/**
 * Best-effort MIME type inference from a file path's extension.
 *
 * Used to label outbound attachments (Gmail/Outlook multipart parts, native
 * email attachments) when the source is a local file with no declared type.
 */

import { extname } from "node:path";

const MIME_MAP: Record<string, string> = {
  ".pdf": "application/pdf",
  ".zip": "application/zip",
  ".gz": "application/gzip",
  ".tar": "application/x-tar",
  ".doc": "application/msword",
  ".docx":
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
  ".xls": "application/vnd.ms-excel",
  ".xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
  ".ppt": "application/vnd.ms-powerpoint",
  ".pptx":
    "application/vnd.openxmlformats-officedocument.presentationml.presentation",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".jpeg": "image/jpeg",
  ".gif": "image/gif",
  ".svg": "image/svg+xml",
  ".webp": "image/webp",
  ".mp3": "audio/mpeg",
  ".mp4": "video/mp4",
  ".wav": "audio/wav",
  ".txt": "text/plain",
  ".html": "text/html",
  ".css": "text/css",
  ".js": "text/javascript",
  ".json": "application/json",
  ".xml": "application/xml",
  ".csv": "text/csv",
};

export function guessMimeType(filePath: string): string {
  return (
    MIME_MAP[extname(filePath).toLowerCase()] ?? "application/octet-stream"
  );
}