echoboard/packages/api/src/routes/avatars.ts

import { FastifyInstance } from "fastify";
import { existsSync, mkdirSync, createReadStream } from "node:fs";
import { unlink, writeFile, realpath } from "node:fs/promises";
import { resolve, extname, sep } from "node:path";
import { randomBytes } from "node:crypto";
import prisma from "../lib/prisma.js";

const UPLOAD_DIR = resolve(process.cwd(), "uploads", "avatars");
const MAX_SIZE = 2 * 1024 * 1024;
const ALLOWED_MIME = new Set(["image/jpeg", "image/png", "image/webp"]);
const ALLOWED_EXT = new Set([".jpg", ".jpeg", ".png", ".webp"]);

const MAGIC_BYTES: Record<string, number[][]> = {
  "image/jpeg": [[0xFF, 0xD8, 0xFF]],
  "image/png": [[0x89, 0x50, 0x4E, 0x47]],
  "image/webp": [[0x52, 0x49, 0x46, 0x46, -1, -1, -1, -1, 0x57, 0x45, 0x42, 0x50]],
};

function validateMagicBytes(buf: Buffer, mime: string): boolean {
  const sigs = MAGIC_BYTES[mime];
  if (!sigs) return false;
  return sigs.some((sig) => sig.every((byte, i) => byte === -1 || buf[i] === byte));
}

export default async function avatarRoutes(app: FastifyInstance) {
  if (!existsSync(UPLOAD_DIR)) mkdirSync(UPLOAD_DIR, { recursive: true });

  app.post(
    "/me/avatar",
    { preHandler: [app.requireUser, app.optionalAdmin], config: { rateLimit: { max: 10, timeWindow: "1 hour" } } },
    async (req, reply) => {
      // if admin, use their linked user instead of the anonymous cookie user
      let userId = req.user!.id;
      if (req.adminId) {
        const admin = await prisma.adminUser.findUnique({ where: { id: req.adminId }, select: { linkedUserId: true } });
        if (admin?.linkedUserId) userId = admin.linkedUserId;
      }

      const user = await prisma.user.findUnique({ where: { id: userId } });
      if (!user) {
        reply.status(403).send({ error: "Not authenticated" });
        return;
      }
      // allow passkey users and admin-linked users
      if (user.authMethod !== "PASSKEY") {
        const isTeamMember = await prisma.adminUser.findUnique({ where: { linkedUserId: user.id }, select: { id: true } });
        if (!isTeamMember) {
          reply.status(403).send({ error: "Save your identity with a passkey to upload avatars" });
          return;
        }
      }

      const data = await req.file();
      if (!data) {
        reply.status(400).send({ error: "No file uploaded" });
        return;
      }

      const ext = extname(data.filename).toLowerCase();
      if (!ALLOWED_EXT.has(ext) || !ALLOWED_MIME.has(data.mimetype)) {
        reply.status(400).send({ error: "Only jpg, png, webp images are allowed" });
        return;
      }

      const chunks: Buffer[] = [];
      let size = 0;
      for await (const chunk of data.file) {
        size += chunk.length;
        if (size > MAX_SIZE) {
          reply.status(400).send({ error: "File too large (max 2MB)" });
          return;
        }
        chunks.push(chunk);
      }
      const buffer = Buffer.concat(chunks);

      if (!validateMagicBytes(buffer, data.mimetype)) {
        reply.status(400).send({ error: "File content does not match declared type" });
        return;
      }

      // delete old avatar if exists (with traversal check)
      if (user.avatarPath) {
        const oldPath = resolve(UPLOAD_DIR, user.avatarPath);
        try {
          const realOld = await realpath(oldPath);
          const realUpload = await realpath(UPLOAD_DIR);
          if (realOld.startsWith(realUpload + sep)) {
            await unlink(realOld).catch(() => {});
          }
        } catch {}
      }

      const storedName = `${randomBytes(16).toString("hex")}${ext}`;
      const filePath = resolve(UPLOAD_DIR, storedName);

      if (!filePath.startsWith(UPLOAD_DIR)) {
        reply.status(400).send({ error: "Invalid file path" });
        return;
      }

      await writeFile(filePath, buffer);

      await prisma.user.update({
        where: { id: user.id },
        data: { avatarPath: storedName },
      });

      reply.send({ avatarUrl: `/api/v1/avatars/${user.id}` });
    }
  );

  app.delete(
    "/me/avatar",
    { preHandler: [app.requireUser], config: { rateLimit: { max: 10, timeWindow: "1 minute" } } },
    async (req, reply) => {
      const user = await prisma.user.findUnique({ where: { id: req.user!.id } });
      if (!user || !user.avatarPath) {
        reply.status(204).send();
        return;
      }

      const filePath = resolve(UPLOAD_DIR, user.avatarPath);
      try {
        const realFile = await realpath(filePath);
        const realUpload = await realpath(UPLOAD_DIR);
        if (realFile.startsWith(realUpload + sep)) {
          await unlink(realFile).catch(() => {});
        }
      } catch {}

      await prisma.user.update({
        where: { id: user.id },
        data: { avatarPath: null },
      });

      reply.status(204).send();
    }
  );

  app.get<{ Params: { userId: string } }>(
    "/avatars/:userId",
    { config: { rateLimit: { max: 200, timeWindow: "1 minute" } } },
    async (req, reply) => {
      const user = await prisma.user.findUnique({
        where: { id: req.params.userId },
        select: { avatarPath: true },
      });

      if (!user?.avatarPath) {
        reply.status(404).send({ error: "No avatar" });
        return;
      }

      const filePath = resolve(UPLOAD_DIR, user.avatarPath);
      let realFile: string;
      try {
        realFile = await realpath(filePath);
      } catch {
        reply.status(404).send({ error: "File missing" });
        return;
      }
      const realUpload = await realpath(UPLOAD_DIR);
      if (!realFile.startsWith(realUpload + sep)) {
        reply.status(404).send({ error: "File missing" });
        return;
      }

      const ext = extname(user.avatarPath).toLowerCase();
      const mimeMap: Record<string, string> = {
        ".jpg": "image/jpeg", ".jpeg": "image/jpeg",
        ".png": "image/png", ".webp": "image/webp",
      };

      reply
        .header("Content-Type", mimeMap[ext] || "application/octet-stream")
        .header("Cache-Control", "public, max-age=3600, stale-while-revalidate=86400")
        .header("X-Content-Type-Options", "nosniff")
        .send(createReadStream(filePath));
    }
  );
}