const decoder = new TextDecoder('utf-8');
export function unpackInt(pSrc: Buffer): {result: number, remaining: Buffer} {
	
	var srcIndex = 0;
	const sign = ((pSrc[srcIndex] >> 6) & 1)
	
	var result = (pSrc[srcIndex] & 0b0011_1111)
	while (srcIndex <= 4) {
		
		if ((pSrc[srcIndex] & 0b1000_0000) === 0)
			break;

		srcIndex++;
		result |= ((pSrc[srcIndex] & 0b0111_1111)) << (6+7*(srcIndex-1))
		
	}
	result ^= -sign;
	
	return {result, remaining: pSrc.slice(srcIndex+1)};
}
export function unpackString(pSrc: Buffer): {result: string, remaining: Buffer} {
	var result = pSrc.slice(0, pSrc.indexOf(0))
	pSrc = pSrc.slice(pSrc.indexOf(0) + 1, pSrc.length)
	return {result: decoder.decode(new Uint8Array(result)), remaining: pSrc}
}

export class MsgUnpacker {
	remaining: Buffer;
	constructor(pSrc: Buffer) {
		this.remaining = pSrc;
	}

	unpackInt(): number {
		// let unpacked;
		// if (!_unpacked)  {
		let unpacked = unpackInt(this.remaining);
		this.remaining = unpacked.remaining;
		// } else {
			// unpacked = {result: this.remaining[0]};
			// this.remaining = this.remaining.slice(1);

		// }
		return unpacked.result;
	}

	unpackString(): string {
		let unpacked = unpackString(this.remaining);
		this.remaining = unpacked.remaining;
		return unpacked.result;
	}

	/** @param size - size in bytes */
	unpackRaw(size: number): Buffer {
		let unpacked = this.remaining.slice(0, size);
		this.remaining = this.remaining.slice(size);
		return unpacked;
	}
}