package bjc.funcdata;

import java.util.StringTokenizer;
import java.util.function.Consumer;
import java.util.function.Function;

/**
 * A string tokenizer that exposes a functional interface.
 *
 * @author ben
 */
public class FunctionalStringTokenizer {
	/**
	 * Create a new tokenizer from the specified string.
	 *
	 * @param strang
	 *               The string to create a tokenizer from.
	 *
	 * @return A new tokenizer that splits the provided string on spaces.
	 */
	public static FunctionalStringTokenizer fromString(final String strang) {
		if (strang == null)
			throw new NullPointerException("String to tokenize must be non-null");

		return new FunctionalStringTokenizer(new StringTokenizer(strang, " "));
	}

	/* The string tokenizer being driven */
	private final StringTokenizer input;

	/**
	 * Create a functional string tokenizer from a given string.
	 *
	 * @param inp
	 *            The string to tokenize.
	 */
	public FunctionalStringTokenizer(final String inp) {
		if (inp == null)
			throw new NullPointerException("String to tokenize must be non-null");

		this.input = new StringTokenizer(inp);
	}

	/**
	 * Create a functional string tokenizer from a given string and set of
	 * separators.
	 *
	 * @param input
	 *                   The string to tokenize.
	 *
	 * @param seperators
	 *                   The set of separating tokens to use for splitting.
	 */
	public FunctionalStringTokenizer(final String input, final String seperators) {
		if (input == null) {
			throw new NullPointerException("String to tokenize must not be null");
		} else if (seperators == null) {
			throw new NullPointerException("Tokens to split on must not be null");
		}

		this.input = new StringTokenizer(input, seperators);
	}

	/**
	 * Create a functional string tokenizer from a non-functional one.
	 *
	 * @param toWrap
	 *               The non-functional string tokenizer to wrap.
	 */
	public FunctionalStringTokenizer(final StringTokenizer toWrap) {
		if (toWrap == null)
			throw new NullPointerException("Wrapped tokenizer must not be null");

		this.input = toWrap;
	}

	/**
	 * Execute a provided action for each of the remaining tokens.
	 *
	 * @param action
	 *               The action to execute for each token.
	 */
	public void forEachToken(final Consumer<String> action) {
		if (action == null)
			throw new NullPointerException("Action must not be null");

		while (input.hasMoreTokens()) {
			action.accept(input.nextToken());
		}
	}

	/**
	 * Get the string tokenizer encapsulated by this tokenizer.
	 *
	 * @return The encapsulated tokenizer.
	 */
	public StringTokenizer getInternal() {
		return input;
	}

	/**
	 * Check if this tokenizer has more tokens.
	 *
	 * @return Whether or not this tokenizer has more tokens.
	 */
	public boolean hasMoreTokens() {
		return input.hasMoreTokens();
	}

	/**
	 * Return the next token from the tokenizer.
	 *
	 * @return The next token from the tokenizer, or null if no more tokens are
	 *         available.
	 */
	public String nextToken() {
		if (input.hasMoreTokens()) {
			/* Return the next available token. */
			return input.nextToken();
		}

		/* Return no token. */
		return null;
	}

	/**
	 * Convert this tokenizer into a list of strings.
	 *
	 * @return This tokenizer, converted into a list of strings.
	 */
	public ListEx<String> toList() {
		return toList((final String element) -> element);
	}

	/**
	 * Convert the contents of this tokenizer into a list. Consumes all of the input
	 * from this tokenizer.
	 *
	 * @param <E>
	 *                    The type of the converted tokens.
	 *
	 * @param transformer
	 *                    The function to use to convert tokens.
	 *
	 * @return A list containing all of the converted tokens.
	 */
	public <E> ListEx<E> toList(final Function<String, E> transformer) {
		if (transformer == null)
			throw new NullPointerException("Transformer must not be null");

		final ListEx<E> returned = new FunctionalList<>();

		/* Add each token to the list after transforming it. */
		forEachToken(token -> {
			final E transformedToken = transformer.apply(token);

			returned.add(transformedToken);
		});

		return returned;
	}

	@Override
	public String toString() {
		return String.format("FunctionalStringTokenizer [input=%s]", input);
	}
}