8 files changed, 269 insertions, 0 deletions
diff --git a/src/file/controller/file.controller.ts b/src/file/controller/file.controller.ts
new file mode 100644
index 0000000..d7632ed
--- /dev/null
+++ b/src/file/controller/file.controller.ts
@@ -0,0 +1,75 @@
+import { Body, Controller, ForbiddenException, Get, GoneException, Param, Post } from '@nestjs/common';
+import { SessionService } from '../../session/service/session.service';
+import { SessionTokenDto } from '../dto/session-key.dto';
+import { CreateFileDto } from '../dto/create-file.dto';
+import { FileService } from '../service/file.service';
+
+@Controller('file')
+export class FileController {
+  constructor(
+    private readonly sessionService: SessionService,
+    private readonly fileService: FileService,
+  ) {}
+
+  @Post('retrieve-keys')
+  async use(@Body() sessionTokenDto: SessionTokenDto) {
+    const sessionMarkedAsUsed = await this.sessionService.markSessionAsUsed(sessionTokenDto.token);
+
+    if (!sessionMarkedAsUsed) {
+      throw new ForbiddenException();
+    }
+
+    const files = await this.fileService.findManyValid(sessionTokenDto.token);
+
+    return {
+      files: files.map((file) => ({
+        key: file.key,
+        purpose: file.purpose?.name,
+        validUntil: file.validUntil,
+      })),
+    };
+  }
+
+  @Post('create')
+  async create(@Body() createFileDto: CreateFileDto) {
+    const session = await this.sessionService.findValid(createFileDto.token);
+
+    if (!session) {
+      throw new ForbiddenException();
+    }
+
+    const data = JSON.stringify(createFileDto.data);
+    const b64EncodedData = Buffer.from(data).toString('base64');
+    const validTo = new Date(Date.now() + 1000 * 60 * 30);
+
+    const file = await this.fileService.createFile(b64EncodedData, createFileDto.purpose, validTo, session);
+    return {
+      creationDate: file.creationDate,
+      validUntil: file.validUntil,
+      purpose: file.purpose,
+      session: {
+        validUntil: file.session.validUntil,
+      },
+    };
+  }
+
+  @Get('retrieve-file/:key')
+  async retrieve(@Param('key') key: string) {
+    const fileMarkedAsUsed = await this.fileService.markFileAsUsed(key);
+
+    if (!fileMarkedAsUsed) {
+      throw new ForbiddenException();
+    }
+
+    const fileData = await this.fileService.fetchFileContents(key);
+    if (!fileData) {
+      throw new GoneException('This file has been deleted');
+    }
+
+    const json = JSON.parse(Buffer.from(fileData, 'base64').toString('utf8'));
+
+    return {
+      data: json,
+    };
+  }
+}
diff --git a/src/file/dto/create-file.dto.ts b/src/file/dto/create-file.dto.ts
new file mode 100644
index 0000000..0fbe4b6
--- /dev/null
+++ b/src/file/dto/create-file.dto.ts
@@ -0,0 +1,12 @@
+import { IsNotEmpty } from 'class-validator';
+
+export class CreateFileDto {
+  @IsNotEmpty()
+  token: string;
+
+  @IsNotEmpty()
+  purpose: string;
+
+  @IsNotEmpty()
+  data: any;
+}
diff --git a/src/file/dto/retrieve-file.dto.ts b/src/file/dto/retrieve-file.dto.ts
new file mode 100644
index 0000000..4623e28
--- /dev/null
+++ b/src/file/dto/retrieve-file.dto.ts
@@ -0,0 +1,6 @@
+import { IsNotEmpty } from 'class-validator';
+
+export class RetrieveFileDto {
+  @IsNotEmpty()
+  key: string;
+}
diff --git a/src/file/dto/session-key.dto.ts b/src/file/dto/session-key.dto.ts
new file mode 100644
index 0000000..fd227d7
--- /dev/null
+++ b/src/file/dto/session-key.dto.ts
@@ -0,0 +1,6 @@
+import { IsNotEmpty } from 'class-validator';
+
+export class SessionTokenDto {
+  @IsNotEmpty()
+  token: string;
+}
diff --git a/src/file/entity/file.entity.ts b/src/file/entity/file.entity.ts
new file mode 100644
index 0000000..49c0ecc
--- /dev/null
+++ b/src/file/entity/file.entity.ts
@@ -0,0 +1,47 @@
+import { nanoid } from 'nanoid';
+import { Session } from '../../session/entity/session.entity';
+import {
+  Entity,
+  Column,
+  BeforeInsert,
+  CreateDateColumn,
+  PrimaryGeneratedColumn,
+  ManyToOne,
+  Index,
+  OneToOne,
+} from 'typeorm';
+import { FilePurpose } from './purpose.entity';
+import { StoredFile } from 'src/storage/entity/stored-file.entity';
+
+@Entity()
+export class FileMetadata {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Index('filekey-idx')
+  @Column({ unique: true, nullable: false })
+  key: string;
+
+  @ManyToOne(() => FilePurpose, { nullable: false })
+  purpose: FilePurpose;
+
+  @CreateDateColumn()
+  creationDate: Date;
+
+  @Column()
+  validUntil: Date;
+
+  @Column({ default: false })
+  used: boolean;
+
+  @ManyToOne(() => Session, (session) => session.files, { nullable: false })
+  session: Session;
+
+  @OneToOne(() => StoredFile, (file) => file.fileMetadata, { nullable: true })
+  contents: StoredFile;
+
+  @BeforeInsert()
+  private beforeInsert() {
+    this.key = nanoid();
+  }
+}
diff --git a/src/file/entity/purpose.entity.ts b/src/file/entity/purpose.entity.ts
new file mode 100644
index 0000000..27c3ad6
--- /dev/null
+++ b/src/file/entity/purpose.entity.ts
@@ -0,0 +1,10 @@
+import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity()
+export class FilePurpose {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ nullable: false })
+  name: string;
+}
diff --git a/src/file/file.module.ts b/src/file/file.module.ts
new file mode 100644
index 0000000..6f5329f
--- /dev/null
+++ b/src/file/file.module.ts
@@ -0,0 +1,17 @@
+import { Module } from '@nestjs/common';
+import { FileController } from './controller/file.controller';
+import { SessionModule } from '../session/session.module';
+import { FileMetadata } from './entity/file.entity';
+import { FilePurpose } from './entity/purpose.entity';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { FileService } from './service/file.service';
+import { Session } from 'src/session/entity/session.entity';
+import { StorageModule } from 'src/storage/storage.module';
+import { StoredFile } from 'src/storage/entity/stored-file.entity';
+
+@Module({
+  imports: [SessionModule, StorageModule, TypeOrmModule.forFeature([FileMetadata, FilePurpose, Session, StoredFile])],
+  controllers: [FileController],
+  providers: [FileService],
+})
+export class FileModule {}
diff --git a/src/file/service/file.service.ts b/src/file/service/file.service.ts
new file mode 100644
index 0000000..24cb55d
--- /dev/null
+++ b/src/file/service/file.service.ts
@@ -0,0 +1,96 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { FileMetadata } from '../entity/file.entity';
+import { FilePurpose } from '../entity/purpose.entity';
+import { DataSource, Repository } from 'typeorm';
+import { Session } from '../../session/entity/session.entity';
+import { StorageService } from 'src/storage/service/storage.service';
+
+@Injectable()
+export class FileService {
+  constructor(
+    @InjectRepository(FileMetadata)
+    private fileMetadataRepository: Repository<FileMetadata>,
+
+    @InjectRepository(FilePurpose)
+    private filePurposeRepository: Repository<FilePurpose>,
+
+    private readonly storageService: StorageService,
+    private readonly dataSource: DataSource,
+  ) {}
+
+  async createFile(
+    b64Contents: string,
+    purpose: string,
+    validTo: Date,
+    session: Session,
+  ): Promise<FileMetadata | null> {
+    const filePurpose = await this.filePurposeRepository.findOneBy({ name: purpose });
+    if (!filePurpose) {
+      throw new NotFoundException(`Unknown file purpose: ${filePurpose}`);
+    }
+
+    const file = new FileMetadata();
+    file.purpose = filePurpose;
+    file.session = session;
+    file.validUntil = validTo;
+
+    const queryRunner = this.dataSource.createQueryRunner();
+    await queryRunner.connect();
+    await queryRunner.startTransaction();
+    try {
+      await this.fileMetadataRepository.save(file);
+      await this.storageService.createFile(b64Contents, file);
+
+      await queryRunner.commitTransaction();
+    } catch (err) {
+      await queryRunner.rollbackTransaction();
+
+      throw err;
+    } finally {
+      queryRunner.release();
+    }
+
+    return file;
+  }
+
+  async markFileAsUsed(fileKey: string): Promise<boolean> {
+    const update = await this.fileMetadataRepository
+      .createQueryBuilder()
+      .update({
+        used: true,
+      })
+      .where('validUntil > :date', {
+        date: new Date(Date.now()),
+      })
+      .andWhere({
+        key: fileKey,
+        used: false,
+      })
+      .execute();
+
+    return update.affected > 0;
+  }
+
+  async fetchFileContents(fileKey: string): Promise<string | null> {
+    const file = await this.fileMetadataRepository.findOne({
+      relations: {
+        contents: true,
+      },
+      where: {
+        key: fileKey,
+      },
+    });
+
+    return file?.contents?.b64Contents;
+  }
+
+  async findManyValid(sessionToken: string): Promise<FileMetadata[]> {
+    return this.fileMetadataRepository
+      .createQueryBuilder('file')
+      .innerJoinAndSelect('file.session', 'session', 'session.token = :token', { token: sessionToken })
+      .leftJoinAndSelect('file.purpose', 'purpose')
+      .where('file.used = :used', { used: false })
+      .getMany();
+  }
+}