/* $Id$ */

/*
 * 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_abstractlist.hpp A list which can keep item/value pairs, which you can walk. */
/** @defgroup AIList Classes that create a list of items. */

#ifndef AI_ABSTRACTLIST_HPP
#define AI_ABSTRACTLIST_HPP

#include "ai_object.hpp"
#include <map>
#include <set>

class AIAbstractListSorter;

/**
 * Class that creates a list which can keep item/value pairs, which you can walk.
 */
class AIAbstractList : public AIObject {
public:
	static const char *GetClassName() { return "AIAbstractList"; }

	/** Type of sorter */
	enum SorterType {
		SORT_BY_VALUE, //!< Sort the list based on the value of the item.
		SORT_BY_ITEM,  //!< Sort the list based on the item itself.
	};

	/** Sort ascending */
	static const bool SORT_ASCENDING = true;
	/** Sort descnding */
	static const bool SORT_DESCENDING = false;

private:
	AIAbstractListSorter *sorter; //!< Sorting algorithm
	SorterType sorter_type;       //!< Sorting type
	bool sort_ascending;          //!< Whether to sort ascending or descending
	bool initialized;             //!< Whether an iteration has been started
	int modifications;            //!< Number of modification that has been done. To prevent changing data while valuating.

public:
	typedef std::set<int32> AIItemList;                       //!< The list of items inside the bucket
	typedef std::map<int32, AIItemList> AIAbstractListBucket; //!< The bucket list per value
	typedef std::map<int32, int32> AIAbstractListMap;         //!< List per item

	AIAbstractListMap items;           //!< The items in the list
	AIAbstractListBucket buckets;      //!< The items in the list, sorted by value

protected:
	/**
	 * Add a single item to the list.
	 * @param item the item to add. Should be unique, otherwise it is ignored.
	 * @note the value is set to 0 by default.
	 */
	void AddItem(int32 item);

	/**
	 * Remove a single item from the list.
	 * @param item the item to remove. If not existing, it is ignored.
	 */
	void RemoveItem(int32 item);

public:
	AIAbstractList();
	~AIAbstractList();

	/**
	 * Clear the list, making Count() returning 0 and IsEmpty() returning true.
	 */
	void Clear();

	/**
	 * Check if an item is in the list.
	 * @param item the item to check for.
	 * @return true if the item is in the list.
	 */
	bool HasItem(int32 item);

	/**
	 * Go to the beginning of the list.
	 * @return the item value of the first item.
	 */
	int32 Begin();

	/**
	 * Go to the next item in the list.
	 * @return the item value of the next item.
	 * @note returns 0 if beyond end-of-list. Use HasNext() to check for end-of-list.
	 */
	int32 Next();

	/**
	 * Check if a list is empty.
	 * @return true if the list is empty.
	 */
	bool IsEmpty();

	/**
	 * Check if there is a next element. In other words, if this is true,
	 *   Next() will return a valid item.
	 * @return true if there is a next item.
	 */
	bool HasNext();

	/**
	 * Returns the amount of items in the list.
	 * @return amount of items in the list.
	 */
	int32 Count();

	/**
	 * Get the value that belongs to this item.
	 * @param item the item to get the value from
	 * @return the value that belongs to this item.
	 */
	int32 GetValue(int32 item);

	/**
	 * Set a value of an item directly.
	 * @param item the item to set the value for.
	 * @param value the value to give to the item
	 * @return true if we could set the item to value, false otherwise.
	 * @note Changing values of items while looping through a list might cause
	 *  entries to be skipped. Be very careful with such operations.
	 */
	bool SetValue(int32 item, int32 value);

	/**
	 * Sort this list by the given sorter and direction.
	 * @param sorter    the type of sorter to use
	 * @param ascending if true, lowest value is on top, else at bottom.
	 * @note the current item stays at the same place.
	 * @see SORT_ASCENDING SORT_DESCENDING
	 */
	void Sort(SorterType sorter, bool ascending);

	/**
	 * Add one list to another one.
	 * @param list The list that will be added to the caller.
	 * @post The list to be added ('list') stays unmodified.
	 * @note All added items keep their value as it was in 'list'.
	 * @note If the item already exists inside the caller, the value of the
	 *  list that is added is set on the item.
	 */
	void AddList(AIAbstractList *list);

	/**
	 * Removes all items with a higher value than 'value'.
	 * @param value the value above which all items are removed.
	 */
	void RemoveAboveValue(int32 value);

	/**
	 * Removes all items with a lower value than 'value'.
	 * @param value the value below which all items are removed.
	 */
	void RemoveBelowValue(int32 value);

	/**
	 * Removes all items with a value above start and below end.
	 * @param start the lower bound of the to be removed values (exclusive).
	 * @param end   the upper bound of the to be removed valuens (exclusive).
	 */
	void RemoveBetweenValue(int32 start, int32 end);

	/**
	 * Remove all items with this value.
	 * @param value the value to remove.
	 */
	void RemoveValue(int32 value);

	/**
	 * Remove the first count items.
	 * @param count the amount of items to remove.
	 */
	void RemoveTop(int32 count);

	/**
	 * Remove the last count items.
	 * @param count the amount of items to remove.
	 */
	void RemoveBottom(int32 count);

	/**
	 * Remove everything that is in the given list from this list (same item index that is).
	 * @param list the list of items to remove.
	 * @pre list != NULL
	 */
	void RemoveList(AIAbstractList *list);

	/**
	 * Keep all items with a higher value than 'value'.
	 * @param value the value above which all items are kept.
	 */
	void KeepAboveValue(int32 value);

	/**
	 * Keep all items with a lower value than 'value'.
	 * @param value the value below which all items are kept.
	 */
	void KeepBelowValue(int32 value);

	/**
	 * Keep all items with a value above start and below end.
	 * @param start the lower bound of the to be kept values (exclusive).
	 * @param end   the upper bound of the to be kept values (exclusive).
	 */
	void KeepBetweenValue(int32 start, int32 end);

	/**
	 * Keep all items with this value.
	 * @param value the value to keep.
	 **/
	void KeepValue(int32 value);

	/**
	 * Keep the first count items, i.e. remove everything except the first count items.
	 * @param count the amount of items to keep.
	 */
	void KeepTop(int32 count);

	/**
	 * Keep the last count items, i.e. remove everything except the last count items.
	 * @param count the amount of items to keep.
	 */
	void KeepBottom(int32 count);

	/**
	 * Keeps everything that is in the given list from this list (same item index that is).
	 * @param list the list of items to keep.
	 * @pre list != NULL
	 */
	void KeepList(AIAbstractList *list);

#ifndef DOXYGEN_SKIP
	/**
	 * Used for 'foreach()' and [] get from Squirrel.
	 */
	SQInteger _get(HSQUIRRELVM vm);

	/**
	 * Used for 'foreach()' from Squirrel.
	 */
	SQInteger _nexti(HSQUIRRELVM vm);

	/**
	 * The Valuate() wrapper from Squirrel.
	 */
	SQInteger Valuate(HSQUIRRELVM vm);
#else
	/**
	 * Give all items a value defined by the valuator you give.
	 * @param valuator_function The function which will be doing the valuation.
	 * @param params The params to give to the valuators (minus the first param,
	 *  which is always the index-value we are valuating).
	 * @note You may not add, remove or change (setting the value of) items while
	 *  valuating. You may also not (re)sort while valuating.
	 * @note You can write your own valuators and use them. Just remember that
	 *  the first parameter should be the index-value, and it should return
	 *  an integer.
	 * @note Example:
	 *  list.Valuate(AIBridge.GetPrice, 5);
	 *  list.Valuate(AIBridge.GetMaxLength);
	 *  function MyVal(bridge_id, myparam)
	 *  {
	 *    return myparam * bridge_id; // This is silly
	 *  }
	 *  list.Valuate(MyVal, 12);
	 */
	void Valuate(void *valuator_function, int params, ...);
#endif /* DOXYGEN_SKIP */
};

#endif /* AI_LIST_HPP */