package hashing;

import java.io.*;
import java.util.Arrays;
import java.util.Scanner;

public class UniversalHashTable {
	private int[] hashArray;
	private boolean[] hashCollided;
	private PerfectHashingFunction hashingFunction;
	private File file;
	private int sizeSquared;
	private int rebuildsNumber;
	private int[] dataArray;

	public static void main(String[] args) {
		UniversalHashTable u = new UniversalHashTable("/Users/FNSY/Desktop/Matlab.txt");
		System.out.println(u.isThere(1221));
		System.out.println(u.isThere(1221));
		System.out.println(u.isThere(902));
		System.out.println(u.getRebuildsNumber());

	}

	public UniversalHashTable(String filePath) {
		try {
			initiallizingHashTable(filePath);
		} catch (FileNotFoundException e) {

		}
		rebuildsNumber = 0;
		createHashTable();
	}

	private PerfectHashingFunction getHachingFunction(int sizeSquared) {
		return new PerfectHashingFunction(sizeSquared);
	}

	private void initiallizingHashTable(String path) throws FileNotFoundException {
		PreHashingOperations preHashing = new PreHashingOperations(path);
		this.sizeSquared = (int) Math.pow(preHashing.getFileSize(), 2);
		this.file = preHashing.getFile();
		this.dataArray = preHashing.getFileArray();
		newChance(sizeSquared);
	}

	private void createHashingFunction(int sizeSquared) {
		hashingFunction = getHachingFunction(sizeSquared);
	}

	private void createHashArray(int sizeSquared) {
		hashArray = new int[sizeSquared];
	}

	private void createHashCollided(int sizeSquared) {
		hashCollided = new boolean[sizeSquared];
		Arrays.fill(hashCollided, false);
	}

	private void newChance(int sizeSquared) {
		createHashArray(sizeSquared);
		createHashCollided(sizeSquared);
		createHashingFunction(sizeSquared);
	}

	private void createHashTable() {
		int scannedFromFile, hashedValue;
		int index = 0;
		newChance(sizeSquared);
		try (Scanner scan = new Scanner(file)) {
			while (scan.hasNextLine()) {
				scannedFromFile = scan.nextInt();
				hashedValue = this.hashingFunction.hashFunction(scannedFromFile);
				if (!hashCollided[hashedValue]) {
					hashArray[hashedValue] = scannedFromFile;
					hashCollided[hashedValue] = true;
				} else {
					++rebuildsNumber;
					createHashTable();
					break;
				}
			}
		} catch (Exception e) {

		}
	}

	public int getRebuildsNumber() {
		return this.rebuildsNumber;
	}

	public boolean isThere(int key) {
		int hashedValue = this.hashingFunction.hashFunction(key);
		if (hashCollided[hashedValue])
			return true;
		return false;
	}

}