/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file ai_group.hpp Everything to put vehicles into groups. */

#ifndef AI_GROUP_HPP
#define AI_GROUP_HPP

#include "ai_object.hpp"
#include "ai_vehicle.hpp"

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

	/**
	 * The group IDs of some special groups.
	 */
	enum GroupID {
		/* Values are important, as they represent the internal state of the game (see group_type.h). */
		GROUP_ALL = 0xFFFD,     //!< All vehicles are in this group.
		GROUP_DEFAULT = 0xFFFE, //!< Vehicles not put in any other group are in this one.
		GROUP_INVALID = 0xFFFF, //!< An invalid group id.
	};

	/**
	 * Checks whether the given group is valid.
	 * @param group_id The group to check.
	 * @pre group_id != GROUP_DEFAULT && group_id != GROUP_ALL.
	 * @return True if and only if the group is valid.
	 */
	static bool IsValidGroup(GroupID group_id);

	/**
	 * Create a new group.
	 * @param vehicle_type The type of vehicle to create a group for.
	 * @return The GroupID of the new group, or an invalid GroupID when
	 *  it failed. Check the return value using IsValidGroup(). In test-mode
	 *  0 is returned if it was successful; any other value indicates failure.
	 */
	static GroupID CreateGroup(AIVehicle::VehicleType vehicle_type);

	/**
	 * Delete the given group. When the deletion succeeds all vehicles in the
	 *  given group will move to the GROUP_DEFAULT.
	 * @param group_id The group to delete.
	 * @pre IsValidGroup(group_id).
	 * @return True if and only if the group was succesfully deleted.
	 */
	static bool DeleteGroup(GroupID group_id);

	/**
	 * Get the vehicle type of a group.
	 * @param group_id The group to get the type from.
	 * @pre IsValidGroup(group_id).
	 * @return The vehicletype of the given group.
	 */
	static AIVehicle::VehicleType GetVehicleType(GroupID group_id);

	/**
	 * Set the name of a group.
	 * @param group_id The group to set the name for.
	 * @param name The name for the group.
	 * @pre IsValidGroup(group_id).
	 * @pre 'name' must have at least one character.
	 * @pre 'name' must have at most 30 characters.
	 * @exception AIError::ERR_NAME_IS_NOT_UNIQUE
	 * @return True if and only if the name was changed.
	 */
	static bool SetName(GroupID group_id, const char *name);

	/**
	 * Get the name of a group.
	 * @param group_id The group to get the name of.
	 * @pre IsValidGroup(group_id).
	 * @return The name the group has.
	 */
	static char *GetName(GroupID group_id);

	/**
	 * Enable or disable autoreplace protected. If the protection is
	 *  enabled, global autoreplace won't affect vehicles in this group.
	 * @param group_id The group to change the protection for.
	 * @param enable True if protection should be enabled.
	 * @pre IsValidGroup(group_id).
	 * @return True if and only if the protection was succesfully changed.
	 */
	static bool EnableAutoReplaceProtection(GroupID group_id, bool enable);

	/**
	 * Get the autoreplace protection status.
	 * @param group_id The group to get the protection status for.
	 * @pre IsValidGroup(group_id).
	 * @return The autoreplace protection status for the given group.
	 */
	static bool GetAutoReplaceProtection(GroupID group_id);

	/**
	 * Get the number of engines in a given group.
	 * @param group_id The group to get the number of engines in.
	 * @param engine_id The engine id to count.
	 * @pre IsValidGroup(group_id) || group_id == GROUP_ALL || group_id == GROUP_DEFAULT.
	 * @return The number of engines with id engine_id in the group with id group_id.
	 */
	static int32 GetNumEngines(GroupID group_id, EngineID engine_id);

	/**
	 * Move a vehicle to a group.
	 * @param group_id The group to move the vehicel to.
	 * @param vehicle_id The vehicle to move to the group.
	 * @pre IsValidGroup(group_id) || group_id == GROUP_DEFAULT.
	 * @pre AIVehicle::IsValidVehicle(vehicle_id).
	 * @return True if and only if the vehicle was succesfully moved to the group.
	 * @note A vehicle can be in only one group at the same time. To remove it from
	 *  a group, move it to another or to GROUP_DEFAULT. Moving the vehicle to the
	 *  given group means removing it from another group.
	 */
	static bool MoveVehicle(GroupID group_id, VehicleID vehicle_id);

	/**
	 * Enable or disable the removal of wagons when a (part of a) vehicle is
	 *  (auto)replaced with a longer variant (longer wagons or longer engines)
	 *  If enabled, wagons are removed from the end of the vehicle until it
	 *  fits in the same number of tiles as it did before.
	 * @param keep_length If true, wagons will be removed if the a new engine is longer.
	 * @return True if and only if the value was succesfully changed.
	 */
	static bool EnableWagonRemoval(bool keep_length);

	/**
	 * Get the current status of wagon removal.
	 * @return Whether or not wagon removal is enabled.
	 */
	static bool HasWagonRemoval();

	/**
	 * Start replacing all vehicles with a specified engine with another engine.
	 * @param group_id The group to replace vehicles from. Use ALL_GROUP to replace
	 *  vehicles from all groups that haven't set autoreplace protection.
	 * @param engine_id_old The engine id to start replacing.
	 * @param engine_id_new The engine id to replace with.
	 * @pre IsValidGroup(group_id) || group_id == GROUP_DEFAULT || group_id == GROUP_ALL.
	 * @pre AIEngine.IsBuildable(engine_id_new).
	 * @note To stop autoreplacing engine_id_old, call StopAutoReplace(group_id, engine_id_old).
	 */
	static bool SetAutoReplace(GroupID group_id, EngineID engine_id_old, EngineID engine_id_new);

	/**
	 * Get the EngineID the given EngineID is replaced with.
	 * @param group_id The group to get the replacement from.
	 * @param engine_id The engine that is being replaced.
	 * @pre IsValidGroup(group_id) || group_id == GROUP_DEFAULT || group_id == GROUP_ALL.
	 * @return The EngineID that is replacing engine_id or an invalid EngineID
	 *   in case engine_id is not begin replaced.
	 */
	static EngineID GetEngineReplacement(GroupID group_id, EngineID engine_id);

	/**
	 * Stop replacing a certain engine in the specified group.
	 * @param group_id The group to stop replacing the engine in.
	 * @param engine_id The engine id to stop replacing with another engine.
	 * @pre IsValidGroup(group_id) || group_id == GROUP_DEFAULT || group_id == GROUP_ALL.
	 * @return True if and if the replacing was succesfully stopped.
	 */
	static bool StopAutoReplace(GroupID group_id, EngineID engine_id);
};

#endif /* AI_GROUP_HPP */