From 623d033af35968b6a4080a8e5aa9603357611a25 Mon Sep 17 00:00:00 2001
From: Alan Cruikshanks <alan.cruikshanks@gmail.com>
Date: Sun, 3 Mar 2024 23:00:18 +0000
Subject: [PATCH] wip

---
 .../charging-module/send-bill-run.service.js  | 45 ++++++++++++
 .../wait-for-status.service.js                | 70 +++++++++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 app/services/charging-module/send-bill-run.service.js
 create mode 100644 app/services/charging-module/wait-for-status.service.js

diff --git a/app/services/charging-module/send-bill-run.service.js b/app/services/charging-module/send-bill-run.service.js
new file mode 100644
index 0000000000..4e73a2adce
--- /dev/null
+++ b/app/services/charging-module/send-bill-run.service.js
@@ -0,0 +1,45 @@
+'use strict'
+
+/**
+ * Connects with the Charging Module to send a bill run
+ * @module ChargingModuleSendBillRunService
+ */
+
+const ChargingModuleRequestLib = require('../../lib/charging-module-request.lib.js')
+
+/**
+ * Approve then send a bill run in the Charging Module API
+ *
+ * Our service does in one step what the CHA does in two; approve the bill run then 'send' it. Approving a CHA bill run
+ * doesn't actually do anything. It just changes the state to `approved` which the bill run has to be in before the bill
+ * run can be sent.
+ *
+ * Sending a bill run is the final step. Once sent a bill run cannot be changed or deleted. Sending involves the CHA
+ * generating a bill number for every bill in the bill run. It then generates a transaction reference for the bill run
+ * itself. This reference is used to name the transaction import file which the CHA also generates at this time. This
+ * is the file that will make it's way to SOP and be used to generate the invoice and credit notes that customers
+ * receive.
+ *
+ * For small bill runs the process is near instantaneous. Larger bill runs however it can take a number of seconds.
+ * Because of this when the request is first made the CHA switches the bill run's status to `sending`. Only when the
+ * process is complete does the status get set to `sent`.
+ *
+ * It's this we are waiting for because then we can extract the generated bill numbers and transaction file reference
+ * and apply them to our bill run records.
+ *
+ * See {@link https://defra.github.io/sroc-charging-module-api-docs/#/bill-run/SendBillRun | CHA API docs} for more
+ * details
+ * @param {string} billRunId - UUID of the charging module API bill run to send
+ *
+ * @returns {Promise<Object>} The result of the request; whether it succeeded and the response or error returned
+ */
+async function go (billRunId) {
+  const path = `v3/wrls/bill-runs/${billRunId}/generate`
+  const result = await ChargingModuleRequestLib.patch(path)
+
+  return result
+}
+
+module.exports = {
+  go
+}
diff --git a/app/services/charging-module/wait-for-status.service.js b/app/services/charging-module/wait-for-status.service.js
new file mode 100644
index 0000000000..6c21013f02
--- /dev/null
+++ b/app/services/charging-module/wait-for-status.service.js
@@ -0,0 +1,70 @@
+'use strict'
+
+/**
+ * Connects with the Charging Module to send a bill run
+ * @module ChargingModuleSendBillRunService
+ */
+
+const { setTimeout } = require('node:timers/promises')
+
+const BillRunStatusService = require('./bill-run-status.service.js')
+const ExpandedError = require('../../errors/expanded.error.js')
+
+const ONE_SECOND = 1000
+
+async function go (billRunId, statusToWaitFor, maximumAttempts = 120) {
+  let attempts = 0
+  let status
+
+  //
+  do {
+    await _pause(attempts)
+
+    const result = await BillRunStatusService.go(billRunId)
+
+    if (!result.succeeded) {
+      _requestFailed(billRunId, result)
+    }
+
+    status = result.response.body.status
+    attempts += 1
+  } while (status !== statusToWaitFor || attempts >= maximumAttempts)
+
+  if (status !== statusToWaitFor) {
+    _statusNotAchieved(billRunId, statusToWaitFor, status, attempts, maximumAttempts)
+  }
+}
+
+/**
+ * Pause for one second between requests so that we are not bombarding the Charging Module
+ */
+function _pause (attempts) {
+  // If attempts is 0 then this is the first attempt so don't pause
+  if (attempts === 0) {
+    return
+  }
+
+  return setTimeout(ONE_SECOND)
+}
+
+function _requestFailed (billRunId, result) {
+  const error = new ExpandedError(
+    'Charging Module status request failed',
+    { billRunExternalId: billRunId, responseBody: result.response.body }
+  )
+
+  throw error
+}
+
+function _statusNotAchieved (billRunId, statusToWaitFor, status, attempts, maximumAttempts) {
+  const error = new ExpandedError(
+    'Charging Module wait for status failed',
+    { billRunExternalId: billRunId, statusToWaitFor, lastStatus: status, attempts, maximumAttempts }
+  )
+
+  throw error
+}
+
+module.exports = {
+  go
+}