TagPattern

package com.hypixel.hytale.protocol;

import com.hypixel.hytale.protocol.io.ProtocolException;
import com.hypixel.hytale.protocol.io.ValidationResult;
import com.hypixel.hytale.protocol.io.VarInt;
import io.netty.buffer.ByteBuf;
import java.util.Arrays;
import java.util.Objects;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;

public class TagPattern {
   public static final int NULLABLE_BIT_FIELD_SIZE = 1;
   public static final int FIXED_BLOCK_SIZE = 6;
   public static final int VARIABLE_FIELD_COUNT = 2;
   public static final int VARIABLE_BLOCK_START = 14;
   public static final int MAX_SIZE = 1677721600;
   @Nonnull
   public TagPatternType type = TagPatternType.Equals;
   public int tagIndex;
   @Nullable
   public TagPattern[] operands;
   @Nullable
   public TagPattern not;

   public TagPattern() {
   }

   public TagPattern(@Nonnull TagPatternType type, int tagIndex, @Nullable TagPattern[] operands, @Nullable TagPattern not) {
      this.type = type;
      this.tagIndex = tagIndex;
      this.operands = operands;
      this.not = not;
   }

   public TagPattern(@Nonnull TagPattern other) {
      this.type = other.type;
      this.tagIndex = other.tagIndex;
      this.operands = other.operands;
      this.not = other.not;
   }

   @Nonnull
   public static TagPattern deserialize(@Nonnull ByteBuf buf, int offset) {
      TagPattern obj = new TagPattern();
      byte nullBits = buf.getByte(offset);
      obj.type = TagPatternType.fromValue(buf.getByte(offset + 1));
      obj.tagIndex = buf.getIntLE(offset + 2);
      if ((nullBits & 1) != 0) {
         int varPos0 = offset + 14 + buf.getIntLE(offset + 6);
         int operandsCount = VarInt.peek(buf, varPos0);
         if (operandsCount < 0) {
            throw ProtocolException.negativeLength("Operands", operandsCount);
         }

         if (operandsCount > 4096000) {
            throw ProtocolException.arrayTooLong("Operands", operandsCount, 4096000);
         }

         int varIntLen = VarInt.length(buf, varPos0);
         if ((long)(varPos0 + varIntLen) + (long)operandsCount * 6L > (long)buf.readableBytes()) {
            throw ProtocolException.bufferTooSmall("Operands", varPos0 + varIntLen + operandsCount * 6, buf.readableBytes());
         }

         obj.operands = new TagPattern[operandsCount];
         int elemPos = varPos0 + varIntLen;

         for (int i = 0; i < operandsCount; i++) {
            obj.operands[i] = deserialize(buf, elemPos);
            elemPos += computeBytesConsumed(buf, elemPos);
         }
      }

      if ((nullBits & 2) != 0) {
         int varPos1 = offset + 14 + buf.getIntLE(offset + 10);
         obj.not = deserialize(buf, varPos1);
      }

      return obj;
   }

   public static int computeBytesConsumed(@Nonnull ByteBuf buf, int offset) {
      byte nullBits = buf.getByte(offset);
      int maxEnd = 14;
      if ((nullBits & 1) != 0) {
         int fieldOffset0 = buf.getIntLE(offset + 6);
         int pos0 = offset + 14 + fieldOffset0;
         int arrLen = VarInt.peek(buf, pos0);
         pos0 += VarInt.length(buf, pos0);

         for (int i = 0; i < arrLen; i++) {
            pos0 += computeBytesConsumed(buf, pos0);
         }

         if (pos0 - offset > maxEnd) {
            maxEnd = pos0 - offset;
         }
      }

      if ((nullBits & 2) != 0) {
         int fieldOffset1 = buf.getIntLE(offset + 10);
         int pos1 = offset + 14 + fieldOffset1;
         pos1 += computeBytesConsumed(buf, pos1);
         if (pos1 - offset > maxEnd) {
            maxEnd = pos1 - offset;
         }
      }

      return maxEnd;
   }

   public void serialize(@Nonnull ByteBuf buf) {
      int startPos = buf.writerIndex();
      byte nullBits = 0;
      if (this.operands != null) {
         nullBits = (byte)(nullBits | 1);
      }

      if (this.not != null) {
         nullBits = (byte)(nullBits | 2);
      }

      buf.writeByte(nullBits);
      buf.writeByte(this.type.getValue());
      buf.writeIntLE(this.tagIndex);
      int operandsOffsetSlot = buf.writerIndex();
      buf.writeIntLE(0);
      int notOffsetSlot = buf.writerIndex();
      buf.writeIntLE(0);
      int varBlockStart = buf.writerIndex();
      if (this.operands != null) {
         buf.setIntLE(operandsOffsetSlot, buf.writerIndex() - varBlockStart);
         if (this.operands.length > 4096000) {
            throw ProtocolException.arrayTooLong("Operands", this.operands.length, 4096000);
         }

         VarInt.write(buf, this.operands.length);

         for (TagPattern item : this.operands) {
            item.serialize(buf);
         }
      } else {
         buf.setIntLE(operandsOffsetSlot, -1);
      }

      if (this.not != null) {
         buf.setIntLE(notOffsetSlot, buf.writerIndex() - varBlockStart);
         this.not.serialize(buf);
      } else {
         buf.setIntLE(notOffsetSlot, -1);
      }
   }

   public int computeSize() {
      int size = 14;
      if (this.operands != null) {
         int operandsSize = 0;

         for (TagPattern elem : this.operands) {
            operandsSize += elem.computeSize();
         }

         size += VarInt.size(this.operands.length) + operandsSize;
      }

      if (this.not != null) {
         size += this.not.computeSize();
      }

      return size;
   }

   public static ValidationResult validateStructure(@Nonnull ByteBuf buffer, int offset) {
      if (buffer.readableBytes() - offset < 14) {
         return ValidationResult.error("Buffer too small: expected at least 14 bytes");
      } else {
         byte nullBits = buffer.getByte(offset);
         if ((nullBits & 1) != 0) {
            int operandsOffset = buffer.getIntLE(offset + 6);
            if (operandsOffset < 0) {
               return ValidationResult.error("Invalid offset for Operands");
            }

            int pos = offset + 14 + operandsOffset;
            if (pos >= buffer.writerIndex()) {
               return ValidationResult.error("Offset out of bounds for Operands");
            }

            int operandsCount = VarInt.peek(buffer, pos);
            if (operandsCount < 0) {
               return ValidationResult.error("Invalid array count for Operands");
            }

            if (operandsCount > 4096000) {
               return ValidationResult.error("Operands exceeds max length 4096000");
            }

            pos += VarInt.length(buffer, pos);

            for (int i = 0; i < operandsCount; i++) {
               ValidationResult structResult = validateStructure(buffer, pos);
               if (!structResult.isValid()) {
                  return ValidationResult.error("Invalid TagPattern in Operands[" + i + "]: " + structResult.error());
               }

               pos += computeBytesConsumed(buffer, pos);
            }
         }

         if ((nullBits & 2) != 0) {
            int notOffset = buffer.getIntLE(offset + 10);
            if (notOffset < 0) {
               return ValidationResult.error("Invalid offset for Not");
            }

            int posx = offset + 14 + notOffset;
            if (posx >= buffer.writerIndex()) {
               return ValidationResult.error("Offset out of bounds for Not");
            }

            ValidationResult notResult = validateStructure(buffer, posx);
            if (!notResult.isValid()) {
               return ValidationResult.error("Invalid Not: " + notResult.error());
            }

            posx += computeBytesConsumed(buffer, posx);
         }

         return ValidationResult.OK;
      }
   }

   public TagPattern clone() {
      TagPattern copy = new TagPattern();
      copy.type = this.type;
      copy.tagIndex = this.tagIndex;
      copy.operands = this.operands != null ? Arrays.stream(this.operands).map(e -> e.clone()).toArray(TagPattern[]::new) : null;
      copy.not = this.not != null ? this.not.clone() : null;
      return copy;
   }

   @Override
   public boolean equals(Object obj) {
      if (this == obj) {
         return true;
      } else {
         return !(obj instanceof TagPattern other)
            ? false
            : Objects.equals(this.type, other.type)
               && this.tagIndex == other.tagIndex
               && Arrays.equals((Object[])this.operands, (Object[])other.operands)
               && Objects.equals(this.not, other.not);
      }
   }

   @Override
   public int hashCode() {
      int result = 1;
      result = 31 * result + Objects.hashCode(this.type);
      result = 31 * result + Integer.hashCode(this.tagIndex);
      result = 31 * result + Arrays.hashCode((Object[])this.operands);
      return 31 * result + Objects.hashCode(this.not);
   }
}