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/*
 Samarth Kamble (21142 F1-Batch)
 DSAL Assignment-5
 Date of starting: 31/03/2022
 Date of completion: 11/04/2022
 Problem Statement:
 Implement all the functions of a dictionary (ADT) using hashing and handle collisions using separate chaining using linked list.
 Data: Set of (key, value) pairs, Keys are mapped to values, Keys must be comparable, Keys must be unique.
 Standard Operations: Insert (key, value),Find(key), Delete(key)
 */

#include <iostream>
#define SIZE 101
using namespace std;

class HashTable {
public:
	class HashEntry;
	static int hashFunction(string key);
	static string capitalise(string &s);
	void insert(string key, string value);
	void deleteKey(string key);
	void findKey(string key);
	void displayHashTable();
	HashTable();

private:
	HashEntry *hashTable[SIZE];

public:
	class HashEntry {
		string word;
		string meaning;
		HashEntry *next;
		int nodeCount;
		friend class HashTable;

	public:
		HashEntry() {
			word = meaning = "";
			next = nullptr;
			nodeCount = 0;
		}
		HashEntry(string key, string value) {
			this->word = key;
			this->meaning = value;
			this->next = nullptr;
			nodeCount = -1;
		}
	};
} HT;

HashTable::HashTable() {
	for (int i = 0; i < SIZE; i++)
		hashTable[i] = new HashEntry();
}

void HashTable::displayHashTable() {
	HashEntry *temp = nullptr;
	for (int i = 0; i < SIZE; i++) {
		temp = hashTable[i];
		if (temp->next != nullptr) {
			cout << "\nBucket-" << i << ":" << endl;
			cout << "Node Count: " << temp->nodeCount << endl;
			temp = temp->next;
			int ct = 1;
			while (temp != nullptr) {
				if (temp != nullptr) {
					cout << ct++ << ": " << temp->word << " ";
					temp = temp->next;
				}
			}
			cout << endl;
		}
	}
}

int HashTable::hashFunction(string key) {
	int hashValue = 0;
	int temp = 0;
	int len = key.length();
	for (int i = 0; i < len; i++)
		hashValue += key[i];
	while (hashValue) {
		temp += hashValue % 100;
		hashValue /= 100;
	}
	hashValue = temp % 100;
	return hashValue;
}

string HashTable::capitalise(string &s) {
	for (auto &ch : s)
		ch = (char) (ch & (~(1 << 5)));
	return s;
}

void HashTable::insert(string key, string value) {
	key = capitalise(key);
	int hashValue = hashFunction(key);
	HashEntry *temp = hashTable[hashValue];
	temp->nodeCount++;
	while (temp->next != nullptr) {
		if (temp != nullptr)
			temp = temp->next;
	}
	temp->next = new HashEntry(key, value);
	cout << "\nWord added to dictionary.";
}

void HashTable::findKey(string key) {
	int comparisons = 0;
	string tempKey = key;
	key = capitalise(key);
	int hashValue = hashFunction(key);
	HashEntry *temp = hashTable[hashValue];
	while (temp != nullptr) {
		if (temp != nullptr) {
			comparisons++;
			if (temp->word == key) {
				cout << "Key found!\n\n" << tempKey << "\nMeaning: "
						<< temp->meaning << endl;
				cout << "Number of comparisons: " << comparisons - 1 << endl;
				return;
			}
			temp = temp->next;
		}
	}
	cout << "Key not found! " << endl;
	if (temp == nullptr)
		comparisons += 1;
	cout << "Number of comparisons: " << comparisons - 1 << endl;
}

void HashTable::deleteKey(string key) {
	key = capitalise(key);
	HashEntry *tail = nullptr;
	HashEntry *temp = nullptr;
	int hashValue = hashFunction(key);
	temp = hashTable[hashValue];
	if (temp->next == nullptr) {
		cout << "Word does not exist!";
		return;
	}
	while (temp != nullptr) {
		tail = temp;
		if (temp != nullptr)
			temp = temp->next;
		if (temp == nullptr) {
			cout << "Word does not exist!";
			return;
		}
		if (temp->word == key) {
			if (temp != nullptr)
				tail->next = temp->next;
			else
				tail->next = nullptr;
			delete temp;
			temp = nullptr;
			return;
		}
	}
}

int main() {
	bool menu = 1;
	int ch;
	string key, val;
	while (menu) {
		cout
				<< "\nMENU\n1.Insert\n2.Find\n3.Delete\n4.Display HashTable\nEnter your choice: ";
		cin >> ch;
		switch (ch) {
		case 1:
			cout << "\nEnter word: ";
			cin >> key;
			cout << "\nEnter value: ";
			cin.ignore();
			getline(cin, val);
			HT.insert(key, val);
			break;

		case 2:
			cout << "\nEnter word: ";
			cin >> key;
			HT.findKey(key);
			break;

		case 3:
			cout << "\nEnter word: ";
			cin >> key;
			HT.deleteKey(key);
			break;

		case 4:
			HT.displayHashTable();
			break;

		case -1:
			menu = 0;
			break;

		default:
			break;
		}
	}

	return 0;
}