📋 User and Event Management System (Java CLI)

🧩 Overview

This is a Command-Line Interface (CLI) system developed in Java for managing users and events. It allows you to:

• Register users
• Register events
• Link users to events
• List events by category
• Search users by name

The program is designed using a state machine architecture that controls user navigation through different commands interactively.

🚀 Features

🔁 Command Menu (State: initialmenu)

The program starts in an interactive menu waiting for a user command. You can list all valid commands by typing listcommands.

📜 Command Listing (State: listcommands)

Prints all available commands defined by:

EnumSet.allOf(State.class)

Excludes the none state, which indicates invalid commands.

👤 User Registration (State: userregister)

Registers a new user with the following details:

• Name
• CPF (Brazilian personal document - parsed and validated)
• Date of Birth (format: yyyy-MM-dd)

The Person object is created and stored in memory.

🔍 Search User by Name (State: searchuserbyname)

Searches for users by name (partial match). Displays:

• Name
• CPF
• Date of Birth
• Registered Event (if any)

🗓️ Event Registration (State: eventregister)

Allows registering a new event with the following fields:

• Name
• Description
• Address
• Category ID (from 0 to 2 based on predefined array)
• Date and Time (yyyy-MM-dd HH:mm)

The event is added to the global asEventList.

🗂️ List Events by Category (State: listeventsbycategory)

Searches for events by category name and displays:

• Name
• Description
• Date and Time
• Address
• Category
• Participant names
• Event occurrence status (past, present, or future)

🏷️ List Events by Tag (State: listeventsbytag)

⚠️ Not implemented yet. The system displays an informational message instead.

🔗 Link User to Event (State: attach_user_to_event)

Associates a previously registered user to an existing event via:

• Exact event name
• User’s CPF

The link is bidirectional: the event stores the user CPF, and the user references the event.

❌ Exit Program (State: exit)

Immediately terminates the program using System.exit(0).

🧠 Technical Analysis

State-Driven Architecture

The program uses an enum-based state machine (State) to control user interaction and command flow.

In-Memory Storage

Data is stored in static lists within Data_Read_Write:

• asPersonaList — list of users
• asEventList — list of events

⚠️ Persistence is not implemented in this version.

External Classes (Required)

• Person: Represents a user with fields like name, CPF, and birthdate.
• EventUnique: Represents an event with details like name, category, and participant list.
• Data_Read_Write: Provides static access to user and event lists.
• State: Enum defining all available states/commands.

Input and Parsing

• User input is read using Scanner
• Dates are parsed using Java’s LocalDateTime
• Integer and string inputs are validated

Event Occurrence Logic

The helper method getString() determines the temporal status of an event:

• Future event: "The event has not happened yet."
• Same day: "The event is happening now."
• Past: "The event has already occurred."

🛠️ How to Use

📦 Requirements

• JDK 11 or higher
• Java-compatible terminal

▶️ Compile and Run

javac -d out src/org/example/*.java
java -cp out org.example.Main

💬 Available Commands

Command	Description
listcommands	Lists all available commands
userregister	Registers a new user
searchuserbyname	Searches for users by name
eventregister	Registers a new event
listeventsbycategory	Lists events by category
listeventsbytag	(Not implemented)
attach_user_to_event	Links a user to a selected event
exit	Exits the program

🧪 Future Improvements

• Add file or database persistence
• Implement listeventsbytag
• Add internationalization and language support

📌 Conclusion

This project is a solid foundation for a basic CLI-based user and event management system. Its state-driven design makes it easy to expand and maintain, and it's well-suited for educational purposes. Future improvements could turn it into a complete and robust system.