# LightTAM: Detailed Overview

LightTAM (Lightweight Time And Attendance Manager) is a terminal-based application for managing employee or student attendance using RFID cards. The system is modular, with each component responsible for a specific aspect of the program's functionality. Below is a detailed overview of how the program works, referencing the component UML diagram (`component_uml.png`).



## Component Overview

![Component UML Diagram](component_uml.png)

### 1. **Main Application (`main.c`)**
- **Role:** Entry point of the program. Initializes all subsystems, parses command-line arguments, loads the user database, and starts the main event loop.
- **Responsibilities:**
  - Initializes the logger, file/database handlers, and TUI.
  - Loads user data from the specified file.
  - Handles program shutdown and resource cleanup.

### 2. **Terminal User Interface (TUI) (`tui.c`, `tui.h`)**
- **Role:** Provides all user interaction via a terminal-based UI using ncurses.
- **Responsibilities:**
  - Displays menus (main, edit, search, user details, etc.).
  - Handles keyboard input and navigation.
  - Calls business logic functions based on user actions.
  - Shows dialogs for success, warnings, and errors.
  - Manages forms for adding/removing users and logging time events.

### 3. **User Management (`users.c`, `users.h`)**
- **Role:** Manages the in-memory linked list of users.
- **Responsibilities:**
  - Defines the `person_t`, `node_t`, and `list_t` structures.
  - Provides functions to add, remove, search, and update users.
  - Handles synchronization (mutex) for thread safety.
  - Calculates presence times and manages user states.

### 4. **File Handler (`file_handler.c`, `file_handler.h`)**
- **Role:** Handles reading and writing user data to CSV files.
- **Responsibilities:**
  - Loads the user list from a CSV file at startup.
  - Saves the user list to a CSV file on demand.
  - Exports user or database information to external files.

### 5. **RFID Handler (`rfid_handler.c`, `rfid_handler.h`)**
- **Role:** Interfaces with the RFID reader hardware via a serial port.
- **Responsibilities:**
  - Opens and manages the serial port connection.
  - Reads RFID card data and matches it to users.
  - Triggers time event logging when a card is detected.

### 6. **Logger (`logger.c`, `logger.h`)**
- **Role:** Logs all actions, errors, and system events to a journal file.
- **Responsibilities:**
  - Provides logging functions for other modules.
  - Records user actions, errors, and system messages for auditing.

### 7. **Utilities (`utils.h`)**
- **Role:** Provides helper functions used throughout the program.
- **Responsibilities:**
  - String manipulation, time formatting, and other common tasks.


## Component Interactions

- **TUI ↔ User Management:** TUI calls user management functions to modify or query the user list.
- **TUI ↔ File Handler:** TUI triggers file operations for loading, saving, and exporting data.
- **TUI ↔ RFID Handler:** TUI may display status or prompt for RFID actions.
- **RFID Handler ↔ User Management:** When a card is read, the handler updates the user list.
- **All Components ↔ Logger:** All modules log actions and errors via the logger.



## Error Handling & Logging

- All errors (file I/O, serial port, invalid input) are reported to the user via TUI dialogs and logged in the journal file.
- The logger ensures traceability for all critical operations.



## Extensibility

- The modular design allows for easy extension, such as supporting new file formats, additional authentication methods, or a graphical UI.

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For further details, see the [README.md](../README.md) and the code documentation in each header file.