import bip39 from 'bip39';
import BigNumber from 'bignumber.js';
import b58 from 'bs58check';
import { randomBytes } from '../rng';
import { AbstractHDWallet } from './abstract-hd-wallet';
const bitcoin = require('bitcoinjs-lib');
const BlueElectrum = require('../../blue_modules/BlueElectrum');
const HDNode = require('bip32');
const reverse = require('buffer-reverse');

/**
 * Electrum - means that it utilizes Electrum protocol for blockchain data
 */
export class AbstractHDElectrumWallet extends AbstractHDWallet {
  static type = 'abstract';
  static typeReadable = 'abstract';
  static defaultRBFSequence = 2147483648; // 1 << 31, minimum for replaceable transactions as per BIP68
  static finalRBFSequence = 4294967295; // 0xFFFFFFFF

  constructor() {
    super();
    this._balances_by_external_index = {}; //  0 => { c: 0, u: 0 } // confirmed/unconfirmed
    this._balances_by_internal_index = {};

    this._txs_by_external_index = {};
    this._txs_by_internal_index = {};

    this._utxo = [];
  }

  /**
   * @inheritDoc
   */
  getBalance() {
    let ret = 0;
    for (const bal of Object.values(this._balances_by_external_index)) {
      ret += bal.c;
    }
    for (const bal of Object.values(this._balances_by_internal_index)) {
      ret += bal.c;
    }
    return ret + (this.getUnconfirmedBalance() < 0 ? this.getUnconfirmedBalance() : 0);
  }

  /**
   * @inheritDoc
   */
  timeToRefreshTransaction() {
    for (const tx of this.getTransactions()) {
      if (tx.confirmations < 7) return true;
    }
    return false;
  }

  /**
   *
   * @inheritDoc
   */
  getUnconfirmedBalance() {
    let ret = 0;
    for (const bal of Object.values(this._balances_by_external_index)) {
      ret += bal.u;
    }
    for (const bal of Object.values(this._balances_by_internal_index)) {
      ret += bal.u;
    }
    return ret;
  }

  async generate() {
    const buf = await randomBytes(32);
    this.secret = bip39.entropyToMnemonic(buf.toString('hex'));
  }

  async generateFromEntropy(user) {
    const random = await randomBytes(user.length < 32 ? 32 - user.length : 0);
    const buf = Buffer.concat([user, random], 32);
    this.secret = bip39.entropyToMnemonic(buf.toString('hex'));
  }

  _getExternalWIFByIndex(index) {
    return this._getWIFByIndex(false, index);
  }

  _getInternalWIFByIndex(index) {
    return this._getWIFByIndex(true, index);
  }

  /**
   * Get internal/external WIF by wallet index
   * @param {Boolean} internal
   * @param {Number} index
   * @returns {string|false} Either string WIF or FALSE if error happened
   * @private
   */
  _getWIFByIndex(internal, index) {
    if (!this.secret) return false;
    const mnemonic = this.secret;
    const seed = bip39.mnemonicToSeed(mnemonic);
    const root = HDNode.fromSeed(seed);
    const path = `m/84'/0'/0'/${internal ? 1 : 0}/${index}`;
    const child = root.derivePath(path);

    return child.toWIF();
  }

  _getNodeAddressByIndex(node, index) {
    index = index * 1; // cast to int
    if (node === 0) {
      if (this.external_addresses_cache[index]) return this.external_addresses_cache[index]; // cache hit
    }

    if (node === 1) {
      if (this.internal_addresses_cache[index]) return this.internal_addresses_cache[index]; // cache hit
    }

    if (node === 0 && !this._node0) {
      const xpub = this.constructor._zpubToXpub(this.getXpub());
      const hdNode = HDNode.fromBase58(xpub);
      this._node0 = hdNode.derive(node);
    }

    if (node === 1 && !this._node1) {
      const xpub = this.constructor._zpubToXpub(this.getXpub());
      const hdNode = HDNode.fromBase58(xpub);
      this._node1 = hdNode.derive(node);
    }

    let address;
    if (node === 0) {
      address = this.constructor._nodeToBech32SegwitAddress(this._node0.derive(index));
    }

    if (node === 1) {
      address = this.constructor._nodeToBech32SegwitAddress(this._node1.derive(index));
    }

    if (node === 0) {
      return (this.external_addresses_cache[index] = address);
    }

    if (node === 1) {
      return (this.internal_addresses_cache[index] = address);
    }
  }

  _getNodePubkeyByIndex(node, index) {
    index = index * 1; // cast to int

    if (node === 0 && !this._node0) {
      const xpub = this.constructor._zpubToXpub(this.getXpub());
      const hdNode = HDNode.fromBase58(xpub);
      this._node0 = hdNode.derive(node);
    }

    if (node === 1 && !this._node1) {
      const xpub = this.constructor._zpubToXpub(this.getXpub());
      const hdNode = HDNode.fromBase58(xpub);
      this._node1 = hdNode.derive(node);
    }

    if (node === 0) {
      return this._node0.derive(index).publicKey;
    }

    if (node === 1) {
      return this._node1.derive(index).publicKey;
    }
  }

  _getExternalAddressByIndex(index) {
    return this._getNodeAddressByIndex(0, index);
  }

  _getInternalAddressByIndex(index) {
    return this._getNodeAddressByIndex(1, index);
  }

  /**
   * Returning zpub actually, not xpub. Keeping same method name
   * for compatibility.
   *
   * @return {String} zpub
   */
  getXpub() {
    if (this._xpub) {
      return this._xpub; // cache hit
    }
    // first, getting xpub
    const mnemonic = this.secret;
    const seed = bip39.mnemonicToSeed(mnemonic);
    const root = HDNode.fromSeed(seed);

    const path = "m/84'/0'/0'";
    const child = root.derivePath(path).neutered();
    const xpub = child.toBase58();

    // bitcoinjs does not support zpub yet, so we just convert it from xpub
    let data = b58.decode(xpub);
    data = data.slice(4);
    data = Buffer.concat([Buffer.from('04b24746', 'hex'), data]);
    this._xpub = b58.encode(data);

    return this._xpub;
  }

  /**
   * @inheritDoc
   */
  async fetchTransactions() {
    // if txs are absent for some internal address in hierarchy - this is a sign
    // we should fetch txs for that address
    // OR if some address has unconfirmed balance - should fetch it's txs
    // OR some tx for address is unconfirmed
    // OR some tx has < 7 confirmations

    // fetching transactions in batch: first, getting batch history for all addresses,
    // then batch fetching all involved txids
    // finally, batch fetching txids of all inputs (needed to see amounts & addresses of those inputs)
    // then we combine it all together

    const addresses2fetch = [];

    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      // external addresses first
      let hasUnconfirmed = false;
      this._txs_by_external_index[c] = this._txs_by_external_index[c] || [];
      for (const tx of this._txs_by_external_index[c]) hasUnconfirmed = hasUnconfirmed || !tx.confirmations || tx.confirmations < 7;

      if (hasUnconfirmed || this._txs_by_external_index[c].length === 0 || this._balances_by_external_index[c].u !== 0) {
        addresses2fetch.push(this._getExternalAddressByIndex(c));
      }
    }

    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      // next, internal addresses
      let hasUnconfirmed = false;
      this._txs_by_internal_index[c] = this._txs_by_internal_index[c] || [];
      for (const tx of this._txs_by_internal_index[c]) hasUnconfirmed = hasUnconfirmed || !tx.confirmations || tx.confirmations < 7;

      if (hasUnconfirmed || this._txs_by_internal_index[c].length === 0 || this._balances_by_internal_index[c].u !== 0) {
        addresses2fetch.push(this._getInternalAddressByIndex(c));
      }
    }

    // first: batch fetch for all addresses histories
    const histories = await BlueElectrum.multiGetHistoryByAddress(addresses2fetch);
    const txs = {};
    for (const history of Object.values(histories)) {
      for (const tx of history) {
        txs[tx.tx_hash] = tx;
      }
    }

    // next, batch fetching each txid we got
    const txdatas = await BlueElectrum.multiGetTransactionByTxid(Object.keys(txs));

    // now, tricky part. we collect all transactions from inputs (vin), and batch fetch them too.
    // then we combine all this data (we need inputs to see source addresses and amounts)
    const vinTxids = [];
    for (const txdata of Object.values(txdatas)) {
      for (const vin of txdata.vin) {
        vinTxids.push(vin.txid);
      }
    }
    const vintxdatas = await BlueElectrum.multiGetTransactionByTxid(vinTxids);

    // fetched all transactions from our inputs. now we need to combine it.
    // iterating all _our_ transactions:
    for (const txid of Object.keys(txdatas)) {
      // iterating all inputs our our single transaction:
      for (let inpNum = 0; inpNum < txdatas[txid].vin.length; inpNum++) {
        const inpTxid = txdatas[txid].vin[inpNum].txid;
        const inpVout = txdatas[txid].vin[inpNum].vout;
        // got txid and output number of _previous_ transaction we shoud look into
        if (vintxdatas[inpTxid] && vintxdatas[inpTxid].vout[inpVout]) {
          // extracting amount & addresses from previous output and adding it to _our_ input:
          txdatas[txid].vin[inpNum].addresses = vintxdatas[inpTxid].vout[inpVout].scriptPubKey.addresses;
          txdatas[txid].vin[inpNum].value = vintxdatas[inpTxid].vout[inpVout].value;
        }
      }
    }

    // now purge all unconfirmed txs from internal hashmaps, since some may be evicted from mempool because they became invalid
    // or replaced. hashmaps are going to be re-populated anyways, since we fetched TXs for addresses with unconfirmed TXs
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      this._txs_by_external_index[c] = this._txs_by_external_index[c].filter(tx => !!tx.confirmations);
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      this._txs_by_internal_index[c] = this._txs_by_internal_index[c].filter(tx => !!tx.confirmations);
    }

    // now, we need to put transactions in all relevant `cells` of internal hashmaps: this._txs_by_internal_index && this._txs_by_external_index

    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      for (const tx of Object.values(txdatas)) {
        for (const vin of tx.vin) {
          if (vin.addresses && vin.addresses.indexOf(this._getExternalAddressByIndex(c)) !== -1) {
            // this TX is related to our address
            this._txs_by_external_index[c] = this._txs_by_external_index[c] || [];
            const clonedTx = Object.assign({}, tx);
            clonedTx.inputs = tx.vin.slice(0);
            clonedTx.outputs = tx.vout.slice(0);
            delete clonedTx.vin;
            delete clonedTx.vout;

            // trying to replace tx if it exists already (because it has lower confirmations, for example)
            let replaced = false;
            for (let cc = 0; cc < this._txs_by_external_index[c].length; cc++) {
              if (this._txs_by_external_index[c][cc].txid === clonedTx.txid) {
                replaced = true;
                this._txs_by_external_index[c][cc] = clonedTx;
              }
            }
            if (!replaced) this._txs_by_external_index[c].push(clonedTx);
          }
        }
        for (const vout of tx.vout) {
          if (vout.scriptPubKey.addresses && vout.scriptPubKey.addresses.indexOf(this._getExternalAddressByIndex(c)) !== -1) {
            // this TX is related to our address
            this._txs_by_external_index[c] = this._txs_by_external_index[c] || [];
            const clonedTx = Object.assign({}, tx);
            clonedTx.inputs = tx.vin.slice(0);
            clonedTx.outputs = tx.vout.slice(0);
            delete clonedTx.vin;
            delete clonedTx.vout;

            // trying to replace tx if it exists already (because it has lower confirmations, for example)
            let replaced = false;
            for (let cc = 0; cc < this._txs_by_external_index[c].length; cc++) {
              if (this._txs_by_external_index[c][cc].txid === clonedTx.txid) {
                replaced = true;
                this._txs_by_external_index[c][cc] = clonedTx;
              }
            }
            if (!replaced) this._txs_by_external_index[c].push(clonedTx);
          }
        }
      }
    }

    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      for (const tx of Object.values(txdatas)) {
        for (const vin of tx.vin) {
          if (vin.addresses && vin.addresses.indexOf(this._getInternalAddressByIndex(c)) !== -1) {
            // this TX is related to our address
            this._txs_by_internal_index[c] = this._txs_by_internal_index[c] || [];
            const clonedTx = Object.assign({}, tx);
            clonedTx.inputs = tx.vin.slice(0);
            clonedTx.outputs = tx.vout.slice(0);
            delete clonedTx.vin;
            delete clonedTx.vout;

            // trying to replace tx if it exists already (because it has lower confirmations, for example)
            let replaced = false;
            for (let cc = 0; cc < this._txs_by_internal_index[c].length; cc++) {
              if (this._txs_by_internal_index[c][cc].txid === clonedTx.txid) {
                replaced = true;
                this._txs_by_internal_index[c][cc] = clonedTx;
              }
            }
            if (!replaced) this._txs_by_internal_index[c].push(clonedTx);
          }
        }
        for (const vout of tx.vout) {
          if (vout.scriptPubKey.addresses && vout.scriptPubKey.addresses.indexOf(this._getInternalAddressByIndex(c)) !== -1) {
            // this TX is related to our address
            this._txs_by_internal_index[c] = this._txs_by_internal_index[c] || [];
            const clonedTx = Object.assign({}, tx);
            clonedTx.inputs = tx.vin.slice(0);
            clonedTx.outputs = tx.vout.slice(0);
            delete clonedTx.vin;
            delete clonedTx.vout;

            // trying to replace tx if it exists already (because it has lower confirmations, for example)
            let replaced = false;
            for (let cc = 0; cc < this._txs_by_internal_index[c].length; cc++) {
              if (this._txs_by_internal_index[c][cc].txid === clonedTx.txid) {
                replaced = true;
                this._txs_by_internal_index[c][cc] = clonedTx;
              }
            }
            if (!replaced) this._txs_by_internal_index[c].push(clonedTx);
          }
        }
      }
    }

    this._lastTxFetch = +new Date();
  }

  getTransactions() {
    let txs = [];

    for (const addressTxs of Object.values(this._txs_by_external_index)) {
      txs = txs.concat(addressTxs);
    }
    for (const addressTxs of Object.values(this._txs_by_internal_index)) {
      txs = txs.concat(addressTxs);
    }

    if (txs.length === 0) return []; // guard clause; so we wont spend time calculating addresses

    // its faster to pre-build hashmap of owned addresses than to query `this.weOwnAddress()`, which in turn
    // iterates over all addresses in hierarchy
    const ownedAddressesHashmap = {};
    for (let c = 0; c < this.next_free_address_index + 1; c++) {
      ownedAddressesHashmap[this._getExternalAddressByIndex(c)] = true;
    }
    for (let c = 0; c < this.next_free_change_address_index + 1; c++) {
      ownedAddressesHashmap[this._getInternalAddressByIndex(c)] = true;
    }
    // hack: in case this code is called from LegacyWallet:
    if (this.getAddress()) ownedAddressesHashmap[this.getAddress()] = true;

    const ret = [];
    for (const tx of txs) {
      tx.received = tx.blocktime * 1000;
      if (!tx.blocktime) tx.received = +new Date() - 30 * 1000; // unconfirmed
      tx.confirmations = tx.confirmations || 0; // unconfirmed
      tx.hash = tx.txid;
      tx.value = 0;

      for (const vin of tx.inputs) {
        // if input (spending) goes from our address - we are loosing!
        if (
          (vin.address && ownedAddressesHashmap[vin.address]) ||
          (vin.addresses && vin.addresses[0] && ownedAddressesHashmap[vin.addresses[0]])
        ) {
          tx.value -= new BigNumber(vin.value).multipliedBy(100000000).toNumber();
        }
      }

      for (const vout of tx.outputs) {
        // when output goes to our address - this means we are gaining!
        if (vout.scriptPubKey.addresses && vout.scriptPubKey.addresses[0] && ownedAddressesHashmap[vout.scriptPubKey.addresses[0]]) {
          tx.value += new BigNumber(vout.value).multipliedBy(100000000).toNumber();
        }
      }
      ret.push(tx);
    }

    // now, deduplication:
    const usedTxIds = {};
    const ret2 = [];
    for (const tx of ret) {
      if (!usedTxIds[tx.txid]) ret2.push(tx);
      usedTxIds[tx.txid] = 1;
    }

    return ret2.sort(function (a, b) {
      return b.received - a.received;
    });
  }

  async _binarySearchIterationForInternalAddress(index) {
    const gerenateChunkAddresses = chunkNum => {
      const ret = [];
      for (let c = this.gap_limit * chunkNum; c < this.gap_limit * (chunkNum + 1); c++) {
        ret.push(this._getInternalAddressByIndex(c));
      }
      return ret;
    };

    let lastChunkWithUsedAddressesNum = null;
    let lastHistoriesWithUsedAddresses = null;
    for (let c = 0; c < Math.round(index / this.gap_limit); c++) {
      const histories = await BlueElectrum.multiGetHistoryByAddress(gerenateChunkAddresses(c));
      if (this.constructor._getTransactionsFromHistories(histories).length > 0) {
        // in this particular chunk we have used addresses
        lastChunkWithUsedAddressesNum = c;
        lastHistoriesWithUsedAddresses = histories;
      } else {
        // empty chunk. no sense searching more chunks
        break;
      }
    }

    let lastUsedIndex = 0;

    if (lastHistoriesWithUsedAddresses) {
      // now searching for last used address in batch lastChunkWithUsedAddressesNum
      for (
        let c = lastChunkWithUsedAddressesNum * this.gap_limit;
        c < lastChunkWithUsedAddressesNum * this.gap_limit + this.gap_limit;
        c++
      ) {
        const address = this._getInternalAddressByIndex(c);
        if (lastHistoriesWithUsedAddresses[address] && lastHistoriesWithUsedAddresses[address].length > 0) {
          lastUsedIndex = Math.max(c, lastUsedIndex) + 1; // point to next, which is supposed to be unsued
        }
      }
    }

    return lastUsedIndex;
  }

  async _binarySearchIterationForExternalAddress(index) {
    const gerenateChunkAddresses = chunkNum => {
      const ret = [];
      for (let c = this.gap_limit * chunkNum; c < this.gap_limit * (chunkNum + 1); c++) {
        ret.push(this._getExternalAddressByIndex(c));
      }
      return ret;
    };

    let lastChunkWithUsedAddressesNum = null;
    let lastHistoriesWithUsedAddresses = null;
    for (let c = 0; c < Math.round(index / this.gap_limit); c++) {
      const histories = await BlueElectrum.multiGetHistoryByAddress(gerenateChunkAddresses(c));
      if (this.constructor._getTransactionsFromHistories(histories).length > 0) {
        // in this particular chunk we have used addresses
        lastChunkWithUsedAddressesNum = c;
        lastHistoriesWithUsedAddresses = histories;
      } else {
        // empty chunk. no sense searching more chunks
        break;
      }
    }

    let lastUsedIndex = 0;

    if (lastHistoriesWithUsedAddresses) {
      // now searching for last used address in batch lastChunkWithUsedAddressesNum
      for (
        let c = lastChunkWithUsedAddressesNum * this.gap_limit;
        c < lastChunkWithUsedAddressesNum * this.gap_limit + this.gap_limit;
        c++
      ) {
        const address = this._getExternalAddressByIndex(c);
        if (lastHistoriesWithUsedAddresses[address] && lastHistoriesWithUsedAddresses[address].length > 0) {
          lastUsedIndex = Math.max(c, lastUsedIndex) + 1; // point to next, which is supposed to be unsued
        }
      }
    }

    return lastUsedIndex;
  }

  async fetchBalance() {
    try {
      if (this.next_free_change_address_index === 0 && this.next_free_address_index === 0) {
        // doing binary search for last used address:
        this.next_free_change_address_index = await this._binarySearchIterationForInternalAddress(1000);
        this.next_free_address_index = await this._binarySearchIterationForExternalAddress(1000);
      } // end rescanning fresh wallet

      // finally fetching balance
      await this._fetchBalance();
    } catch (err) {
      console.warn(err);
    }
  }

  async _fetchBalance() {
    // probing future addressess in hierarchy whether they have any transactions, in case
    // our 'next free addr' pointers are lagging behind
    // for that we are gona batch fetch history for all addresses between last used and last used + gap_limit

    const lagAddressesToFetch = [];
    for (let c = this.next_free_address_index; c < this.next_free_address_index + this.gap_limit; c++) {
      lagAddressesToFetch.push(this._getExternalAddressByIndex(c));
    }
    for (let c = this.next_free_change_address_index; c < this.next_free_change_address_index + this.gap_limit; c++) {
      lagAddressesToFetch.push(this._getInternalAddressByIndex(c));
    }

    const txs = await BlueElectrum.multiGetHistoryByAddress(lagAddressesToFetch); // <------ electrum call

    for (let c = this.next_free_address_index; c < this.next_free_address_index + this.gap_limit; c++) {
      const address = this._getExternalAddressByIndex(c);
      if (txs[address] && Array.isArray(txs[address]) && txs[address].length > 0) {
        // whoa, someone uses our wallet outside! better catch up
        this.next_free_address_index = c + 1;
      }
    }

    for (let c = this.next_free_change_address_index; c < this.next_free_change_address_index + this.gap_limit; c++) {
      const address = this._getInternalAddressByIndex(c);
      if (txs[address] && Array.isArray(txs[address]) && txs[address].length > 0) {
        // whoa, someone uses our wallet outside! better catch up
        this.next_free_change_address_index = c + 1;
      }
    }

    // next, business as usuall. fetch balances

    const addresses2fetch = [];

    // generating all involved addresses.
    // basically, refetch all from index zero to maximum. doesnt matter
    // since we batch them 100 per call

    // external
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      addresses2fetch.push(this._getExternalAddressByIndex(c));
    }

    // internal
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      addresses2fetch.push(this._getInternalAddressByIndex(c));
    }

    const balances = await BlueElectrum.multiGetBalanceByAddress(addresses2fetch);

    // converting to a more compact internal format
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      const addr = this._getExternalAddressByIndex(c);
      if (balances.addresses[addr]) {
        // first, if balances differ from what we store - we delete transactions for that
        // address so next fetchTransactions() will refetch everything
        if (this._balances_by_external_index[c]) {
          if (
            this._balances_by_external_index[c].c !== balances.addresses[addr].confirmed ||
            this._balances_by_external_index[c].u !== balances.addresses[addr].unconfirmed
          ) {
            delete this._txs_by_external_index[c];
          }
        }
        // update local representation of balances on that address:
        this._balances_by_external_index[c] = {
          c: balances.addresses[addr].confirmed,
          u: balances.addresses[addr].unconfirmed,
        };
      }
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      const addr = this._getInternalAddressByIndex(c);
      if (balances.addresses[addr]) {
        // first, if balances differ from what we store - we delete transactions for that
        // address so next fetchTransactions() will refetch everything
        if (this._balances_by_internal_index[c]) {
          if (
            this._balances_by_internal_index[c].c !== balances.addresses[addr].confirmed ||
            this._balances_by_internal_index[c].u !== balances.addresses[addr].unconfirmed
          ) {
            delete this._txs_by_internal_index[c];
          }
        }
        // update local representation of balances on that address:
        this._balances_by_internal_index[c] = {
          c: balances.addresses[addr].confirmed,
          u: balances.addresses[addr].unconfirmed,
        };
      }
    }

    this._lastBalanceFetch = +new Date();
  }

  async fetchUtxo() {
    // fetching utxo of addresses that only have some balance
    let addressess = [];

    // considering confirmed balance:
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      if (this._balances_by_external_index[c] && this._balances_by_external_index[c].c && this._balances_by_external_index[c].c > 0) {
        addressess.push(this._getExternalAddressByIndex(c));
      }
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      if (this._balances_by_internal_index[c] && this._balances_by_internal_index[c].c && this._balances_by_internal_index[c].c > 0) {
        addressess.push(this._getInternalAddressByIndex(c));
      }
    }

    // considering UNconfirmed balance:
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      if (this._balances_by_external_index[c] && this._balances_by_external_index[c].u && this._balances_by_external_index[c].u > 0) {
        addressess.push(this._getExternalAddressByIndex(c));
      }
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      if (this._balances_by_internal_index[c] && this._balances_by_internal_index[c].u && this._balances_by_internal_index[c].u > 0) {
        addressess.push(this._getInternalAddressByIndex(c));
      }
    }

    // note: we could remove checks `.c` and `.u` to simplify code, but the resulting `addressess` array would be bigger, thus bigger batch
    // to fetch (or maybe even several fetches), which is not critical but undesirable.
    // anyway, result has `.confirmations` property for each utxo, so outside caller can easily filter out unconfirmed if he wants to

    addressess = [...new Set(addressess)]; // deduplicate just for any case

    const fetchedUtxo = await BlueElectrum.multiGetUtxoByAddress(addressess);
    this._utxo = [];
    for (const arr of Object.values(fetchedUtxo)) {
      this._utxo = this._utxo.concat(arr);
    }

    // backward compatibility TODO: remove when we make sure `.utxo` is not used
    this.utxo = this._utxo;
    // this belongs in `.getUtxo()`
    for (const u of this.utxo) {
      u.txid = u.txId;
      u.amount = u.value;
      u.wif = this._getWifForAddress(u.address);
      u.confirmations = u.height ? 1 : 0;
    }

    this.utxo = this.utxo.sort((a, b) => a.amount - b.amount);
    // more consistent, so txhex in unit tests wont change
  }

  /**
   * Getter for previously fetched UTXO. For example:
   *     [ { height: 0,
   *    value: 666,
   *    address: 'string',
   *    txId: 'string',
   *    vout: 1,
   *    txid: 'string',
   *    amount: 666,
   *    wif: 'string',
   *    confirmations: 0 } ]
   *
   * @returns {[]}
   */
  getUtxo({ frozen = false } = {}) {
    let ret = [];

    if (this._utxo.length === 0) {
      ret = this.getDerivedUtxoFromOurTransaction(); // oy vey, no stored utxo. lets attempt to derive it from stored transactions
    } else {
      ret = this._utxo;
    }
    if (!frozen) {
      ret = ret.filter(({ txid, vout }) => !this.getUTXOMetadata(txid, vout).frozen);
    }
    return ret;
  }

  getDerivedUtxoFromOurTransaction(returnSpentUtxoAsWell = false) {
    const utxos = [];

    // its faster to pre-build hashmap of owned addresses than to query `this.weOwnAddress()`, which in turn
    // iterates over all addresses in hierarchy
    const ownedAddressesHashmap = {};
    for (let c = 0; c < this.next_free_address_index + 1; c++) {
      ownedAddressesHashmap[this._getExternalAddressByIndex(c)] = true;
    }
    for (let c = 0; c < this.next_free_change_address_index + 1; c++) {
      ownedAddressesHashmap[this._getInternalAddressByIndex(c)] = true;
    }

    for (const tx of this.getTransactions()) {
      for (const output of tx.outputs) {
        let address = false;
        if (output.scriptPubKey && output.scriptPubKey.addresses && output.scriptPubKey.addresses[0]) {
          address = output.scriptPubKey.addresses[0];
        }
        if (ownedAddressesHashmap[address]) {
          const value = new BigNumber(output.value).multipliedBy(100000000).toNumber();
          utxos.push({
            txid: tx.txid,
            txId: tx.txid,
            vout: output.n,
            address,
            value,
            amount: value,
            confirmations: tx.confirmations,
            wif: false,
            height: BlueElectrum.estimateCurrentBlockheight() - tx.confirmations,
          });
        }
      }
    }

    if (returnSpentUtxoAsWell) return utxos;

    // got all utxos we ever had. lets filter out the ones that are spent:
    const ret = [];
    for (const utxo of utxos) {
      let spent = false;
      for (const tx of this.getTransactions()) {
        for (const input of tx.inputs) {
          if (input.txid === utxo.txid && input.vout === utxo.vout) spent = true;
          // utxo we got previously was actually spent right here ^^
        }
      }

      if (!spent) {
        // filling WIFs only for legit unspent UTXO, as it is a slow operation
        utxo.wif = this._getWifForAddress(utxo.address);
        ret.push(utxo);
      }
    }

    return ret;
  }

  _getDerivationPathByAddress(address, BIP = 84) {
    const path = `m/${BIP}'/0'/0'`;
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      if (this._getExternalAddressByIndex(c) === address) return path + '/0/' + c;
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      if (this._getInternalAddressByIndex(c) === address) return path + '/1/' + c;
    }

    return false;
  }

  /**
   *
   * @param address {string} Address that belongs to this wallet
   * @returns {Buffer|boolean} Either buffer with pubkey or false
   */
  _getPubkeyByAddress(address) {
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      if (this._getExternalAddressByIndex(c) === address) return this._getNodePubkeyByIndex(0, c);
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      if (this._getInternalAddressByIndex(c) === address) return this._getNodePubkeyByIndex(1, c);
    }

    return false;
  }

  weOwnAddress(address) {
    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      if (this._getExternalAddressByIndex(c) === address) return true;
    }
    for (let c = 0; c < this.next_free_change_address_index + this.gap_limit; c++) {
      if (this._getInternalAddressByIndex(c) === address) return true;
    }
    return false;
  }

  /**
   *
   * @param utxos {Array.<{vout: Number, value: Number, txId: String, address: String}>} List of spendable utxos
   * @param targets {Array.<{value: Number, address: String}>} Where coins are going. If theres only 1 target and that target has no value - this will send MAX to that address (respecting fee rate)
   * @param feeRate {Number} satoshi per byte
   * @param changeAddress {String} Excessive coins will go back to that address
   * @param sequence {Number} Used in RBF
   * @param skipSigning {boolean} Whether we should skip signing, use returned `psbt` in that case
   * @param masterFingerprint {number} Decimal number of wallet's master fingerprint
   * @returns {{outputs: Array, tx: Transaction, inputs: Array, fee: Number, psbt: Psbt}}
   */
  createTransaction(utxos, targets, feeRate, changeAddress, sequence, skipSigning = false, masterFingerprint) {
    if (targets.length === 0) throw new Error('No destination provided');
    const { inputs, outputs, fee } = this.coinselect(utxos, targets, feeRate, changeAddress);

    sequence = sequence || AbstractHDElectrumWallet.defaultRBFSequence;
    let psbt = new bitcoin.Psbt();
    let c = 0;
    const keypairs = {};
    const values = {};

    inputs.forEach(input => {
      let keyPair;
      if (!skipSigning) {
        // skiping signing related stuff
        keyPair = bitcoin.ECPair.fromWIF(this._getWifForAddress(input.address));
        keypairs[c] = keyPair;
      }
      values[c] = input.value;
      c++;
      if (!skipSigning) {
        // skiping signing related stuff
        if (!input.address || !this._getWifForAddress(input.address)) throw new Error('Internal error: no address or WIF to sign input');
      }

      let masterFingerprintBuffer;
      if (masterFingerprint) {
        let masterFingerprintHex = Number(masterFingerprint).toString(16);
        if (masterFingerprintHex.length < 8) masterFingerprintHex = '0' + masterFingerprintHex; // conversion without explicit zero might result in lost byte
        const hexBuffer = Buffer.from(masterFingerprintHex, 'hex');
        masterFingerprintBuffer = Buffer.from(reverse(hexBuffer));
      } else {
        masterFingerprintBuffer = Buffer.from([0x00, 0x00, 0x00, 0x00]);
      }
      // this is not correct fingerprint, as we dont know real fingerprint - we got zpub with 84/0, but fingerpting
      // should be from root. basically, fingerprint should be provided from outside  by user when importing zpub

      psbt = this._addPsbtInput(psbt, input, sequence, masterFingerprintBuffer);
    });

    outputs.forEach(output => {
      // if output has no address - this is change output
      let change = false;
      if (!output.address) {
        change = true;
        output.address = changeAddress;
      }

      const path = this._getDerivationPathByAddress(output.address);
      const pubkey = this._getPubkeyByAddress(output.address);
      let masterFingerprintBuffer;

      if (masterFingerprint) {
        let masterFingerprintHex = Number(masterFingerprint).toString(16);
        if (masterFingerprintHex.length < 8) masterFingerprintHex = '0' + masterFingerprintHex; // conversion without explicit zero might result in lost byte
        const hexBuffer = Buffer.from(masterFingerprintHex, 'hex');
        masterFingerprintBuffer = Buffer.from(reverse(hexBuffer));
      } else {
        masterFingerprintBuffer = Buffer.from([0x00, 0x00, 0x00, 0x00]);
      }

      // this is not correct fingerprint, as we dont know realfingerprint - we got zpub with 84/0, but fingerpting
      // should be from root. basically, fingerprint should be provided from outside  by user when importing zpub

      const outputData = {
        address: output.address,
        value: output.value,
      };

      if (change) {
        outputData.bip32Derivation = [
          {
            masterFingerprint: masterFingerprintBuffer,
            path,
            pubkey,
          },
        ];
      }

      psbt.addOutput(outputData);
    });

    if (!skipSigning) {
      // skiping signing related stuff
      for (let cc = 0; cc < c; cc++) {
        psbt.signInput(cc, keypairs[cc]);
      }
    }

    let tx;
    if (!skipSigning) {
      tx = psbt.finalizeAllInputs().extractTransaction();
    }
    return { tx, inputs, outputs, fee, psbt };
  }

  _addPsbtInput(psbt, input, sequence, masterFingerprintBuffer) {
    const pubkey = this._getPubkeyByAddress(input.address);
    const path = this._getDerivationPathByAddress(input.address);
    const p2wpkh = bitcoin.payments.p2wpkh({ pubkey });

    psbt.addInput({
      hash: input.txId,
      index: input.vout,
      sequence,
      bip32Derivation: [
        {
          masterFingerprint: masterFingerprintBuffer,
          path,
          pubkey,
        },
      ],
      witnessUtxo: {
        script: p2wpkh.output,
        value: input.value,
      },
    });

    return psbt;
  }

  /**
   * Combines 2 PSBTs into final transaction from which you can
   * get HEX and broadcast
   *
   * @param base64one {string|Psbt}
   * @param base64two {string|Psbt}
   * @returns {Transaction}
   */
  combinePsbt(base64one, base64two) {
    const final1 = typeof base64one === 'string' ? bitcoin.Psbt.fromBase64(base64one) : base64one;
    const final2 = typeof base64two === 'string' ? bitcoin.Psbt.fromBase64(base64two) : base64two;
    final1.combine(final2);

    let extractedTransaction;
    try {
      extractedTransaction = final1.finalizeAllInputs().extractTransaction();
    } catch (_) {
      // probably already finalized
      extractedTransaction = final1.extractTransaction();
    }

    return extractedTransaction;
  }

  /**
   * Creates Segwit Bech32 Bitcoin address
   *
   * @param hdNode
   * @returns {String}
   */
  static _nodeToBech32SegwitAddress(hdNode) {
    return bitcoin.payments.p2wpkh({
      pubkey: hdNode.publicKey,
    }).address;
  }

  static _nodeToLegacyAddress(hdNode) {
    return bitcoin.payments.p2pkh({
      pubkey: hdNode.publicKey,
    }).address;
  }

  static _getTransactionsFromHistories(histories) {
    const txs = [];
    for (const history of Object.values(histories)) {
      for (const tx of history) {
        txs.push(tx);
      }
    }
    return txs;
  }

  /**
   * Probes zero address in external hierarchy for transactions, if there are any returns TRUE.
   * Zero address is a pretty good indicator, since its a first one to fund the wallet. How can you use the wallet and
   * not fund it first?
   *
   * @returns {Promise<boolean>}
   */
  async wasEverUsed() {
    const txs = await BlueElectrum.getTransactionsByAddress(this._getExternalAddressByIndex(0));
    return txs.length > 0;
  }

  /**
   * @inheritDoc
   */
  getAllExternalAddresses() {
    const ret = [];

    for (let c = 0; c < this.next_free_address_index + this.gap_limit; c++) {
      ret.push(this._getExternalAddressByIndex(c));
    }

    return ret;
  }

  // check if address is a Change address. Needed for Coin control
  addressIsChange(address) {
    for (let c = 0; c < this.next_free_change_address_index + 1; c++) {
      if (address === this._getInternalAddressByIndex(c)) return true;
    }
    return false;
  }
}