From f20d33f4e4c2df7f6505f8524279b7750b732cf9 Mon Sep 17 00:00:00 2001
From: Chris Cooksley <chris.cooksley@digital.cabinet-office.gov.uk>
Date: Thu, 16 Jan 2025 10:56:38 +0000
Subject: [PATCH] Implement UpdateSessionOperation in dynamo-agnostic way

---
 .../src/functions/adapters/dynamoDbAdapter.ts | 89 +++++++++++++++++++
 .../BiometricTokenIssued.ts                   | 23 +++++
 .../UpdateSessionOperation.ts                 |  9 ++
 3 files changed, 121 insertions(+)
 create mode 100644 backend-api/src/functions/common/session/updateOperations/BiometricTokenIssued/BiometricTokenIssued.ts
 create mode 100644 backend-api/src/functions/common/session/updateOperations/UpdateSessionOperation.ts

diff --git a/backend-api/src/functions/adapters/dynamoDbAdapter.ts b/backend-api/src/functions/adapters/dynamoDbAdapter.ts
index 208d27dd..263944a9 100644
--- a/backend-api/src/functions/adapters/dynamoDbAdapter.ts
+++ b/backend-api/src/functions/adapters/dynamoDbAdapter.ts
@@ -1,4 +1,5 @@
 import {
+  AttributeValue,
   ConditionalCheckFailedException,
   DynamoDBClient,
   PutItemCommand,
@@ -6,6 +7,7 @@ import {
   QueryCommand,
   QueryCommandInput,
   QueryCommandOutput,
+  UpdateItemCommand,
 } from "@aws-sdk/client-dynamodb";
 import { CreateSessionAttributes } from "../services/session/sessionService";
 import { NodeHttpHandler } from "@smithy/node-http-handler";
@@ -14,6 +16,13 @@ import {
   NativeAttributeValue,
   unmarshall,
 } from "@aws-sdk/util-dynamodb";
+import { UpdateSessionOperation } from "../common/session/updateOperations/UpdateSessionOperation";
+import {
+  emptySuccess,
+  ErrorCategory,
+  errorResult,
+  Result,
+} from "../utils/result";
 
 const sessionStates = {
   ASYNC_AUTH_SESSION_CREATED: "ASYNC_AUTH_SESSION_CREATED",
@@ -114,7 +123,87 @@ export class DynamoDbAdapter {
     }
   }
 
+  async updateSession(
+    sessionId: string,
+    updateOperation: UpdateSessionOperation,
+  ): Promise<Result<void>> {
+    const updateItemCommand = new UpdateItemCommand({
+      TableName: "mockTableName",
+      Key: {
+        sessionId: {
+          S: "mockSessionId",
+        },
+      },
+      ExpressionAttributeValues: getExpressionAttributeValues(updateOperation),
+      ConditionExpression: getConditionExpression(updateOperation),
+      UpdateExpression: getUpdateExpression(updateOperation),
+    });
+
+    try {
+      console.log(
+        "Update session attempt",
+        updateItemCommand.input.UpdateExpression,
+      ); // replace with proper logging
+      await this.dynamoDbClient.send(updateItemCommand);
+    } catch (error) {
+      if (error instanceof ConditionalCheckFailedException) {
+        console.log(
+          "Conditional check failed",
+          updateItemCommand.input.ConditionExpression,
+        ); // replace with proper logging
+        return errorResult({
+          errorMessage: "Conditional check failed",
+          errorCategory: ErrorCategory.CLIENT_ERROR,
+        });
+      } else {
+        console.log("Unexpected error", error); // replace with proper logging
+        return errorResult({
+          errorMessage: "Unexpected error",
+          errorCategory: ErrorCategory.SERVER_ERROR,
+        });
+      }
+    }
+    console.log("Update session success"); // replace with proper logging
+    return emptySuccess();
+  }
+
   private getTimeNowInSeconds() {
     return Math.floor(Date.now() / 1000);
   }
 }
+
+function getExpressionAttributeValues(
+  updateOperation: UpdateSessionOperation,
+): Record<string, AttributeValue> {
+  const attributeValues: Record<string, AttributeValue> = {
+    ":sessionState": marshall(updateOperation.targetState),
+  };
+  updateOperation.eligibleStartingStates.forEach((state) => {
+    attributeValues[`:${state}`] = marshall(state);
+  });
+  Object.entries(updateOperation.getFieldUpdates()).forEach(([key, value]) => {
+    attributeValues[`:${key}`] = marshall(value);
+  });
+  return attributeValues;
+}
+
+function getConditionExpression(
+  updateOperation: UpdateSessionOperation,
+): string {
+  const permissibleStatesAsAttributes: string =
+    updateOperation.eligibleStartingStates
+      .map((state) => `:${state}`)
+      .join(", ");
+  return `sessionState in (${permissibleStatesAsAttributes})`; // sessionState in (:EXAMPLE_SESSION_STATE_1, :EXAMPLE_SESSION_STATE_2)
+}
+
+function getUpdateExpression(updateOperation: UpdateSessionOperation): string {
+  const fieldsToUpdate = [
+    "sessionState",
+    ...Object.keys(updateOperation.getFieldUpdates()),
+  ];
+  const updateExpressions = fieldsToUpdate.map(
+    (fieldName) => `${fieldName} = :${fieldName}`,
+  );
+  return `set ${updateExpressions.join(", ")}`; // set sessionState = :EXAMPLE_SESSION_STATE, field1 = :field1, field2 = :field2
+}
diff --git a/backend-api/src/functions/common/session/updateOperations/BiometricTokenIssued/BiometricTokenIssued.ts b/backend-api/src/functions/common/session/updateOperations/BiometricTokenIssued/BiometricTokenIssued.ts
new file mode 100644
index 00000000..7e78e41b
--- /dev/null
+++ b/backend-api/src/functions/common/session/updateOperations/BiometricTokenIssued/BiometricTokenIssued.ts
@@ -0,0 +1,23 @@
+import {
+  SessionState,
+  UpdateSessionOperation,
+} from "../UpdateSessionOperation";
+import { DocumentType } from "../../../../types/document";
+
+export class BiometricTokenIssued implements UpdateSessionOperation {
+  constructor(
+    private readonly documentType: DocumentType,
+    private readonly opaqueId: string,
+  ) {}
+
+  readonly targetState = SessionState.BIOMETRIC_TOKEN_ISSUED;
+
+  readonly eligibleStartingStates = [SessionState.AUTH_SESSION_CREATED];
+
+  getFieldUpdates() {
+    return {
+      documentType: this.documentType,
+      opaqueId: this.opaqueId,
+    };
+  }
+}
diff --git a/backend-api/src/functions/common/session/updateOperations/UpdateSessionOperation.ts b/backend-api/src/functions/common/session/updateOperations/UpdateSessionOperation.ts
new file mode 100644
index 00000000..753a20e4
--- /dev/null
+++ b/backend-api/src/functions/common/session/updateOperations/UpdateSessionOperation.ts
@@ -0,0 +1,9 @@
+import { SessionState } from "../session";
+
+type SessionFieldValue = string | number;
+
+export interface UpdateSessionOperation {
+  readonly targetState: SessionState;
+  readonly eligibleStartingStates: SessionState[];
+  getFieldUpdates(): Record<string, SessionFieldValue>;
+}