/*
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*/

#ifndef __Ogre_TerrainGroup_H__
#define __Ogre_TerrainGroup_H__

#include "OgreTerrainPrerequisites.h"
#include "OgreTerrain.h"
#include "OgreWorkQueue.h"
#include "OgreIteratorWrappers.h"

namespace Ogre
{
	/** \addtogroup Optional Components
	*  @{
	*/
	/** \addtogroup Terrain
	*  Some details on the terrain component
	*  @{
	*/

	/** Helper class to assist you in managing multiple terrain instances
		that are connected to each other. 
	@remarks
		This class makes it easy to specify the same options for a group of
		terrain instances and have them positioned relative to each other and
		associated via each other's neighbour connections. You can do all this
		manually but this class just makes things easier, so that you only 
		have to specify most options once. 
	@par
		Terrains are maintained in a grid of entries, and for simplicity
		the grid cells are indexed from 0 as a 'centre' slot, supporting both 
		positive and negative values. so (0,0) is the centre slot, (1,0) is the
		slot to the right of the centre, (1,0) is the slot above the centre, (-2,1) 
		is the slot two to the left of the centre and one up, etc. The maximum
		extent of each axis is -32768 to +32767, so in other words enough for
		over 4 billion entries. That should be enough for anyone!
	@par
		Note that this is not a 'paging' class as such. It's simply a way to make it easier to 
		perform common tasks with multiple terrain instances, which you choose when 
		to define, load and remove. Automatic paging is handled separately by the Paging
		component. 
	*/
	class _OgreTerrainExport TerrainGroup : public WorkQueue::RequestHandler, 
		public WorkQueue::ResponseHandler, public TerrainAlloc
	{
	public:
		/** Constructor.
		@param sm The SceneManager which will parent the terrain instances. 
		@param align The alignment that all terrain instances will use
		@param terrainSize The size of each terrain down one edge in vertices (2^n+1)
		@param terrainWorldSize The world size of each terrain instance
		*/
		TerrainGroup(SceneManager* sm, Terrain::Alignment align, uint16 terrainSize, 
			Real terrainWorldSize);
		/** Alternate constructor.
		@remarks
			You can ONLY use this constructor if you subsequently call loadGroupDefinition
			to populate the rest.
		*/
		TerrainGroup(SceneManager* sm);
		virtual ~TerrainGroup();

		/** Retrieve a shared structure which will provide the base settings for
			all terrains created via this group.
		@remarks
			All neighbouring terrains should have the same basic settings (particularly
			the size parameters) - to avoid having to set the terrain import information 
			more than once, you can retrieve the standard settings for this group
			here and modify them to your needs. Once you've done that you can 
			use the shortcut methods in this class to create new terrain instances
			using these base settings (plus any per-instance settings you might
			want to use). 
		@note 
			The structure returned from this method is intended for in-place modification, 
			that's why it is not const and there is no equivalent 'set' method.
			You should not, however, change the alignment or any of the size parameters 
			after you start constructing instances, since neighbouring terrains
			should have the same size & alignment.
		*/
		virtual Terrain::ImportData& getDefaultImportSettings() { return mDefaultImportData; }

		/** Define the centre position of the grid of terrain.
		*/
		virtual void setOrigin(const Vector3& pos);

		/** Retrieve the centre position of the grid of terrain.
		*/
		virtual const Vector3& getOrigin() const { return mOrigin; }

		/** Retrieve the alignment of the grid of terrain (cannot be modified after construction).
		*/
		virtual Terrain::Alignment getAlignment() const { return mAlignment; }

		/** Retrieve the world size of each terrain instance (cannot be modified after construction).
		*/
		virtual Real getTerrainWorldSize() const { return mTerrainWorldSize; }

		/** Retrieve the SceneManager being used for this group.
		*/
		virtual SceneManager* getSceneManager() const { return mSceneManager; }

		/** Set the naming convention for file names in this terrain group. 
		@remarks
			You can more easily generate file names for saved / loaded terrain slots
			if you define a naming prefix. When you call saveAllTerrains(), all the
			terrain instances currently loaded will be saved to a file named
			&lt;prefix&gt;_&lt;index&gt;.&lt;extension&gt;, where &lt;index&gt; is
			given by packing the x and y coordinates of the entry into a 32-bit
			index (@see packIndex). 
		*/
		void setFilenameConvention(const String& prefix, const String& extension);
		/// @see setFilenameConvention
		void setFilenamePrefix(const String& prefix);
		/// @see setFilenameConvention
		void setFilenameExtension(const String& extension);
		/// @see setFilenameConvention
		const String& getFilenamePrefix() const { return mFilenamePrefix; }
		/// @see setFilenameConvention
		const String& getFilenameExtension() const { return mFilenameExtension; }

		/** Set the resource group in which files will be located. */
		void setResourceGroup(const String& grp) { mResourceGroup = grp; }
		/** Get the resource group in which files will be located. */
		const String& getResourceGroup() const { return mResourceGroup; }
		/** Define a 'slot' in the terrain grid - in this case to be loaded from 
			a generated file name.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@note This method assumes that you want a file name to be generated from 
			the naming convention that you have supplied (@see setFilenameConvention).
			If a file of that name isn't found during loading, then a flat terrain is
			created instead at height 0.
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		*/
		virtual void defineTerrain(long x, long y);

		/** Define a 'slot' in the terrain grid - in this case a flat terrain.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param constantHeight The constant, uniform height that you want the terrain
			to start at
		*/
		virtual void defineTerrain(long x, long y, float constantHeight);

		/** Define the content of a 'slot' in the terrain grid.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param importData Import data - this data is copied during the
			call so  you may destroy your copy afterwards.
		*/
		virtual void defineTerrain(long x, long y, const Terrain::ImportData* importData);

		/** Define the content of a 'slot' in the terrain grid.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param img Heightfield image - this data is copied during the call so  you may destroy your copy afterwards.
		@param layers Optional texture layers to use (if not supplied, default import
			data layers will be used) - this data is copied during the
			call so  you may destroy your copy afterwards.
		*/
		virtual void defineTerrain(long x, long y, const Image* img, const Terrain::LayerInstanceList* layers = 0);

		/** Define the content of a 'slot' in the terrain grid.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param pFloat Heights array 
		@param layers Optional texture layers to use (if not supplied, default import
			data layers will be used) - this data is copied during the
			call so  you may destroy your copy afterwards.
		*/
		virtual void defineTerrain(long x, long y, const float* pFloat, const Terrain::LayerInstanceList* layers = 0);

		/** Define the content of a 'slot' in the terrain grid.
		@remarks
			At this stage the terrain instance isn't actually present in the grid, 
			you're merely expressing an intention for it to take its place there
			once it's loaded. The reason we do it like this is to support
			background preparation of this terrain instance. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param filename The name of a file which fully defines the terrain (as 
			written by Terrain::save). Size settings from all files must agree.
		*/
		virtual void defineTerrain(long x, long y, const String& filename);


		/** Load any terrain instances that have been defined but not loaded yet. 
		@param synchronous Whether we should force this to happen entirely in the
			primary thread (default false, operations are threaded if possible)
		*/
		virtual void loadAllTerrains(bool synchronous = false);
		
		/** Load a specific terrain slot based on the definition that has already 
			been supplied.
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@param synchronous Whether we should force this to happen entirely in the
			primary thread (default false, operations are threaded if possible)
		*/
		virtual void loadTerrain(long x, long y, bool synchronous = false);
		
		/** Unload a specific terrain slot.
		@remarks
			This destroys the Terrain instance but retains the slot definition (so
			it would be reloaded next time you call loadAllTerrains() if you did not
			remove it beforehand).
		@note
			While the definition of the terrain is kept, if you used import data
			to populate it, this will have been lost so repeat loading cannot occur. 
			The only way to support repeat loading is via the 'filename' option of
			defineTerrain instead.
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		*/
		virtual void unloadTerrain(long x, long y);

		/** Remove a specific terrain slot.
		@remarks
			This destroys any Terrain instance at this position and also removes the 
			definition, so it essentially no longer exists. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		*/
		virtual void removeTerrain(long x, long y);

		/** Remove all terrain instances. 
		*/
		void removeAllTerrains();

		/** Save all terrain instances using the assigned file names, or
			via the filename convention.
		@see setFilenameConvention
		@see setResourceGroup
		@param onlyIfModified If true, only terrains that have been modified since load(),
			or since the last save(), will be saved. You want to set this to true if
			you loaded the terrain from these same files, but false if you 
			defined them using some other input data since the files wouldn't exist.
		@param replaceManualFilenames If true, replaces any manually defined filenames
			in the TerrainSlotDefinition with the generated names from the convention.
			This is recommended since it makes everything more consistent, although
			you might want to use manual filenames in the original definition to import 
			previously separate data. 
		*/
		void saveAllTerrains(bool onlyIfModified, bool replaceManualFilenames = true);
		
		/** Definition of how to populate a 'slot' in the terrain group.
		*/
		struct _OgreTerrainExport TerrainSlotDefinition
		{
			/// Filename, if this is to be loaded from a file
			String filename;
			/// Import data, if this is to be defined based on importing
			Terrain::ImportData* importData;

			TerrainSlotDefinition() :importData(0) {}
			~TerrainSlotDefinition();

			/// Set to use import data 
			void useImportData();
			/// Set to use file name
			void useFilename();
			/// Destroy temp import resources
			void freeImportData();
		};

		/** Slot for a terrain instance, together with its definition. */
		struct _OgreTerrainExport TerrainSlot : public TerrainAlloc
		{
			/// The coordinates of the terrain slot relative to the centre slot (signed).
			long x, y;
			/// Definition used to load the terrain
			TerrainSlotDefinition def;
			/// Actual terrain instance
			Terrain* instance;

			TerrainSlot(long _x, long _y) : x(_x), y(_y), instance(0) {}
			~TerrainSlot();
			void freeInstance();
		};
		
		/** Get the definition of a slot in the terrain.
		@remarks
			Definitions exist before the actual instances to allow background loading.
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@returns The definition, or null if nothing is in this slot. While this return value is
			not const, you should be careful about modifying it; it will have no effect unless you load
			the terrain afterwards, and can cause a race condition if you modify it while a background
			load is in progress.
		*/
		virtual TerrainSlotDefinition* getTerrainDefinition(long x, long y) const;
		
		/** Get the terrain instance at a given slot, if loaded. 
		@param x, y The coordinates of the terrain slot relative to the centre slot (signed).
		@returns The terrain, or null if no terrain is loaded in this slot (call getTerrainDefinition if
			you want to access the definition before it is loaded).
		*/
		virtual Terrain* getTerrain(long x, long y) const;

		/** Free as many resources as possible for optimal run-time memory use for all
			terrain tiles.
		@see Terrain::freeTemporaryResources
		*/
		void freeTemporaryResources();

		/** Trigger the update process for all terrain instances. 
		@see Terrain::update
		*/
		void update(bool synchronous = false);

		/** Performs an update on all terrain geometry.
		@see Terrain::updateGeometry
		*/
		void updateGeometry();

		/** Updates derived data for all terrains (LOD, lighting) to reflect changed height data.
		@see Terrain::updateDerivedData
		*/
		void updateDerivedData(bool synchronous = false, uint8 typeMask = 0xFF);
		
		/** Result from a terrain ray intersection with the terrain group. 
		*/
		struct _OgreTerrainExport RayResult
		{
			/// Whether an intersection occurred
			bool hit;
			/// Which terrain instance was hit, if any
			Terrain* terrain;
			/// Position at which the intersection occurred
			Vector3 position;

			RayResult(bool _hit, Terrain* _terrain, const Vector3& _pos)
				: hit(_hit), terrain(_terrain), position(_pos) {}
		};
		
		/** Get the height data for a given world position (projecting the point
		down on to the terrain underneath). 
		@param x, y,z Position in world space. Positions will be clamped to the edge
		of the terrain
		@param ppTerrain Pointer to a pointer to a terrain which will be completed
			with the terrain that was found to resolve this query, or null if none were
		*/
		float getHeightAtWorldPosition(Real x, Real y, Real z, Terrain** ppTerrain = 0);

		/** Get the height data for a given world position (projecting the point
		down on to the terrain). 
		@param pos Position in world space. Positions will be clamped to the edge
		of the terrain
		@param ppTerrain Pointer to a pointer to a terrain which will be completed
		with the terrain that was found to resolve this query, or null if none were
		*/
		float getHeightAtWorldPosition(const Vector3& pos, Terrain** ppTerrain = 0);

		/** Test for intersection of a given ray with any terrain in the group. If the ray hits
		 a terrain, the point of intersection and terrain instance is returned.
		 @param ray The ray to test for intersection
		 @param distanceLimit The distance from the ray origin at which we will stop looking,
			0 indicates no limit
		 @return A result structure which contains whether the ray hit a terrain and if so, where.
		 @remarks This can be called from any thread as long as no parallel write to
		 the terrain data occurs.
		 */
		RayResult rayIntersects(const Ray& ray, Real distanceLimit = 0) const; 
		
		typedef vector<Terrain*>::type TerrainList; 
		/** Test intersection of a box with the terrain. 
		@remarks
			Tests an AABB for overlap with a terrain bounding box. Note that this does not mean that the box
			touches the terrain itself, just the bounding box for the terrain. You can use this to get region
			results for further testing or use (e.g. painting areas). 
		@param box The AABB you want to test in world units
		@param resultList Pointer to a list of terrain pointers which will be updated to include just
			the terrains that overlap
		*/
		void boxIntersects(const AxisAlignedBox& box, TerrainList* resultList) const;
		/** Test intersection of a sphere with the terrain. 
		@remarks
			Tests a sphere for overlap with a terrain bounding box. Note that this does not mean that the sphere
			touches the terrain itself, just the bounding box for the terrain. You can use this to get region
			results for further testing or use (e.g. painting areas). 
		@param sphere The sphere you want to test in world units
		@param resultList Pointer to a list of terrain pointers which will be updated to include just
			the terrains that overlap
		*/
		void sphereIntersects(const Sphere& sphere, TerrainList* resultList) const;
		
		/** Convert a world position to terrain slot coordinates. 
		@param pos The world position
		@param x,y Pointers to the coordinates to be completed.
		*/
		void convertWorldPositionToTerrainSlot(const Vector3& pos, long *x, long *y) const;

		/** Convert a slot location to a world position at the centre
		@param x,y The slot coordinates
		@param pos Pointer to the world position to be completed
		*/
		void convertTerrainSlotToWorldPosition(long x, long y, Vector3* pos) const;
		
		/** Calls Terrain::isDerivedDataUpdateInProgress on each loaded instance and returns true
			if any of them are undergoing a derived update.
		*/
		bool isDerivedDataUpdateInProgress() const;

		/// Packed map, signed 16 bits for each axis from -32767 to +32767
		typedef map<uint32, TerrainSlot*>::type TerrainSlotMap;
		typedef MapIterator<TerrainSlotMap> TerrainIterator;
		typedef ConstMapIterator<TerrainSlotMap> ConstTerrainIterator;

		/// Get an iterator over the defined terrains.
		TerrainIterator getTerrainIterator();
		/// Get an iterator over the defined terrains (const)
		ConstTerrainIterator getTerrainIterator() const;

		/// WorkQueue::RequestHandler override
		bool canHandleRequest(const WorkQueue::Request* req, const WorkQueue* srcQ);
		/// WorkQueue::RequestHandler override
		WorkQueue::Response* handleRequest(const WorkQueue::Request* req, const WorkQueue* srcQ);
		/// WorkQueue::ResponseHandler override
		bool canHandleResponse(const WorkQueue::Response* res, const WorkQueue* srcQ);
		/// WorkQueue::ResponseHandler override
		void handleResponse(const WorkQueue::Response* res, const WorkQueue* srcQ);

		/// Convert coordinates to a packed integer index
		uint32 packIndex(long x, long y) const;
		
		/// Convert a packed integer index to coordinates
		void unpackIndex(uint32 key, long *x, long *y);

		/// Generate a file name based on the current naming convention
		String generateFilename(long x, long y) const;

		/** Save the group data only in native form to a file.
		*/
		void saveGroupDefinition(const String& filename);
		/** Save the group data only in native form to a serializing stream.
		*/
		void saveGroupDefinition(StreamSerialiser& stream);
		/** Load the group definition only in native form from a file.
		*/
		void loadGroupDefinition(const String& filename);
		/** Load the group definition only in native form from a serializing stream.
		*/
		void loadGroupDefinition(StreamSerialiser& stream);


		static const uint16 WORKQUEUE_LOAD_REQUEST;
		static const uint32 CHUNK_ID;
		static const uint16 CHUNK_VERSION;

	protected:
		SceneManager *mSceneManager;
		Terrain::Alignment mAlignment;
		uint16 mTerrainSize;
		Real mTerrainWorldSize;
		Terrain::ImportData mDefaultImportData;
		Vector3 mOrigin;
		TerrainSlotMap mTerrainSlots;
		uint16 mWorkQueueChannel;
		String mFilenamePrefix;
		String mFilenameExtension;
		String mResourceGroup;
		Terrain::DefaultGpuBufferAllocator mBufferAllocator;
		
		/// Get the position of a terrain instance
		Vector3 getTerrainSlotPosition(long x, long y);
		/// Retrieve a slot, potentially allocate one
		TerrainSlot* getTerrainSlot(long x, long y, bool createIfMissing);
		TerrainSlot* getTerrainSlot(long x, long y) const;
		void connectNeighbour(TerrainSlot* slot, long offsetx, long offsety);

		void loadTerrainImpl(TerrainSlot* slot, bool synchronous);

		/// Structure for holding the load request
		struct LoadRequest
		{
			TerrainSlot* slot;
			TerrainGroup* origin;
			_OgreTerrainExport friend std::ostream& operator<<(std::ostream& o, const LoadRequest& r)
			{ return o; }		
		};
		

	};


	/** @} */
	/** @} */

}

#endif

