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/* $Id$ */

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/** @file ai_bridge.hpp Everything to query and build bridges. */

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#ifndef AI_BRIDGE_HPP

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#define AI_BRIDGE_HPP

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#include "ai_object.hpp"

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#include "ai_vehicle.hpp"

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#include "ai_error.hpp"

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#include "../../bridge.h"

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/** In OpenTTD Core 'BridgeID' is called 'BridgeType', so map it to make this API more logic. */

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typedef BridgeType BridgeID;

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/**

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 * Class that handles all bridge related functions.

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 */

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class AIBridge : public AIObject {

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public:

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	enum ErrorMessages {

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		/** Base for bridge related errors */

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		ERR_BRIDGE_BASE = AIError::ERR_CAT_BRIDGE << AIError::ERR_CAT_BIT_SIZE,

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		/**

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		 * The bridge you want to build is not available yet,

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		 * or it is not available for the requested length.

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		 */

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		ERR_BRIDGE_TYPE_UNAVAILABLE,         // [STR_5015_CAN_T_BUILD_BRIDGE_HERE]

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		/** One (or more) of the bridge head(s) ends in water. */

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		ERR_BRIDGE_CANNOT_END_IN_WATER,      // [STR_02A0_ENDS_OF_BRIDGE_MUST_BOTH]

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		/** Slope of the land does not allow the required bridge head. */

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		ERR_BRIDGE_SLOPE_WRONG,              // [STR_1000_LAND_SLOPED_IN_WRONG_DIRECTION]

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		/** The bride heads need to be on the same height */

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		ERR_BRIDGE_HEADS_NOT_ON_SAME_HEIGHT, // [STR_BRIDGEHEADS_NOT_SAME_HEIGHT]

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	};

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	static const char *GetClassName() { return "AIBridge"; }

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	/**

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	 * Checks whether the given bridge type is valid.

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	 * @param bridge_id The bridge to check.

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	 * @return True if and only if the bridge type is valid.

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	 */

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	static bool IsValidBridge(BridgeID bridge_id);

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	/**

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	 * Checks whether the given tile is actually a bridge start or end tile.

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	 * @param tile The tile to check.

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	 * @pre AIMap::IsValidTile(tile).

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	 * @return True if and only if the tile is the beginning or end of a bridge.

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	 */

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	static bool IsBridgeTile(TileIndex tile);

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	/**

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	 * Get the name of a bridge.

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	 * @param bridge_id The bridge to get the name of.

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	 * @pre IsValidBridge(bridge_id).

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	 * @return The name the bridge has.

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	 */

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	static char *GetName(BridgeID bridge_id);

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	/**

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	 * Get the maximum speed of a bridge (in km/h).

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	 * @param bridge_id The bridge to get the maximum speed of.

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	 * @pre IsValidBridge(bridge_id).

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	 * @return The maximum speed the bridge has.

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	 */

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	static uint32 GetMaxSpeed(BridgeID bridge_id);

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	/**

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	 * Get the new cost of a bridge.

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	 * @param bridge_id The bridge to get the new cost of.

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	 * @param length The length of the bridge.

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	 * @pre IsValidBridge(bridge_id).

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	 * @return The new cost the bridge has.

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	 */

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	static uint32 GetPrice(BridgeID bridge_id, uint length);

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	/**

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	 * Get the maximum length of a bridge.

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	 * @param bridge_id The bridge to get the maximum length of.

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	 * @pre IsValidBridge(bridge_id).

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	 * @returns The maximum length the bridge has.

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	 */

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	static uint32 GetMaxLength(BridgeID bridge_id);

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	/**

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	 * Get the minimum length of a bridge.

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	 * @param bridge_id The bridge to get the minimum length of.

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	 * @pre IsValidBridge(bridge_id).

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	 * @returns The minimum length the bridge has.

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	 */

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	static uint32 GetMinLength(BridgeID bridge_id);

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	/**

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	 * Get the year in which a bridge becomes available.

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	 * @param bridge_id The bridge to get the year of availability of.

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	 * @pre IsValidBridge(bridge_id).

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	 * @returns The year of availability the bridge has.

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	 * @note Years are like 2010, -10 (10 B.C.), 1950, ..

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	 */

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	static int32 GetYearAvailable(BridgeID bridge_id);

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	/**

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	 * Build a bridge from one tile to the other.

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	 * @param vehicle_type The vehicle-type of bridge to build.

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	 * @param bridge_id The bridge-type to build.

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	 * @param start Where to start the bridge.

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	 * @param end Where to end the bridge.

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	 * @pre AIMap::IsValidTile(start).

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	 * @pre AIMap::IsValidTile(end).

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	 * @pre 'start' and 'end' are in a straight line, i.e.

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	 *  AIMap::GetTileX(start) == AIMap::GetTileX(end) or

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	 *  AIMap::GetTileY(start) == AIMap::GetTileY(end).

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	 * @exception AIError::ERR_ALREADY_BUILT

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	 * @exception AIError::ERR_AREA_NOT_CLEAR

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	 * @exception AIBridge::ERR_BRIDGE_TYPE_UNAVAILABLE

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	 * @exception AIBridge::ERR_BRIDGE_CANNOT_END_IN_WATER

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	 * @exception AIBridge::ERR_BRIDGE_SLOPE_WRONG

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	 * @exception AIBridge::ERR_BRIDGE_HEADS_NOT_ON_SAME_HEIGHT

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	 * @return Whether the bridge has been/can be build or not.

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	 */

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	static bool BuildBridge(AIVehicle::VehicleType vehicle_type, BridgeID bridge_id, TileIndex start, TileIndex end);

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	/**

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	 * Removes a bridge, by executing it on either the start or end tile.

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	 * @param tile An end or start tile of the bridge.

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	 * @pre AIMap::IsValidTile(tile).

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	 * @return Whether the bridge has been/can be removed or not.

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	 */

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	static bool RemoveBridge(TileIndex tile);

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};

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#endif /* AI_BRIDGE_HPP */