const { ethGetBlock } = require('./web3');
const pify = require('pify');

function advanceBlock () {
  return pify(web3.currentProvider.sendAsync)({
    jsonrpc: '2.0',
    method: 'evm_mine',
  });
}

// Returns the time of the last mined block in seconds
async function latest () {
  const block = await ethGetBlock('latest');
  return block.timestamp;
}

// Increases ganache time by the passed duration in seconds
async function increase (duration) {
  if (duration < 0) throw Error(`Cannot increase time by a negative amount (${duration})`);

  await pify(web3.currentProvider.sendAsync)({
    jsonrpc: '2.0',
    method: 'evm_increaseTime',
    params: [duration],
  });

  await advanceBlock();
}

/**
 * Beware that due to the need of calling two separate ganache methods and rpc calls overhead
 * it's hard to increase time precisely to a target point so design your test to tolerate
 * small fluctuations from time to time.
 *
 * @param target time in seconds
 */
async function increaseTo (target) {
  const now = (await latest());

  if (target < now) throw Error(`Cannot increase current time (${now}) to a moment in the past (${target})`);
  const diff = target - now;
  return increase(diff);
}

const duration = {
  seconds: function (val) { return val; },
  minutes: function (val) { return val * this.seconds(60); },
  hours: function (val) { return val * this.minutes(60); },
  days: function (val) { return val * this.hours(24); },
  weeks: function (val) { return val * this.days(7); },
  years: function (val) { return val * this.days(365); },
};

module.exports = {
  advanceBlock,
  latest,
  increase,
  increaseTo,
  duration,
};