Implement group deletion and add group files retrieval

Added logic to delete a group and update the associated files to have a null group reference. Also implemented a method to retrieve files associated with a group using pagination and search functionality.

apps/backend/src/app/groups/groups.service.ts

@@ -1,13 +1,12 @@
-import { Injectable } from "@nestjs/common";
+import { Injectable, InternalServerErrorException, NotFoundException } from '@nestjs/common';
 import { DbService } from "apps/backend/src/app/db/db.service";
-import { FilesGroupTable } from "apps/backend/src/app/db/schema";
-import { ilike } from "drizzle-orm";
+import { FilesGroupTable, FilesTable } from 'apps/backend/src/app/db/schema';
+import { and, eq, ilike } from 'drizzle-orm';
 
 @Injectable()
 export class GroupsService {
 	constructor(private readonly database: DbService) {}
 
-	//TODO a method to fetch groups in the database by a specific search with limit, offset and a search field (can be blank)
 	async getGroupsByName(limit: number, offset: number, search: string) {
 		return await this.database
 			.use()
@@ -34,13 +33,48 @@ export class GroupsService {
 	}
 
 	//TODO a method to delete a group and place the associated file at a null group reference
-	async deleteGroup(groupId: string) {}
-
-	//TODO a method to get the files of a group in the database by a specific search with limit, offset and a search field (can be blank)
+	async deleteGroup(groupId: string) {
+		const groupInDb = await this.database.use()
+			.select()
+			.from(FilesGroupTable)
+			.where(eq(FilesGroupTable.uuid, groupId))
+			.prepare("findGroupById")
+			.execute();
+		if (groupInDb.length === 0) throw new NotFoundException("Group not found");
+		// Replace entry by null
+		await this.database
+          .use()
+          .update(FilesTable)
+					// @ts-ignore
+          .set({ groupId: null })
+          .where(eq(FilesTable.groupId, groupId))
+          .prepare("updateFilesGroupReference")
+          .execute();
+		try {
+			await this.database
+				.use()
+				.delete(FilesGroupTable)
+				.where(eq(FilesGroupTable.uuid, groupId))
+			return true
+		} catch (e) {
+			throw new InternalServerErrorException("Error while deleting group");
+		}
+	}
+	
 	async findFilesForGroup(
 		limit: number,
 		offset: number,
 		searchField: string,
 		groupId: string,
-	) {}
+	) {
+		return await this.database
+			.use()
+			.select()
+			.from(FilesTable)
+			.where(and(eq(FilesTable.groupId, groupId), ilike(FilesTable.fileName, String(`%${searchField}%`)) ) )
+			.limit(limit)
+			.offset(offset)
+			.prepare('findFilesInGroup')
+			.execute();
+	}
 }