fix(database): wrong balance and decay values

database/migrations/0054-recalculate-balance-and-decay.ts

@@ -0,0 +1,122 @@
+/* MIGRATION TO FIX WRONG BALANCE
+ *
+ * Due to a bug in the code
+ * the amount of a receive balance is substracted
+ * from the previous balance instead of added.
+ *
+ * Therefore all balance and decay fields must
+ * be recalculated
+ *
+ * WARNING: This Migration must be run in TZ=UTC
+ */
+
+/* eslint-disable @typescript-eslint/explicit-module-boundary-types */
+/* eslint-disable @typescript-eslint/no-explicit-any */
+
+import Decimal from 'decimal.js-light'
+
+// Set precision value
+Decimal.set({
+  precision: 25,
+  rounding: Decimal.ROUND_HALF_UP,
+})
+
+const DECAY_START_TIME = new Date('2021-05-13 17:46:31') // GMT+0
+
+interface Decay {
+  balance: Decimal
+  decay: Decimal | null
+  start: Date | null
+  end: Date | null
+  duration: number | null
+}
+
+export enum TransactionTypeId {
+  CREATION = 1,
+  SEND = 2,
+  RECEIVE = 3,
+}
+
+function decayFormula(value: Decimal, seconds: number): Decimal {
+  return value.mul(new Decimal('0.99999997803504048973201202316767079413460520837376').pow(seconds))
+}
+
+function calculateDecay(
+  amount: Decimal,
+  from: Date,
+  to: Date,
+  startBlock: Date = DECAY_START_TIME,
+): Decay {
+  const fromMs = from.getTime()
+  const toMs = to.getTime()
+  const startBlockMs = startBlock.getTime()
+
+  if (toMs < fromMs) {
+    throw new Error('to < from, reverse decay calculation is invalid')
+  }
+
+  // Initialize with no decay
+  const decay: Decay = {
+    balance: amount,
+    decay: null,
+    start: null,
+    end: null,
+    duration: null,
+  }
+
+  // decay started after end date; no decay
+  if (startBlockMs > toMs) {
+    return decay
+  }
+  // decay started before start date; decay for full duration
+  if (startBlockMs < fromMs) {
+    decay.start = from
+    decay.duration = (toMs - fromMs) / 1000
+  }
+  // decay started between start and end date; decay from decay start till end date
+  else {
+    decay.start = startBlock
+    decay.duration = (toMs - startBlockMs) / 1000
+  }
+
+  decay.end = to
+  decay.balance = decayFormula(amount, decay.duration)
+  decay.decay = decay.balance.minus(amount)
+  return decay
+}
+
+export async function upgrade(queryFn: (query: string, values?: any[]) => Promise<Array<any>>) {
+  // Find all users & loop over them
+  const users = await queryFn('SELECT user_id FROM transactions GROUP BY user_id;')
+  for (let u = 0; u < users.length; u++) {
+    // find all transactions for a user
+    const transactions = await queryFn(
+      `SELECT * FROM transactions WHERE user_id = ${users[u].user_id} ORDER BY balance_date ASC;`,
+    )
+    let previous = null
+    let balance = new Decimal(0)
+    for (let t = 0; t < transactions.length; t++) {
+      const transaction = transactions[t]
+
+      const decayStartDate = previous ? previous.balance_date : transaction.balance_date
+      const amount = new Decimal(transaction.amount)
+      const decay = calculateDecay(balance, decayStartDate, transaction.balance_date)
+      balance = decay.balance.add(amount)
+
+      // Update
+      await queryFn(`
+        UPDATE transactions SET
+          balance = ${balance},
+          decay = ${decay.decay ? decay.decay : 0}
+        WHERE id = ${transaction.id};
+      `)
+
+      // previous
+      previous = transaction
+    }
+  }
+}
+
+/* eslint-disable @typescript-eslint/no-empty-function */
+/* eslint-disable-next-line @typescript-eslint/no-unused-vars */
+export async function downgrade(queryFn: (query: string, values?: any[]) => Promise<Array<any>>) {}