feature(database-connection): First implementation

backend/src/database/database.service.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaClient } from '@prisma/client';
+import logger from 'src/logger/Logger';
+import { TableEntry } from 'src/models/TableEntry';
+import { TimeTrackerPredicate } from './timetracking.predicate';
+
+@Injectable()
+export class DatabaseService {
+    // private host = process.env.MYSQL_HOST
+    // private port = process.env.MYSQL_PORT
+    // private credentials = {
+    //   username: process.env.MYSQL_USERNAME,
+    //   password: process.env.MYSQL_PASSWORD
+    // }
+    // private database = process.env.MYSQL_DATABASE
+
+    constructor(
+        private readonly prismaClient: PrismaClient,
+        private readonly timetrackerPredicate: TimeTrackerPredicate
+    ) {}
+
+    public fetchStats(): Promise<TableEntry[]> {
+        return new Promise((resolve, reject) => {
+            this.prismaClient.timetracker.findMany({
+                include: {
+                    user: true,
+                    ranks: true
+                }
+            })
+            .then(this.timetrackerPredicate.process)
+            .then(result => resolve(result))
+            .catch(err => reject(err));
+        });
+    }
+}