Reorganize project. Add folder for shared code between backend/dashboard. Switch from jest to ava for tests.

backend/src/data/UsernameHistory.ts

@@ -0,0 +1,65 @@
+import { getRepository, Repository } from "typeorm";
+import { UsernameHistoryEntry } from "./entities/UsernameHistoryEntry";
+import { sorter } from "../utils";
+import { BaseRepository } from "./BaseRepository";
+
+export const MAX_USERNAME_ENTRIES_PER_USER = 10;
+
+export class UsernameHistory extends BaseRepository {
+  private usernameHistory: Repository<UsernameHistoryEntry>;
+
+  constructor() {
+    super();
+    this.usernameHistory = getRepository(UsernameHistoryEntry);
+  }
+
+  async getByUserId(userId): Promise<UsernameHistoryEntry[]> {
+    return this.usernameHistory.find({
+      where: {
+        user_id: userId,
+      },
+      order: {
+        id: "DESC",
+      },
+      take: MAX_USERNAME_ENTRIES_PER_USER,
+    });
+  }
+
+  getLastEntry(userId): Promise<UsernameHistoryEntry> {
+    return this.usernameHistory.findOne({
+      where: {
+        user_id: userId,
+      },
+      order: {
+        id: "DESC",
+      },
+    });
+  }
+
+  async addEntry(userId, username) {
+    await this.usernameHistory.insert({
+      user_id: userId,
+      username,
+    });
+
+    // Cleanup (leave only the last MAX_USERNAME_ENTRIES_PER_USER entries)
+    const lastEntries = await this.getByUserId(userId);
+    if (lastEntries.length > MAX_USERNAME_ENTRIES_PER_USER) {
+      const earliestEntry = lastEntries
+        .sort(sorter("timestamp", "DESC"))
+        .slice(0, 10)
+        .reduce((earliest, entry) => {
+          if (earliest == null) return entry;
+          if (entry.id < earliest.id) return entry;
+          return earliest;
+        }, null);
+
+      this.usernameHistory
+        .createQueryBuilder()
+        .andWhere("user_id = :userId", { userId })
+        .andWhere("id < :id", { id: earliestEntry.id })
+        .delete()
+        .execute();
+    }
+  }
+}