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/* $Id$ */

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/** @file ai_subsidy.hpp Everything to query subsidies. */

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#ifndef AI_SUBSIDY_HPP

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#define AI_SUBSIDY_HPP

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#include "ai_object.hpp"

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#include "ai_company.hpp"

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/**

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 * Class that handles all subsidy related functions.

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 */

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class AISubsidy : public AIObject {

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public:

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

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	/**

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	 * Check whether this is a valid SubsidyID.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @return True if and only if this subsidy is still valid.

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	 */

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	static bool IsValidSubsidy(SubsidyID subsidy_id);

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	/**

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	 * Checks whether this subsidy is already awarded to some company.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy).

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	 * @return True if and only if this subsidy is already awarded.

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	 */

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	static bool IsAwarded(SubsidyID subsidy_id);

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	/**

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	 * Get the company index of the company this subsidy is awarded to.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsAwarded(subsidy_id).

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	 * @return The companyindex of the company this subsidy is awarded to.

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	 */

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	static AICompany::CompanyIndex GetAwardedTo(SubsidyID subsidy_id);

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	/**

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	 * Get the date this subsidy expires. In case the subsidy is already

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	 *  awarded, return the date the subsidy expires, else, return the date the

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	 *  offer expires.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id).

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	 * @return The last valid date of this subsidy.

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	 * @note The return value of this function will change if the subsidy is

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	 *  awarded.

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	 */

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	static int32 GetExpireDate(SubsidyID subsidy_id);

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	/**

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	 * Get the cargo type that has to be transported in order to be awarded this

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	 *  subsidy.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id).

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	 * @return The cargo type to transport.

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	 */

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	static CargoID GetCargoType(SubsidyID subsidy_id);

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	/**

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	 * Is the source of the subsidy a town or an industry.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id) && !IsAwarded(subsidy_id).

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	 * @return True if the source is a town, false if it is an industry.

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	 */

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	static bool SourceIsTown(SubsidyID subsidy_id);

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	/**

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	 * Return the source TownID/IndustryID/StationID the subsidy is for.

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	 * 1) IsAwarded(subsidy_id) -> return the StationID the subsidy is awarded to.

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	 * 2) !IsAwarded(subsidy_id) && SourceIsTown(subsidy_id) -> return the TownID.

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	 * 3) !IsAwarded(subsidy_id) && !SourceIsTown(subsidy_id) -> return the IndustryID.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id).

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	 * @return One of TownID/IndustryID/StationID.

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	 */

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	static int32 GetSource(SubsidyID subsidy_id);

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	/**

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	 * Is the destination of the subsidy a town or an industry.

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	 * @param subsidy_id The SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id) && !IsAwarded(subsidy_id).

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	 * @return True if the destination is a town, false if it is an industry.

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	 */

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	static bool DestinationIsTown(SubsidyID subsidy_id);

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	/**

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	 * Return the destination TownID/IndustryID/StationID the subsidy is for.

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	 * 1) IsAwarded(subsidy_id) -> return the StationID the subsidy is awarded to.

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	 * 2) !IsAwarded(subsidy_id) && SourceIsTown(subsidy_id) -> return the TownID.

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	 * 3) !IsAwarded(subsidy_id) && !SourceIsTown(subsidy_id) -> return the IndustryID.

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	 * @param subsidy_id the SubsidyID to check.

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	 * @pre IsValidSubsidy(subsidy_id).

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	 * @return One of TownID/IndustryID/StationID.

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	 */

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	static int32 GetDestination(SubsidyID subsidy_id);

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};

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#endif /* AI_SUBSIDY_HPP */