package de.ostfalia.algo.ws18.s1;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.function.Predicate;

import de.ostfalia.algo.ws18.base.IManagement;
import de.ostfalia.algo.ws18.base.IMember;
import de.ostfalia.algo.ws18.base.KindOfSport;

public class Management implements IManagement {
	/**
	 * Track the number of operations.
	 */
	private int numberOfOperations = 0;
	/**
	 * Track the execution time.
	 */
	private long lastCheckpointNs;
	
	/**
	 * Current head node.
	 */
	private LinkedListNode<IMember> head;
	/**
	 * Length of the list.
	 */
	private int size = 0;
	/**
	 * Whether the list is reversed, i. e. the head is the tail.
	 */
	private boolean reversed = false;
	
	/**
	 * Empty constructor.
	 */
	public Management() {
	}

	/**
	 * Insert from an array of strings.
	 * 
	 * @param membersCsv Array of CSV rows.
	 */
	public Management(String[] membersCsv) {
		for (String memberCsv : membersCsv) {
			this.insert(new Member(memberCsv));
		}
	}

	/**
	 * Read from the CSV file and insert.
	 * 
	 * @param filename Path to the CSV file.
	 */
	public Management(String filename) {
		this.importFromFile(filename);
	}

	/**
	 * Read from the CSV file and insert.
	 * 
	 * @param filename Path to the CSV file.
	 */
	public void importFromFile(String filename) {
		File file = new File(filename);

		try (BufferedReader bufferedReader = new BufferedReader(new FileReader(file))) {
			bufferedReader.lines().forEach(line -> insert(new Member(line)));
		} catch (IOException exception) {
			throw new IllegalArgumentException(exception);
		}
	}

	/**
	 * Create a filtered version of this list.
	 * 
	 * @param criteria Criteria to filter for.
	 * @param breakAfterFirstMatch If true, return after the first match.
	 * @return A new list where all elements meet the given criteria.
	 */
	private Management filter(Predicate<IMember> criteria, boolean breakAfterFirstMatch) {
		Management result = new Management();
		if (this.size == 0) {
			return result;
		}

		// searches from head, inserts at head -> result is reversed
		result.reverse();
		
		LinkedListNode<IMember> currentNode = this.head;
		do {
			// traverse = 1 operation
			this.numberOfOperations++;

			IMember currentValue = currentNode.getValue();
			if (criteria.test(currentValue)) {
				result.insert(currentValue);
				if (breakAfterFirstMatch) {
					break;
				}
			}
		} while ((currentNode = currentNode.getNext()) != null);

		return result;
	}

	/**
	 * Find the first element that matches the given criteria.
	 * 
	 * @param criteria Criteria to search for.
	 * @return The first element that matches the given criteria or null.
	 */
	private IMember search(Predicate<IMember> criteria) {
		Management filteredList = this.filter(criteria, true);
		if (filteredList.size() == 0) {
			return null;
		} else {
			return filteredList.head.getValue();
		}
	}

	/**
	 * Count the number of elements that match the given criteria.
	 * 
	 * @param criteria Criteria to filter for.
	 * @return The number of elements that match the given criteria.
	 */
	private long size(Predicate<IMember> criteria) {
		return this.filter(criteria, false).size;
	}
	
	/**
	 * Reverse the order of the list.
	 */
	public void reverse() {
		this.reversed = !this.reversed;
	}

	/**
	 * @return The length of this list.
	 */
	@Override
	public int size() {
		return this.size;
	}

	/**
	 * Add an element at the start of the list.
	 * Replace the current head with a new node and link this node to the old head.
	 * 
	 * @return TODO?
	 */
	@Override
	public boolean insert(IMember value) {
		this.numberOfOperations++;
		
		LinkedListNode<IMember> newHead = new LinkedListNode<IMember>(value);
		if (this.head != null) {
			newHead.setNext(this.head);
		}
		this.head = newHead;

		this.size++;
		return true; // TODO?
	}

	/**
	 * Find the first member with the given key.
	 * 
	 * @param key The key to search for.
	 * @return The member or null.
	 */
	@Override
	public IMember search(long key) {
		return this.search(member -> member.getKey() == key);
	}

	/**
	 * Find the first member with the given name.
	 * 
	 * @param name The name of the member.
	 * @param firstName first name of the member.
	 * @return The member or null.
	 */
	@Override
	public IMember search(String name, String firstName) {
		return this.search(member -> member.getName().equals(name)
				&& member.getFirstName().equals(firstName));
	}

	/**
	 * Count the number of members which have an association to the given kindOfSport.
	 * 
	 * @param kindOfSport The kindOfSport of the members.
	 * @return The number of members with the given kindOfSport.
	 */
	@Override
	public int size(KindOfSport kindOfSport) {
		return (int) this.size(member -> member.getKindOfSport().equals(kindOfSport));
	}

	/**
	 * Return the members which have an association to the given kindOfSport.
	 * 
	 * @param kindOfSport The kindOfSport of the members.
	 * @return An array of the members with the given kindOfSport.
	 */
	@Override
	public IMember[] discipline(KindOfSport kindOfSport) {
		return this.filter(member -> member.getKindOfSport().equals(kindOfSport), false)
				.toArray();
	}

	/**
	 * Convert the list to an array.
	 * 
	 * @return The elements of this list as array.
	 */
	@Override
	public IMember[] toArray() {
		IMember[] array = new IMember[this.size];
		if (this.size() == 0) {
			return array;
		}

		LinkedListNode<IMember> currentNode = this.head;

		for (int index = 0; index < this.size; index++) {
			if (reversed) {
				array[this.size - index - 1] = currentNode.getValue();
			} else {
				array[index] = currentNode.getValue();
			}
			currentNode = currentNode.getNext();
		}
		
		return array;
	}

	/**
	 * Reset the number of operation counter and get the last value.
	 * 
	 * @return The number of operations recorded since the last call.
	 */
	@Override
	public int numberOfOperations() {
		int numberOfOperations = this.numberOfOperations;
		this.numberOfOperations = 0;
		return numberOfOperations;
	}
	
	/**
	 * Reset the timer and get the time difference in ns.
	 * 
	 * @return Nanoseconds since the last call.
	 */
	public long checkpoint() {
		long nanoseconds = this.lastCheckpointNs;
		this.lastCheckpointNs = System.nanoTime();
		return this.lastCheckpointNs - nanoseconds;
	}
}