied) string
-        // data, decoded size, and original size? Original size is needed
-        // so the parser knows where to continue.
         ErrorOr<tiny_utf8::string> readString(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
             if(dataSize > 0xFFFF){
                 return ErrorOr<tiny_utf8::string>(true, ErrorCodes::OVERRUN);
@@ -381,6 +378,58 @@ namespace NBT {
         }
     }
 
+    //Tag constructors
+
+    template <typename T>
+    Tag<T>::Tag(uint8_t tagType, tiny_utf8::string name, uint16_t nameSize, T content, uint32_t size)
+        : tagType(tagType), name(name), nameSize(nameSize), content(content) ,size(size)
+    {}
+
+    End::End() : Tag::Tag(0, "", 0, 0, 0) {}
+
+    Byte::Byte(tiny_utf8::string name, uint16_t nameSize, int8_t content)
+        : Tag::Tag(1, name, nameSize, content, 1)
+    {}
+
+    Byte::Byte(uint8_t data[]){
+        if(validate(data)){
+            this->tagType = 1;
+
+            uint8_t nameSizeSlice[] = {data[1], data[2]};
+
+            ErrorOr<int16_t> readIntResult = helper::readInt16(nameSizeSlice, 2, 0);
+            if(!readIntResult.isError){
+                this->nameSize = readIntResult.value;
+            }else{
+                throw readIntResult.errorCode;
+            }
+
+            uint8_t nameSlice[this->nameSize+2];
+            for(int i=0; i<this->nameSize+2; i++){
+                nameSlice[i] = data[i+1];
+            }
+
+            ErrorOr<tiny_utf8::string> readStringResult = helper::readString(nameSlice, this->nameSize, 0);
+            if(!readStringResult.isError){
+                this->name = readStringResult.value;
+            }else{
+                throw readStringResult.errorCode;
+            }
+
+            //int8 needs only one byte
+            this->content = data[this->nameSize+4];
+        }
+    }
+
+    //more conditions will be added
+    bool Byte::validate(uint8_t data[]){
+        if(data[0] == 0x01){
+            return true;
+        }else{
+            return false;
+        }
+    }
+
     bool validateRawNBTData(uint8_t data[], uint64_t dataSize){
         //state machine?
         //TODO: implement
diff --git a/src/lib/nbt.hpp b/src/lib/nbt.hpp
index 6eca6db..3042b16 100644
--- a/src/lib/nbt.hpp
+++ b/src/lib/nbt.hpp
@@ -76,5 +76,31 @@ namespace NBT {
         void writeInt64Array(std::vector<uint8_t>* destination, int64_t data[], uint32_t dataSize);
     }
 
+    //Generic parent class to make declaration easier
+    template <typename T>
+    class Tag{
+        public:
+        uint8_t tagType;
+        tiny_utf8::string name;
+        uint16_t nameSize;
+        T content;
+        int32_t size;
+
+        Tag(){}
+        Tag(uint8_t tagType, tiny_utf8::string name, uint16_t nameSize, T content, uint32_t size);
+    };
+
+    class End: public Tag<uint8_t>{
+        public:
+        End();
+    };
+
+    class Byte: public Tag<int8_t>{
+        public:
+        Byte(tiny_utf8::string name, uint16_t nameSize, int8_t content);
+        Byte(uint8_t data[]);
+        bool validate(uint8_t data[]);
+    };
+
     bool validateRawNBTData(uint8_t data[], int length);
 }
diff --git a/src/test/nbt_helpers.cpp b/src/test/nbt_helpers.cpp
index 803bfd5..95a082d 100644
--- a/src/test/nbt_helpers.cpp
+++ b/src/test/nbt_helpers.cpp
@@ -523,5 +523,16 @@ int main(){
     ASSERT(javaStdString1 == *exportedString);
 
     std::cout << "Passed writeString NBT helper test." << std::endl;
+
+    //Byte tag constructor test
+    uint8_t bytetest[] = {0x01, 0x00, 0x02, 0x68, 0x69, 0x32};
+    NBT::Byte byte = NBT::Byte(bytetest);
+
+    ASSERT(byte.tagType == 1);
+    ASSERT(byte.nameSize == 2);
+    ASSERT(byte.content = 0x32);
+    ASSERT(byte.name == tiny_utf8::string("hi"));
+    
+    std::cout << "Passed Byte Tag constructor test." << std::endl;
     return 0;
 }