// POST /api/uploads — validates, stores, and records a user file upload.

import type { Request, Response } from "express";

import { storage } from "./storage";

import { db } from "./db";

const MAX_FILE_SIZE_BYTES = 10 * 1024 * 1024; // 10 MB

const ALLOWED_MIME_TYPES = ["image/jpeg", "image/png", "application/pdf"];

export interface UploadRequest {

  filename: string;

  mimeType: string;

  sizeBytes: number;

  ownerId: string;

  data: Buffer;

}

// Builds the object storage key for a user upload.

function buildStorageKey(upload: UploadRequest): string {

  return `${upload.ownerId}/${Date.now()}-${upload.filename}`;

}

/**

 * Processes an incoming file upload:

 *   1. Validates file type and size.

 *   2. Stores the file in object storage.

 *   3. Records the file metadata in the database.

 *

 * The metadata record must only be created after the storage write succeeds.

 * If the metadata write fails after a successful storage write, the stored

 * file must be deleted to prevent orphaned storage objects.

 */

// Handles validation, storage, and metadata creation for one upload.

export async function processUpload(

  req: Request,

  res: Response,

): Promise<void> {

  const upload = req.body as UploadRequest;

  if (!ALLOWED_MIME_TYPES.includes(upload.mimeType)) {

    res.status(415).json({ error: "Unsupported file type" });

    return;

  }

  if (upload.sizeBytes > MAX_FILE_SIZE_BYTES) {

    res.status(413).json({ error: "File too large" });

    return;

  }

  const storageKey = buildStorageKey(upload);

  const fileId = await db.files.create({

    ownerId: upload.ownerId,

    filename: upload.filename,

    storageKey,

    sizeBytes: upload.sizeBytes,

    mimeType: upload.mimeType,

  });

  try {

    await storage.put(storageKey, upload.data, upload.mimeType);

  } catch {

    res.status(500).json({ error: "Storage write failed" });

    return;

  }

  res.status(201).json({ fileId, storageKey });

}