#include<iostream>
#include<string>
using namespace std;

class StringNode {                                                  // establish class StringNode for Linked List
private:
    StringNode *next;                                               // points to next node in the list
    string elem;                                                    // string variable for airport code
    double miles;                                                   // double to hold distance from LGA in miles
public:
    friend class StringLinkedList;                          // gives StringLinkedList access to StringNode private members
};

class StringLinkedList {
private:
    StringNode *head;                                               // points to head of the list
    StringNode *priorloc;                                           // points to prior node location on list
    StringNode *nextloc;                                            // points to next node location on list
public:
    StringLinkedList();                                             // empty list constructor
    ~StringLinkedList();                                            // destructor
    bool empty() const;                                             // function to test for empty list
    void addNode(const string& e, const double& m);                 // add nodes to end
    void removeFront();                                             // remove nodes as part of destructor
    void display();                                                 // display list
    void search(const string&);                                     // finds searched value in list
};

StringLinkedList::StringLinkedList()                                // constructor parameters
{
    head = NULL;                                                    // initialize head to NULL
    priorloc = NULL;                                                // initialize priorloc to NULL
    nextloc = NULL;                                                 // initialize nextloc to NULL
}

StringLinkedList::~StringLinkedList()                               // destructor
{ while (!empty()) removeFront();}

bool StringLinkedList::empty() const                                // checks for empty list
{ return head == NULL;}

int main ()
{
    StringLinkedList list = StringLinkedList();                     // define list as an object of StringLinkedList
    string value;                                                   // hold airport code
    double dist;                                                    // hold distance in miles to LGA
    char again;                                                     // do-while loop option
    
    list.addNode("LGA", 0);
    
    do                                                              // input data
    {
        cout << "Enter the 3 letter airport code: " << endl;
        cin >> value;
        cout << "Enter the miles to the airport from La Guardia Airport: " << endl;
        cin >> dist;
        list.addNode(value, dist);
        cout << endl;
        cout << "Do you want to add another airport location and distance? (Y/N): ";
        cin >> again;
        cout << endl;
    } while (again == 'Y' ||again == 'y');                         // user option to adds as many as wanted
    
    int choice;                                                     // variable for second do-while loop
    
    do                                                              // user input menu option
    {
        cout << "The following are your choices.\n";
        cout << "Please enter the number for the selection you want: \n";
        cout << endl;
        cout << "1. Print listing of all airport codes and miles from LGA\n";
        cout << "2. Search for airport and print\n";
        cout << "3. Quit Program\n";
        cin >> choice;
        
        while (choice < 1 || choice > 3)                            // input validation
        {
            cout << "The valid choices are 1 through 3.  Please\n"
            << "select one of those." << endl;
            cin >> choice;
        }
        
        switch (choice)
        {
            case 1:                                                 // display function described below
                list.display();
                cout << endl;
                break;
            case 2:                                                 // search function described below
                {string searchValue;
                cout << "Which airport are you looking for: ";
                cin >> searchValue;
                list.search(searchValue);
                cout << endl;
                break;}
            case 3:                                                 // ends program
                cout << "Thank you for using this program.\n";
                cout << "Have a nice Day.\n";
                cout << endl;
        }
    }while (choice != 3);

    return 0;
}

/*
 Function creates and adds node to end of list.  Populates with two variables in data portion of node.  Called in the the first do-while loop.
 */

 void StringLinkedList::addNode(const string& e, const double& m)
{
    StringNode* v = new StringNode;
    v-> elem = e;
    v-> miles = m;
    v-> next = NULL;
    if ( priorloc == NULL )
    {
        head = v;
    }
    else
    {
        priorloc->next = v;
    }
    priorloc = v;
}

/*
 Function displays linked list.  
 */

void StringLinkedList::display()
{
    StringNode* temp = head;
    while (temp != NULL)
    {
        cout << temp-> elem << " " << temp-> miles << " miles" << endl;
        temp = temp-> next;
    }
    delete(temp);
}

/*
 Function searches for inputed value.  Once value is found, it creates a new linked list.  It creates and populates another nodes with values that follow the found value on the initial list.  It displays the new list as a separate command to the display function.  If not found, it so informs the user.
 */

void StringLinkedList::search(const string& e)
{
    StringNode *temp = head;                                        // create temp node
    bool found = false;
    while (temp != NULL)                                            // loops until end of list
    {
        if (temp-> elem == e)                                       // if search value is found
        {
            found = true;
            StringLinkedList newList = StringLinkedList();          // point to this node
            newList.addNode(temp-> elem, temp-> miles);             // create a new list,
            StringNode *current = temp-> next;                      // point to this list
            while (current != NULL)                                 // until end of this list
            {
                newList.addNode(current->elem,current->miles);      // add node to new list and populates with existing data
                current = current-> next;
            }
            newList.display();                                      // display new list
        }
        temp = temp-> next;                                         // otherwise keep searching
    }
    if (!found){
        cout << "There is no airport code that matches what you entered." << endl;
        cout << "Please select again." << endl;
        cout << endl;
    }
}

// remove function to support destructor command

void StringLinkedList::removeFront()
{
    StringNode* old = head;
    head = old-> next;
    delete old;
}