/*
Open Asset Import Library (assimp)
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*/

/** @file Declares a helper class, "SceneCombiner" providing various
 *  utilities to merge scenes.
 */
#ifndef AI_SCENE_COMBINER_H_INC
#define AI_SCENE_COMBINER_H_INC

#include "../include/assimp/ai_assert.h"

namespace Assimp	{

// ---------------------------------------------------------------------------
/** \brief Helper data structure for SceneCombiner.
 *
 *  Describes to which node a scene must be attached to.
 */
struct AttachmentInfo
{
	AttachmentInfo()
		:	scene			(NULL)
		,	attachToNode	(NULL)
	{}

	AttachmentInfo(aiScene* _scene, aiNode* _attachToNode)
		:	scene			(_scene)
		,	attachToNode	(_attachToNode)
	{}

	aiScene* scene;
	aiNode*  attachToNode;
};

// ---------------------------------------------------------------------------
struct NodeAttachmentInfo
{
	NodeAttachmentInfo()
		:	node			(NULL)
		,	attachToNode	(NULL)
		,	resolved		(false)
		,	src_idx			(SIZE_MAX)
	{}

	NodeAttachmentInfo(aiNode* _scene, aiNode* _attachToNode,size_t idx)
		:	node			(_scene)
		,	attachToNode	(_attachToNode)
		,	resolved		(false)
		,	src_idx			(idx)
	{}

	aiNode*  node;
	aiNode*  attachToNode;
	bool     resolved;
	size_t   src_idx;
};

// ---------------------------------------------------------------------------
/** @def AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES
 *  Generate unique names for all named scene items
 */
#define AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES      0x1

/** @def AI_INT_MERGE_SCENE_GEN_UNIQUE_MATNAMES
 *  Generate unique names for materials, too. 
 *  This is not absolutely required to pass the validation.
 */
#define AI_INT_MERGE_SCENE_GEN_UNIQUE_MATNAMES   0x2

/** @def AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY
 * Use deep copies of duplicate scenes
 */
#define AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY   0x4

/** @def AI_INT_MERGE_SCENE_RESOLVE_CROSS_ATTACHMENTS
 * If attachment nodes are not found in the given master scene,
 * search the other imported scenes for them in an any order.
 */
#define AI_INT_MERGE_SCENE_RESOLVE_CROSS_ATTACHMENTS 0x8

/** @def AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY
 * Can be combined with AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES.
 * Unique names are generated, but only if this is absolutely
 * required to avoid name conflicts.
 */
#define AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY 0x10


typedef std::pair<aiBone*,unsigned int> BoneSrcIndex;

// ---------------------------------------------------------------------------
/** @brief Helper data structure for SceneCombiner::MergeBones.
 */
struct BoneWithHash : public std::pair<uint32_t,aiString*>	{
	std::vector<BoneSrcIndex> pSrcBones;
};


// ---------------------------------------------------------------------------
/** @brief Utility for SceneCombiner
 */
struct SceneHelper
{
	SceneHelper ()
		: scene		(NULL)
		, idlen		(0)
	{
		id[0] = 0;
	}

	SceneHelper (aiScene* _scene)
		: scene		(_scene)
		, idlen		(0)
	{
		id[0] = 0;
	}

	AI_FORCE_INLINE aiScene* operator-> () const
	{
		return scene;
	}

	// scene we're working on
	aiScene* scene;

	// prefix to be added to all identifiers in the scene ...
	char id [32];

	// and its strlen() 
	unsigned int idlen;

	// hash table to quickly check whether a name is contained in the scene
	std::set<unsigned int> hashes;
};

// ---------------------------------------------------------------------------
/** \brief Static helper class providing various utilities to merge two
 *    scenes. It is intended as internal utility and NOT for use by 
 *    applications.
 * 
 * The class is currently being used by various postprocessing steps
 * and loaders (ie. LWS).
 */
class SceneCombiner
{
	// class cannot be instanced
	SceneCombiner() {}

public:

	// -------------------------------------------------------------------
	/** Merges two or more scenes.
	 *
	 *  @param dest  Receives a pointer to the destination scene. If the
	 *    pointer doesn't point to NULL when the function is called, the
	 *    existing scene is cleared and refilled.
	 *  @param src Non-empty list of scenes to be merged. The function
	 *    deletes the input scenes afterwards. There may be duplicate scenes.
	 *  @param flags Combination of the AI_INT_MERGE_SCENE flags defined above
	 */
	static void MergeScenes(aiScene** dest,std::vector<aiScene*>& src,
		unsigned int flags = 0);


	// -------------------------------------------------------------------
	/** Merges two or more scenes and attaches all sceenes to a specific
	 *  position in the node graph of the masteer scene.
	 *
	 *  @param dest Receives a pointer to the destination scene. If the
	 *    pointer doesn't point to NULL when the function is called, the
	 *    existing scene is cleared and refilled.
	 *  @param master Master scene. It will be deleted afterwards. All 
	 *    other scenes will be inserted in its node graph.
	 *  @param src Non-empty list of scenes to be merged along with their
	 *    corresponding attachment points in the master scene. The function
	 *    deletes the input scenes afterwards. There may be duplicate scenes.
	 *  @param flags Combination of the AI_INT_MERGE_SCENE flags defined above
	 */
	static void MergeScenes(aiScene** dest, aiScene* master, 
		std::vector<AttachmentInfo>& src,
		unsigned int flags = 0);


	// -------------------------------------------------------------------
	/** Merges two or more meshes
	 *
	 *  The meshes should have equal vertex formats. Only components
	 *  that are provided by ALL meshes will be present in the output mesh.
	 *  An exception is made for VColors - they are set to black. The 
	 *  meshes should have the same material indices, too. The output
	 *  material index is always the material index of the first mesh.
	 *
	 *  @param dest Destination mesh. Must be empty.
	 *  @param flags Currently no parameters
	 *  @param begin First mesh to be processed
	 *  @param end Points to the mesh after the last mesh to be processed
	 */
	static void MergeMeshes(aiMesh** dest,unsigned int flags,
		std::vector<aiMesh*>::const_iterator begin,
		std::vector<aiMesh*>::const_iterator end);


	// -------------------------------------------------------------------
	/** Merges two or more bones
	 *
	 *  @param out Mesh to receive the output bone list
	 *  @param flags Currently no parameters
	 *  @param begin First mesh to be processed
	 *  @param end Points to the mesh after the last mesh to be processed
	 */
	static void MergeBones(aiMesh* out,std::vector<aiMesh*>::const_iterator it,
		std::vector<aiMesh*>::const_iterator end);

	// -------------------------------------------------------------------
	/** Merges two or more materials
	 *
	 *  The materials should be complementary as much as possible. In case
	 *  of a property present in different materials, the first occurence
	 *  is used.
	 *
	 *  @param dest Destination material. Must be empty.
	 *  @param begin First material to be processed
	 *  @param end Points to the material after the last material to be processed
	 */
	static void MergeMaterials(aiMaterial** dest,
		std::vector<aiMaterial*>::const_iterator begin,
		std::vector<aiMaterial*>::const_iterator end);

	// -------------------------------------------------------------------
	/** Builds a list of uniquely named bones in a mesh list
	 *
	 *  @param asBones Receives the output list
	 *  @param it First mesh to be processed
	 *  @param end Last mesh to be processed
	 */
	static void BuildUniqueBoneList(std::list<BoneWithHash>& asBones,
		std::vector<aiMesh*>::const_iterator it,
		std::vector<aiMesh*>::const_iterator end);

	// -------------------------------------------------------------------
	/** Add a name prefix to all nodes in a scene.
	 *
	 *  @param Current node. This function is called recursively.
	 *  @param prefix Prefix to be added to all nodes
	 *  @param len STring length
	 */
	static void AddNodePrefixes(aiNode* node, const char* prefix,
		unsigned int len);

	// -------------------------------------------------------------------
	/** Add an offset to all mesh indices in a node graph
	 *
	 *  @param Current node. This function is called recursively.
	 *  @param offset Offset to be added to all mesh indices
	 */
	static void OffsetNodeMeshIndices (aiNode* node, unsigned int offset);

	// -------------------------------------------------------------------
	/** Attach a list of node graphs to well-defined nodes in a master
	 *  graph. This is a helper for MergeScenes()
	 *
	 *  @param master Master scene
	 *  @param srcList List of source scenes along with their attachment
	 *    points. If an attachment point is NULL (or does not exist in
	 *    the master graph), a scene is attached to the root of the master
	 *    graph (as an additional child node)
	 *  @duplicates List of duplicates. If elem[n] == n the scene is not
	 *    a duplicate. Otherwise elem[n] links scene n to its first occurence.
	 */
	static void AttachToGraph ( aiScene* master, 
		std::vector<NodeAttachmentInfo>& srcList);

	static void AttachToGraph (aiNode* attach, 
		std::vector<NodeAttachmentInfo>& srcList);


	// -------------------------------------------------------------------
	/** Get a deep copy of a scene
	 *
	 *  @param dest Receives a pointer to the destination scene
	 *  @param src Source scene - remains unmodified.
	 */
	static void CopyScene(aiScene** dest,const aiScene* source,bool allocate = true);


	// -------------------------------------------------------------------
	/** Get a flat copy of a scene
	 *
	 *  Only the first hierarchy layer is copied. All pointer members of
	 *  aiScene are shared by source and destination scene.  If the
	 *    pointer doesn't point to NULL when the function is called, the
	 *    existing scene is cleared and refilled.
	 *  @param dest Receives a pointer to the destination scene
	 *  @param src Source scene - remains unmodified.
	 */
	static void CopySceneFlat(aiScene** dest,const aiScene* source);


	// -------------------------------------------------------------------
	/** Get a deep copy of a mesh
	 *
	 *  @param dest Receives a pointer to the destination mesh
	 *  @param src Source mesh - remains unmodified.
	 */
	static void Copy     (aiMesh** dest, const aiMesh* src);

	// similar to Copy():
	static void Copy  (aiMaterial** dest, const aiMaterial* src);
	static void Copy  (aiTexture** dest, const aiTexture* src);
	static void Copy  (aiAnimation** dest, const aiAnimation* src);
	static void Copy  (aiCamera** dest, const aiCamera* src);
	static void Copy  (aiBone** dest, const aiBone* src);
	static void Copy  (aiLight** dest, const aiLight* src);
	static void Copy  (aiNodeAnim** dest, const aiNodeAnim* src);

	// recursive, of course
	static void Copy     (aiNode** dest, const aiNode* src);


private:

	// -------------------------------------------------------------------
	// Same as AddNodePrefixes, but with an additional check
	static void AddNodePrefixesChecked(aiNode* node, const char* prefix, 
		unsigned int len,
		std::vector<SceneHelper>& input, 
		unsigned int cur);

	// -------------------------------------------------------------------
	// Add node identifiers to a hashing set
	static void AddNodeHashes(aiNode* node, std::set<unsigned int>& hashes);


	// -------------------------------------------------------------------
	// Search for duplicate names
	static bool FindNameMatch(const aiString& name, 
		std::vector<SceneHelper>& input, unsigned int cur);
};

}

#endif // !! AI_SCENE_COMBINER_H_INC
