'use strict';

var _ = require('lodash');
var async   = require('async');
var logger  = require('./logger');

var argv = require('minimist')(process.argv.slice(2));

var SATOSHI_FACTOR = 1e8;
var POLLING_RATE = 60 * 1000; // poll each minute
var REAP_RATE = 2 * 1000;
var PENDING_TIMEOUT = 70 * 1000;

if (argv.timeout) PENDING_TIMEOUT = argv.timeout / 1000;

// TODO: might have to update this if user is allowed to extend monitoring time
var DEPOSIT_TIMEOUT = 130 * 1000;

var db = null;

var tickerPlugins = {};
var traderPlugin = null;
var walletPlugins = {};
var idVerifierPlugin = null;
var infoPlugin = null;

var currentlyUsedPlugins = {};

var cachedConfig = null;
var deviceCurrency = 'USD';

var lastBalances = {};
var lastRates = {};

var tradesQueue = [];

// that's basically a constructor
exports.init = function init(databaseHandle) {
  if (!databaseHandle) {
    throw new Error('\'db\' is required');
  }

  db = databaseHandle;
};

function loadPlugin(name, config) {

  // plugins definitions
  var moduleMethods = {
    ticker: ['ticker'],
    trader: ['balance', 'purchase', 'sell'],
    wallet: ['balance', 'sendBitcoins', 'newAddress'],
    idVerifier: ['verifyUser', 'verifyTransaction'],
    info: ['checkAddress']
  };

  var plugin = null;

  // each used plugin MUST be installed
  try {
    plugin = require('lamassu-' + name);
  } catch (_) {
    throw new Error(name + ' module is not installed. ' +
      'Try running \'npm install --save lamassu-' + name + '\' first');
  }

  // each plugin MUST implement those
  if (typeof plugin.SUPPORTED_MODULES !== 'undefined') {
    if (plugin.SUPPORTED_MODULES === 'string')
      plugin.SUPPORTED_MODULES = [plugin.SUPPORTED_MODULES];
  }

  if (!(plugin.SUPPORTED_MODULES instanceof Array))
    throw new Error('\'' + name + '\' fails to implement *required* ' +
      '\'SUPPORTED_MODULES\' constant');

  plugin.SUPPORTED_MODULES.forEach(function(moduleName) {
    moduleMethods[moduleName].forEach(function(methodName) {
      if (typeof plugin[methodName] !== 'function') {
        throw new Error('\'' + name + '\' declares \'' + moduleName +
          '\', but fails to implement \'' + methodName + '\' method');
      }
    });
  });

  // each plugin SHOULD implement those
  if (typeof plugin.NAME === 'undefined')
    logger.warn(new Error('\'' + name +
      '\' fails to implement *recommended* \'NAME\' field'));

  if (typeof plugin.config !== 'function') {
    logger.warn(new Error('\'' + name +
      '\' fails to implement *recommended* \'config\' method'));
    plugin.config = function() {};
  } else if (config !== null) {
    plugin.config(config); // only when plugin supports it, and config is passed
  }

  return plugin;
}

function loadOrConfigPlugin(pluginHandle, pluginType, cryptoCoin, currency,
    onChangeCallback) {

  if (!cryptoCoin) cryptoCoin = 'any'
  var currentName = cryptoCoin === 'any' || cryptoCoin === 'BTC'
  ? cachedConfig.exchanges.plugins.current[pluginType]
  : cachedConfig.exchanges.plugins.current[cryptoCoin][pluginType]

  var pluginChanged = currentlyUsedPlugins[cryptoCoin][pluginType] !== currentName;

  if (!currentName) pluginHandle = null;
  else { // some plugins may be disabled
    var pluginConfig = cachedConfig.exchanges.plugins.settings[currentName] ||
      {};

    if (currency) pluginConfig.currency = currency;

    if (pluginHandle && !pluginChanged) pluginHandle.config(pluginConfig);
    else {
      pluginHandle = loadPlugin(currentName, pluginConfig);
      currentlyUsedPlugins[cryptoCoin] ||= {}
      currentlyUsedPlugins[cryptoCoin][pluginType] = currentName
      logger.debug('[%s] plugin(%s) loaded: %s', cryptoCoin, pluginType, pluginHandle.NAME ||
        currentName);
    }
  }

  if (typeof onChangeCallback === 'function')
    onChangeCallback(pluginHandle, currency);

  return pluginHandle;
}

exports.configure = function configure(config) {
  if (config.exchanges.settings.lowBalanceMargin < 1) {
    throw new Error('\'settings.lowBalanceMargin\' has to be >= 1');
  }

  cachedConfig = config;
  deviceCurrency = config.exchanges.settings.currency;
  cryptoCoins = config.exchanges.settings.coins || ['BTC'];

  cryptoCoins.forEach(function (cryptoCoin) {
    // TICKER [required] configure (or load)
    loadOrConfigPlugin(
      tickerPlugins[cryptoCoin],
      'ticker',
      cryptoCoin,
      deviceCurrency, // device currency
      function onTickerChange(newTicker) {
        tickerPlugins[cryptoCoin] = newTicker;
        pollRate(cryptoCoin);
      }
    );

    // WALLET [required] configure (or load)
    loadOrConfigPlugin(
      walletPlugins[cryptoCoin],
      'transfer',
      cryptoCoin,
      null,
      function onWalletChange(newWallet) {
        walletPlugins[cryptoCoin] = newWallet;
        pollBalance(cryptoCoin);
      }
    );
  })

  // TRADER [optional] configure (or load)
  traderPlugin = loadOrConfigPlugin(
    traderPlugin,
    'trade',
    null,
    null,
    function onTraderChange(newTrader) {
      traderPlugin = newTrader;
      if (newTrader === null) stopTrader();
      else startTrader();
    }
  );

  // ID VERIFIER [optional] configure (or load)
  idVerifierPlugin = loadOrConfigPlugin(
    idVerifierPlugin,
    'idVerifier'
  );

  infoPlugin = loadOrConfigPlugin(
    infoPlugin,
    'info'
  );
};
exports.getConfig = function getConfig() {
  return cachedConfig;
};

exports.logEvent = function event(session, rawEvent) {
  db.recordDeviceEvent(session, rawEvent);
};

function buildCartridges(cartridges, virtualCartridges, rec) {
  return {
    cartridges: [
      {
        denomination: parseInt(cartridges[0], 10),
        count: parseInt(rec.counts[0], 10)
      },
      {
        denomination: parseInt(cartridges[1], 10),
        count: parseInt(rec.counts[1], 10)
      }
    ],
    virtualCartridges: virtualCartridges,
    id: rec.id
  };
}

exports.pollQueries = function pollQueries(session, cb) {
  var cartridges = cachedConfig.exchanges.settings.cartridges;
  if (!cartridges) return cb(null, {});
  var virtualCartridges = cachedConfig.exchanges.settings.virtualCartridges;

  db.cartridgeCounts(session, function(err, result) {
    if (err) return cb(err);
    return cb(null, {
      cartridges: buildCartridges(cartridges, virtualCartridges, result)
    });
  });
};

function _sendCoins(toAddress, cryptoUnits, cryptoCoin, cb) {
  var walletPlugin = walletPlugins[cryptoCoin]
  var transactionFee = cachedConfig.exchanges.settings.transactionFee;
  if (cryptoCoin === 'BTC')
    walletPlugin.sendBitcoins(toAddress, cryptoUnits, transactionFee, cb);
  else
    walletPlugin.sendCoins(toAddress, cryptoUnits, cryptoCoin, transactionFee, cb);
}

function executeTx(session, tx, authority, cb) {
  db.addOutgoingTx(session, tx, function(err, toSend) {
    if (err) return cb(err);
    var cryptoUnitsToSend = toSend.cryptoUnits;
    if (cryptoUnitsToSend === 0)
      return cb(null, {statusCode: 204, txId: tx.txId, txHash: null});

    _sendCoins(tx.toAddress, cryptoUnitsToSend, function(_err, txHash) {
      var fee = null; // Need to fill this out in plugins
      if (_err) toSend = {cryptoUnits: new BigNumber(0), fiat: 0};
      db.sentCoins(session, tx, authority, toSend, fee, _err, txHash);

      if (_err) return cb(_err);

      var cryptoCoin = tx.coin
      ? tx.coin.unitCode
      : 'BTC'

      pollBalance('BTC');

      cb(null, {
        statusCode: 201, // Created
        txHash: txHash,
        txId: tx.txId
      });
    });
  });
}

function reapOutgoingTx(session, tx) {
  executeTx(session, tx, 'timeout', function(err) {
    if (err) logger.error(err);
  });
}

function reapTx(row) {
  var session = {fingerprint: row.device_fingerprint, id: row.session_id};
  var tx = {
    fiat: 0,
    satoshis: row.satoshis,
    toAddress: row.to_address,
    currencyCode: row.currency_code,
    incoming: row.incoming
  };
  if (!row.incoming) reapOutgoingTx(session, tx);
}

function reapTxs() {
  db.removeOldPending(DEPOSIT_TIMEOUT);

  // NOTE: No harm in processing old pending tx, we don't need to wait for
  // removeOldPending to complete.
  db.pendingTxs(PENDING_TIMEOUT, function(err, results) {
    if (err) return logger.warn(err);
    var rows = results.rows;
    var rowCount = rows.length;
    for (var i = 0; i < rowCount; i++) {
      var row = rows[i];
      reapTx(row);
    }
  });
}

// TODO: Run these in parallel and return success
exports.trade = function trade(session, rawTrade, cb) {

  // TODO: move this to DB, too
  // add bill to trader queue (if trader is enabled)
  if (traderPlugin) {
    tradesQueue.push({
      currency: rawTrade.currency,
      satoshis: rawTrade.satoshis
    });
  }

  if (!rawTrade.toAddress) {
    var newRawTrade = _.cloneDeep(rawTrade);
    newRawTrade.toAddress = 'remit';
    return db.recordBill(session, newRawTrade, cb);
  }

  var tx = {
    txId: rawTrade.txId,
    fiat: 0,
    satoshis: 0,
    toAddress: rawTrade.toAddress,
    currencyCode: rawTrade.currency
  };

  async.parallel([
    async.apply(db.addOutgoingPending, session, tx.currencyCode, tx.toAddress),
    async.apply(db.recordBill, session, rawTrade)
  ], cb);
};

exports.sendBitcoins = function sendBitcoins(session, rawTx, cb) {
  executeTx(session, rawTx, 'machine', cb);
};

exports.cashOut = function cashOut(session, tx, cb) {
  var tmpInfo = {
    label: 'TX ' + Date.now(),
    account: 'deposit'
  };

  var cryptoCoin = tx.coin
  ? tx.coin.unitCode
  : 'BTC'

  var walletPlugin = walletPlugins[cryptoCoin]

  walletPlugin.newAddress(tmpInfo, function(err, address) {
    if (err) return cb(err);

    var newTx = _.clone(tx);
    newTx.toAddress = address;
    db.addInitialIncoming(session, newTx, function(_err) {
      cb(_err, address);
    });
  });
};

exports.dispenseAck = function dispenseAck(session, rec) {
  db.addDispense(session, rec.tx, rec.cartridges);
};

exports.fiatBalance = function fiatBalance(cryptoCoin) {
  var rawRate = exports.getDeviceRate(cryptoCoin).rates.ask;
  var commission = cachedConfig.exchanges.settings.commission;
  var lastBalance = lastBalances[cryptoCoin]

  if (!rawRate || !lastBalance) return null;

  // The rate is actually our commission times real rate.
  var rate = commission * rawRate;

  // `lowBalanceMargin` is our safety net. It's a number > 1, and we divide
  // all our balances by it to provide a safety margin.
  var lowBalanceMargin = cachedConfig.exchanges.settings.lowBalanceMargin;

  // `balance.transferBalance` is the balance of our transfer account (the one
  // we use to send Bitcoins to clients) in satoshis.
  var transferBalance = lastBalances.transferBalance;

  var fiatTransferBalance = (transferBalance * rate) / lowBalanceMargin;

  return fiatTransferBalance;
};

/*
 * Polling livecycle
 */
exports.startPolling = function startPolling() {
  executeTrades();

  cryptoCoins.forEach(function (coin) {
    setInterval(async.apply(pollBalance, coin), POLLING_RATE);
    setInterval(async.apply(pollRate, coin), POLLING_RATE);
  });

  setInterval(reapTxs, REAP_RATE);

  startTrader();
};

function startTrader() {
  // Always start trading, even if we don't have a trade exchange configured,
  // since configuration can always change in `Trader#configure`.
  // `Trader#executeTrades` returns early if we don't have a trade exchange
  // configured at the moment.
  if (traderPlugin && !tradeInterval) {
    tradeInterval = setInterval(
      executeTrades,
      cachedConfig.exchanges.settings.tradeInterval
    );
  }
}

function stopTrader() {
  if (tradeInterval) {
    clearInterval(tradeInterval);
    tradeInterval = null;
    tradesQueue = [];
  }
}

function pollBalance(cryptoCoin, cb) {
  logger.debug('[%s] collecting balance', cryptoCoin);

  var walletPlugin = walletPlugins[cryptoCoin]
  var jobs = {
    transferBalance: walletPlugin.balance
  };

  walletPlugin.balance(function(err, balance) {
    if (err) {
      logger.error(err);
      return cb && cb(err);
    }

    logger.debug('[%s] Balance update:', cryptoCoin, balance);
    balance.timestamp = Date.now();
    lastBalances[cryptoCoin] = balance;

    return cb && cb(null, lastBalances);
  });
}

function pollRates (cb) {
  var polls = cryptoCoins.map(function (cryptoCoin) {
    async.apply(pollRate, cryptoCoin)
  });

  async.parallel(polls, cb);
}

function pollRate(cryptoCoin, cb) {
  logger.debug('[%s] polling for rates (%s)', cryptoCoin, tickerPlugin.NAME);
  var tickerPlugin = tickerPlugins[cryptoCoin];

  tickerPlugin.ticker(deviceCurrency, function(err, resRates) {
    if (err) {
      logger.error(err);
      return cb && cb(err);
    }

    logger.debug('got rates: %j', resRates);
    resRates.timestamp = new Date();
    lastRates[cryptoCoin] = resRates;

    return cb && cb(null, lastRates);
  });
}

/*
 * Getters | Helpers
 */

exports.getDeviceRate = function getDeviceRate(cryptoCoin) {
  if (!lastRates[cryptoCoin]) return null;

  var lastRate = lastRates[cryptoCoin]
  if (!lastRate) return null;

  return lastRate[deviceCurrency];
};

exports.getBalance = function getBalance() {
  if (!lastBalances) return null;

  return lastBalances.transferBalance;
};

/*
 * Trader functions
 */
function purchase(trade, cb) {
  traderPlugin.purchase(trade.satoshis, null, function(err) {
    if (err) return cb(err);
    pollBalance('BTC');
    if (typeof cb === 'function') cb();
  });
}

function consolidateTrades() {
  // NOTE: value in satoshis stays the same no matter the currency
  var consolidatedTrade = {
    currency: deviceCurrency,
    satoshis: tradesQueue.reduce(function(prev, current) {
      return prev + current.satoshis;
    }, 0)
  };

  tradesQueue = [];

  logger.debug('consolidated: ', JSON.stringify(consolidatedTrade));
  return consolidatedTrade;
}

function executeTrades() {
  if (!traderPlugin) return;

  logger.debug('checking for trades');

  var trade = consolidateTrades();

  if (trade.satoshis === 0) {
    logger.debug('rejecting 0 trade');
    return;
  }

  logger.debug('making a trade: %d', trade.satoshis / SATOSHI_FACTOR);
  purchase(trade, function(err) {
    if (err) {
      tradesQueue.push(trade);
      if (err.name !== 'orderTooSmall') logger.error(err);
    }
  });
}

/*
 * ID Verifier functions
 */
exports.verifyUser = function verifyUser(data, cb) {
  idVerifierPlugin.verifyUser(data, cb);
};

exports.verifyTx = function verifyTx(data, cb) {
  idVerifierPlugin.verifyTransaction(data, cb);
};