// Lab Problem 9.1

// CS211 ADS2

// T Naughton, CS NUIM

// 28 Apr 2000

#include<iostream>

#include<string.h> // for strcmp()



const int ISBNSize = 11; // one more than required (extra space for \0)

const int TitleSize = 50;

enum EntryType {USED, EMPTY, DELETED};



class HashEntry {

 public:

  char isbn[ISBNSize]; // the key

  char title[TitleSize];

  EntryType status;

};



class HashTable {



  int HTableSize; // should make this a static



  HashEntry * Entry;



 public:

  HashTable();

  HashTable(int tablesize);

  ~HashTable();



  // Methods that acts on HTable

  void AddEntry(char newisbn[ISBNSize], char newtitle[TitleSize]);

  void Print();

  void Clear();

  int CountFree();

  void Remove(char rmisbn[ISBNSize]);



 private:

  int Hash(char isbn[ISBNSize]);



};



HashTable::HashTable(){

  // Initialise values

  HTableSize = 10;



  Entry = new HashEntry[HTableSize];

  Clear();

}



HashTable::HashTable(int tablesize){

  HTableSize = tablesize;



  Entry = new HashEntry[HTableSize];

  Clear();

}



HashTable::~HashTable(){

  delete [] Entry;

}



void HashTable::AddEntry(char newisbn[ISBNSize], char newtitle[TitleSize]){

  int count;

  int index;

  if (CountFree() < 1) {

    cout << endl << "Table is full!";

  } else {

    index = Hash(newisbn);

    while (Entry[index].status != EMPTY) {

      index = (index + 1) % HTableSize;

    }

    count = 0;

    while (count < ISBNSize) {

      Entry[index].isbn[count] = newisbn[count];

      count++;

    }

    count = 0;

    while (count < TitleSize) {

      Entry[index].title[count] = newtitle[count];

      count++;

    }

    Entry[index].status = USED;

  }

}



void HashTable::Print(){

  int count;

  cout << endl << "Table Contents (Free = " << CountFree() << "):";

  count = 0;

  while (count < HTableSize) {

    cout << "\n  " << count << '\t';

    switch (Entry[count].status) {

      case USED :

        cout << "USED    " << Entry[count].isbn << ' ';

        cout << Entry[count].title;

        break;

      case EMPTY :

        // don't print out rubbish

        cout << "EMPTY "; break;

      case DELETED :

        cout << "DELETED " << Entry[count].isbn << ' ';

        cout << Entry[count].title;

        break;

      default:

        cout << "??????? ";

    }

    count++;

  }

}



void HashTable::Clear(){

  int count;

  count = 0;

  while (count < HTableSize) {

    Entry[count].status = EMPTY;

    count++;

  }

}



int HashTable::CountFree(){

  int count;

  int free;

  free = 0;

  count = 0;

  while (count < HTableSize) {

    if (Entry[count].status == EMPTY) {

      free++;

    }

    count++;

  }

  return free;

}



void HashTable::Remove(char rmisbn[ISBNSize]){

  int hashindex;

  int count;

  hashindex = Hash(rmisbn);

  count = 0;

  while ((count < HTableSize) &&

                    (strcmp(rmisbn, Entry[hashindex].isbn) != 0) &&

                    (Entry[hashindex].status != EMPTY)) {

    hashindex = (hashindex + 1) % HTableSize;

    count++;

  }

  if (strcmp(rmisbn, Entry[hashindex].isbn) == 0) {

    Entry[hashindex].status = DELETED;

  } else {

    cout << endl << "Item " << rmisbn <<  " not found.";

  }

}



int HashTable::Hash(char isbn[ISBNSize]){

  return int(isbn[0]) % HTableSize;

}



void main(void){



  HashTable books(3);



  cout << endl << endl;



  books.AddEntry("1111111111\0", "Book A");

  books.AddEntry("2222222222\0", "Book B");

  books.Print();



  books.AddEntry("999999999X\0", "Book C");

  books.AddEntry("3434343434\0", "Book D");

  books.AddEntry("4444444444\0", "Book E");

  books.Print();



  books.Remove("2222222222\0");

  books.Remove("3333333333\0");

  books.Print();



  cout << endl << "Calling Clear()...";

  books.Clear();

  books.AddEntry("9876543210\0", "Book F");

  books.Print();

}