Design Dropbox

Design a file storage system similar to Dropbox. The specific requirements are as follows: Support file upload, download, and deletion features. Each user has a unique directory. Support file sharing, where users can share files with others. Consider the scalability of the system: how to support a large number of simultaneous uploads and downloads. Provide a detailed system architecture, including database schema, API designs, and technology stack used. Please provide a detailed description of the implementation for the above features and a comprehensive design diagram of the system.