feat(backend revision): add clean-up note revisions job (#5349)

backend/src/revisions/revisions.service.ts

@@ -3,11 +3,13 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import { Injectable } from '@nestjs/common';
+import { Inject, Injectable } from '@nestjs/common';
+import { Cron, Timeout } from '@nestjs/schedule';
 import { InjectRepository } from '@nestjs/typeorm';
 import { createPatch } from 'diff';
 import { Repository } from 'typeorm';
 
+import noteConfiguration, { NoteConfig } from '../config/note.config';
 import { NotInDBError } from '../errors/errors';
 import { ConsoleLoggerService } from '../logger/console-logger.service';
 import { Note } from '../notes/note.entity';
@@ -29,6 +31,9 @@ export class RevisionsService {
     private readonly logger: ConsoleLoggerService,
     @InjectRepository(Revision)
     private revisionRepository: Repository<Revision>,
+    @InjectRepository(Note)
+    private noteRepository: Repository<Note>,
+    @Inject(noteConfiguration.KEY) private noteConfig: NoteConfig,
     private editService: EditService,
   ) {
     this.logger.setContext(RevisionsService.name);
@@ -230,4 +235,80 @@ export class RevisionsService {
       await this.revisionRepository.save(revision);
     }
   }
+
+  // Delete all old revisions everyday on 0:00 AM
+  @Cron('0 0 * * *')
+  async handleRevisionCleanup(): Promise<void> {
+    return await this.removeOldRevisions();
+  }
+
+  // Delete all old revisions 5 sec after startup
+  @Timeout(5000)
+  async handleRevisionCleanupTimeout(): Promise<void> {
+    return await this.removeOldRevisions();
+  }
+
+  /**
+   * Delete old {@link Revision}s except the latest one.
+   *
+   * @async
+   */
+  async removeOldRevisions(): Promise<void> {
+    const currentTime = new Date().getTime();
+    const revisionRetentionDays: number = this.noteConfig.revisionRetentionDays;
+    if (revisionRetentionDays <= 0) {
+      return;
+    }
+    const revisionRetentionSeconds =
+      revisionRetentionDays * 24 * 60 * 60 * 1000;
+
+    const notes: Note[] = await this.noteRepository.find();
+    for (const note of notes) {
+      const revisions: Revision[] = await this.revisionRepository.find({
+        where: {
+          note: { id: note.id },
+        },
+        order: {
+          createdAt: 'ASC',
+        },
+      });
+
+      const oldRevisions = revisions
+        .slice(0, -1) // always keep the latest revision
+        .filter(
+          (revision) =>
+            new Date(revision.createdAt).getTime() <=
+            currentTime - revisionRetentionSeconds,
+        );
+      const remainedRevisions = revisions.filter(
+        (val) => !oldRevisions.includes(val),
+      );
+
+      if (!oldRevisions.length) {
+        continue;
+      } else if (oldRevisions.length === revisions.length - 1) {
+        const beUpdatedRevision = revisions.slice(-1)[0];
+        beUpdatedRevision.patch = createPatch(
+          note.publicId,
+          '', // there is no older revision
+          beUpdatedRevision.content,
+        );
+        await this.revisionRepository.save(beUpdatedRevision);
+      } else {
+        const beUpdatedRevision = remainedRevisions.slice(0)[0];
+        beUpdatedRevision.patch = createPatch(
+          note.publicId,
+          oldRevisions.slice(-1)[0].content,
+          beUpdatedRevision.content,
+        );
+        await this.revisionRepository.save(beUpdatedRevision);
+      }
+
+      await this.revisionRepository.remove(oldRevisions);
+      this.logger.log(
+        `${oldRevisions.length} old revisions of the note '${note.id}' were removed from the DB`,
+        'removeOldRevisions',
+      );
+    }
+  }
 }