From 647abac4fa1323a1cfc83ed9054436357b76934c Mon Sep 17 00:00:00 2001
From: John Brunton <john_brunton@live.co.uk>
Date: Mon, 12 Aug 2024 22:36:52 +0100
Subject: [PATCH] refactor: extract message parser

---
 .../api/src/app/messages/messages.service.ts  |  8 +++--
 .../usecases/messages/parse-message.spec.ts   | 36 +++++++++++++++++++
 .../usecases}/messages/parse-message.ts       | 25 ++++++++-----
 3 files changed, 59 insertions(+), 10 deletions(-)
 create mode 100644 services/api/src/domain/usecases/messages/parse-message.spec.ts
 rename services/api/src/{app => domain/usecases}/messages/parse-message.ts (64%)

diff --git a/services/api/src/app/messages/messages.service.ts b/services/api/src/app/messages/messages.service.ts
index c29fed94..ebff4649 100644
--- a/services/api/src/app/messages/messages.service.ts
+++ b/services/api/src/app/messages/messages.service.ts
@@ -1,9 +1,9 @@
 import { HttpException, Injectable } from '@nestjs/common';
 import { CreateMessageDto } from './dto/create-message.dto';
-import { isCommand, parseMessage } from './parse-message';
 import { User, systemUser } from '@entities/user.entity';
 import { SendMessageUseCase } from '@usecases/messages/send';
 import { CommandService } from '@app/messages/command.service';
+import { isCommand, parseMessage } from '@usecases/messages/parse-message';
 
 @Injectable()
 export class MessagesService {
@@ -16,7 +16,11 @@ export class MessagesService {
     incoming: CreateMessageDto,
     authenticatedUser: User,
   ): Promise<void> {
-    const message = parseMessage(incoming, authenticatedUser);
+    const message = parseMessage({
+      ...incoming,
+      authorId: authenticatedUser.id,
+    });
+
     try {
       if (isCommand(message)) {
         await this.command.exec(message, authenticatedUser);
diff --git a/services/api/src/domain/usecases/messages/parse-message.spec.ts b/services/api/src/domain/usecases/messages/parse-message.spec.ts
new file mode 100644
index 00000000..dcda6ea2
--- /dev/null
+++ b/services/api/src/domain/usecases/messages/parse-message.spec.ts
@@ -0,0 +1,36 @@
+import { parseMessage } from './parse-message';
+
+describe('parseMessage', () => {
+  const roomId = 'room-id';
+  const authorId = 'user-id';
+
+  it('parses commands', () => {
+    expect(
+      parseMessage({ content: '/lorem 3 words', roomId, authorId }),
+    ).toEqual({
+      canonicalInput: '/lorem 3 words',
+      roomId,
+      tokens: ['lorem', '3', 'words'],
+    });
+  });
+
+  it('ignores excess whitespace in commands', () => {
+    expect(
+      parseMessage({ content: '/lorem    3  words', roomId, authorId }),
+    ).toEqual({
+      canonicalInput: '/lorem 3 words',
+      roomId,
+      tokens: ['lorem', '3', 'words'],
+    });
+  });
+
+  it('parses normal messages', () => {
+    expect(
+      parseMessage({ content: 'Hello, World!', roomId, authorId }),
+    ).toEqual({
+      content: 'Hello, World!',
+      roomId,
+      authorId,
+    });
+  });
+});
diff --git a/services/api/src/app/messages/parse-message.ts b/services/api/src/domain/usecases/messages/parse-message.ts
similarity index 64%
rename from services/api/src/app/messages/parse-message.ts
rename to services/api/src/domain/usecases/messages/parse-message.ts
index 806c6b74..bc0cc7ae 100644
--- a/services/api/src/app/messages/parse-message.ts
+++ b/services/api/src/domain/usecases/messages/parse-message.ts
@@ -1,7 +1,5 @@
 import { Command } from '@entities/command.entity';
 import { DraftMessage } from '@entities/message.entity';
-import { User } from '@entities/user.entity';
-import { CreateMessageDto } from 'src/app/messages/dto/create-message.dto';
 
 export type ParsedMessage = DraftMessage | Command;
 
@@ -9,12 +7,23 @@ export const isCommand = (message: ParsedMessage): message is Command => {
   return (message as Command).tokens !== undefined;
 };
 
-export const parseMessage = (
-  { content, roomId }: CreateMessageDto,
-  authenticatedUser: User,
-): ParsedMessage => {
+type ParseMessageParams = {
+  content: string;
+  roomId: string;
+  authorId: string;
+};
+
+export const parseMessage = ({
+  content,
+  roomId,
+  authorId,
+}: ParseMessageParams): ParsedMessage => {
   if (content.startsWith('/')) {
-    const tokens = content.slice(1).split(' ');
+    const tokens = content
+      .slice(1)
+      .split(' ')
+      .filter((token) => token.length > 0);
+
     const canonicalInput = `/${tokens.join(' ')}`;
 
     const command: Command = {
@@ -29,7 +38,7 @@ export const parseMessage = (
   const message: ParsedMessage = {
     content,
     roomId,
-    authorId: authenticatedUser.id,
+    authorId,
   };
 
   return message;