package bjc.utils.ioutils;

import java.util.function.BiConsumer;

import bjc.utils.exceptions.PragmaFormatException;
import bjc.utils.funcdata.FunctionalStringTokenizer;
import bjc.utils.funcutils.ListUtils;

/**
 * Contains factory methods for common pragma types
 *
 * @author ben
 *
 */
public class RuleBasedReaderPragmas {

	/**
	 * Creates a pragma that takes a single integer argument
	 *
	 * @param <StateType>
	 *                The type of state that goes along with this pragma
	 * @param name
	 *                The name of this pragma, for error message purpose
	 * @param consumer
	 *                The function to invoke with the parsed integer
	 * @return A pragma that functions as described above.
	 */
	public static <StateType> BiConsumer<FunctionalStringTokenizer, StateType> buildInteger(final String name,
			final BiConsumer<Integer, StateType> consumer) {
		return (tokenizer, state) -> {
			// Check our input is correct
			if (!tokenizer.hasMoreTokens())
				throw new PragmaFormatException("Pragma " + name + " requires one integer argument");

			// Read the argument
			final String token = tokenizer.nextToken();

			try {
				// Run the pragma
				consumer.accept(Integer.parseInt(token), state);
			} catch (final NumberFormatException nfex) {
				// Tell the user their argument isn't correct
				final PragmaFormatException pfex = new PragmaFormatException(
						"Argument " + token + " to " + name + " pragma isn't a valid integer. "
								+ "This pragma requires a integer argument");

				pfex.initCause(nfex);

				throw pfex;
			}
		};
	}

	/**
	 * Creates a pragma that takes any number of arguments and collapses
	 * them all into a single string
	 *
	 * @param <StateType>
	 *                The type of state that goes along with this pragma
	 * @param name
	 *                The name of this pragma, for error message purpose
	 * @param consumer
	 *                The function to invoke with the parsed string
	 * @return A pragma that functions as described above.
	 */
	public static <StateType> BiConsumer<FunctionalStringTokenizer, StateType> buildStringCollapser(
			final String name, final BiConsumer<String, StateType> consumer) {
		return (tokenizer, state) -> {
			// Check our input
			if (!tokenizer.hasMoreTokens()) throw new PragmaFormatException(
					"Pragma " + name + " requires one or more string arguments");

			// Build our argument
			final String collapsed = ListUtils.collapseTokens(tokenizer.toList());

			// Run the pragma
			consumer.accept(collapsed, state);
		};
	}
}