Project 8 — The Contact Management System

// contacts.cpp — Programming Fundamentals Using C++
// Project 8 · The Contact Management System
// Build: g++ -std=c++17 -Wall -Wextra contacts.cpp -o contacts

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
#include <cctype>
using namespace std;

// Format contract — contacts.csv, one record per line:
//   name,phone,email
//   (names unique & case-sensitive; phone = 10..13 digits; email contains '@')
// This comment governs BOTH loadContacts and saveContacts; change them together.

struct Contact {
    string name, phone, email;
};

bool phoneIsLegal(const string& phone) {
    if (phone.size() < 10 || phone.size() > 13) return false;
    for (char ch : phone)
        if (!isdigit(static_cast<unsigned char>(ch))) return false;
    return true;
}

bool emailIsLegal(const string& email) {
    return email.find('@') != string::npos;      // presence, not shape — documented
}

bool contactIsLegal(const Contact& c) {          // the whole-record contract
    return !c.name.empty() && phoneIsLegal(c.phone) && emailIsLegal(c.email);
}

int loadContacts(const string& path, vector<Contact>& out) {
    ifstream in(path);
    if (!in) return 0;
    string line;
    int skipped = 0;
    while (getline(in, line)) {
        if (line.empty()) continue;
        size_t c1 = line.find(',');
        size_t c2 = (c1 == string::npos) ? string::npos : line.find(',', c1 + 1);
        if (c2 == string::npos) { ++skipped; continue; }
        Contact c;
        c.name  = line.substr(0, c1);
        c.phone = line.substr(c1 + 1, c2 - c1 - 1);
        c.email = line.substr(c2 + 1);
        if (!contactIsLegal(c)) { ++skipped; continue; }
        out.push_back(c);
    }
    return skipped;
}

void saveContacts(const string& path, const vector<Contact>& contacts) {
    ofstream out(path);
    for (const Contact& c : contacts)
        out << c.name << "," << c.phone << "," << c.email << "\n";
}

Contact* findByName(vector<Contact>& contacts, const string& name) {
    for (Contact& c : contacts)
        if (c.name == name) return &c;
    return nullptr;
}

Contact* findByPhone(vector<Contact>& contacts, const string& phone) {
    for (Contact& c : contacts)
        if (c.phone == phone) return &c;
    return nullptr;
}

void printContact(const Contact& c) {
    cout << "  " << c.name << " — " << c.phone << " — " << c.email << "\n";
}

string readPhone() {                             // the entry-layer validator
    string phone;
    cout << "Phone (10-13 digits): ";
    getline(cin, phone);
    while (!phoneIsLegal(phone)) {
        cout << "Digits only, 10-13 of them: ";
        getline(cin, phone);
    }
    return phone;
}

string readEmail() {
    string email;
    cout << "Email: ";
    getline(cin, email);
    while (!emailIsLegal(email)) {
        cout << "Must contain '@': ";
        getline(cin, email);
    }
    return email;
}

bool addContact(vector<Contact>& contacts, const Contact& candidate) {
    if (findByName(contacts, candidate.name) != nullptr) return false;   // unique key
    if (!contactIsLegal(candidate)) return false;
    contacts.push_back(candidate);
    return true;
}

int main() {
    const string PATH = "contacts.csv";
    vector<Contact> contacts;

    int skipped = loadContacts(PATH, contacts);
    if (skipped) cout << "Skipped " << skipped << " malformed line(s)\n";
    cout << "Loaded " << contacts.size() << " contacts\n";

    int choice;
    do {
        cout << "\n1 List (sorted) · 2 Find by name · 3 Find by phone · "
                "4 Add · 5 Delete · 6 Save · 0 Save & quit: ";
        cin >> choice;
        cin.ignore(1000, '\n');

        if (choice == 1) {
            if (contacts.empty()) { cout << "Contact book empty\n"; continue; }
            vector<Contact> view = contacts;     // sort the COPY — storage keeps arrival order
            sort(view.begin(), view.end(),
                 [](const Contact& a, const Contact& b) { return a.name < b.name; });
            for (const Contact& c : view) printContact(c);
        } else if (choice == 2 || choice == 3) {
            cout << (choice == 2 ? "Name: " : "Phone: ");
            string key; getline(cin, key);
            Contact* c = (choice == 2) ? findByName(contacts, key)
                                       : findByPhone(contacts, key);
            if (c) printContact(*c);
            else   cout << "  not found\n";
        } else if (choice == 4) {
            Contact candidate;
            cout << "Name: ";
            getline(cin, candidate.name);
            if (findByName(contacts, candidate.name)) {   // the unique-key guard, first
                cout << "Refused: name already present\n";
                continue;
            }
            candidate.phone = readPhone();
            candidate.email = readEmail();
            if (addContact(contacts, candidate)) cout << "Added\n";
            else cout << "Refused\n";
        } else if (choice == 5) {
            cout << "Name to delete: ";
            string name; getline(cin, name);
            Contact* c = findByName(contacts, name);
            if (!c) { cout << "  not found\n"; continue; }
            cout << "Deleted " << c->name << " (" << c->phone << ")\n";
            contacts.erase(contacts.begin() + (c - &contacts[0]));
        } else if (choice == 6) {
            saveContacts(PATH, contacts);
            cout << "Saved " << contacts.size() << " contacts\n";
        } else if (choice != 0) {
            cout << "Invalid choice\n";
        }
    } while (choice != 0);

    saveContacts(PATH, contacts);
    cout << "Saved " << contacts.size() << " contacts — goodbye\n";
    return 0;
}