move decay into shared

backend/src/graphql/model/Decay.ts

@@ -1,14 +1,6 @@
 import { Decimal } from 'decimal.js-light'
 import { Field, Int, ObjectType } from 'type-graphql'
-
-interface DecayInterface {
-  balance: Decimal
-  decay: Decimal
-  roundedDecay: Decimal
-  start: Date | null
-  end: Date | null
-  duration: number | null
-}
+import { Decay as DecayInterface } from 'shared'
 
 @ObjectType()
 export class Decay {

backend/src/graphql/resolver/BalanceResolver.ts

@@ -9,7 +9,7 @@ import { RIGHTS } from '@/auth/RIGHTS'
 import { BalanceLoggingView } from '@/logging/BalanceLogging.view'
 import { DecayLoggingView } from '@/logging/DecayLogging.view'
 import { Context, getUser } from '@/server/context'
-import { calculateDecay } from '@/util/decay'
+import { calculateDecay } from 'shared'
 
 import { getLogger } from 'log4js'
 import { LOG4JS_RESOLVER_CATEGORY_NAME } from '.'

backend/src/graphql/resolver/ContributionResolver.ts

@@ -19,7 +19,6 @@ import { ContributionType } from '@enum/ContributionType'
 import { TransactionTypeId } from '@enum/TransactionTypeId'
 import { AdminUpdateContribution } from '@model/AdminUpdateContribution'
 import { Contribution, ContributionListResult } from '@model/Contribution'
-import { Decay } from '@model/Decay'
 import { OpenCreation } from '@model/OpenCreation'
 import { UnconfirmedContribution } from '@model/UnconfirmedContribution'
 
@@ -44,7 +43,7 @@ import { UpdateUnconfirmedContributionContext } from '@/interactions/updateUncon
 import { LogError } from '@/server/LogError'
 import { Context, getClientTimezoneOffset, getUser } from '@/server/context'
 import { TRANSACTIONS_LOCK } from '@/util/TRANSACTIONS_LOCK'
-import { calculateDecay } from '@/util/decay'
+import { calculateDecay, Decay } from 'shared'
 import { fullName } from '@/util/utilities'
 
 import { LOG4JS_RESOLVER_CATEGORY_NAME } from '@/graphql/resolver'

backend/src/graphql/resolver/StatisticsResolver.ts

@@ -5,7 +5,7 @@ import { Authorized, FieldResolver, Query, Resolver } from 'type-graphql'
 import { CommunityStatistics, DynamicStatisticsFields } from '@model/CommunityStatistics'
 
 import { RIGHTS } from '@/auth/RIGHTS'
-import { calculateDecay } from '@/util/decay'
+import { calculateDecay } from 'shared'
 
 const db = AppDatabase.getInstance()
 

backend/src/graphql/resolver/TransactionLinkResolver.ts

@@ -39,7 +39,7 @@ import { LogError } from '@/server/LogError'
 import { Context, getClientTimezoneOffset, getUser } from '@/server/context'
 import { TRANSACTIONS_LOCK } from '@/util/TRANSACTIONS_LOCK'
 import { TRANSACTION_LINK_LOCK } from '@/util/TRANSACTION_LINK_LOCK'
-import { calculateDecay } from '@/util/decay'
+import { calculateDecay } from 'shared'
 import { fullName } from '@/util/utilities'
 import { calculateBalance } from '@/util/validate'
 

backend/src/logging/DecayLogging.view.ts

@@ -1,9 +1,10 @@
 import { AbstractLoggingView } from 'database'
 
 import { Decay } from '@/graphql/model/Decay'
+import type { Decay as DecayType } from 'shared'
 
 export class DecayLoggingView extends AbstractLoggingView {
-  public constructor(private self: Decay) {
+  public constructor(private self: Decay | DecayType) {
     super()
   }
 

backend/src/util/calculateSenderBalance.ts

@@ -4,7 +4,7 @@ import { Decay } from '@model/Decay'
 
 import { getLastTransaction } from '@/graphql/resolver/util/getLastTransaction'
 
-import { calculateDecay } from './decay'
+import { calculateDecay } from 'shared'
 
 export async function calculateSenderBalance(
   userId: number,
@@ -16,7 +16,7 @@ export async function calculateSenderBalance(
     return null
   }
 
-  const decay = calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time)
+  const decay = new Decay(calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time))
 
   const balance = decay.balance.add(amount.toString())
   return { balance, lastTransactionId: lastTransaction.id, decay }

backend/src/util/decay.ts

@@ -1,71 +0,0 @@
-import { Decimal } from 'decimal.js-light'
-
-import { Decay } from '@model/Decay'
-
-import { LogError } from '@/server/LogError'
-import { DECAY_START_TIME } from 'config-schema'
-
-Decimal.set({
-  precision: 25,
-  rounding: Decimal.ROUND_HALF_UP,
-})
-
-// TODO: externalize all those definitions and functions into an external decay library
-
-function decayFormula(value: Decimal, seconds: number): Decimal {
-  // TODO why do we need to convert this here to a stting to work properly?
-  return value.mul(
-    new Decimal('0.99999997803504048973201202316767079413460520837376').pow(seconds).toString(),
-  )
-}
-
-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 LogError('calculateDecay: to < from, reverse decay calculation is invalid')
-  }
-
-  // Initialize with no decay
-  const decay: Decay = {
-    balance: amount,
-    decay: new Decimal(0),
-    roundedDecay: new Decimal(0),
-    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)
-  decay.roundedDecay = amount
-    .toDecimalPlaces(2, Decimal.ROUND_DOWN)
-    .minus(decay.balance.toDecimalPlaces(2, Decimal.ROUND_DOWN).toString())
-    .mul(-1)
-  return decay
-}
-
-export { decayFormula, calculateDecay }

backend/src/util/validate.ts

@@ -7,7 +7,7 @@ import { Decay } from '@model/Decay'
 import { getLastTransaction } from '@/graphql/resolver/util/getLastTransaction'
 import { transactionLinkSummary } from '@/graphql/resolver/util/transactionLinkSummary'
 
-import { calculateDecay } from './decay'
+import { calculateDecay } from 'shared'
 
 function isStringBoolean(value: string): boolean {
   const lowerValue = value.toLowerCase()
@@ -36,7 +36,7 @@ async function calculateBalance(
     return null
   }
 
-  const decay = calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time)
+  const decay = new Decay(calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time))
 
   const balance = decay.balance.add(amount.toString())
   const { sumHoldAvailableAmount } = await transactionLinkSummary(userId, time)

backend/src/util/virtualTransactions.ts

@@ -6,7 +6,7 @@ import { TransactionTypeId } from '@enum/TransactionTypeId'
 import { Transaction } from '@model/Transaction'
 import { User } from '@model/User'
 
-import { calculateDecay } from './decay'
+import { calculateDecay } from 'shared'
 
 const defaultModelFunctions = {
   hasId: function (): boolean {

bun.lock

@@ -420,6 +420,7 @@
       "name": "shared",
       "version": "2.6.0",
       "dependencies": {
+        "decimal.js-light": "^2.5.1",
         "esbuild": "^0.25.2",
         "log4js": "^6.9.1",
         "zod": "^3.25.61",

federation/src/config/schema.ts

@@ -1,5 +1,4 @@
 import {
-  DECAY_START_TIME,
   GRAPHIQL,
   LOG4JS_CONFIG_PLACEHOLDER,
   LOG_FILES_BASE_PATH,
@@ -10,7 +9,6 @@ import {
 import Joi from 'joi'
 
 export const schema = Joi.object({
-  DECAY_START_TIME,
   GRAPHIQL,
   LOG4JS_CONFIG_PLACEHOLDER,
   LOG_FILES_BASE_PATH,

federation/src/graphql/api/1_0/model/Decay.ts

@@ -1,14 +1,6 @@
 import { Decimal } from 'decimal.js-light'
 import { Field, Int, ObjectType } from 'type-graphql'
-
-interface DecayInterface {
-  balance: Decimal
-  decay: Decimal
-  roundedDecay: Decimal
-  start: Date | null
-  end: Date | null
-  duration: number | null
-}
+import { Decay as DecayInterface} from 'shared'
 
 @ObjectType()
 export class Decay {

federation/src/graphql/api/1_0/util/calculateRecipientBalance.ts

@@ -1,4 +1,4 @@
-import { calculateDecay } from '@/graphql/util/decay'
+import { calculateDecay } from 'shared'
 import { getLastTransaction } from '@/graphql/util/getLastTransaction'
 import { Decimal } from 'decimal.js-light'
 import { Decay } from '../model/Decay'
@@ -13,7 +13,7 @@ export async function calculateRecipientBalance(
     return null
   }
 
-  const decay = calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time)
+  const decay = new Decay(calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time))
 
   const balance = decay.balance.add(amount.toString())
 

federation/src/graphql/util/decay.test.ts

@@ -1,42 +0,0 @@
-import { Decimal } from 'decimal.js-light'
-
-import { calculateDecay, decayFormula } from './decay'
-
-describe('utils/decay', () => {
-  describe('decayFormula', () => {
-    it('has base 0.99999997802044727', () => {
-      const amount = new Decimal(1.0)
-      const seconds = 1
-      // TODO: toString() was required, we could not compare two decimals
-      expect(decayFormula(amount, seconds).toString()).toBe('0.999999978035040489732012')
-    })
-    it('has correct backward calculation', () => {
-      const amount = new Decimal(1.0)
-      const seconds = -1
-      expect(decayFormula(amount, seconds).toString()).toBe('1.000000021964959992727444')
-    })
-    // we get pretty close, but not exact here, skipping
-
-    it.skip('has correct forward calculation', () => {
-      const amount = new Decimal(1.0).div(
-        new Decimal('0.99999997803504048973201202316767079413460520837376'),
-      )
-      const seconds = 1
-      expect(decayFormula(amount, seconds).toString()).toBe('1.0')
-    })
-  })
-  it('has base 0.99999997802044727', () => {
-    const now = new Date()
-    now.setSeconds(1)
-    const oneSecondAgo = new Date(now.getTime())
-    oneSecondAgo.setSeconds(0)
-    expect(calculateDecay(new Decimal(1.0), oneSecondAgo, now).balance.toString()).toBe(
-      '0.999999978035040489732012',
-    )
-  })
-
-  it('returns input amount when from and to is the same', () => {
-    const now = new Date()
-    expect(calculateDecay(new Decimal(100.0), now, now).balance.toString()).toBe('100')
-  })
-})

shared/package.json

@@ -31,6 +31,7 @@
     "uuid": "^8.3.2"
   },
   "dependencies": {
+    "decimal.js-light": "^2.5.1",
     "esbuild": "^0.25.2",
     "log4js": "^6.9.1",
     "zod": "^3.25.61"

shared/src/const/index.ts

@@ -0,0 +1,2 @@
+export const DECAY_START_TIME = new Date('2021-05-13T17:46:31Z')
+export const LOG4JS_BASE_CATEGORY_NAME = 'shared'

shared/src/index.ts

@@ -1,2 +1,3 @@
 export * from './schema'
-export * from './enum'
+export * from './enum'
+export * from './logic'

shared/src/logic/decay.ts

@@ -1,34 +1,47 @@
 import { Decimal } from 'decimal.js-light'
 
-import { LogError } from '@/server/LogError'
-import { DECAY_START_TIME } from 'config-schema'
-import { Decay } from '../api/1_0/model/Decay'
+import { getLogger } from 'log4js'
+import { LOG4JS_LOGIC_CATEGORY } from '.'
+import { DECAY_START_TIME } from '../const'
+
+const logger = getLogger(`${LOG4JS_LOGIC_CATEGORY}.DecayLogic`)
 
 Decimal.set({
   precision: 25,
   rounding: Decimal.ROUND_HALF_UP,
 })
 
-// TODO: externalize all those definitions and functions into an external decay library
-function decayFormula(value: Decimal, seconds: number): Decimal {
+export interface Decay {
+  balance: Decimal
+  decay: Decimal
+  roundedDecay: Decimal
+  start: Date | null
+  end: Date | null
+  duration: number | null
+}
+  
+export function decayFormula(value: Decimal, seconds: number): Decimal {
   // TODO why do we need to convert this here to a string to work properly?
+  // chatgpt: We convert to string here to avoid precision loss: 
+  //          .pow(seconds) can internally round the result, especially for large values of `seconds`. 
+  //          Using .toString() ensures full precision is preserved in the multiplication.
   return value.mul(
     new Decimal('0.99999997803504048973201202316767079413460520837376').pow(seconds).toString(),
   )
 }
 
-function calculateDecay(
+export function calculateDecay(
   amount: Decimal,
   from: Date,
-  to: Date,
-  startBlock: Date = DECAY_START_TIME,
+  to: Date
 ): Decay {
   const fromMs = from.getTime()
   const toMs = to.getTime()
-  const startBlockMs = startBlock.getTime()
+  const startBlockMs = DECAY_START_TIME.getTime()
 
   if (toMs < fromMs) {
-    throw new LogError('calculateDecay: to < from, reverse decay calculation is invalid')
+    logger.error('calculateDecay: to < from, reverse decay calculation is invalid', from, to)
+    throw new Error('calculateDecay: to < from, reverse decay calculation is invalid')
   }
 
   // Initialize with no decay
@@ -52,7 +65,7 @@ function calculateDecay(
   }
   // decay started between start and end date; decay from decay start till end date
   else {
-    decay.start = startBlock
+    decay.start = DECAY_START_TIME
     decay.duration = (toMs - startBlockMs) / 1000
   }
 
@@ -65,5 +78,3 @@ function calculateDecay(
     .mul(-1)
   return decay
 }
-
-export { decayFormula, calculateDecay }

shared/src/logic/index.ts

@@ -0,0 +1,4 @@
+import { LOG4JS_BASE_CATEGORY_NAME } from '../const'
+
+export const LOG4JS_LOGIC_CATEGORY = `${LOG4JS_BASE_CATEGORY_NAME}.logic`
+export { calculateDecay, Decay } from './decay'