package edu.caltech.cs2.datastructures;

import edu.caltech.cs2.interfaces.ICollection;
import edu.caltech.cs2.interfaces.IDictionary;

import java.util.Iterator;
import java.util.function.Supplier;

public class ChainingHashDictionary<K, V> implements IDictionary<K, V> {
    // chain, supplier<idict>
    //int size, capacity, double load factor (1)
    //array of dictionary data
    private Supplier<IDictionary<K, V>> chain;
    private IDictionary<K,V>[] data;
    private double loadFactor = 1.0;
    private int size;
    private int capacity = 17;

    public ChainingHashDictionary(Supplier<IDictionary<K, V>> chain) {
        this.chain = chain;
        this.data = new IDictionary[capacity];
        this.size = 0;
        for (int i = 0; i < data.length; i++){
            this.data[i] = chain.get();
        }
    }

    /**
     * @param key
     * @return value corresponding to key
     */
    @Override
    public V get(K key) {
        // V val = this.data[index].get(key);
        IDictionary<K,V> chain = this.data[Math.abs((key.hashCode() % capacity + capacity) % capacity)];
        if (chain == null || key == null) {
            return null;
        }
        return chain.get(key);
    }

    @Override
    public V remove(K key) {
        int index = (key.hashCode() % capacity + capacity) % capacity;
        IDictionary<K,V> chain = this.data[index];
        V val = chain.remove(key);
        if (val == null) {
            return null;
        } else {
            this.size--;
            this.data[index] = chain;
        }
        return val;
    }

    @Override
    public V put(K key, V value) {
        if (this.size/this.data.length > this.loadFactor) {
            rehash();
        }
        V val = null;
        int index = Math.abs((key.hashCode() % capacity + capacity) % capacity);
        IDictionary<K,V> chain = this.data[index];
        if (chain == null) {
            chain = this.chain.get();
        }
        if (chain.get(key) != null) {
            val = chain.get(key);
        } else {
            this.size++;
        }
        this.data[index] = chain;
        chain.put(key, value);
        return val;
    }

    public void rehash(){
        //make bigger array
        //copy items over
        //this.data = new Arr
        IDictionary<K,V>[] arr = new IDictionary[(this.data.length * 2) + 1];
        for (IDictionary<K,V> chain : this.data){
            if (chain != null) {
                for (K key : chain.keys()) {
                    int idx = Math.abs((key.hashCode() % arr.length + arr.length) % arr.length);
                    IDictionary<K, V> data = arr[idx];
                    if (data == null) {
                        data = this.chain.get();
                    }
                    arr[idx] = data;
                    data.put(key, chain.get(key));
                }
            }
        }
        this.data = arr;
        this.capacity = arr.length;
    }

    @Override
    public boolean containsKey(K key) {

        return (this.get(key) != null);
    }

    /**
     * @param value
     * @return true if the HashDictionary contains a key-value pair with
     * this value, and false otherwise
     */
    @Override
    public boolean containsValue(V value) {
        return this.values().contains(value);
    }

    /**
     * @return number of key-value pairs in the HashDictionary
     */
    @Override
    public int size() {
        return this.size;
    }

    @Override
    public ICollection<K> keys() {
        ICollection<K> keys = new ArrayDeque<>();
        for (IDictionary<K,V> dict : this.data){
            if (dict != null) {
                for (K key : dict.keys()) {
                    keys.add(key);
                }
            }
        }
        return keys;
    }

    @Override
    public ICollection<V> values() {
        ICollection<V> values = new ArrayDeque<>();
        for (IDictionary<K, V> dict: this.data){
            if (dict != null) {
                for (V value : dict.values()) {
                    values.add(value);
                }
            }
        }
        return values;
    }

    /**
     * @return An iterator for all entries in the HashDictionary
     */
    @Override
    public Iterator<K> iterator() {
        return this.keys().iterator();
    }
}