Dropbox-System-Design.md

Designing an File System like Dropbox and Google Drive

In this article, we will explore the object-oriented design and implementation of a Restaurant Management System using Java. System Requirements:

User Account Management:

Allow users to create accounts, log in, and log out. Manage user profiles, preferences, and access control.

1. File and Folder Management:

Enable users to upload, download, and delete files. Support organizing files into folders and subfolders. Implement file versioning and history.

2. Sharing and Collaboration:

Allow users to share files/folders with others. Support collaborative editing and real-time synchronization. Implement permission settings for shared items.

3. Syncing Across Devices:

Provide desktop and mobile clients for cross-device syncing. Ensure seamless integration with various operating systems.

4. Security and Encryption:

Implement secure data transmission (SSL/TLS). Encrypt user data on servers and in transit. Provide features like two-factor authentication. 5. Search Functionality:

Implement a robust search feature for quick file retrieval. Support advanced search based on file metadata.

6. Offline Access:

Allow users to mark files for offline access. Implement efficient offline synchronization.

7. Notification System:

Notify users about file changes, shares, and collaboration activities. Support email and in-app notifications.

8. Subscription Management:

Handle subscription plans, billing, and payment processing. Allow users to upgrade, downgrade, or cancel subscriptions.

9. Audit Trail and Logging:

Maintain an audit trail for user actions and system changes. Log relevant events for security and debugging purposes.

Core Use Cases:

1. User Registration and Authentication:

Users can create accounts, log in, and log out securely.

2. Uploading and Downloading Files:

Users can upload files to the cloud and download them.

3. File and Folder Organization:

Users can create folders, organize files, and manage file versions.

4. Sharing and Collaboration:

Users can share files/folders and collaborate in real-time.

5. Syncing Across Devices:

Changes made on one device are synced across all linked devices.

6. Security Measures:

Ensuring secure data transmission and storage.

7. Search Functionality:

Users can search for files based on metadata.

8. Offline Access:

Users can access certain files offline.

9. Notification Handling:

Users receive notifications about relevant activities.

10. Subscription Management:

Users can manage their subscription plans.

Key Classes:

1. CloudStorageSystem:

Manages overall operations, user accounts, and subscriptions.

2. User:

Represents a user with account details and preferences.

3. File:

Represents an uploaded file with metadata and versioning.

4. Folder:

Represents a folder containing files and subfolders.

5. SharingManager:

Manages file/folder sharing and collaboration.

6. SyncManager:

Handles syncing and offline access.

7. SecurityManager:

Implements security measures like encryption.

8. NotificationSystem:

Manages notification generation and delivery. 9. SubscriptionManager:

Handles subscription plans and billing.

10. AuditLogger:

Logs user actions and system events for auditing.

#include <iostream>
#include <vector>
#include <map>
#include <ctime>

// User class representing a user account
class User {
public:
    std::string username;
    std::string password;
    // Other user details

    User(const std::string& uname, const std::string& pwd)
        : username(uname), password(pwd) {}
};

// File class representing an uploaded file
class File {
public:
    std::string name;
    std::string content;
    time_t lastModified;

    File(const std::string& fname, const std::string& fcontent)
        : name(fname), content(fcontent) {
        lastModified = time(nullptr);
    }
};

// CloudStorageSystem class managing overall operations
class CloudStorageSystem {
private:
    std::map<std::string, User> users;
    std::map<std::string, std::vector<File>> userFiles;

public:
    void registerUser(const std::string& username, const std::string& password) {
        users[username] = User(username, password);
        userFiles[username] = std::vector<File>();
    }

    bool loginUser(const std::string& username, const std::string& password) {
        auto it = users.find(username);
        return it != users.end() && it->second.password == password;
    }

    void uploadFile(const std::string& username, const std::string& filename, const std::string& content) {
        if (users.find(username) != users.end()) {
            userFiles[username].emplace_back(filename, content);
            std::cout << "File '" << filename << "' uploaded successfully.\n";
        } else {
            std::cout << "User not found. Please log in.\n";
        }
    }

    void listUserFiles(const std::string& username) {
        if (users.find(username) != users.end()) {
            std::cout << "Files for user '" << username << "':\n";
            for (const auto& file : userFiles[username]) {
                std::cout << file.name << " (Last Modified: " << ctime(&file.lastModified) << ")\n";
            }
        } else {
            std::cout << "User not found. Please log in.\n";
        }
    }
};

int main() {
    CloudStorageSystem cloudStorage;

    // Register users
    cloudStorage.registerUser("user1", "password1");
    cloudStorage.registerUser("user2", "password2");

    // Login users
    if (cloudStorage.loginUser("user1", "password1")) {
        std::cout << "User1 logged in successfully.\n";

        // Upload files
        cloudStorage.uploadFile("user1", "file1.txt", "File content 1");
        cloudStorage.uploadFile("user1", "file2.txt", "File content 2");

        // List user files
        cloudStorage.listUserFiles("user1");
    } else {
        std::cout << "Login failed for User1.\n";
    }

    return 0;
}