/*
Open Asset Import Library (assimp)
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*/

/** @file  FBXMeshGeometry.cpp
 *  @brief Assimp::FBX::MeshGeometry implementation
 */
#include "AssimpPCH.h"

#ifndef ASSIMP_BUILD_NO_FBX_IMPORTER

#include "FBXParser.h"
#include "FBXDocument.h"
#include "FBXImporter.h"
#include "FBXImportSettings.h"
#include "FBXDocumentUtil.h"


namespace Assimp {
namespace FBX {

	using namespace Util;

// ------------------------------------------------------------------------------------------------
MeshGeometry::MeshGeometry(uint64_t id, const Element& element, const std::string& name, const Document& doc)
: Geometry(id, element,name)
{
	const Scope* sc = element.Compound();
	if (!sc) {
		DOMError("failed to read Geometry object (class: Mesh), no data scope found");
	}

	// must have Mesh elements:
	const Element& Vertices = GetRequiredElement(*sc,"Vertices",&element);
	const Element& PolygonVertexIndex = GetRequiredElement(*sc,"PolygonVertexIndex",&element);

	// optional Mesh elements:
	const ElementCollection& Layer = sc->GetCollection("Layer");
	const ElementCollection& LayerElementMaterial = sc->GetCollection("LayerElementMaterial");
	const ElementCollection& LayerElementUV = sc->GetCollection("LayerElementUV");
	const ElementCollection& LayerElementNormal = sc->GetCollection("LayerElementNormal");

	std::vector<aiVector3D> tempVerts;
	ReadVectorDataArray(tempVerts,Vertices);

	if(tempVerts.empty()) {
		FBXImporter::LogWarn("encountered mesh with no vertices");
		return;
	}

	std::vector<int> tempFaces;
	ReadVectorDataArray(tempFaces,PolygonVertexIndex);

	if(tempFaces.empty()) {
		FBXImporter::LogWarn("encountered mesh with no faces");
		return;
	}

	vertices.reserve(tempFaces.size());
	faces.reserve(tempFaces.size() / 3);

	mapping_offsets.resize(tempVerts.size());
	mapping_counts.resize(tempVerts.size(),0);
	mappings.resize(tempFaces.size());

	const size_t vertex_count = tempVerts.size();

	// generate output vertices, computing an adjacency table to
	// preserve the mapping from fbx indices to *this* indexing.
	unsigned int count = 0;
	BOOST_FOREACH(int index, tempFaces) {
		const int absi = index < 0 ? (-index - 1) : index;
		if(static_cast<size_t>(absi) >= vertex_count) {
			DOMError("polygon vertex index out of range",&PolygonVertexIndex);
		}

		vertices.push_back(tempVerts[absi]);
		++count;

		++mapping_counts[absi];

		if (index < 0) {
			faces.push_back(count);
			count = 0;
		}
	}

	unsigned int cursor = 0;
	for (size_t i = 0, e = tempVerts.size(); i < e; ++i) {
		mapping_offsets[i] = cursor;
		cursor += mapping_counts[i];

		mapping_counts[i] = 0;
	}

	cursor = 0;
	BOOST_FOREACH(int index, tempFaces) {
		const int absi = index < 0 ? (-index - 1) : index;
		mappings[mapping_offsets[absi] + mapping_counts[absi]++] = cursor;
	}
	
	// if settings.readAllLayers is true:
	//  * read all layers, try to load as many vertex channels as possible
	// if settings.readAllLayers is false:
	//  * read only the layer with index 0, but warn about any further layers 
	for (ElementMap::const_iterator it = Layer.first; it != Layer.second; ++it) {
		const TokenList& tokens = (*it).second->Tokens();

		const char* err;
		const int index = ParseTokenAsInt(*tokens[0], err);
		if(err) {
			DOMError(err,&element);
		}

		if(doc.Settings().readAllLayers || index == 0) {
			const Scope& layer = GetRequiredScope(*(*it).second);
			ReadLayer(layer);
		}
		else {
			FBXImporter::LogWarn("ignoring additional geometry layers");
		}
	}
}


// ------------------------------------------------------------------------------------------------
MeshGeometry::~MeshGeometry()
{

}



// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadLayer(const Scope& layer)
{
	const ElementCollection& LayerElement = layer.GetCollection("LayerElement");
	for (ElementMap::const_iterator eit = LayerElement.first; eit != LayerElement.second; ++eit) {
		const Scope& elayer = GetRequiredScope(*(*eit).second);

		ReadLayerElement(elayer);
	}
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadLayerElement(const Scope& layerElement)
{
	const Element& Type = GetRequiredElement(layerElement,"Type");
	const Element& TypedIndex = GetRequiredElement(layerElement,"TypedIndex");

	const std::string& type = ParseTokenAsString(GetRequiredToken(Type,0));
	const int typedIndex = ParseTokenAsInt(GetRequiredToken(TypedIndex,0));

	const Scope& top = GetRequiredScope(element);
	const ElementCollection candidates = top.GetCollection(type);

	for (ElementMap::const_iterator it = candidates.first; it != candidates.second; ++it) {
		const int index = ParseTokenAsInt(GetRequiredToken(*(*it).second,0));
		if(index == typedIndex) {
			ReadVertexData(type,typedIndex,GetRequiredScope(*(*it).second));
			return;
		}
	}

	FBXImporter::LogError(Formatter::format("failed to resolve vertex layer element: ") 
		<< type << ", index: " << typedIndex);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexData(const std::string& type, int index, const Scope& source)
{
	const std::string& MappingInformationType = ParseTokenAsString(GetRequiredToken(
		GetRequiredElement(source,"MappingInformationType"),0)
	);

	const std::string& ReferenceInformationType = ParseTokenAsString(GetRequiredToken(
		GetRequiredElement(source,"ReferenceInformationType"),0)
	);
	
	if (type == "LayerElementUV") {
		if(index >= AI_MAX_NUMBER_OF_TEXTURECOORDS) {
			FBXImporter::LogError(Formatter::format("ignoring UV layer, maximum number of UV channels exceeded: ") 
				<< index << " (limit is " << AI_MAX_NUMBER_OF_TEXTURECOORDS << ")" );
			return;
		}

		const Element* Name = source["Name"];
		uvNames[index] = "";
		if(Name) {
			uvNames[index] = ParseTokenAsString(GetRequiredToken(*Name,0));
		}

		ReadVertexDataUV(uvs[index],source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
	else if (type == "LayerElementMaterial") {
		if (materials.size() > 0) {
			FBXImporter::LogError("ignoring additional material layer");
			return;
		}

		ReadVertexDataMaterials(materials,source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
	else if (type == "LayerElementNormal") {
		if (normals.size() > 0) {
			FBXImporter::LogError("ignoring additional normal layer");
			return;
		}

		ReadVertexDataNormals(normals,source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
	else if (type == "LayerElementTangent") {
		if (tangents.size() > 0) {
			FBXImporter::LogError("ignoring additional tangent layer");
			return;
		}

		ReadVertexDataTangents(tangents,source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
	else if (type == "LayerElementBinormal") {
		if (binormals.size() > 0) {
			FBXImporter::LogError("ignoring additional binormal layer");
			return;
		}

		ReadVertexDataBinormals(binormals,source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
	else if (type == "LayerElementColor") {
		if(index >= AI_MAX_NUMBER_OF_COLOR_SETS) {
			FBXImporter::LogError(Formatter::format("ignoring vertex color layer, maximum number of color sets exceeded: ") 
				<< index << " (limit is " << AI_MAX_NUMBER_OF_COLOR_SETS << ")" );
			return;
		}

		ReadVertexDataColors(colors[index],source,
			MappingInformationType,
			ReferenceInformationType
		);
	}
}


// ------------------------------------------------------------------------------------------------
// Lengthy utility function to read and resolve a FBX vertex data array - that is, the
// output is in polygon vertex order. This logic is used for reading normals, UVs, colors,
// tangents ..
template <typename T>
void ResolveVertexDataArray(std::vector<T>& data_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType,
	const char* dataElementName,
	const char* indexDataElementName,
	size_t vertex_count,
	const std::vector<unsigned int>& mapping_counts,
	const std::vector<unsigned int>& mapping_offsets,
	const std::vector<unsigned int>& mappings)
{
	std::vector<T> tempUV;
	ReadVectorDataArray(tempUV,GetRequiredElement(source,dataElementName));

	// handle permutations of Mapping and Reference type - it would be nice to
	// deal with this more elegantly and with less redundancy, but right
	// now it seems unavoidable.
	if (MappingInformationType == "ByVertice" && ReferenceInformationType == "Direct") {	
		data_out.resize(vertex_count);
		for (size_t i = 0, e = tempUV.size(); i < e; ++i) {

			const unsigned int istart = mapping_offsets[i], iend = istart + mapping_counts[i];
			for (unsigned int j = istart; j < iend; ++j) {
				data_out[mappings[j]] = tempUV[i];
			}
		}
	}
	else if (MappingInformationType == "ByVertice" && ReferenceInformationType == "IndexToDirect") {	
		data_out.resize(vertex_count);

		std::vector<int> uvIndices;
		ReadVectorDataArray(uvIndices,GetRequiredElement(source,indexDataElementName));

		for (size_t i = 0, e = uvIndices.size(); i < e; ++i) {

			const unsigned int istart = mapping_offsets[i], iend = istart + mapping_counts[i];
			for (unsigned int j = istart; j < iend; ++j) {
				if(static_cast<size_t>(uvIndices[i]) >= tempUV.size()) {
					DOMError("index out of range",&GetRequiredElement(source,indexDataElementName));
				}
				data_out[mappings[j]] = tempUV[uvIndices[i]];
			}
		}
	}
	else if (MappingInformationType == "ByPolygonVertex" && ReferenceInformationType == "Direct") {	
		if (tempUV.size() != vertex_count) {
			FBXImporter::LogError(Formatter::format("length of input data unexpected for ByPolygon mapping: ") 
				<< tempUV.size() << ", expected " << vertex_count
			);
			return;
		}

		data_out.swap(tempUV);
	}
	else if (MappingInformationType == "ByPolygonVertex" && ReferenceInformationType == "IndexToDirect") {	
		data_out.resize(vertex_count);

		std::vector<int> uvIndices;
		ReadVectorDataArray(uvIndices,GetRequiredElement(source,indexDataElementName));

		if (uvIndices.size() != vertex_count) {
			FBXImporter::LogError("length of input data unexpected for ByPolygonVertex mapping");
			return;
		}

		unsigned int next = 0;
		BOOST_FOREACH(int i, uvIndices) {
			if(static_cast<size_t>(i) >= tempUV.size()) {
				DOMError("index out of range",&GetRequiredElement(source,indexDataElementName));
			}

			data_out[next++] = tempUV[i];
		}
	}
	else {
		FBXImporter::LogError(Formatter::format("ignoring vertex data channel, access type not implemented: ") 
			<< MappingInformationType << "," << ReferenceInformationType);
	}
}

// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataNormals(std::vector<aiVector3D>& normals_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	ResolveVertexDataArray(normals_out,source,MappingInformationType,ReferenceInformationType,
		"Normals",
		"NormalsIndex",
		vertices.size(),
		mapping_counts,
		mapping_offsets,
		mappings);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataUV(std::vector<aiVector2D>& uv_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	ResolveVertexDataArray(uv_out,source,MappingInformationType,ReferenceInformationType,
		"UV",
		"UVIndex",
		vertices.size(),
		mapping_counts,
		mapping_offsets,
		mappings);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataColors(std::vector<aiColor4D>& colors_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	ResolveVertexDataArray(colors_out,source,MappingInformationType,ReferenceInformationType,
		"Colors",
		"ColorIndex",
		vertices.size(),
		mapping_counts,
		mapping_offsets,
		mappings);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataTangents(std::vector<aiVector3D>& tangents_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	ResolveVertexDataArray(tangents_out,source,MappingInformationType,ReferenceInformationType,
		"Tangent",
		"TangentIndex",
		vertices.size(),
		mapping_counts,
		mapping_offsets,
		mappings);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataBinormals(std::vector<aiVector3D>& binormals_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	ResolveVertexDataArray(binormals_out,source,MappingInformationType,ReferenceInformationType,
		"Binormal",
		"BinormalIndex",
		vertices.size(),
		mapping_counts,
		mapping_offsets,
		mappings);
}


// ------------------------------------------------------------------------------------------------
void MeshGeometry::ReadVertexDataMaterials(std::vector<unsigned int>& materials_out, const Scope& source, 
	const std::string& MappingInformationType,
	const std::string& ReferenceInformationType)
{
	const size_t face_count = faces.size();
	ai_assert(face_count);

	// materials are handled separately. First of all, they are assigned per-face
	// and not per polyvert. Secondly, ReferenceInformationType=IndexToDirect
	// has a slightly different meaning for materials.
	ReadVectorDataArray(materials_out,GetRequiredElement(source,"Materials"));

	if (MappingInformationType == "AllSame") {
		// easy - same material for all faces
		if (materials_out.empty()) {
			FBXImporter::LogError(Formatter::format("expected material index, ignoring"));
			return;
		}
		else if (materials_out.size() > 1) {
			FBXImporter::LogWarn(Formatter::format("expected only a single material index, ignoring all except the first one"));
			materials_out.clear();
		}
 
		materials.assign(vertices.size(),materials_out[0]);
	}
	else if (MappingInformationType == "ByPolygon" && ReferenceInformationType == "IndexToDirect") {
		materials.resize(face_count);

		if(materials_out.size() != face_count) {
			FBXImporter::LogError(Formatter::format("length of input data unexpected for ByPolygon mapping: ") 
				<< materials_out.size() << ", expected " << face_count
			);
			return;
		}
	}
	else {
		FBXImporter::LogError(Formatter::format("ignoring material assignments, access type not implemented: ") 
			<< MappingInformationType << "," << ReferenceInformationType);
	}
}

} // !FBX
} // !Assimp

#endif