[Feat] Get code snippet contents

Added a service method for retrieving code snippet file contents.
Added the service method to the GET "/code-snppets" endpoint.
References #18.

server/src/code-snippets/controllers/code-snippets.controller.ts

@@ -26,20 +26,27 @@ import { CodeSnippetsService } from '../services/code-snippets.service';
 export class CodeSnippetsController {
   constructor(private readonly codeSnippetsService: CodeSnippetsService) {}
 
-  @Get(':subdirectory(*)|/')
+  @Get(':path(*)')
   @HttpCode(HttpStatus.OK)
   @UseGuards(AuthSessionGuard)
   @ApiCookieAuth()
-  @ApiOkResponse({ description: 'Tree of user files.' })
+  @ApiOkResponse({
+    description:
+      'Tree of user files in a directory or the contents of a file specified.',
+  })
   @ApiForbiddenResponse({ description: 'No user logon.' })
-  async getSubdirectory(
-    @Req() req: Request,
-    @Param('subdirectory') subdirectory: string,
-  ) {
-    return await this.codeSnippetsService.listUserCodeSnippets(
-      req.user['username'],
-      subdirectory ?? '',
-    );
+  async getSubdirectory(@Req() req: Request, @Param('path') path: string) {
+    path ??= '';
+
+    return path.endsWith('/') || path === ''
+      ? await this.codeSnippetsService.listUserCodeSnippets(
+          req.user['username'],
+          path,
+        )
+      : await this.codeSnippetsService.getUserCodeSnippet(
+          req.user['username'],
+          path,
+        );
   }
 
   @Put(':filepath(*)')

server/src/code-snippets/services/code-snippets.service.ts

@@ -45,6 +45,23 @@ export class CodeSnippetsService {
     return tree;
   }
 
+  async getUserCodeSnippet(username: string, filepath: string) {
+    const completeFilepath = `${username}/${filepath}`;
+
+    if (completeFilepath.endsWith('/')) {
+      throw new CodeSnippetsError(CodeSnippetsErrorCode.INVALID_FILE_PATH);
+    }
+
+    const queryResponse = await this.s3
+      .getObject({
+        Bucket: configObject.aws.codeSnippetsS3Bucket,
+        Key: completeFilepath,
+      })
+      .promise();
+
+    return queryResponse.Body.toString();
+  }
+
   async saveUserCodeSnippet(username: string, filepath: string, body: string) {
     const completeFilepath = `${username}/${filepath}`;
 
@@ -68,6 +85,6 @@ export class CodeSnippetsService {
     }
 
     // If directory => create empty object if it doesn't already exist and run again
-    return this.addToFileTree((tree[item.shift()] ??= {}), item);
+    return this.addToFileTree((tree[item.shift() + '/'] ??= {}), item);
   }
 }