package org.bukkit.conversations;

import org.bukkit.ChatColor;

/**
 * ValidatingPrompt is the base class for any prompt that requires validation.
 * ValidatingPrompt will keep replaying the prompt text until the user enters
 * a valid response.
 */
public abstract class ValidatingPrompt implements Prompt
{
	public ValidatingPrompt()
	{
		super();
	}

	/**
	 * Accepts and processes input from the user and validates it. If
	 * validation fails, this prompt is returned for re-execution, otherwise
	 * the next Prompt in the prompt graph is returned.
	 *
	 * @param context Context information about the conversation.
	 * @param input   The input text from the user.
	 * @return This prompt or the next Prompt in the prompt graph.
	 */
	public Prompt acceptInput(ConversationContext context, String input)
	{
		if(isInputValid(context, input))
		{
			return acceptValidatedInput(context, input);
		}
		else
		{
			String failPrompt = getFailedValidationText(context, input);
			if(failPrompt != null)
			{
				context.getForWhom().sendRawMessage(ChatColor.RED + failPrompt);
			}
			// Redisplay this prompt to the user to re-collect input
			return this;
		}
	}

	/**
	 * Ensures that the prompt waits for the user to provide input.
	 *
	 * @param context Context information about the conversation.
	 * @return True.
	 */
	public boolean blocksForInput(ConversationContext context)
	{
		return true;
	}

	/**
	 * Override this method to check the validity of the player's input.
	 *
	 * @param context Context information about the conversation.
	 * @param input   The player's raw console input.
	 * @return True or false depending on the validity of the input.
	 */
	protected abstract boolean isInputValid(ConversationContext context, String input);

	/**
	 * Override this method to accept and processes the validated input from
	 * the user. Using the input, the next Prompt in the prompt graph should
	 * be returned.
	 *
	 * @param context Context information about the conversation.
	 * @param input   The validated input text from the user.
	 * @return The next Prompt in the prompt graph.
	 */
	protected abstract Prompt acceptValidatedInput(ConversationContext context, String input);

	/**
	 * Optionally override this method to display an additional message if the
	 * user enters an invalid input.
	 *
	 * @param context      Context information about the conversation.
	 * @param invalidInput The invalid input provided by the user.
	 * @return A message explaining how to correct the input.
	 */
	protected String getFailedValidationText(ConversationContext context, String invalidInput)
	{
		return null;
	}
}