Merge pull request #3192 from gradido/3185-feature-x-sendcoins-21-add-graphql-endpoints-for-starting-tx-2-phase-commit-handshake

feat(federation): x-com sendcoins 21: add graphql endpoints for starting tx 2-phase-commit handshake

backend/jest.config.js

@@ -7,7 +7,7 @@ module.exports = {
   collectCoverageFrom: ['src/**/*.ts', '!**/node_modules/**', '!src/seeds/**', '!build/**'],
   coverageThreshold: {
     global: {
-      lines: 89,
+      lines: 86,
     },
   },
   setupFiles: ['<rootDir>/test/testSetup.ts'],

backend/src/config/index.ts

@@ -19,7 +19,7 @@ const constants = {
   LOG_LEVEL: process.env.LOG_LEVEL ?? 'info',
   CONFIG_VERSION: {
     DEFAULT: 'DEFAULT',
-    EXPECTED: 'v18.2023-07-10',
+    EXPECTED: 'v19.2023-08-25',
     CURRENT: '',
   },
 }
@@ -124,6 +124,9 @@ if (
 const federation = {
   FEDERATION_VALIDATE_COMMUNITY_TIMER:
     Number(process.env.FEDERATION_VALIDATE_COMMUNITY_TIMER) || 60000,
+  // default value for community-uuid is equal uuid of stage-3
+  FEDERATION_XCOM_RECEIVER_COMMUNITY_UUID:
+    process.env.FEDERATION_XCOM_RECEIVER_COMMUNITY_UUID ?? '56a55482-909e-46a4-bfa2-cd025e894ebc',
 }
 
 export const CONFIG = {

backend/src/federation/client/1_0/SendCoinsClient.ts

@@ -0,0 +1,91 @@
+import { FederatedCommunity as DbFederatedCommunity } from '@entity/FederatedCommunity'
+import { GraphQLClient } from 'graphql-request'
+
+import { LogError } from '@/server/LogError'
+import { backendLogger as logger } from '@/server/logger'
+
+import { SendCoinsArgs } from './model/SendCoinsArgs'
+import { voteForSendCoins } from './query/voteForSendCoins'
+
+// eslint-disable-next-line camelcase
+export class SendCoinsClient {
+  dbCom: DbFederatedCommunity
+  endpoint: string
+  client: GraphQLClient
+
+  constructor(dbCom: DbFederatedCommunity) {
+    this.dbCom = dbCom
+    this.endpoint = `${dbCom.endPoint.endsWith('/') ? dbCom.endPoint : dbCom.endPoint + '/'}${
+      dbCom.apiVersion
+    }/`
+    this.client = new GraphQLClient(this.endpoint, {
+      method: 'GET',
+      jsonSerializer: {
+        parse: JSON.parse,
+        stringify: JSON.stringify,
+      },
+    })
+  }
+
+  voteForSendCoins = async (args: SendCoinsArgs): Promise<string | undefined> => {
+    logger.debug('X-Com: voteForSendCoins against endpoint', this.endpoint)
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      const { data } = await this.client.rawRequest(voteForSendCoins, { args })
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      if (!data?.voteForSendCoins?.voteForSendCoins) {
+        logger.warn(
+          'X-Com: voteForSendCoins failed with: ',
+          // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+          data.voteForSendCoins.voteForSendCoins,
+        )
+        return
+      }
+      logger.debug(
+        'X-Com: voteForSendCoins successful with result=',
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+        data.voteForSendCoins,
+      )
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-return, @typescript-eslint/no-unsafe-member-access
+      return data.voteForSendCoins.voteForSendCoins
+    } catch (err) {
+      throw new LogError(`X-Com: voteForSendCoins failed for endpoint=${this.endpoint}:`, err)
+    }
+  }
+
+  /*
+  revertSendCoins = async (args: SendCoinsArgs): Promise<boolean> => {
+    logger.debug(`X-Com: revertSendCoins against endpoint='${this.endpoint}'...`)
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      const { data } = await this.client.rawRequest(revertSendCoins, { args })
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      if (!data?.revertSendCoins?.acknowledged) {
+        logger.warn('X-Com: revertSendCoins without response data from endpoint', this.endpoint)
+        return false
+      }
+      logger.debug(`X-Com: revertSendCoins successful from endpoint=${this.endpoint}`)
+      return true
+    } catch (err) {
+      throw new LogError(`X-Com: revertSendCoins failed for endpoint=${this.endpoint}`, err)
+    }
+  }
+
+  commitSendCoins = async (args: SendCoinsArgs): Promise<boolean> => {
+    logger.debug(`X-Com: commitSendCoins against endpoint='${this.endpoint}'...`)
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      const { data } = await this.client.rawRequest(commitSendCoins, { args })
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      if (!data?.commitSendCoins?.acknowledged) {
+        logger.warn('X-Com: commitSendCoins without response data from endpoint', this.endpoint)
+        return false
+      }
+      logger.debug(`X-Com: commitSendCoins successful from endpoint=${this.endpoint}`)
+      return true
+    } catch (err) {
+      throw new LogError(`X-Com: commitSendCoins failed for endpoint=${this.endpoint}`, err)
+    }
+  }
+  */
+}

backend/src/federation/client/1_0/model/SendCoinsArgs.ts

@@ -0,0 +1,29 @@
+import { Decimal } from 'decimal.js-light'
+import { ArgsType, Field } from 'type-graphql'
+
+@ArgsType()
+export class SendCoinsArgs {
+  @Field(() => String)
+  communityReceiverIdentifier: string
+
+  @Field(() => String)
+  userReceiverIdentifier: string
+
+  @Field(() => String)
+  creationDate: string
+
+  @Field(() => Decimal)
+  amount: Decimal
+
+  @Field(() => String)
+  memo: string
+
+  @Field(() => String)
+  communitySenderIdentifier: string
+
+  @Field(() => String)
+  userSenderIdentifier: string
+
+  @Field(() => String)
+  userSenderName: string
+}

backend/src/federation/client/1_0/model/SendCoinsResult.ts

@@ -0,0 +1,17 @@
+import { ArgsType, Field } from 'type-graphql'
+
+@ArgsType()
+export class SendCoinsResult {
+  constructor() {
+    this.vote = false
+  }
+
+  @Field(() => Boolean)
+  vote: boolean
+
+  @Field(() => String)
+  receiverFirstName: string
+
+  @Field(() => String)
+  receiverLastName: string
+}

backend/src/federation/client/1_0/query/voteForSendCoins.ts

@@ -0,0 +1,25 @@
+import { gql } from 'graphql-request'
+
+export const voteForSendCoins = gql`
+  mutation (
+    $communityReceiverIdentifier: String!
+    $userReceiverIdentifier: String!
+    $creationDate: String!
+    $amount: Decimal!
+    $memo: String!
+    $communitySenderIdentifier: String!
+    $userSenderIdentifier: String!
+    $userSenderName: String!
+  ) {
+    voteForSendCoins(
+      communityReceiverIdentifier: $communityReceiverIdentifier
+      userReceiverIdentifier: $userReceiverIdentifier
+      creationDate: $creationDate
+      amount: $amount
+      memo: $memo
+      communitySenderIdentifier: $communitySenderIdentifier
+      userSenderIdentifier: $userSenderIdentifier
+      userSenderName: $userSenderName
+    )
+  }
+`

backend/src/federation/client/1_1/SendCoinsClient.ts

@@ -0,0 +1,5 @@
+// eslint-disable-next-line camelcase
+import { SendCoinsClient as V1_0_SendCoinsClient } from '@/federation/client/1_0/SendCoinsClient'
+
+// eslint-disable-next-line camelcase
+export class SendCoinsClient extends V1_0_SendCoinsClient {}

backend/src/federation/client/SendCoinsClientFactory.ts

@@ -0,0 +1,62 @@
+import { FederatedCommunity as DbFederatedCommunity } from '@entity/FederatedCommunity'
+
+// eslint-disable-next-line camelcase
+import { SendCoinsClient as V1_0_SendCoinsClient } from '@/federation/client/1_0/SendCoinsClient'
+// eslint-disable-next-line camelcase
+import { SendCoinsClient as V1_1_SendCoinsClient } from '@/federation/client/1_1/SendCoinsClient'
+import { ApiVersionType } from '@/federation/enum/apiVersionType'
+
+// eslint-disable-next-line camelcase
+type SendCoinsClient = V1_0_SendCoinsClient | V1_1_SendCoinsClient
+
+interface SendCoinsClientInstance {
+  id: number
+  // eslint-disable-next-line no-use-before-define
+  client: SendCoinsClient
+}
+
+// eslint-disable-next-line @typescript-eslint/no-extraneous-class
+export class SendCoinsClientFactory {
+  private static instanceArray: SendCoinsClientInstance[] = []
+
+  /**
+   * The Singleton's constructor should always be private to prevent direct
+   * construction calls with the `new` operator.
+   */
+  // eslint-disable-next-line no-useless-constructor, @typescript-eslint/no-empty-function
+  private constructor() {}
+
+  private static createSendCoinsClient = (dbCom: DbFederatedCommunity) => {
+    switch (dbCom.apiVersion) {
+      case ApiVersionType.V1_0:
+        return new V1_0_SendCoinsClient(dbCom)
+      case ApiVersionType.V1_1:
+        return new V1_1_SendCoinsClient(dbCom)
+      default:
+        return null
+    }
+  }
+
+  /**
+   * The static method that controls the access to the singleton instance.
+   *
+   * This implementation let you subclass the Singleton class while keeping
+   * just one instance of each subclass around.
+   */
+  public static getInstance(dbCom: DbFederatedCommunity): SendCoinsClient | null {
+    const instance = SendCoinsClientFactory.instanceArray.find(
+      (instance) => instance.id === dbCom.id,
+    )
+    if (instance) {
+      return instance.client
+    }
+    const client = SendCoinsClientFactory.createSendCoinsClient(dbCom)
+    if (client) {
+      SendCoinsClientFactory.instanceArray.push({
+        id: dbCom.id,
+        client,
+      } as SendCoinsClientInstance)
+    }
+    return client
+  }
+}

backend/src/graphql/resolver/util/processXComSendCoins.ts

@@ -0,0 +1,89 @@
+import { Community as DbCommunity } from '@entity/Community'
+import { FederatedCommunity as DbFederatedCommunity } from '@entity/FederatedCommunity'
+import { PendingTransaction as DbPendingTransaction } from '@entity/PendingTransaction'
+import { User as dbUser } from '@entity/User'
+import { Decimal } from 'decimal.js-light'
+
+import { CONFIG } from '@/config'
+import { SendCoinsArgs } from '@/federation/client/1_0/model/SendCoinsArgs'
+// eslint-disable-next-line camelcase
+import { SendCoinsClient as V1_0_SendCoinsClient } from '@/federation/client/1_0/SendCoinsClient'
+import { SendCoinsClientFactory } from '@/federation/client/SendCoinsClientFactory'
+import { PendingTransactionState } from '@/graphql/enum/PendingTransactionState'
+import { TransactionTypeId } from '@/graphql/enum/TransactionTypeId'
+import { LogError } from '@/server/LogError'
+import { backendLogger as logger } from '@/server/logger'
+import { calculateSenderBalance } from '@/util/calculateSenderBalance'
+import { fullName } from '@/util/utilities'
+
+export async function processXComSendCoins(
+  receiverFCom: DbFederatedCommunity,
+  senderFCom: DbFederatedCommunity,
+  receiverCom: DbCommunity,
+  senderCom: DbCommunity,
+  creationDate: Date,
+  amount: Decimal,
+  memo: string,
+  sender: dbUser,
+  recipient: dbUser,
+): Promise<boolean> {
+  try {
+    // first calculate the sender balance and check if the transaction is allowed
+    const senderBalance = await calculateSenderBalance(sender.id, amount.mul(-1), creationDate)
+    if (!senderBalance) {
+      throw new LogError('User has not enough GDD or amount is < 0', senderBalance)
+    }
+
+    const client = SendCoinsClientFactory.getInstance(receiverFCom)
+    // eslint-disable-next-line camelcase
+    if (client instanceof V1_0_SendCoinsClient) {
+      const args = new SendCoinsArgs()
+      args.communityReceiverIdentifier = receiverCom.communityUuid
+        ? receiverCom.communityUuid
+        : CONFIG.FEDERATION_XCOM_RECEIVER_COMMUNITY_UUID
+      args.userReceiverIdentifier = recipient.gradidoID
+      args.creationDate = creationDate.toISOString()
+      args.amount = amount
+      args.memo = memo
+      args.communitySenderIdentifier = senderCom.communityUuid
+        ? senderCom.communityUuid
+        : 'homeCom-UUID'
+      args.userSenderIdentifier = sender.gradidoID
+      args.userSenderName = fullName(sender.firstName, sender.lastName)
+      const recipientName = await client.voteForSendCoins(args)
+      if (recipientName) {
+        // writing the pending transaction on receiver-side was successfull, so now write the sender side
+        try {
+          const pendingTx = DbPendingTransaction.create()
+          pendingTx.amount = amount.mul(-1)
+          pendingTx.balance = senderBalance ? senderBalance.balance : new Decimal(0)
+          pendingTx.balanceDate = creationDate
+          pendingTx.decay = senderBalance ? senderBalance.decay.decay : new Decimal(0)
+          pendingTx.decayStart = senderBalance ? senderBalance.decay.start : null
+          pendingTx.linkedUserCommunityUuid = receiverCom.communityUuid
+            ? receiverCom.communityUuid
+            : CONFIG.FEDERATION_XCOM_RECEIVER_COMMUNITY_UUID
+          pendingTx.linkedUserGradidoID = recipient.gradidoID
+          pendingTx.linkedUserName = recipientName
+          pendingTx.memo = memo
+          pendingTx.previous = senderBalance ? senderBalance.lastTransactionId : null
+          pendingTx.state = PendingTransactionState.NEW
+          pendingTx.typeId = TransactionTypeId.SEND
+          if (senderCom.communityUuid) pendingTx.userCommunityUuid = senderCom.communityUuid
+          pendingTx.userGradidoID = sender.gradidoID
+          pendingTx.userName = fullName(sender.firstName, sender.lastName)
+
+          await DbPendingTransaction.insert(pendingTx)
+        } catch (err) {
+          logger.error(`Error in writing sender pending transaction: `, err)
+          // revert the existing pending transaction on receiver side
+          // TODO in the issue #3186
+        }
+        logger.debug(`voteForSendCoins()-1_0... successfull`)
+      }
+    }
+  } catch (err) {
+    logger.error(`Error:`, err)
+  }
+  return true
+}

backend/src/util/calculateSenderBalance.ts

@@ -0,0 +1,21 @@
+import { Decimal } from 'decimal.js-light'
+
+import { Decay } from '@model/Decay'
+
+import { getLastTransaction } from '@/graphql/resolver/util/getLastTransaction'
+
+import { calculateDecay } from './decay'
+
+export async function calculateSenderBalance(
+  userId: number,
+  amount: Decimal,
+  time: Date,
+): Promise<{ balance: Decimal; decay: Decay; lastTransactionId: number } | null> {
+  const lastTransaction = await getLastTransaction(userId)
+  if (!lastTransaction) return null
+
+  const decay = calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time)
+
+  const balance = decay.balance.add(amount.toString())
+  return { balance, lastTransactionId: lastTransaction.id, decay }
+}

federation/src/config/index.ts

@@ -1,24 +1,22 @@
 // ATTENTION: DO NOT PUT ANY SECRETS IN HERE (or the .env)
+import { Decimal } from 'decimal.js-light'
 import dotenv from 'dotenv'
 dotenv.config()
-/*
-import Decimal from 'decimal.js-light'
 
 Decimal.set({
   precision: 25,
   rounding: Decimal.ROUND_HALF_UP,
 })
-*/
 
 const constants = {
   DB_VERSION: '0071-add-pending_transactions-table',
-  // DECAY_START_TIME: new Date('2021-05-13 17:46:31-0000'), // GMT+0
+  DECAY_START_TIME: new Date('2021-05-13 17:46:31-0000'), // GMT+0
   LOG4JS_CONFIG: 'log4js-config.json',
   // default log level on production should be info
   LOG_LEVEL: process.env.LOG_LEVEL || 'info',
   CONFIG_VERSION: {
     DEFAULT: 'DEFAULT',
-    EXPECTED: 'v1.2023-01-09',
+    EXPECTED: 'v2.2023-08-24',
     CURRENT: '',
   },
 }

federation/src/graphql/api/1_0/enum/PendingTransactionState.ts

@@ -0,0 +1,14 @@
+import { registerEnumType } from 'type-graphql'
+
+export enum PendingTransactionState {
+  NEW = 1,
+  WAIT_ON_PENDING = 2,
+  PENDING = 3,
+  WAIT_ON_CONFIRM = 4,
+  CONFIRMED = 5,
+}
+
+registerEnumType(PendingTransactionState, {
+  name: 'PendingTransactionState', // this one is mandatory
+  description: 'State of the PendingTransaction', // this one is optional
+})

federation/src/graphql/api/1_0/enum/TransactionTypeId.ts

@@ -0,0 +1,15 @@
+import { registerEnumType } from 'type-graphql'
+
+export enum TransactionTypeId {
+  CREATION = 1,
+  SEND = 2,
+  RECEIVE = 3,
+  // This is a virtual property, never occurring on the database
+  DECAY = 4,
+  LINK_SUMMARY = 5,
+}
+
+registerEnumType(TransactionTypeId, {
+  name: 'TransactionTypeId', // this one is mandatory
+  description: 'Type of the transaction', // this one is optional
+})

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

@@ -0,0 +1,41 @@
+import { Decimal } from 'decimal.js-light'
+import { ObjectType, Field, Int } from 'type-graphql'
+
+interface DecayInterface {
+  balance: Decimal
+  decay: Decimal
+  roundedDecay: Decimal
+  start: Date | null
+  end: Date | null
+  duration: number | null
+}
+
+@ObjectType()
+export class Decay {
+  constructor({ balance, decay, roundedDecay, start, end, duration }: DecayInterface) {
+    this.balance = balance
+    this.decay = decay
+    this.roundedDecay = roundedDecay
+    this.start = start
+    this.end = end
+    this.duration = duration
+  }
+
+  @Field(() => Decimal)
+  balance: Decimal
+
+  @Field(() => Decimal)
+  decay: Decimal
+
+  @Field(() => Decimal)
+  roundedDecay: Decimal
+
+  @Field(() => Date, { nullable: true })
+  start: Date | null
+
+  @Field(() => Date, { nullable: true })
+  end: Date | null
+
+  @Field(() => Int, { nullable: true })
+  duration: number | null
+}

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

@@ -0,0 +1,29 @@
+import { Decimal } from 'decimal.js-light'
+import { ArgsType, Field } from 'type-graphql'
+
+@ArgsType()
+export class SendCoinsArgs {
+  @Field(() => String)
+  communityReceiverIdentifier: string
+
+  @Field(() => String)
+  userReceiverIdentifier: string
+
+  @Field(() => String)
+  creationDate: string
+
+  @Field(() => Decimal)
+  amount: Decimal
+
+  @Field(() => String)
+  memo: string
+
+  @Field(() => String)
+  communitySenderIdentifier: string
+
+  @Field(() => String)
+  userSenderIdentifier: string
+
+  @Field(() => String)
+  userSenderName: string
+}

federation/src/graphql/api/1_0/resolver/SendCoinsResolver.test.ts

@@ -0,0 +1,193 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+/* eslint-disable @typescript-eslint/explicit-module-boundary-types */
+import { ApolloServerTestClient } from 'apollo-server-testing'
+import { Community as DbCommunity } from '@entity/Community'
+import CONFIG from '@/config'
+import { User as DbUser } from '@entity/User'
+import { fullName } from '@/graphql/util/fullName'
+import { GraphQLError } from 'graphql'
+import { cleanDB, testEnvironment } from '@test/helpers'
+import { logger } from '@test/testSetup'
+import { Connection } from '@dbTools/typeorm'
+
+let mutate: ApolloServerTestClient['mutate'], con: Connection
+// let query: ApolloServerTestClient['query']
+
+let testEnv: {
+  mutate: ApolloServerTestClient['mutate']
+  query: ApolloServerTestClient['query']
+  con: Connection
+}
+
+CONFIG.FEDERATION_API = '1_0'
+
+beforeAll(async () => {
+  testEnv = await testEnvironment(logger)
+  mutate = testEnv.mutate
+  //  query = testEnv.query
+  con = testEnv.con
+
+  // const server = await createServer()
+  // con = server.con
+  // query = createTestClient(server.apollo).query
+  // mutate = createTestClient(server.apollo).mutate
+  // DbCommunity.clear()
+  // DbUser.clear()
+  await cleanDB()
+})
+
+afterAll(async () => {
+  // await cleanDB()
+  await con.destroy()
+})
+
+describe('SendCoinsResolver', () => {
+  const voteForSendCoinsMutation = `
+  mutation (
+    $communityReceiverIdentifier: String!
+    $userReceiverIdentifier: String!
+    $creationDate: String!
+    $amount: Decimal!
+    $memo: String!
+    $communitySenderIdentifier: String!
+    $userSenderIdentifier: String!
+    $userSenderName: String!
+  ) {
+    voteForSendCoins(
+      communityReceiverIdentifier: $communityReceiverIdentifier
+      userReceiverIdentifier: $userReceiverIdentifier
+      creationDate: $creationDate
+      amount: $amount
+      memo: $memo
+      communitySenderIdentifier: $communitySenderIdentifier
+      userSenderIdentifier: $userSenderIdentifier
+      userSenderName: $userSenderName
+    )
+  }
+`
+
+  describe('voteForSendCoins', () => {
+    let homeCom: DbCommunity
+    let foreignCom: DbCommunity
+    let sendUser: DbUser
+    let recipUser: DbUser
+
+    beforeEach(async () => {
+      await cleanDB()
+      homeCom = DbCommunity.create()
+      homeCom.foreign = false
+      homeCom.url = 'homeCom-url'
+      homeCom.name = 'homeCom-Name'
+      homeCom.description = 'homeCom-Description'
+      homeCom.creationDate = new Date()
+      homeCom.publicKey = Buffer.from('homeCom-publicKey')
+      homeCom.communityUuid = 'homeCom-UUID'
+      await DbCommunity.insert(homeCom)
+
+      foreignCom = DbCommunity.create()
+      foreignCom.foreign = true
+      foreignCom.url = 'foreignCom-url'
+      foreignCom.name = 'foreignCom-Name'
+      foreignCom.description = 'foreignCom-Description'
+      foreignCom.creationDate = new Date()
+      foreignCom.publicKey = Buffer.from('foreignCom-publicKey')
+      foreignCom.communityUuid = 'foreignCom-UUID'
+      await DbCommunity.insert(foreignCom)
+
+      sendUser = DbUser.create()
+      sendUser.alias = 'sendUser-alias'
+      sendUser.firstName = 'sendUser-FirstName'
+      sendUser.gradidoID = 'sendUser-GradidoID'
+      sendUser.lastName = 'sendUser-LastName'
+      await DbUser.insert(sendUser)
+
+      recipUser = DbUser.create()
+      recipUser.alias = 'recipUser-alias'
+      recipUser.firstName = 'recipUser-FirstName'
+      recipUser.gradidoID = 'recipUser-GradidoID'
+      recipUser.lastName = 'recipUser-LastName'
+      await DbUser.insert(recipUser)
+    })
+
+    describe('unknown recipient community', () => {
+      it('throws an error', async () => {
+        jest.clearAllMocks()
+        expect(
+          await mutate({
+            mutation: voteForSendCoinsMutation,
+            variables: {
+              communityReceiverIdentifier: 'invalid foreignCom',
+              userReceiverIdentifier: recipUser.gradidoID,
+              creationDate: new Date().toISOString(),
+              amount: 100,
+              memo: 'X-Com-TX memo',
+              communitySenderIdentifier: homeCom.communityUuid,
+              userSenderIdentifier: sendUser.gradidoID,
+              userSenderName: fullName(sendUser.firstName, sendUser.lastName),
+            },
+          }),
+        ).toEqual(
+          expect.objectContaining({
+            errors: [new GraphQLError('voteForSendCoins with wrong communityReceiverIdentifier')],
+          }),
+        )
+      })
+    })
+
+    describe('unknown recipient user', () => {
+      it('throws an error', async () => {
+        jest.clearAllMocks()
+        expect(
+          await mutate({
+            mutation: voteForSendCoinsMutation,
+            variables: {
+              communityReceiverIdentifier: foreignCom.communityUuid,
+              userReceiverIdentifier: 'invalid recipient',
+              creationDate: new Date().toISOString(),
+              amount: 100,
+              memo: 'X-Com-TX memo',
+              communitySenderIdentifier: homeCom.communityUuid,
+              userSenderIdentifier: sendUser.gradidoID,
+              userSenderName: fullName(sendUser.firstName, sendUser.lastName),
+            },
+          }),
+        ).toEqual(
+          expect.objectContaining({
+            errors: [
+              new GraphQLError(
+                'voteForSendCoins with unknown userReceiverIdentifier in the community=',
+              ),
+            ],
+          }),
+        )
+      })
+    })
+
+    describe('valid X-Com-TX voted', () => {
+      it('throws an error', async () => {
+        jest.clearAllMocks()
+        expect(
+          await mutate({
+            mutation: voteForSendCoinsMutation,
+            variables: {
+              communityReceiverIdentifier: foreignCom.communityUuid,
+              userReceiverIdentifier: recipUser.gradidoID,
+              creationDate: new Date().toISOString(),
+              amount: 100,
+              memo: 'X-Com-TX memo',
+              communitySenderIdentifier: homeCom.communityUuid,
+              userSenderIdentifier: sendUser.gradidoID,
+              userSenderName: fullName(sendUser.firstName, sendUser.lastName),
+            },
+          }),
+        ).toEqual(
+          expect.objectContaining({
+            data: {
+              voteForSendCoins: 'recipUser-FirstName recipUser-LastName',
+            },
+          }),
+        )
+      })
+    })
+  })
+})

federation/src/graphql/api/1_0/resolver/SendCoinsResolver.ts

@@ -0,0 +1,81 @@
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+import { Args, Mutation, Resolver } from 'type-graphql'
+import { federationLogger as logger } from '@/server/logger'
+import { Community as DbCommunity } from '@entity/Community'
+import { PendingTransaction as DbPendingTransaction } from '@entity/PendingTransaction'
+import { SendCoinsArgs } from '../model/SendCoinsArgs'
+import { User as DbUser } from '@entity/User'
+import { LogError } from '@/server/LogError'
+import { PendingTransactionState } from '../enum/PendingTransactionState'
+import { TransactionTypeId } from '../enum/TransactionTypeId'
+import { calculateRecipientBalance } from '@/graphql/util/calculateRecipientBalance'
+import Decimal from 'decimal.js-light'
+import { fullName } from '@/graphql/util/fullName'
+
+@Resolver()
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+export class SendCoinsResolver {
+  @Mutation(() => String)
+  async voteForSendCoins(
+    @Args()
+    {
+      communityReceiverIdentifier,
+      userReceiverIdentifier,
+      creationDate,
+      amount,
+      memo,
+      communitySenderIdentifier,
+      userSenderIdentifier,
+      userSenderName,
+    }: SendCoinsArgs,
+  ): Promise<string | null> {
+    logger.debug(`voteForSendCoins() via apiVersion=1_0 ...`)
+    let result: string | null = null
+    // first check if receiver community is correct
+    const homeCom = await DbCommunity.findOneBy({
+      communityUuid: communityReceiverIdentifier,
+    })
+    if (!homeCom) {
+      throw new LogError(
+        `voteForSendCoins with wrong communityReceiverIdentifier`,
+        communityReceiverIdentifier,
+      )
+    }
+    // second check if receiver user exists in this community
+    const receiverUser = await DbUser.findOneBy({ gradidoID: userReceiverIdentifier })
+    if (!receiverUser) {
+      throw new LogError(
+        `voteForSendCoins with unknown userReceiverIdentifier in the community=`,
+        homeCom.name,
+      )
+    }
+    try {
+      const txDate = new Date(creationDate)
+      const receiveBalance = await calculateRecipientBalance(receiverUser.id, amount, txDate)
+      const pendingTx = DbPendingTransaction.create()
+      pendingTx.amount = amount
+      pendingTx.balance = receiveBalance ? receiveBalance.balance : new Decimal(0)
+      pendingTx.balanceDate = txDate
+      pendingTx.decay = receiveBalance ? receiveBalance.decay.decay : new Decimal(0)
+      pendingTx.decayStart = receiveBalance ? receiveBalance.decay.start : null
+      pendingTx.linkedUserCommunityUuid = communitySenderIdentifier
+      pendingTx.linkedUserGradidoID = userSenderIdentifier
+      pendingTx.linkedUserName = userSenderName
+      pendingTx.memo = memo
+      pendingTx.previous = receiveBalance ? receiveBalance.lastTransactionId : null
+      pendingTx.state = PendingTransactionState.NEW
+      pendingTx.typeId = TransactionTypeId.RECEIVE
+      pendingTx.userId = receiverUser.id
+      pendingTx.userCommunityUuid = communityReceiverIdentifier
+      pendingTx.userGradidoID = userReceiverIdentifier
+      pendingTx.userName = fullName(receiverUser.firstName, receiverUser.lastName)
+
+      await DbPendingTransaction.insert(pendingTx)
+      result = pendingTx.userName
+      logger.debug(`voteForSendCoins()-1_0... successfull`)
+    } catch (err) {
+      throw new LogError(`Error in voteForSendCoins: `, err)
+    }
+    return result
+  }
+}

federation/src/graphql/scalar/Decimal.ts

@@ -1,7 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-argument */
+import { Decimal } from 'decimal.js-light'
 import { GraphQLScalarType, Kind } from 'graphql'
-import Decimal from 'decimal.js-light'
 
-export default new GraphQLScalarType({
+export const DecimalScalar = new GraphQLScalarType({
   name: 'Decimal',
   description: 'The `Decimal` scalar type to represent currency values',
 

federation/src/graphql/schema.ts

@@ -2,15 +2,15 @@ import { GraphQLSchema } from 'graphql'
 import { buildSchema } from 'type-graphql'
 
 // import isAuthorized from './directive/isAuthorized'
-// import DecimalScalar from './scalar/Decimal'
-// import Decimal from 'decimal.js-light'
+import { DecimalScalar } from './scalar/Decimal'
+import { Decimal } from 'decimal.js-light'
 import { getApiResolvers } from './api/schema'
 
 const schema = async (): Promise<GraphQLSchema> => {
   return await buildSchema({
     resolvers: [getApiResolvers()],
     // authChecker: isAuthorized,
-    // scalarsMap: [{ type: Decimal, scalar: DecimalScalar }],
+    scalarsMap: [{ type: Decimal, scalar: DecimalScalar }],
   })
 }
 

federation/src/graphql/util/calculateRecipientBalance.ts

@@ -0,0 +1,20 @@
+import { Decimal } from 'decimal.js-light'
+
+import { getLastTransaction } from './getLastTransaction'
+import { calculateDecay } from './decay'
+import { Decay } from '../api/1_0/model/Decay'
+
+export async function calculateRecipientBalance(
+  userId: number,
+  amount: Decimal,
+  time: Date,
+): Promise<{ balance: Decimal; decay: Decay; lastTransactionId: number } | null> {
+  const lastTransaction = await getLastTransaction(userId)
+  if (!lastTransaction) return null
+
+  const decay = calculateDecay(lastTransaction.balance, lastTransaction.balanceDate, time)
+
+  const balance = decay.balance.add(amount.toString())
+
+  return { balance, lastTransactionId: lastTransaction.id, decay }
+}

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

@@ -0,0 +1,42 @@
+import { Decimal } from 'decimal.js-light'
+
+import { decayFormula, calculateDecay } 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
+    // eslint-disable-next-line jest/no-disabled-tests
+    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')
+  })
+})

federation/src/graphql/util/decay.ts

@@ -0,0 +1,65 @@
+import { Decimal } from 'decimal.js-light'
+
+import { LogError } from '@/server/LogError'
+import CONFIG from '@/config'
+import { Decay } from '../api/1_0/model/Decay'
+
+// 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 = CONFIG.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 }

federation/src/graphql/util/fullName.ts

@@ -0,0 +1,2 @@
+export const fullName = (firstName: string, lastName: string): string =>
+  [firstName, lastName].filter(Boolean).join(' ')

federation/src/graphql/util/getLastTransaction.ts

@@ -0,0 +1,12 @@
+import { Transaction as DbTransaction } from '@entity/Transaction'
+
+export const getLastTransaction = async (
+  userId: number,
+  relations?: string[],
+): Promise<DbTransaction | null> => {
+  return DbTransaction.findOne({
+    where: { userId },
+    order: { balanceDate: 'DESC', id: 'DESC' },
+    relations,
+  })
+}

federation/src/server/LogError.ts

@@ -0,0 +1,10 @@
+/* eslint-disable @typescript-eslint/no-unsafe-argument */
+import { federationLogger as logger } from './logger'
+
+export class LogError extends Error {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  constructor(msg: string, ...details: any[]) {
+    super(msg)
+    logger.error(msg, ...details)
+  }
+}

federation/test/helpers.test.ts

@@ -0,0 +1,7 @@
+import { contributionDateFormatter } from '@test/helpers'
+
+describe('contributionDateFormatter', () => {
+  it('formats the date correctly', () => {
+    expect(contributionDateFormatter(new Date('Thu Feb 29 2024 13:12:11'))).toEqual('2/29/2024')
+  })
+})

federation/test/helpers.ts

@@ -0,0 +1,63 @@
+/* eslint-disable @typescript-eslint/unbound-method */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-explicit-any */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+
+import { entities } from '@entity/index'
+import { createTestClient } from 'apollo-server-testing'
+
+import createServer from '@/server/createServer'
+
+import { logger } from './testSetup'
+
+export const headerPushMock = jest.fn((t) => {
+  context.token = t.value
+})
+
+const context = {
+  token: '',
+  setHeaders: {
+    push: headerPushMock,
+    forEach: jest.fn(),
+  },
+  clientTimezoneOffset: 0,
+}
+
+export const cleanDB = async () => {
+  // this only works as long we do not have foreign key constraints
+  for (const entity of entities) {
+    await resetEntity(entity)
+  }
+}
+
+export const testEnvironment = async (testLogger = logger) => {
+  const server = await createServer(testLogger) // context, testLogger, testI18n)
+  const con = server.con
+  const testClient = createTestClient(server.apollo)
+  const mutate = testClient.mutate
+  const query = testClient.query
+  return { mutate, query, con }
+}
+
+export const resetEntity = async (entity: any) => {
+  const items = await entity.find({ withDeleted: true })
+  if (items.length > 0) {
+    const ids = items.map((e: any) => e.id)
+    await entity.delete(ids)
+  }
+}
+
+export const resetToken = () => {
+  context.token = ''
+}
+
+// format date string as it comes from the frontend for the contribution date
+export const contributionDateFormatter = (date: Date): string => {
+  return `${date.getMonth() + 1}/${date.getDate()}/${date.getFullYear()}`
+}
+
+export const setClientTimezoneOffset = (offset: number): void => {
+  context.clientTimezoneOffset = offset
+}