/* @flow weak */
'use strict';

// TODO: Consider using serializable transactions for true ACID

var pg = require('pg');
var async = require('async');
var _ = require('lodash');

var logger = require('./logger');

/*
function inspect(rec) {
  console.log(require('util').inspect(rec, {depth: null, colors: true}));
}
*/

var SATOSHI_FACTOR = 1e8;

function isUniqueViolation(err) {
  return err.code === '23505';
}

function isLowSeverity(err) {
  return isUniqueViolation(err) || err.severity === 'low';
}

var conString = null;

function rollback(client, done) {
  client.query('ROLLBACK', function(err) {
    return done(err);
  });
}

function getInsertQuery(tableName, fields, hasId) {

  // outputs string like: '$1, $2, $3...' with proper No of items
  var placeholders = fields.map(function(_, i) {
    return '$' + (i + 1);
  }).join(', ');

  var query = 'INSERT INTO ' + tableName +
    ' (' + fields.join(', ') + ')' +
    ' VALUES' +
    ' (' + placeholders + ')';

  if (hasId) query += ' RETURNING id';

  return query;
}

exports.init = function init(_conString) {
  conString = _conString;
  if (!conString) {
    throw new Error('Postgres connection string is required');
  }
};

function connect(cb) {
  pg.connect(conString, function(err, client, done) {
    if (err) logger.error(err);
    cb(err, client, done);
  });
}

// logs inputted bill and overall tx status (if available)
exports.recordBill = function recordBill(session, rec, cb) {
  var fields = [
    'id',
    'device_fingerprint',
    'currency_code',
    'to_address',
    'session_id',
    'device_time',
    'satoshis',
    'denomination'
  ];

  var values = [
    rec.uuid,
    session.fingerprint,
    rec.currency,
    rec.toAddress,
    session.id,
    rec.deviceTime,
    rec.satoshis,
    rec.fiat
  ];

  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    query(client, getInsertQuery('bills', fields, false), values, function(err) {
      done();
      if (err && isUniqueViolation(err)) {
        logger.warn('Attempt to report bill twice');
        return cb();
      }
      cb(err);
    });
  });
};

exports.recordDeviceEvent = function recordDeviceEvent(session, event) {
  connect(function(cerr, client, done) {
    if (cerr) return;
    var sql = 'INSERT INTO device_events (device_fingerprint, event_type, ' +
      'note, device_time) VALUES ($1, $2, $3, $4)';
    var values = [session.fingerprint, event.eventType, event.note,
      event.deviceTime];
    client.query(sql, values, done);
  });
};

function query(client, queryStr, values, cb) {
  if (!cb) {
    cb = values;
    values = [];
  }

  client.query(queryStr, values, function(err, results) {
    if (err) {
      if (!isLowSeverity(err)) {
        console.log(queryStr);
        console.log(values);
      }
      return cb(err);
    }
    cb(null, results);
  });
}

function silentQuery(client, queryStr, values, cb) {
  if (!cb) {
    cb = values;
    values = [];
  }

  client.query(queryStr, values, function(err) {
    if (err) {
      if (!isLowSeverity(err)) {
        console.log(queryStr);
        console.log(values);
      }
      cb(err);
    }
    cb();
  });
}

// OPTIMIZE: No need to query bills if tx.fiat and tx.satoshis are set
function billsAndTxs(client, session, cb) {
  var sessionId = session.id;
  var fingerprint = session.fingerprint;
  var billsQuery = 'SELECT COALESCE(SUM(denomination), 0) as fiat, ' +
    'COALESCE(SUM(satoshis), 0) AS satoshis ' +
    'FROM bills ' +
    'WHERE device_fingerprint=$1 AND session_id=$2';
  var billsValues = [fingerprint, sessionId];
  var txQuery = 'SELECT COALESCE(SUM(fiat), 0) AS fiat, ' +
    'COALESCE(SUM(satoshis), 0) AS satoshis ' +
    'FROM transactions ' +
    'WHERE device_fingerprint=$1 AND session_id=$2 AND stage=$3';
  var txValues = [fingerprint, sessionId, 'partial_request'];

  async.parallel([
    async.apply(query, client, billsQuery, billsValues),
    async.apply(query, client, txQuery, txValues)
  ], function(err, results) {
    if (err) return cb(err);

    // Note: PG SUM function returns int8, which is returned as a string, so
    // we need to parse, since we know these won't be huge numbers.
    cb(null, {
      billsFiat: parseInt(results[0].rows[0].fiat),
      billsSatoshis: parseInt(results[0].rows[0].satoshis),
      txFiat: parseInt(results[1].rows[0].fiat),
      txSatoshis: parseInt(results[1].rows[0].satoshis)
    });
  });
}


// TODO: these should broken out to a common library, they are used by both
// lamassu-machine and lamassu-server and need to stay in sync.
function bitcoinFractionalDigits(amount) {
  var log = Math.floor(Math.log(amount) / Math.log(10));
  if (log < -8) log = -8;
  return (log > 0) ? 2 : 2 - log;
}

function truncateBitcoins(bitcoins) {
  if (bitcoins < 0) logger.error('Negative amount in truncateBitcoins');
  var decimalDigits = bitcoinFractionalDigits(bitcoins);
  var adjuster = Math.pow(10, decimalDigits);
  return (Math.round(bitcoins * adjuster) / adjuster);
}

function truncateSatoshis(satoshis) {
  var bitcoins = satoshis / SATOSHI_FACTOR;
  var truncated = truncateBitcoins(bitcoins);
  return Math.round(truncated * SATOSHI_FACTOR);
}
// END TODO

function computeSendAmount(tx, totals) {
  var fiatRemaining = (tx.fiat || totals.billsFiat) - totals.txFiat;
  var satoshisRemaining = (tx.satoshis || totals.billsSatoshis) -
    totals.txSatoshis;
  var result = {
    fiat: fiatRemaining,
    satoshis: truncateSatoshis(satoshisRemaining)
  };
  if (result.fiat < 0 || result.satoshis < 0) {
    logger.warn({tx: tx, totals: totals, result: result},
      'computeSendAmount result < 0, this shouldn\'t happen. ' +
      'Maybe timeout arrived after machineSend.');
    result.fiat = 0;
    result.satoshis = 0;
  }
  return result;
}

exports.removeOldPending = function removeOldPending(timeoutMS) {
  connect(function(cerr, client, done) {
    if (cerr) return;
    var sql = 'DELETE FROM pending_transactions ' +
      'WHERE incoming AND extract(EPOCH FROM now() - updated) > $1';
    var timeoutS = timeoutMS / 1000;
    var values = [timeoutS];
    query(client, sql, values, function(err) {
      done();
      if (err) logger.error(err);
    });
  });
};

exports.pendingTxs = function pendingTxs(timeoutMS, cb) {
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    var sql = 'SELECT * ' +
      'FROM pending_transactions ' +
      'WHERE (incoming OR extract(EPOCH FROM now() - updated) > $1) ' +
      'ORDER BY updated ASC';
    var timeoutS = timeoutMS / 1000;
    var values = [timeoutS];
    query(client, sql, values, function(err, results) {
      done();
      cb(err, results);
    });
  });
};

function removePendingTx(client, session, cb) {
  var sql = 'DELETE FROM pending_transactions ' +
    'WHERE device_fingerprint=$1 AND session_id=$2';
  silentQuery(client, sql, [session.fingerprint, session.id], cb);
}

function insertOutgoingTx(client, session, tx, totals, cb) {
  var sendAmount = computeSendAmount(tx, totals);
  var stage = 'partial_request';
  var authority = tx.fiat ? 'machine' : 'timeout';
  var satoshis = sendAmount.satoshis;
  var fiat = sendAmount.fiat;
  if (satoshis === 0) return cb(null, {satoshis: 0, fiat: 0});

  insertOutgoing(client, session, tx, satoshis, fiat, stage, authority,
      function(err) {

    if (err) return cb(err);
    cb(null, {satoshis: satoshis, fiat: fiat});
  });
}

function insertOutgoingCompleteTx(client, session, tx, cb) {

  // Only relevant for machine source transactions, not timeouts
  if (!tx.fiat) return cb();

  var stage = 'final_request';
  var authority = 'machine';
  var satoshis = tx.satoshis;
  var fiat = tx.fiat;
  insertOutgoing(client, session, tx, satoshis, fiat, stage, authority, cb);
}

function insertIncoming(client, session, tx, satoshis, fiat, stage, authority,
    cb) {
  var realSatoshis = satoshis || 0;
  insertTx(client, session, true, tx, realSatoshis, fiat, stage, authority, cb);
}

function insertOutgoing(client, session, tx, satoshis, fiat, stage, authority,
    cb) {
  insertTx(client, session, false, tx, satoshis, fiat, stage, authority, cb);
}

function insertTx(client, session, incoming, tx, satoshis, fiat, stage,
    authority, cb) {
  var fields = [
    'session_id',
    'stage',
    'authority',
    'incoming',
    'device_fingerprint',
    'to_address',
    'satoshis',
    'currency_code',
    'fiat',
    'tx_hash',
    'error'
  ];

  var values = [
    session.id,
    stage,
    authority,
    incoming,
    session.fingerprint,
    tx.toAddress,
    satoshis,
    tx.currencyCode,
    fiat,
    tx.txHash,
    tx.error
  ];

  query(client, getInsertQuery('transactions', fields, true), values,
      function(err, results) {
    if (err) return cb(err);
    cb(null, results.rows[0].id);
  });
}

function refreshPendingTx(client, session, cb) {
  var sql = 'UPDATE pending_transactions SET updated=now() ' +
    'WHERE device_fingerprint=$1 AND session_id=$2';
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    query(client, sql, [session.fingerprint, session.id], function(err) {
      done(err);
      cb(err);
    });
  });
}

function addPendingTx(client, session, incoming, currencyCode, toAddress,
    satoshis, cb) {
  var fields = ['device_fingerprint', 'session_id', 'incoming',
    'currency_code', 'to_address', 'satoshis'];
  var sql = getInsertQuery('pending_transactions', fields, false);
  var values = [session.fingerprint, session.id, incoming, currencyCode,
    toAddress, satoshis];
  query(client, sql, values, function(err) {
    cb(err);
  });
}

function buildOutgoingTx(client, session, tx, cb) {
  async.waterfall([
    async.apply(billsAndTxs, client, session),
    async.apply(insertOutgoingTx, client, session, tx)
  ], cb);
}

// Calling function should only send bitcoins if result.satoshisToSend > 0
exports.addOutgoingTx = function addOutgoingTx(session, tx, cb) {
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    async.series([
      async.apply(silentQuery, client, 'BEGIN'),
      async.apply(insertOutgoingCompleteTx, client, session, tx),
      async.apply(removePendingTx, client, session),
      async.apply(buildOutgoingTx, client, session, tx)
    ], function(err, results) {
      if (err) {
        rollback(client, done);
        return cb(err);
      }
      silentQuery(client, 'COMMIT', [], function() {
        done();
        var toSend = results[3];
        cb(null, toSend);
      });
    });
  });
};

exports.sentCoins = function sentCoins(session, tx, authority, toSend, fee,
  error, txHash) {
  connect(function(cerr, client, done) {
    if (cerr) return logger.error(cerr);

    var newTx = _.clone(tx);
    newTx.txHash = txHash;
    newTx.error = error;
    insertOutgoing(client, session, newTx, toSend.satoshis, toSend.fiat,
        'partial_send', authority, function(err) {
      done();
      if (err) logger.error(err);
    });
  });
};

function ensureNotFinal(client, session, cb) {
  var sql = 'SELECT id FROM transactions ' +
    'WHERE device_fingerprint=$1 AND session_id=$2 AND incoming=$3 ' +
    'AND stage=$4' +
    'LIMIT 1';
  var values = [session.fingerprint, session.id, false, 'final_request'];

  client.query(sql, values, function(err, results) {
    var error;
    if (err) return cb(err);
    if (results.rows.length > 0) {
      error = new Error('Final request already exists');
      error.name = 'staleBill';
      error.severity = 'low';
      return cb(error);
    }
    cb();
  });
}

exports.addOutgoingPending = function addOutgoingPending(session, currencyCode,
    toAddress, cb) {
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);

    async.series([
      async.apply(silentQuery, client, 'BEGIN', null),
      async.apply(ensureNotFinal, client, session),
      async.apply(addPendingTx, client, session, false, currencyCode, toAddress,
        0)
    ], function(err) {
      if (err) {
        return rollback(client, function(rberr) {
          done(rberr);

          if (isUniqueViolation(err)) {
            // Pending tx exists, refresh it.
            return refreshPendingTx(client, session, cb);
          }
          if (err.name === 'staleBill') {
            logger.info('Received a bill insert after send coins request');
            return cb();
          }
          logger.error(err);
          return cb(err);
        });
      }
      silentQuery(client, 'COMMIT', null, function() {
        done();
        cb();
      });
    });
  });
};

exports.addInitialIncoming = function addInitialIncoming(session, tx, cb) {
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    async.series([
      async.apply(silentQuery, client, 'BEGIN', null),
      async.apply(addPendingTx, client, session, true, tx.currencyCode,
        tx.toAddress, tx.satoshis),
      async.apply(insertIncoming, client, session, tx, tx.satoshis, tx.fiat,
        'initial_request', 'pending')
    ], function(err) {
      if (err) {
        rollback(client, done);
        return cb(err);
      }
      silentQuery(client, 'COMMIT', null, function() {
        done();
        cb();
      });
    });
  });
};

function insertDispense(client, session, tx, cartridges, transactionId, cb) {
  var fields = [
    'device_fingerprint', 'transaction_id',
    'dispense1', 'reject1', 'count1',
    'dispense2', 'reject2', 'count2',
    'refill', 'error'
  ];

  var sql = getInsertQuery('dispenses', fields, true);

  var dispense1 = tx.bills[0].actualDispense;
  var dispense2 = tx.bills[1].actualDispense;
  var reject1 = tx.bills[0].rejected;
  var reject2 = tx.bills[1].rejected;
  var count1 = cartridges[0].count;
  var count2 = cartridges[1].count;
  var values = [
    session.fingerprint, transactionId,
    dispense1, reject1, count1, dispense2, reject2, count2,
    false, tx.error
  ];
  client.query(sql, values, cb);
}

exports.addDispense = function addDispense(session, tx, cartridges) {
  connect(function(cerr, client, done) {
    if (cerr) return;

    async.waterfall([
      async.apply(insertIncoming, client, session, tx, 0, tx.fiat,
        'dispense', 'authorized'),
      async.apply(insertDispense, client, session, tx, cartridges)
    ], function(err) {
      done();
      if (err) logger.error(err);
    });
  });
};

exports.cartridgeCounts = function cartridgeCounts(session, cb) {
  connect(function(cerr, client, done) {
    if (cerr) return cb(cerr);
    var sql = 'SELECT id, count1, count2 FROM dispenses ' +
      'WHERE device_fingerprint=$1 AND refill=$2 ' +
      'ORDER BY id DESC LIMIT 1';
    query(client, sql, [session.fingerprint, true], function(err, results) {
      done();
      if (err) return cb(err);
      var counts = results.rows.length === 1 ?
        [results.rows[0].count1, results.rows[0].count2] :
        [0, 0];
      cb(null, {id: results.rows[0].id, counts: counts});
    });
  });
};

/*
exports.init('postgres://lamassu:lamassu@localhost/lamassu');
connect(function(err, client, done) {
  var sql = 'select * from transactions where id=$1';
  query(client, sql, [130], function(_err, results) {
    done();
    console.dir(results.rows[0]);
  });
});
*/