@xmr-core/xmr-mymonero-libs/src/mymonero-send-tx/internal_libs/output_selection.ts

A collection of utilities for building ontop of a MyMonero compatible API

import { popRandElement } from "./arr_utils";
import { Log } from "./logger";
import { BigInt } from "@xmr-core/biginteger";
import { config } from "@xmr-core/xmr-constants";
import { JSONPrettyPrint } from "@xmr-core/xmr-str-utils";
import { Output } from "@xmr-core/xmr-transaction";

export function selectOutputsAndAmountForMixin(
	targetAmount: BigInt,
	unusedOuts: Output[],
	isRingCT: boolean,
	sweeping: boolean,
) {
	JSONPrettyPrint(
		"selectOutputsAndAmountForMixin",
		{
			targetAmount,
			unusedOuts,
			isRingCT,
			sweeping,
		},
		"args",
	);

	Log.SelectOutsAndAmtForMix.target(targetAmount);

	let usingOutsAmount = new BigInt(0);
	const usingOuts: Output[] = [];
	const remainingUnusedOuts = unusedOuts.slice(); // take copy so as to prevent issue if we must re-enter tx building fn if fee too low after building
	while (
		usingOutsAmount.compare(targetAmount) < 0 &&
		remainingUnusedOuts.length > 0
	) {
		const out = popRandElement(remainingUnusedOuts);
		if (!isRingCT && out.rct) {
			// out.rct is set by the server
			continue; // skip rct outputs if not creating rct tx
		}
		const outAmount = new BigInt(out.amount);
		if (outAmount.compare(config.dustThreshold) < 0) {
			// amount is dusty..
			if (!sweeping) {
				Log.SelectOutsAndAmtForMix.Dusty.notSweeping();
				continue;
			}
			if (!out.rct) {
				Log.SelectOutsAndAmtForMix.Dusty.rct();
				continue;
			} else {
				Log.SelectOutsAndAmtForMix.Dusty.nonRct();
			}
		}
		usingOuts.push(out);
		usingOutsAmount = usingOutsAmount.add(outAmount);

		Log.SelectOutsAndAmtForMix.usingOut(outAmount, out);
	}

	JSONPrettyPrint(
		"selectOutputsAndAmountForMixin",
		{
			usingOuts,
			usingOutsAmount,
			remainingUnusedOuts,
		},
		"ret",
	);

	return {
		usingOuts,
		usingOutsAmount,
		remainingUnusedOuts,
	};
}