Minecraft-protocol-1.20.4-kick-msg-parser/kick.js

const lang = require("./en_us.json"); // translate message
const nbt = require('prismarine-nbt');

function uuidFromIntArray (arr) {
  const buf = Buffer.alloc(16)
  arr.forEach((num, index) => { buf.writeInt32BE(num, index * 4) })
  return buf.toString('hex')
}

function processNbtMessage(msg) {
  try {
    if (typeof msg === 'string') { // just create simple nbt structure
      msg = {
        id: 'string',
        value: msg
      };
    }

    if (!msg || msg.type === 'end') return msg;

    const simplified = nbt.simplify(msg); // Ensure nbt is defined elsewhere
    const json = JSON.stringify(simplified, (key, val) => {
      if (key === 'id' && Array.isArray(val)) return uuidFromIntArray(val);
      return val;
    });

    return json;
  } catch (e) {
    return '{"text":""}';
  }
}

const msg = {
  reason: '{"translate":"multiplayer.disconnect.unverified_username"}'
}

const msg2 = {
  "reason": {
    "type": "compound",
    "value": {
      "with": {
        "type": "list",
        "value": {
          "type": "string",
          "value": [ "Internal Exception: io.netty.handler.codec.EncoderException: java.io.UTFDataFormatException: encoded string (t§k腻腻腻腻腻...腻腻腻腻§rno) too long: 97869 bytes" ]
        }
      },
      "translate": {
        "type": "string",
        "value": "disconnect.genericReason"
      }
    }
  }
}

console.log(kickparser(processNbtMessage(msg.reason)));
console.log(kickparser(processNbtMessage(msg2.reason)));

// lazy to make it color
function kickparser(component) {
	if (component === undefined) return;
	try { 
   	  jsonComponent = JSON.parse(component);
	} catch (e) { 	
	  console.error("Invalid JSON format:", component);
	  return '';
	}
	
    function kickparserText(comp) {
        let text = '';
        
        if (typeof comp === 'string') {
            text += comp;
        }
		if (typeof comp.value === 'string') {
            text += comp.value;
        }
        if (comp.with) {
            text += kickparserText(comp.with);
        }
		
        if (comp.value) {
            [comp.value].forEach(subComp => {
				if (typeof subComp === 'string') text += subComp;
                text += kickparserText(subComp);
            });
		}
		
		if (comp.translate) {
			let translateString = lang[comp.translate] || comp.translate;
			let DefaultTranslateString = lang[comp.translate] || comp.translate;
			let DefaultMsg = false;

			if (comp.with) {
				const withArgs = comp.with.map(arg => extractText(arg));

				let usedReplacements = 0;

				translateString = translateString.replace(/%s/g, (match, offset, string) => {
					if (offset > 0 && string[offset - 1] === '%') {
						return 's';
					}
					
					if (usedReplacements < withArgs.length) {
						const formattedArg = withArgs[usedReplacements];
						if (translateString.length + formattedArg.length > 2048) return 'Translate Crash';
						usedReplacements++;
						return formattedArg;
					}
					
					DefaultMsg = true;
					return "%s";
				});

				translateString = translateString.replace(/%(\d+)\$s/g, (match, index, stringindex, string) => {
					const argIndex = parseInt(index) - 1;

					if (argIndex >= withArgs.length) {
						DefaultMsg = true;
						return match;
					}

					if (stringindex > 0 && string[stringindex - 1] === '%') {
						return match;
					}

					const formattedArg = withArgs[argIndex];
					if (translateString.length + formattedArg.length > 2048) return 'Translate Crash';
					return formattedArg;
				});
			}

			if (DefaultMsg) { 
				text += DefaultTranslateString;
			} else {
				text += translateString;
			}
		}
            
        

        return text;
    }

    
    return kickparserText(jsonComponent);
}