functions.cpp

#include "functions.h"
#include <iostream>
#include <fstream>
#include <algorithm>
#include <iomanip>

using namespace std;

void showMenu()
{
    cout << "\n========== STUDENT MANAGEMENT ==========\n";
    cout << "1. Add Student\n";
    cout << "2. Display All Students\n";
    cout << "3. Search Student\n";
    cout << "4. Delete Student\n";
    cout << "5. Calculate Average Grade\n";
    cout << "6. Save to File\n";
    cout << "7. Load from File\n";
    cout << "0. Exit\n";
    cout << "========================================\n";
    cout << "Choose: ";
}

void addStudent(vector<Student> &students)
{
    int id;
    string name;
    double grade;

    cout << "Enter ID: ";
    cin >> id;

    // Check if ID already exists
    for (const auto &s : students)
    {
        if (s.getId() == id)
        {
            cout << "Student with this ID already exists!\n";
            return;
        }
    }

    cout << "Enter Name: ";
    cin.ignore();
    getline(cin, name);

    cout << "Enter Grade (0-100): ";
    cin >> grade;

    while (grade < 0 || grade > 100)
    {
        cout << "Invalid grade! Enter (0-100): ";
        cin >> grade;
    }

    students.push_back(Student(id, name, grade));
    cout << "Student added successfully!\n";
}

void displayAllStudents(const vector<Student> &students)
{
    if (students.empty())
    {
        cout << "No students found!\n";
        return;
    }

    cout << "\n"
         << left << setw(10) << "ID"
         << setw(20) << "Name"
         << setw(10) << "Grade" << endl;
    cout << "----------------------------------------\n";

    for (const auto &s : students)
    {
        s.display();
    }
}

void searchStudent(const vector<Student> &students)
{
    if (students.empty())
    {
        cout << "No students in database!\n";
        return;
    }

    int id;
    cout << "Enter student ID to search: ";
    cin >> id;

    for (const auto &s : students)
    {
        if (s.getId() == id)
        {
            cout << "\nStudent found:\n";
            cout << left << setw(10) << "ID"
                 << setw(20) << "Name"
                 << setw(10) << "Grade" << endl;
            cout << "----------------------------------------\n";
            s.display();
            return;
        }
    }

    cout << "Student with ID " << id << " not found!\n";
}

void deleteStudent(vector<Student> &students)
{
    if (students.empty())
    {
        cout << "No students to delete!\n";
        return;
    }

    int id;
    cout << "Enter student ID to delete: ";
    cin >> id;

    auto it = find_if(students.begin(), students.end(),
                      [id](const Student &s)
                      { return s.getId() == id; });

    if (it != students.end())
    {
        students.erase(it);
        cout << "Student deleted successfully!\n";
    }
    else
    {
        cout << "Student not found!\n";
    }
}

void saveToFile(const vector<Student> &students)
{
    ofstream file("students.txt");
    if (!file)
    {
        cout << "Error opening file!\n";
        return;
    }

    for (const auto &s : students)
    {
        file << s.getId() << ","
             << s.getName() << ","
             << s.getGrade() << "\n";
    }

    file.close();
    cout << "Data saved to students.txt successfully!\n";
}

void loadFromFile(vector<Student> &students)
{
    ifstream file("students.txt");
    if (!file)
    {
        cout << "No saved data found!\n";
        return;
    }

    students.clear();
    int id;
    string name;
    double grade;
    char comma;

    while (file >> id >> comma >> ws && getline(file, name, ','))
    {
        file >> grade;
        students.push_back(Student(id, name, grade));
    }

    file.close();
    cout << "Data loaded successfully! " << students.size() << " students found.\n";
}

double calculateAverage(const vector<Student> &students)
{
    if (students.empty())
        return 0.0;

    double sum = 0;
    for (const auto &s : students)
    {
        sum += s.getGrade();
    }
    return sum / students.size();
}