Fabo/new emoney rewards (#357)

* intent to fix the emoney rewards

* intent to fix emoney rewards

* simplified code

* comments

* hack to fix reduce function

* eligable -> eligible

* correct reducer fix

Co-authored-by: Ana G. <40721795+Bitcoinera@users.noreply.github.com>
Co-authored-by: Jordan Bibla <jbibla@gmail.com>

lib/reducers/emoneyV0-reducers.js

@@ -67,54 +67,35 @@ async function expectedRewardsPerToken(
   inflations,
   totalBackedValues
 ) {
-  const percentTotalStakedNGM = BigNumber(validator.votingPower).times(1000)
-  const totalNGMStakedToValidator = validator.tokens
-  const division = BigNumber(percentTotalStakedNGM)
+  const percentOfAllEligibleStake = validator.votingPower
+  const totalStakeToValidator = validator.tokens // used to answer the question "How many rewards per ONE token invested?"
+  const percentOfAllRewardsPerToken = BigNumber(percentOfAllEligibleStake)
     .times(BigNumber(1).minus(BigNumber(commission)))
-    .div(BigNumber(totalNGMStakedToValidator))
+    .div(BigNumber(totalStakeToValidator))
+
   // Now we need to multiply each total supply of backed tokens with its corresponding
   // inflation
-  let accumulator = BigNumber(0)
   const totalBackedValueDictionary = _.keyBy(totalBackedValues, 'denom')
-
-  inflations.forEach(inflation => {
-    accumulator = BigNumber(accumulator)
-      .plus(accumulator)
-      .plus(
-        BigNumber(inflation.inflation)
-          .times(totalBackedValueDictionary[inflation.denom].amount)
-          .div(1000000)
+  const rewardsSumInEur = inflations.reduce((sum, inflation) => {
+    return BigNumber(sum).plus(
+      BigNumber(inflation.inflation).times(
+        totalBackedValueDictionary[inflation.denom].eurValue // we use the eur value to be able to sum up the individual token values
       )
-  })
-  const totalBackedValuesTimesInflations = accumulator
-  // First we calculate the total value of rewards we get for staking one single
-  // NGM in this particular validator
-  let delegatorSharePerToken = totalBackedValuesTimesInflations.div(division)
-  // In testnet some validators have commission at 100% and therefore division is
-  // equal to 0. Dividing by 0 we get infinity, and we want to make sure that
-  // we don't display such value
-  const infinity = new BigNumber(Infinity)
-  // This is just how BigNumber works. Comparing to 0 and if true, bignumber equals the given parameter.
-  // Documentation on this method can be found here: https://mikemcl.github.io/bignumber.js/#cmp
-  delegatorSharePerToken =
-    delegatorSharePerToken.comparedTo(infinity) === 0
-      ? BigNumber(0)
-      : delegatorSharePerToken.div(1000000)
-  // Now we get the total net value in EUR of all token's total supplies
-  let eurAccumulator = 0
-  totalBackedValues.forEach(totalBackedValue => {
-    eurAccumulator += totalBackedValue.eurValue
-  })
-  const totalEURGains = eurAccumulator * delegatorSharePerToken.toNumber()
+    )
+  }, 0)
+
+  // now we calculate the total rewards in eur per token delegated to the validator
+  const totalEURGainsPerTokenInvested = BigNumber(rewardsSumInEur).times(
+    percentOfAllRewardsPerToken
+  )
+
   // How many NGM tokens can we buy with the total gain in EUR we make in a year's time?
   // 0.50€ is the price the NGM tokens will be first sold. Therefore, this is the official value
   // until they reach an exchange
   const pricePerNGM = 0.5
-  const ngmGains = totalEURGains / pricePerNGM
-  // We divide by 1 because we assume 1 NGM > gain per 1 NGM
-  const expectedReturns = parseFloat(ngmGains / 1).toFixed(2)
-  // TODO the FE is the one converting to percentage now, so we need to divide by 100
-  return expectedReturns / 100
+  const ngmGains = totalEURGainsPerTokenInvested / pricePerNGM
+
+  return ngmGains.toFixed(2) // we don't need more then a precision of 2
 }
 
 module.exports = {