Frontend Review MCP

/** * Returns an array of indices. * The indices are the cut-off points for the split transaction. * That is: If the original transaction had 600 UTXOs lined up, * and the maximum number of transactions is 200, then the returned * array would be: * idx = [0, 200, 400, 599] * So the new transactions would contain inputs * Transaction 1: inputs 0 to and excluding 200, * Transaction 2: inputs 200 to and excluding 400, * Transaction 3. inputs 400 to and including 599 (end of array). * @param {*} nUTXO The number of transactions * @param {*} maxUnspents Maximum number of unspents */ function getIdx(nUTXO, maxUnspents) { if (nUTXO <= maxUnspents || nUTXO <= 1 || maxUnspents <= 1) return -1 var divide; /* We are after the smallest possible natural number of subintervals of the UTXO list, which puts each interval at length of maxUnspents or less. */ for (i = 2; i <= nUTXO; i++) { // divide is the length of each interval divide = Math.ceil(nUTXO / i) if (divide <= maxUnspents) { // k is the number of intervals var k = i break } } var idx = [] /* Construct index array by multiplying interval index (j) by the length of each interval (divide). Up to and excluding k. */ for (j = 0; j < k; j++) { idx.push(j*divide) } /* Push end of array. The last transaction might have a slightly different number of inputs than the rest, because of the use of the ceil() function above. */ if (idx[idx.length-1] != nUTXO-1) idx.push(nUTXO-1) /* The intervals are roughly equal in length. This is to decrease the chance of a small interval not having enough value to pay for its own transaction fee. */ return idx } function newBuilder(to, unspents, builder, that) { unspents.forEach(function(unspent, i) { builder.addInput(unspent.txId, unspent.vout) }) return builder } function utxoValues(unspents) { var accum = 0 unspents.forEach(function(unspent) { accum += unspent.value }) return accum } /** * Shuffles the LAST element of the input array with some other element in the array. * @param {*} array the array to shuffle */ function shuffle(array) { var tmpArray = array // We only need to swap the last element with some other, since the others have already been shuffled. for (let i = tmpArray.length - 1; i > tmpArray.length - 2; i--) { let j = Math.floor(Math.random() * (i + 1)); // random index from 0 to i // swap elements array[i] and array[j] // we use "destructuring assignment" syntax to achieve that // let t = array[i]; array[i] = array[j]; array[j] = t [tmpArray[i], tmpArray[j]] = [tmpArray[j], tmpArray[i]]; } return tmpArray } function argmax(arr) { if (arr.length === 0) { return -1; } var max = arr[0]; var maxIndex = 0; for (var i = 1; i < arr.length; i++) { if (arr[i] > max) { maxIndex = i; max = arr[i]; } } return maxIndex; } module.exports = { getIdx: getIdx, newBuilder: newBuilder, utxoValues: utxoValues, shuffle: shuffle, argmax: argmax }