4-automatic switching between service providers

banktransfer.js

@@ -0,0 +1,85 @@
+const models = require('./models');
+const {
+  exists, zrevrange, zadd, expire, zincrby,
+} = require('./redis');
+
+function processResult(amount) {
+  if (amount === 10) {
+    return {
+      success: false,
+      error: 'Bank transfer failed',
+    };
+  }
+  return {
+    success: true,
+    message: 'Transfer was successful',
+  };
+}
+
+const BANK_TRANSFER_PROCESSORS_SET_NAME = 'banktf_processors_list';
+
+// function that calls paystack endpoint
+function paystackBT(amount) {
+  return processResult(amount);
+}
+
+// function that calls flutterwave endpoint
+function flutterwaveBT(amount) {
+  return processResult(amount);
+}
+
+// function that calls monnify endpoint
+function monnifyBT(amount) {
+  return processResult(amount);
+}
+
+// general function that calls processor function based on processor
+function processBankTransfer(processor, amount) {
+  if (processor === 'paystack') {
+    return paystackBT(amount);
+  }
+  if (processor === 'flutterwave') {
+    return flutterwaveBT(amount);
+  }
+  if (processor === 'monnify') {
+    return monnifyBT(amount);
+  }
+}
+
+// main function
+async function transferToBank(amount) {
+  const processors = await models.bank_transfer_processors.find(
+    { where: { enabled: true }, raw: true },
+  );
+  const setArray = [];
+  const setExists = await exists(BANK_TRANSFER_PROCESSORS_SET_NAME);
+
+  if (!setExists) {
+    processors.forEach((processor) => {
+      let score = 0;
+      if (processor.position === 1) {
+        score = 30;
+      }
+      if (processor.position === 2) {
+        score = 10;
+      }
+      setArray.push(score);
+      setArray.push(processor.name);
+    });
+    await zadd(BANK_TRANSFER_PROCESSORS_SET_NAME, setArray);
+    await expire(BANK_TRANSFER_PROCESSORS_SET_NAME, 1800); // set should refresh in 30mins
+  }
+  const processorList = await zrevrange(BANK_TRANSFER_PROCESSORS_SET_NAME, 0, -1, 'WITHSCORES');
+
+  const [highestScoredProcessor] = processorList;
+
+  const bankTransferResult = processBankTransfer(highestScoredProcessor, amount);
+  if (!bankTransferResult.success) {
+    await zincrby(BANK_TRANSFER_PROCESSORS_SET_NAME, -10, highestScoredProcessor);
+  } else {
+    await zincrby(BANK_TRANSFER_PROCESSORS_SET_NAME, 10, highestScoredProcessor);
+  }
+  return bankTransferResult;
+}
+
+// await trasferToBank(10);

migrations/20210220170629-create-bank-transfer-processors-table.js

@@ -0,0 +1,36 @@
+module.exports = {
+  up: async (queryInterface, Sequelize) => queryInterface.createTable('bank_transfer_processors', {
+    id: {
+      type: Sequelize.INTEGER,
+      allowNull: false,
+      autoIncrement: true,
+      primaryKey: true,
+    },
+    name: {
+      type: Sequelize.STRING,
+      allowNull: false,
+      unique: true,
+    },
+    position: {
+      type: Sequelize.INTEGER,
+      allowNull: false,
+    },
+    enabled: {
+      type: Sequelize.BOOLEAN,
+      allowNull: false,
+      defaultValue: true,
+    },
+    created_at: {
+      allowNull: false,
+      type: Sequelize.DATE,
+      defaultValue: Sequelize.fn('NOW'),
+    },
+    updated_at: {
+      allowNull: false,
+      type: Sequelize.DATE,
+      defaultValue: Sequelize.fn('NOW'),
+    },
+  }),
+
+  down: async (queryInterface, _Sequelize) => queryInterface.dropTable('bank_transfer_processors'),
+};

models/bank_transfer_processors.js

@@ -0,0 +1,48 @@
+const { Model } = require('sequelize');
+
+module.exports = (sequelize, DataTypes) => {
+  class BankTransferProcessors extends Model {
+    /**
+     * Helper method for defining associations.
+     * This method is not a part of Sequelize lifecycle.
+     * The `models/index` file will call this method automatically.
+     */
+  }
+  BankTransferProcessors.init({
+    id: {
+      type: DataTypes.INTEGER,
+      autoIncrement: true,
+      primaryKey: true,
+      allowNull: false,
+    },
+    name: {
+      type: DataTypes.STRING,
+      allowNull: false,
+      unique: true,
+    },
+    position: {
+      type: DataTypes.INTEGER,
+      allowNull: false,
+    },
+    enabled: {
+      type: DataTypes.BOOLEAN,
+      allowNull: false,
+      defaultValue: true,
+    },
+    created_at: {
+      type: DataTypes.DATE,
+      allowNull: false,
+      defaultValue: DataTypes.NOW,
+    },
+    updated_at: {
+      type: DataTypes.DATE,
+      allowNull: false,
+      defaultValue: DataTypes.NOW,
+    },
+  }, {
+    sequelize,
+    modelName: 'bank_transfer_processors',
+    underscored: true,
+  });
+  return BankTransferProcessors;
+};

package.json

@@ -7,7 +7,8 @@
     "test": "echo \"Error: no test specified\" && exit 1",
     "migrate": "sequelize db:migrate",
     "migrate:undo": "sequelize db:migrate:undo",
-    "migrate:undo:all": "sequelize db:migrate:undo:all"
+    "migrate:undo:all": "sequelize db:migrate:undo:all",
+    "seed": "sequelize db:seed:all"
   },
   "keywords": [
     "wallet",
@@ -22,6 +23,7 @@
     "dotenv": "^8.2.0",
     "joi": "^17.3.0",
     "mysql2": "^2.2.5",
+    "redis": "^3.0.2",
     "sequelize": "^6.3.5",
     "sequelize-cli": "^6.2.0",
     "uuid": "^8.3.2"

redis.js

@@ -0,0 +1,18 @@
+const redis = require('redis');
+const { promisify } = require('util');
+
+const client = redis.createClient();
+
+client.on('error', (error) => {
+  console.error(error);
+});
+
+const zadd = promisify(client.zadd).bind(client);
+const zrevrange = promisify(client.zrevrange).bind(client);
+const exists = promisify(client.exists).bind(client);
+const expire = promisify(client.expire).bind(client);
+const zincrby = promisify(client.zincrby).bind(client);
+
+module.exports = {
+  zadd, zrevrange, exists, expire, zincrby,
+};

seeders/20210220200445-populate-bank-transfer-processors-table.js

@@ -0,0 +1,30 @@
+module.exports = {
+  up: async (queryInterface, Sequelize) => queryInterface.bulkInsert('bank_transfer_processors', [
+    {
+      name: 'monnify',
+      position: 1,
+      enabled: true,
+      created_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+      updated_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+    },
+    {
+      name: 'paystack',
+      position: 2,
+      enabled: true,
+      created_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+      updated_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+    },
+    {
+      name: 'flutterwave',
+      position: 3,
+      enabled: true,
+      created_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+      updated_at: Sequelize.literal('CURRENT_TIMESTAMP(3)'),
+    },
+  ],
+  {
+    updateOnDuplicate: ['name'],
+  }),
+
+  down: async (queryInterface, _Sequelize) => queryInterface.bulkDelete('bank_transfer_processors', null),
+};