#include "Hashtable.h"

// Default constructor, initializes the hash table

// creates an empty "item" for each index in the hashtable, setting itemName and itemDescription

// to "empty" and the next pointer to nullptr

// this initialization helps check whether an index is empty when adding new items

HashTable::HashTable() {

for (int i = 0; i < SIZE; i++) {

table[i] = new Item;

table[i]->itemName = "Empty Data";

table[i]->itemDescription = "Empty Data";

table[i]->next = nullptr;

}

}

// This method computes a hash value for the provided key (item name)

// Sums ASCII values of each char in the string to generate a hash

// Hash value is then taken to modulo "SIZE" to ensure it falls within bounds of array indices

int HashTable::HashFunction(std::string key) {

int hash = 0;

int index;

for (int i = 0; i < key.length(); i++) {

hash = hash + (int)key[i];

}

index = hash % SIZE;

return index;

}

// This method adds new item to the hash table

// First computes the index using the Hash function

// If slot is empty, directly stores the item

// If slot not empty, creates a new 'item' and traverses the

// linked list at the end to append the new item

void HashTable::AddItem(std::string itemName, std::string itemDescription) {

int index = HashFunction(itemName);

if (table[index]->itemName == "Empty Data") {

table[index]->itemName = itemName;

table[index]->itemDescription = itemDescription;

} else {

Item* current = table[index];

while (current->next != nullptr) {

current = current->next;

}

Item* newItem = new Item{ itemName, itemDescription, nullptr};

current->next = newItem;

}

}

// This method counts how many times items are stored at a specific index in the hash table

// Returns 0 if slot is empty, otherwise, it counts the items in the linked list

int HashTable::countItemsAtIndex(int index) {

int count = 0;

Item* current = table[index];

while (current != nullptr && current->itemName != "Empty Data") {

++count;

current = current->next;

}

return count;

}

// This method prints the contents of the entire hash table

// Iterators thru each index and uses NumberOfItemsInIndex

// method to display name, description and count of items

void HashTable::PrintTable() {

for (int i = 0; i < SIZE; ++i) {

int itemCount = countItemsAtIndex(i);

std::cout << "------------------------------------------------\n";

std::cout << "Index: " << i << "\n";

std::cout << table[i]->itemName << " | " << table[i]->itemDescription << "\n";

std::cout << "Items at this index: " << itemCount << "\n";

std::cout << "------------------------------------------------\n";

}

}

// This method prints all items stored at a specific index

// Handles the case where index is empty by printing a corresponding message

// If items are present, traverses the linked list and prints each item's name and description

void HashTable::PrintItemsInIndex(int index) {

Item* current = table[index];

if (current->itemName == "empty") {

std::cout << "Index " << index << " is empty.\n";

}

else {

std::cout << "Items at index " << index << ":\n";

while (current != nullptr) {

std::cout << "------------------------------------------------\n";

std::cout << "Item Name: " << current->itemName << "\n";

std::cout << "Item Description: " << current->itemDescription << "\n";

std::cout << "------------------------------------------------\n";

current = current->next;

}

}

}

// This method searches for an item by name and prints its description if found

// It computes the index using the Hash fucnction and traverses the linked list at the index

// If the item name matches, it sets a flag and stores the description for later display

// if item not found, outputs a message indicating that the item wasnt found

void HashTable::FindDescription(std::string name) {

int index = HashFunction(name);

bool foundItemName = false;

std::string description;

Item* current = table[index];

while (current != nullptr) {

if (current->itemName == name) {

foundItemName = true;

description = current->itemDescription;

}

current = current->next;

}

if (foundItemName == true) {

std::cout << "\n------------------------------------------------\nItem Description for " << name << ":\n------------------------------------------------\n" << description << " \n------------------------------------------------\n" << std::endl;

}

else {

std::cout << name << "'s description was not found in the HashTable\n";

}

}