(function(EXPORTS) { //btcOperator v1.0.9
    /* BTC Crypto and API Operator */
    const btcOperator = EXPORTS;

    //This library uses API provided by chain.so (https://chain.so/)
    const URL = "https://chain.so/api/v2/";

    const fetch_api = btcOperator.fetch = function(api) {
        return new Promise((resolve, reject) => {
            console.debug(URL + api);
            fetch(URL + api).then(response => {
                response.json()
                    .then(result => result.status === "success" ? resolve(result) : reject(result))
                    .catch(error => reject(error))
            }).catch(error => reject(error))
        })
    };

    const SATOSHI_IN_BTC = 1e8;

    function get_fee_rate() {
        return new Promise((resolve, reject) => {
            fetch('https://api.blockchain.info/mempool/fees').then(response => {
                if (response.ok)
                    response.json()
                    .then(result => resolve(parseFloat((result.regular / SATOSHI_IN_BTC).toFixed(8))))
                    .catch(error => reject(error));
                else
                    reject(response);
            }).catch(error => reject(error))
        })
    }

    const broadcast = btcOperator.broadcast = rawtx => new Promise((resolve, reject) => {
        $.ajax({
            type: "POST",
            url: URL + "send_tx/BTC/",
            data: {
                "tx_hex": rawtx
            },
            dataType: "json",
            error: e => reject(e.responseJSON),
            success: r => r.status === "success" ? resolve(r.data) : reject(r)
        })
    });

    Object.defineProperties(btcOperator, {
        newKeys: {
            get: () => {
                let r = coinjs.newKeys();
                r.segwitAddress = coinjs.segwitAddress(r.pubkey).address;
                r.bech32Address = coinjs.bech32Address(r.pubkey).address;
                return r;
            }
        },
        pubkey: {
            value: key => key.length >= 66 ? key : (key.length == 64 ? coinjs.newPubkey(key) : coinjs.wif2pubkey(key).pubkey)
        },
        address: {
            value: (key, prefix = undefined) => coinjs.pubkey2address(btcOperator.pubkey(key), prefix)
        },
        segwitAddress: {
            value: key => coinjs.segwitAddress(btcOperator.pubkey(key)).address
        },
        bech32Address: {
            value: key => coinjs.bech32Address(btcOperator.pubkey(key)).address
        }
    });

    coinjs.compressed = true;

    const verifyKey = btcOperator.verifyKey = function(addr, key) {
        if (!addr || !key)
            return undefined;
        switch (coinjs.addressDecode(addr).type) {
            case "standard":
                return btcOperator.address(key) === addr;
            case "multisig":
                return btcOperator.segwitAddress(key) === addr;
            case "bech32":
                return btcOperator.bech32Address(key) === addr;
            default:
                return null;
        }
    }

    const validateAddress = btcOperator.validateAddress = function(addr) {
        if (!addr)
            return undefined;
        let type = coinjs.addressDecode(addr).type;
        if (["standard", "multisig", "bech32"].includes(type))
            return type;
        else
            return false;
    }

    btcOperator.multiSigAddress = function(pubKeys, minRequired) {
        if (!Array.isArray(pubKeys))
            throw "pubKeys must be an array of public keys";
        else if (pubKeys.length < minRequired)
            throw "minimum required should be less than the number of pubKeys";
        return coinjs.pubkeys2MultisigAddress(pubKeys, minRequired);
    }

    //convert from one blockchain to another blockchain (target version)
    btcOperator.convert = {};

    btcOperator.convert.wif = function(source_wif, target_version = coinjs.priv) {
        let keyHex = decodeLegacy(source_wif).hex;
        if (!keyHex || keyHex.length < 66 || !/01$/.test(keyHex))
            return null;
        else
            return encodeLegacy(keyHex, target_version);
    }

    btcOperator.convert.legacy2legacy = function(source_addr, target_version = coinjs.pub) {
        let rawHex = decodeLegacy(source_addr).hex;
        if (!rawHex)
            return null;
        else
            return encodeLegacy(rawHex, target_version);
    }

    btcOperator.convert.legacy2bech = function(source_addr, target_version = coinjs.bech32.version, target_hrp = coinjs.bech32.hrp) {
        let rawHex = decodeLegacy(source_addr).hex;
        if (!rawHex)
            return null;
        else
            return encodeBech32(rawHex, target_version, target_hrp);
    }

    btcOperator.convert.bech2bech = function(source_addr, target_version = coinjs.bech32.version, target_hrp = coinjs.bech32.hrp) {
        let rawHex = decodeBech32(source_addr).hex;
        if (!rawHex)
            return null;
        else
            return encodeBech32(rawHex, target_version, target_hrp);
    }

    btcOperator.convert.bech2legacy = function(source_addr, target_version = coinjs.pub) {
        let rawHex = decodeBech32(source_addr).hex;
        if (!rawHex)
            return null;
        else
            return encodeLegacy(rawHex, target_version);
    }

    function decodeLegacy(source) {
        var decode = coinjs.base58decode(source);
        var raw = decode.slice(0, decode.length - 4),
            checksum = decode.slice(decode.length - 4);
        var hash = Crypto.SHA256(Crypto.SHA256(raw, {
            asBytes: true
        }), {
            asBytes: true
        });
        if (hash[0] != checksum[0] || hash[1] != checksum[1] || hash[2] != checksum[2] || hash[3] != checksum[3])
            return null;
        let version = raw.shift();
        return {
            version: version,
            hex: Crypto.util.bytesToHex(raw)
        }
    }

    function encodeLegacy(hex, version) {
        var bytes = Crypto.util.hexToBytes(hex);
        bytes.unshift(version);
        var hash = Crypto.SHA256(Crypto.SHA256(bytes, {
            asBytes: true
        }), {
            asBytes: true
        });
        var checksum = hash.slice(0, 4);
        return coinjs.base58encode(bytes.concat(checksum));
    }

    function decodeBech32(source) {
        let decode = coinjs.bech32_decode(source);
        if (!decode)
            return null;
        var raw = decode.data;
        let version = raw.shift();
        raw = coinjs.bech32_convert(raw, 5, 8, false);
        return {
            hrp: decode.hrp,
            version: version,
            hex: Crypto.util.bytesToHex(raw)
        }
    }

    function encodeBech32(hex, version, hrp) {
        var bytes = Crypto.util.hexToBytes(hex);
        bytes = coinjs.bech32_convert(bytes, 8, 5, true);
        bytes.unshift(version)
        return coinjs.bech32_encode(hrp, bytes);
    }

    //BTC blockchain APIs

    btcOperator.getBalance = addr => new Promise((resolve, reject) => {
        fetch_api(`get_address_balance/BTC/${addr}`)
            .then(result => resolve(parseFloat(result.data.confirmed_balance)))
            .catch(error => reject(error))
    });

    const BASE_TX_SIZE = 12,
        BASE_INPUT_SIZE = 41,
        LEGACY_INPUT_SIZE = 107,
        BECH32_INPUT_SIZE = 27,
        SEGWIT_INPUT_SIZE = 59,
        MULTISIG_INPUT_SIZE_ES = 351,
        BASE_OUTPUT_SIZE = 9,
        LEGACY_OUTPUT_SIZE = 25,
        BECH32_OUTPUT_SIZE = 23,
        SEGWIT_OUTPUT_SIZE = 23;

    function _redeemScript(addr, key) {
        let decode = coinjs.addressDecode(addr);
        switch (decode.type) {
            case "standard":
                return false;
            case "multisig":
                return key ? coinjs.segwitAddress(btcOperator.pubkey(key)).redeemscript : null;
            case "bech32":
                return decode.redeemscript;
            default:
                return null;
        }
    }

    function _sizePerInput(addr, rs) {
        switch (coinjs.addressDecode(addr).type) {
            case "standard":
                return BASE_INPUT_SIZE + LEGACY_INPUT_SIZE;
            case "bech32":
                return BASE_INPUT_SIZE + BECH32_INPUT_SIZE;
            case "multisig":
                switch (coinjs.script().decodeRedeemScript(rs).type) {
                    case "segwit__":
                        return BASE_INPUT_SIZE + SEGWIT_INPUT_SIZE;
                    case "multisig__":
                        return BASE_INPUT_SIZE + MULTISIG_INPUT_SIZE_ES;
                    default:
                        return null;
                };
            default:
                return null;
        }
    }

    function _sizePerOutput(addr) {
        switch (coinjs.addressDecode(addr).type) {
            case "standard":
                return BASE_OUTPUT_SIZE + LEGACY_OUTPUT_SIZE;
            case "bech32":
                return BASE_OUTPUT_SIZE + BECH32_OUTPUT_SIZE;
            case "multisig":
                return BASE_OUTPUT_SIZE + SEGWIT_OUTPUT_SIZE;
            default:
                return null;
        }
    }

    function validateTxParameters(parameters) {
        let invalids = [];
        //sender-ids
        if (parameters.senders) {
            if (!Array.isArray(parameters.senders))
                parameters.senders = [parameters.senders];
            parameters.senders.forEach(id => !validateAddress(id) ? invalids.push(id) : null);
            if (invalids.length)
                throw "Invalid senders:" + invalids;
        }
        if (parameters.privkeys) {
            if (!Array.isArray(parameters.privkeys))
                parameters.privkeys = [parameters.privkeys];
            if (parameters.senders.length != parameters.privkeys.length)
                throw "Array length for senders and privkeys should be equal";
            parameters.senders.forEach((id, i) => {
                let key = parameters.privkeys[i];
                if (!verifyKey(id, key)) //verify private-key
                    invalids.push(id);
                if (key.length === 64) //convert Hex to WIF if needed
                    parameters.privkeys[i] = coinjs.privkey2wif(key);
            });
            if (invalids.length)
                throw "Invalid keys:" + invalids;
        }
        //receiver-ids (and change-id)
        if (!Array.isArray(parameters.receivers))
            parameters.receivers = [parameters.receivers];
        parameters.receivers.forEach(id => !validateAddress(id) ? invalids.push(id) : null);
        if (invalids.length)
            throw "Invalid receivers:" + invalids;
        if (parameters.change_addr && !validateAddress(parameters.change_addr))
            throw "Invalid change_address:" + parameters.change_addr;
        //fee and amounts
        if ((typeof parameters.fee !== "number" || parameters.fee <= 0) && parameters.fee !== null) //fee = null (auto calc)
            throw "Invalid fee:" + parameters.fee;
        if (!Array.isArray(parameters.amounts))
            parameters.amounts = [parameters.amounts];
        if (parameters.receivers.length != parameters.amounts.length)
            throw "Array length for receivers and amounts should be equal";
        parameters.amounts.forEach(a => typeof a !== "number" || a <= 0 ? invalids.push(a) : null);
        if (invalids.length)
            throw "Invalid amounts:" + invalids;
        //return
        return parameters;
    }

    function createTransaction(senders, redeemScripts, receivers, amounts, fee, change_addr) {
        return new Promise((resolve, reject) => {
            let total_amount = parseFloat(amounts.reduce((t, a) => t + a, 0).toFixed(8));
            const tx = coinjs.transaction();
            let output_size = addOutputs(tx, receivers, amounts, change_addr);
            addInputs(tx, senders, redeemScripts, total_amount, fee, output_size).then(result => {
                if (result.change_amount > 0)
                    tx.outs[tx.outs.length - 1].value = parseInt(result.change_amount * SATOSHI_IN_BTC); //values are in satoshi
                else
                    tx.outs.pop(); //remove the change output if no change_amount
                result.output_size = output_size;
                result.output_amount = total_amount;
                result.total_size = BASE_TX_SIZE + output_size + result.input_size;
                result.transaction = tx;
                resolve(result);
            }).catch(error => reject(error))
        })
    }

    function addInputs(tx, senders, redeemScripts, total_amount, fee, output_size) {
        return new Promise((resolve, reject) => {
            if (fee !== null) {
                addUTXOs(tx, senders, redeemScripts, total_amount + fee, false).then(result => {
                    result.fee = fee;
                    resolve(result);
                }).catch(error => reject(error))
            } else {
                get_fee_rate().then(fee_rate => {
                    let net_fee = BASE_TX_SIZE * fee_rate;
                    net_fee += (output_size * fee_rate);
                    addUTXOs(tx, senders, redeemScripts, total_amount + net_fee, fee_rate).then(result => {
                        result.fee_amount = parseFloat((net_fee + (result.input_size * fee_rate)).toFixed(8));
                        result.fee_rate = fee_rate;
                        resolve(result);
                    }).catch(error => reject(error))
                }).catch(error => reject(error))
            }
        })
    }

    function addUTXOs(tx, senders, redeemScripts, required_amount, fee_rate, rec_args = {}) {
        return new Promise((resolve, reject) => {
            required_amount = parseFloat(required_amount.toFixed(8));
            if (typeof rec_args.n === "undefined") {
                rec_args.n = 0;
                rec_args.input_size = 0;
                rec_args.input_amount = 0;
            }
            if (required_amount <= 0)
                return resolve({
                    input_size: rec_args.input_size,
                    input_amount: rec_args.input_amount,
                    change_amount: required_amount * -1 //required_amount will be -ve of change_amount
                });
            else if (rec_args.n >= senders.length)
                return reject("Insufficient Balance");
            let addr = senders[rec_args.n],
                rs = redeemScripts[rec_args.n];
            let size_per_input = _sizePerInput(addr, rs);
            fetch_api(`get_tx_unspent/BTC/${addr}`).then(result => {
                let utxos = result.data.txs;
                console.debug("add-utxo", addr, rs, required_amount, utxos);
                for (let i = 0; i < utxos.length && required_amount > 0; i++) {
                    if (!utxos[i].confirmations) //ignore unconfirmed utxo
                        continue;
                    var script;
                    if (!rs || !rs.length) //legacy script
                        script = utxos[i].script_hex;
                    else if (((rs.match(/^00/) && rs.length == 44)) || (rs.length == 40 && rs.match(/^[a-f0-9]+$/gi))) {
                        //redeemScript for segwit/bech32
                        let s = coinjs.script();
                        s.writeBytes(Crypto.util.hexToBytes(rs));
                        s.writeOp(0);
                        s.writeBytes(coinjs.numToBytes((utxos[i].value * SATOSHI_IN_BTC).toFixed(0), 8));
                        script = Crypto.util.bytesToHex(s.buffer);
                    } else //redeemScript for multisig
                        script = rs;
                    tx.addinput(utxos[i].txid, utxos[i].output_no, script, 0xfffffffd /*sequence*/ ); //0xfffffffd for Replace-by-fee
                    //update track values
                    rec_args.input_size += size_per_input;
                    rec_args.input_amount += parseFloat(utxos[i].value);
                    required_amount -= parseFloat(utxos[i].value);
                    if (fee_rate) //automatic fee calculation (dynamic)
                        required_amount += size_per_input * fee_rate;
                }
                rec_args.n += 1;
                addUTXOs(tx, senders, redeemScripts, required_amount, fee_rate, rec_args)
                    .then(result => resolve(result))
                    .catch(error => reject(error))
            }).catch(error => reject(error))
        })
    }

    function addOutputs(tx, receivers, amounts, change_addr) {
        let size = 0;
        for (let i in receivers) {
            tx.addoutput(receivers[i], amounts[i]);
            size += _sizePerOutput(receivers[i]);
        }
        tx.addoutput(change_addr, 0);
        size += _sizePerOutput(change_addr);
        return size;
    }

    /*
    function autoFeeCalc(tx) {
        return new Promise((resolve, reject) => {
            get_fee_rate().then(fee_rate => {
                let tx_size = tx.size();
                for (var i = 0; i < this.ins.length; i++)
                    switch (tx.extractScriptKey(i).type) {
                        case 'scriptpubkey':
                            tx_size += SIGN_SIZE;
                            break;
                        case 'segwit':
                        case 'multisig':
                            tx_size += SIGN_SIZE * 0.25;
                            break;
                        default:
                            console.warn('Unknown script-type');
                            tx_size += SIGN_SIZE;
                    }
                resolve(tx_size * fee_rate);
            }).catch(error => reject(error))
        })
    }

    function editFee(tx, current_fee, target_fee, index = -1) {
        //values are in satoshi
        index = parseInt(index >= 0 ? index : tx.outs.length - index);
        if (index < 0 || index >= tx.outs.length)
            throw "Invalid index";
        let edit_value = parseInt(current_fee - target_fee), //rip of any decimal places
            current_value = tx.outs[index].value; //could be BigInterger
        if (edit_value < 0 && edit_value > current_value)
            throw "Insufficient value at vout";
        tx.outs[index].value = current_value instanceof BigInteger ?
            current_value.add(new BigInteger('' + edit_value)) : parseInt(current_value + edit_value);
    }
    */

    btcOperator.sendTx = function(senders, privkeys, receivers, amounts, fee, change_addr = null) {
        return new Promise((resolve, reject) => {
            try {
                ({
                    senders,
                    privkeys,
                    receivers,
                    amounts
                } = validateTxParameters({
                    senders,
                    privkeys,
                    receivers,
                    amounts,
                    fee,
                    change_addr
                }));
            } catch (e) {
                return reject(e)
            }
            let redeemScripts = [],
                wif_keys = [];
            for (let i in senders) {
                let rs = _redeemScript(senders[i], privkeys[i]); //get redeem-script (segwit/bech32)
                redeemScripts.push(rs);
                rs === false ? wif_keys.unshift(privkeys[i]) : wif_keys.push(privkeys[i]); //sorting private-keys (wif)
            }
            if (redeemScripts.includes(null)) //TODO: segwit
                return reject("Unable to get redeem-script");
            //create transaction
            createTransaction(senders, redeemScripts, receivers, amounts, fee, change_addr || senders[0]).then(result => {
                let tx = result.transaction;
                console.debug("Unsigned:", tx.serialize());
                new Set(wif_keys).forEach(key => console.debug("Signing key:", key, tx.sign(key, 1 /*sighashtype*/ ))); //Sign the tx using private key WIF
                console.debug("Signed:", tx.serialize());
                debugger;
                broadcast(tx.serialize())
                    .then(result => resolve(result))
                    .catch(error => reject(error));
            }).catch(error => reject(error));
        })
    }

    btcOperator.createTx = function(senders, receivers, amounts, fee = null, change_addr = null) {
        return new Promise((resolve, reject) => {
            try {
                ({
                    senders,
                    receivers,
                    amounts
                } = validateTxParameters({
                    senders,
                    receivers,
                    amounts,
                    fee,
                    change_addr
                }));
            } catch (e) {
                return reject(e)
            }
            let redeemScripts = senders.map(id => _redeemScript(id));
            if (redeemScripts.includes(null)) //TODO: segwit
                return reject("Unable to get redeem-script");
            //create transaction
            createTransaction(senders, redeemScripts, receivers, amounts, fee, change_addr || senders[0]).then(result => {
                result.tx_hex = result.transaction.serialize();
                delete result.transaction;
                resolve(result);
            }).catch(error => reject(error))
        })
    }

    btcOperator.createMultiSigTx = function(sender, redeemScript, receivers, amounts, fee) {
        return new Promise((resolve, reject) => {
            //validate tx parameters
            if (validateAddress(sender) !== "multisig")
                return reject("Invalid sender (multisig):" + sender);
            else {
                let script = coinjs.script();
                let decode = script.decodeRedeemScript(redeemScript);
                if (!decode || decode.address !== sender)
                    return reject("Invalid redeem-script");
            }
            try {
                ({
                    receivers,
                    amounts
                } = validateTxParameters({
                    receivers,
                    amounts,
                    fee
                }));
            } catch (e) {
                return reject(e)
            }
            //create transaction
            createTransaction([sender], [redeemScript], receivers, amounts, fee, sender).then(result => {
                result.tx_hex = result.transaction.serialize();
                delete result.transaction;
                resolve(result);
            }).catch(error => reject(error))

        })
    }

    function deserializeTx(tx) {
        if (typeof tx === 'string' || Array.isArray(tx)) {
            try {
                tx = coinjs.transaction().deserialize(tx);
            } catch {
                throw "Invalid transaction hex";
            }
        } else if (typeof tx !== 'object' || typeof tx.sign !== 'function')
            throw "Invalid transaction object";
        return tx;
    }

    btcOperator.signTx = function(tx, privkeys, sighashtype = 1) {
        tx = deserializeTx(tx);
        if (!Array.isArray(privkeys))
            privkeys = [privkeys];
        for (let i in privkeys)
            if (privkeys[i].length === 64)
                privkeys[i] = coinjs.privkey2wif(privkeys[i]);
        new Set(privkeys).forEach(key => tx.sign(key, sighashtype)); //Sign the tx using private key WIF
        return tx.serialize();
    }

    btcOperator.checkSigned = function(tx, bool = true) {
        tx = deserializeTx(tx);
        let n = [];
        for (let i in tx.ins) {
            var s = tx.extractScriptKey(i);
            if (s['type'] !== 'multisig')
                n.push(s.signed == 'true' || (tx.witness[i] && tx.witness[i].length == 2))
            else {
                var rs = coinjs.script().decodeRedeemScript(s.script);
                let x = {
                    s: s['signatures'],
                    r: rs['signaturesRequired'],
                    t: rs['pubkeys'].length
                };
                if (x.r > x.t)
                    throw "signaturesRequired is more than publicKeys";
                else if (x.s < x.r)
                    n.push(x);
                else
                    n.push(true);
            }
        }
        return bool ? !(n.filter(x => x !== true).length) : n;
    }

    btcOperator.checkIfSameTx = function(tx1, tx2) {
        tx1 = deserializeTx(tx1);
        tx2 = deserializeTx(tx2);
        if (tx1.ins.length !== tx2.ins.length || tx1.outs.length !== tx2.outs.length)
            return false;
        for (let i = 0; i < tx1.ins.length; i++)
            if (tx1.ins[i].outpoint.hash !== tx2.ins[i].outpoint.hash || tx1.ins[i].outpoint.index !== tx2.ins[i].outpoint.index)
                return false;
        for (let i = 0; i < tx2.ins.length; i++)
            if (tx1.outs[i].value !== tx2.outs[i].value || Crypto.util.bytesToHex(tx1.outs[i].script.buffer) !== Crypto.util.bytesToHex(tx2.outs[i].script.buffer))
                return false;
        return true;
    }

    btcOperator.getTx = txid => new Promise((resolve, reject) => {
        fetch_api(`get_tx/BTC/${txid}`)
            .then(result => resolve(result.data))
            .catch(error => reject(error))
    });

    btcOperator.getAddressData = addr => new Promise((resolve, reject) => {
        fetch_api(`address/BTC/${addr}`)
            .then(result => resolve(result.data))
            .catch(error => reject(error))
    });

    btcOperator.getBlock = block => new Promise((resolve, reject) => {
        fetch_api(`get_block/BTC/${block}`)
            .then(result => resolve(result.data))
            .catch(error => reject(error))
    });

})('object' === typeof module ? module.exports : window.btcOperator = {});