package joins;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Random;

public class Iterator {
	
	int size;  
	ArrayList<Integer> data;
	
	Random r = new Random(); 
	
	Iterator(int range, int size){
		this.size = size;
		this.data = new ArrayList<Integer>(); 
		for (int i = 0; i < size; i ++) {
			data.add((int)(r.nextDouble()*range)); 
		}
	}
	Iterator(ArrayList<Integer> data){
		this.data = data; 
		this.size = data.size(); 
	}
	public int getSize() {
		return size; 
	}
	public int getItem(int i) {
		return data.get(i); 
	}
	public ArrayList<Integer> getData(){
		return data; 
	}
	public Iterator nestedLoopsJoin(Iterator other){
		ArrayList<Integer> result = new ArrayList<Integer>();
		for (int i = 0; i <  size; i ++) {
			for (int j = 0; j < other.getSize(); j ++) {
				if (data.get(i) == other.getItem(j)) {
					result.add(data.get(i)); 
				}
			}
		}
		return new Iterator(result); 
	}

	static void run1NestedLoopsJoin(Iterator it1, Iterator it2) {
		long start = System.currentTimeMillis(); 
		Iterator resJoin = it1.nestedLoopsJoin(it2); 
		long stop = System.currentTimeMillis();
		System.out.println((stop - start) + " ms, " + resJoin.getSize() + " results");  

	}
	
	static void run2NestedLoopsJoins(Iterator it1, Iterator it2, Iterator it3) {
		long start = System.currentTimeMillis();
		Iterator resJoin = it1.nestedLoopsJoin(it2).nestedLoopsJoin(it3);
		long stop = System.currentTimeMillis();
		System.out.println((stop - start) + " ms, " + resJoin.getSize() + " results");  
	}
	
	
	public Iterator hashJoin(Iterator other) {
		Iterator inner, outer;
		if (this.size > other.getSize()) {
			outer = this; 
			inner = other; 
		}
		else {
			outer = other; 
			inner = this; 
		}
		HashMap<Integer, Integer> hashTable = new HashMap<Integer, Integer>();
		fillHashTable(hashTable, inner); 
		ArrayList<Integer> result = new ArrayList<Integer>();
		for (int i = 0; i < outer.getSize(); i ++) {
			Integer countI = hashTable.get(outer.getItem(i));
			if (countI != null) {
				for (int j = 1; j <= countI; j ++) {
					result.add(outer.getItem(i)); 
				}
			}
		}
		return new Iterator(result); 
	}
	
	private void fillHashTable(HashMap<Integer, Integer> hashTable, Iterator iter) {
		for (int i = 0; i < iter.getSize(); i ++) {
			Integer countI = hashTable.get(iter.getItem(i)); 
			if (countI == null) {
				countI = new Integer(1); 
			}
			else {
				countI = new Integer(countI + 1); 
			}
			hashTable.put(iter.getItem(i), countI); 
		}
	}
	static void run1HashJoin(Iterator it1, Iterator it2) {
		long start = System.currentTimeMillis(); 
		Iterator resJoin = it1.hashJoin(it2); 
		long stop = System.currentTimeMillis();
		System.out.println((stop - start) + " ms, " + resJoin.getSize() + " results");  
	}
	
	static void run2HashJoins(Iterator it1, Iterator it2, Iterator it3) {
		long start = System.currentTimeMillis();
		Iterator resJoin = it1.hashJoin(it2).hashJoin(it3);
		long stop = System.currentTimeMillis();
		System.out.println((stop - start) + " ms, " + resJoin.getSize() + " results");  
	}
	
	public static void main(String[] argv) throws IOException {
		Iterator it1 = new Iterator(4000, 1000000);
		Iterator it2 = new Iterator(50, 1000);
		Iterator it3 = new Iterator(50, 1000);
		
		System.out.println("\nNestedLoops(it1, it2)"); 
		run1NestedLoopsJoin(it1, it2); 
	
		System.out.println("\nNestedLoops(NestedLoops(it1, it2), it3): ");
		run2NestedLoopsJoins(it1, it2, it3); 
		
		System.out.println("\nNestedLoops(NestedLoops(it3, it2), it1): ");
		run2NestedLoopsJoins(it3, it2, it1); 
	
		System.out.println("\nHashJoin(it1, it2)"); 
		run1HashJoin(it1, it2); 
	
		System.out.println("\nHashJoin(HashJoin(it1, it2), it3): ");
		run2HashJoins(it1, it2, it3); 
		
		// I had the plan to also dump these into files and let Postgres do the
		// join, for comparison, but I didn't code that yet. 
		// it1.dump("/Users/ioanamanolescu/data/it1.csv");
		// it2.dump("/Users/ioanamanolescu/data/it2.csv");
		// it3.dump("/Users/ioanamanolescu/data/it3.csv");
		
	}
	
	public void dump(String fileName) throws IOException {
		OutputStream os = new FileOutputStream(new File(fileName));
		for (Integer i: data) {
			os.write(i);
			os.write('\n'); 
		}
		os.close();
	}
	
}