Messenger/packages/backend/src/modules/media/media.service.ts

import { randomUUID } from 'node:crypto';
import type { Client } from 'minio';
import type { MediaKind } from '@altricade/core';
import { HttpError } from '../../shared/http-error';

export interface MediaServiceDeps {
  // The presigning (browser-facing) MinIO client.
  minio: Client;
  mediaBucket: string;
  avatarsBucket: string;
  publicUrl: string;
}

export interface UploadTarget {
  uploadUrl: string;
  objectKey: string;
}

export interface AvatarTarget extends UploadTarget {
  publicUrl: string;
}

export interface MediaService {
  createUploadUrl(userId: string, kind: MediaKind, mime: string, size: number): Promise<UploadTarget>;
  createAvatarUploadUrl(userId: string, mime: string): Promise<AvatarTarget>;
  downloadUrl(objectKey: string): Promise<string>;
  avatarPublicUrl(objectKey: string): string;
}

const UPLOAD_EXPIRY = 3600;
const DOWNLOAD_EXPIRY = 3600;

const kindMatches = (kind: MediaKind, mime: string): boolean => {
  if (kind === 'image') return mime.startsWith('image/');
  if (kind === 'video') return mime.startsWith('video/');
  if (kind === 'voice') return mime.startsWith('audio/');
  return true;
};

export const createMediaService = (deps: MediaServiceDeps): MediaService => ({
  createUploadUrl: async (userId, kind, mime, _size) => {
    if (!kindMatches(kind, mime)) {
      throw new HttpError(400, 'invalid_media', `Content type ${mime} does not match kind ${kind}`);
    }
    const objectKey = `${userId}/${randomUUID()}`;
    const uploadUrl = await deps.minio.presignedPutObject(deps.mediaBucket, objectKey, UPLOAD_EXPIRY);
    return { uploadUrl, objectKey };
  },

  createAvatarUploadUrl: async (userId, mime) => {
    if (!mime.startsWith('image/')) {
      throw new HttpError(400, 'invalid_media', 'Avatar must be an image');
    }
    const objectKey = `${userId}/${randomUUID()}`;
    const uploadUrl = await deps.minio.presignedPutObject(
      deps.avatarsBucket,
      objectKey,
      UPLOAD_EXPIRY,
    );
    return {
      uploadUrl,
      objectKey,
      publicUrl: `${deps.publicUrl}/${deps.avatarsBucket}/${objectKey}`,
    };
  },

  downloadUrl: (objectKey) =>
    deps.minio.presignedGetObject(deps.mediaBucket, objectKey, DOWNLOAD_EXPIRY),

  avatarPublicUrl: (objectKey) => `${deps.publicUrl}/${deps.avatarsBucket}/${objectKey}`,
});

declare module 'fastify' {
  interface FastifyInstance {
    mediaService: MediaService;
  }
}