#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>

const int NAME_SIZE=16;
const int ID_SIZE=10;

struct Student
{
char fname[NAME_SIZE];
char lname[NAME_SIZE];
char id[ID_SIZE];
double grade1;
double grade2;
double grade3;
};

struct Node
{
char fname[NAME_SIZE];
char lname[NAME_SIZE];
char id[ID_SIZE];
Node* next;
};

Node* buildList(void);
Node* insertNode(Node*,Node*);
void searchNode(Node*,char*);
Node* deleteNode(Node*,char*);
Node* addNode(Node*,char*);
void displayList(Node*);
Node* cleanupList(Node*);
Node* searchnode2(Node*, char*);

int main()
{
  int x;
  char id[ID_SIZE];
  Node* head=(Node*)0;
  head=buildList();
  while(x!=5)
  {
    std::cout<<"1.Display all keys\n"
             <<"2.Display specified records\n"
             <<"3.Delete a specified record\n"
             <<"4.Add a specified record\n"
             <<"5.Quit\n"<<std::endl;
    std::cin>>x;
    if(x==1)
    {
      std::cout<<"Here is your list:"<<std::endl;
      displayList(head);
    }
    if(x==2)
    {
      std::cout<<"\nEnter an id to search for ===> "<<std::flush;
      std::cin>>id;
      searchNode(head,id);
    }
    if(x==3)
    {
      std::cout<<"\nEnter an id to delete ===> "<<std::flush;
      std::cin>>id;
      head=deleteNode(head,id);
      std::cout<<"\nHere is your list after the delete:"<<std::endl;
      displayList(head);
    }
    if(x==4)
    {
      std::cout<<"\nEnter an id to add ===> "<<std::flush;
      std::cin>>id;
      head=addNode(head,id);
      std::cout<<"\nHere is your list after the add:"<<std::endl;
      displayList(head);
    }
  }
head=cleanupList(head);

displayList(head);
return(0);
}

Node* buildList(void)
{
  Node* head=(Node*)0;
  Node* newNode=(Node*)0;
  Student person;
  std::ifstream infile;
  infile.open("students.txt",std::ios::in);
  if(!infile)
  {
    std::cerr<<"\n\nFile not opened...\n"<<std::endl;
    exit(-1);
  }
  infile>>person.fname
        >>person.lname
        >>person.id
        >>person.grade1
        >>person.grade2
        >>person.grade3;
  for(;!infile.eof();)
    {
      newNode=new Node;
      strncpy(newNode->fname,person.fname,NAME_SIZE);
      newNode->fname[NAME_SIZE-1]='\0';
      strncpy(newNode->lname,person.lname,NAME_SIZE);
      newNode->lname[NAME_SIZE-1]='\0';
      strncpy(newNode->id,person.id,ID_SIZE);
      newNode->id[ID_SIZE-1]='\0';
      newNode->next=(Node*)0;
      head=insertNode(head,newNode);
      infile>>person.fname
            >>person.lname
            >>person.id
            >>person.grade1
            >>person.grade2
            >>person.grade3;
    }
infile.close();
return(head);
}

Node* insertNode(Node* head,Node* newNode)
{
  Node* current=head;
  Node* prior=NULL;
  while((current)&&(strncmp(current->id,newNode->id,ID_SIZE)<0))
    {
    prior=current;
    current=current->next;
    }
  newNode->next=current;
  if(!prior)
    head=newNode;
  else
    prior->next=newNode;
return(head);
}

void searchNode(Node* head,char* id)
{
  Node* current=head;
  int found=0;
  while((current)&&(!found))
  {
    if(strncmp(id,current->id,ID_SIZE)==0)
      found=1;
    else
      current=current->next;
  }
  if(found)
  {
    std::cout<<std::endl
             <<current->fname<<"\t"
             <<current->lname<<"\t"
             <<current->id<<std::endl;
  }
  else
    std::cout<<"\nRecord not in the list..."<<std::endl;
}

Node* searchNode2(Node* head, char*id)
{
  Node* current=head;
  int found=0;
  while((current)&&(!found))
  {
    if(strncmp(id,current->id,ID_SIZE)==0)
      found=0;
    else
      current=current->next;
  }
return(current);
}

Node* deleteNode(Node* head,char* id)
{
  Node* current=head;
  Node* prior=(Node*)0;
  int found=0;
  while((current)&&(!found))
  {
    if(strncmp(id,current->id,ID_SIZE)==0)
      found=1;
    else
    {
      prior=current;
      current=current->next;
    }
  }
  if(found)
  {
    if(prior)
      prior->next=current->next;
    else
      head=current->next;
    delete current;
  }
  else
    std::cout<<"\nNo one by that name to delete..."<<std::endl;
return(head);
}

Node* addNode(Node* head,char* id)
{
  Node* newNode=(Node*)0;
  Student person;
  Node* newNode= new Node;
  if(searchNode2(head, id))
  {
    newNode= new Node;
    strncpy(newNode->id.id,ID_SIZE);
    std::cout<<"\nEnter first name ===> "<<std::flush;
    std::cin>>person.fname;
    std::cout<<"Enter last name ===> "<<std::flush;
    std::cin>>person.lname;
    std::cout<<"Enter id  ===> "<<std::flush;
    std::cin>>person.id;

    strncpy(newNode->fname,person.fname,NAME_SIZE);
    newNode->fname[NAME_SIZE-1]='\0';
    strncpy(newNode->lname,person.lname,NAME_SIZE);
    newNode->lname[NAME_SIZE-1]='\0';
    strncpy(newNode->id,person.id,ID_SIZE);
    newNode->id[ID_SIZE-1]='\0';
    newNode->next=(Node*)0;
    head=insertNode(head, newNode);
  }
  else
  {
    std::cout<<"id already in list"<<std::endl;
  }
return(head);
}

void displayList(Node* head)
{
  Node* current=head;
  if(!head)
  std::cout<<"error"<<std::flush;
  while(current)
  {
    std::cout<<std::endl
             <<current->fname<<"\t"
             <<current->lname<<"\t"
             <<current->id<<std::endl;
    current=current->next;
  }
}

Node* cleanupList(Node* head)
{
  Node* current=head;
  while(head)
  {
    current=head;
    head=current->next;
    delete current;
  }
return(head);
}