/* $Id$ */

/** @file ai_sign.hpp Everything to query and build signs. */

#ifndef AI_SIGN_HPP
#define AI_SIGN_HPP

#include "ai_object.hpp"
#include "ai_error.hpp"

/**
 * Class that handles all sign related functions.
 */
class AISign : public AIObject {
public:
	static const char *GetClassName() { return "AISign"; }

	enum ErrorMessages {

		/** Base for sign building related errors */
		ERR_SIGN_BASE = AIError::ERR_CAT_SIGN << AIError::ERR_CAT_BIT_SIZE,

		/** Too many signs have been placed */
		ERR_SIGN_TOO_MANY_SIGNS,             // [STR_2808_TOO_MANY_SIGNS]
	};

	/**
	 * Gets the maximum sign index; there are no valid signs with a higher index.
	 * @return The maximum sign index.
	 * @post Return value is always non-negative.
	 */
	static SignID GetMaxSignID();

	/**
	 * Gets the number of signs. This is different than GetMaxSignID()
	 *   because of the way OpenTTD works internally.
	 * @return The number of signs.
	 * @post Return value is always non-negative.
	 */
	static int32 GetSignCount();

	/**
	 * Checks whether the given sign index is valid.
	 * @param sign_id The index to check.
	 * @return True if and only if the sign is valid.
	 */
	static bool IsValidSign(SignID sign_id);

	/**
	 * Get the text on the sign.
	 * @param sign_id The sign to get the text of.
	 * @pre IsValidSign(sign_id).
	 * @return The text on the sign.
	 */
	static char *GetText(SignID sign_id);

	/**
	 * Gets the location of the sign.
	 * @param sign_id The sign to get the location of.
	 * @pre IsValidSign(sign_id).
	 * @return The location of the sign.
	 */
	static TileIndex GetLocation(SignID sign_id);

	/**
	 * Builds a sign on the map.
	 * @param location The place to build the sign.
	 * @param text The text to place on the sign.
	 * @pre AIMap::IsValidTile(location).
	 * @pre text is of non-zero length.
	 * @exception ERR_SIGN_TOO_MANY_SIGNS
	 * @return The SignID of the build sign (use IsValidSign() to check for validity).
	 *   In test-mode it returns 0 if successful, or any other value to indicate
	 *   failure.
	 */
	static SignID BuildSign(TileIndex location, const char *text);

	/**
	 * Removes a sign from the map.
	 * @param sign_id The sign to remove.
	 * @pre IsValidSign(sign_id).
	 * @return True if and only if the sign has been removed.
	 */
	static bool RemoveSign(SignID sign_id);
};

#endif /* AI_SIGN_HPP */