/*
---------------------------------------------------------------------------
Open Asset Import Library (assimp)
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  copyright notice, this list of conditions and the
  following disclaimer.

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*/

/** @file Implementation of the XGL/ZGL importer class */

#ifndef ASSIMP_BUILD_NO_XGL_IMPORTER

#include "XGLLoader.h"
#include "Common/Compression.h"

#include <assimp/ParsingUtils.h>
#include <assimp/fast_atof.h>
#include <assimp/MemoryIOWrapper.h>
#include <assimp/StreamReader.h>
#include <assimp/importerdesc.h>
#include <assimp/mesh.h>
#include <assimp/scene.h>

#include <memory>
#include <utility>
//#include <cctype>
//#include <memory>

using namespace Assimp;

namespace Assimp { // this has to be in here because LogFunctions is in ::Assimp

template <>
const char *LogFunctions<XGLImporter>::Prefix() {
	return "XGL: ";
}

} // namespace Assimp

static const aiImporterDesc desc = {
	"XGL Importer",
	"",
	"",
	"",
	aiImporterFlags_SupportTextFlavour | aiImporterFlags_SupportCompressedFlavour,
	0,
	0,
	0,
	0,
	"xgl zgl"
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
XGLImporter::XGLImporter() :
        mXmlParser(nullptr),
        m_scene(nullptr) {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
XGLImporter::~XGLImporter() {
	delete mXmlParser;
}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool XGLImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool /*checkSig*/) const {
	static const char *tokens[] = { "<world>", "<World>", "<WORLD>" };
	return SearchFileHeaderForToken(pIOHandler, pFile, tokens, AI_COUNT_OF(tokens));
}

// ------------------------------------------------------------------------------------------------
// Get a list of all file extensions which are handled by this class
const aiImporterDesc *XGLImporter::GetInfo() const {
	return &desc;
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void XGLImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
 #ifndef ASSIMP_BUILD_NO_COMPRESSED_XGL
	std::vector<char> uncompressed;
#endif

	m_scene = pScene;
	std::shared_ptr<IOStream> stream(pIOHandler->Open(pFile, "rb"));

	// check whether we can read from the file
    if (stream == nullptr) {
        throw DeadlyImportError("Failed to open XGL/ZGL file " + pFile);
    }

    // see if its compressed, if so uncompress it
	if (GetExtension(pFile) == "zgl") {
#ifdef ASSIMP_BUILD_NO_COMPRESSED_XGL
		ThrowException("Cannot read ZGL file since Assimp was built without compression support");
#else
		std::unique_ptr<StreamReaderLE> raw_reader(new StreamReaderLE(stream));

        Compression compression;
        size_t total = 0l;
        if (compression.open(Compression::Format::Binary, Compression::FlushMode::NoFlush, -Compression::MaxWBits)) {
            // skip two extra bytes, zgl files do carry a crc16 upfront (I think)
            raw_reader->IncPtr(2);
            total = compression.decompress((unsigned char *)raw_reader->GetPtr(), raw_reader->GetRemainingSize(), uncompressed);
            compression.close();
        }
		// replace the input stream with a memory stream
        stream = std::make_shared<MemoryIOStream>(reinterpret_cast<uint8_t *>(uncompressed.data()), total);
#endif
	}

	// parse the XML file
    mXmlParser = new XmlParser;
    if (!mXmlParser->parse(stream.get())) {
        throw DeadlyImportError("XML parse error while loading XGL file ", pFile);
	}

	TempScope scope;
    XmlNode *worldNode = mXmlParser->findNode("WORLD");
    if (nullptr != worldNode) {
		ReadWorld(*worldNode, scope);
	}

	std::vector<aiMesh *> &meshes = scope.meshes_linear;
	std::vector<aiMaterial *> &materials = scope.materials_linear;
	if (!meshes.size() || !materials.size()) {
		ThrowException("failed to extract data from XGL file, no meshes loaded");
	}

	// copy meshes
	m_scene->mNumMeshes = static_cast<unsigned int>(meshes.size());
	m_scene->mMeshes = new aiMesh *[m_scene->mNumMeshes]();
	std::copy(meshes.begin(), meshes.end(), m_scene->mMeshes);

	// copy materials
	m_scene->mNumMaterials = static_cast<unsigned int>(materials.size());
	m_scene->mMaterials = new aiMaterial *[m_scene->mNumMaterials]();
	std::copy(materials.begin(), materials.end(), m_scene->mMaterials);

	if (scope.light) {
		m_scene->mNumLights = 1;
		m_scene->mLights = new aiLight *[1];
		m_scene->mLights[0] = scope.light;

		scope.light->mName = m_scene->mRootNode->mName;
	}

	scope.dismiss();
}

// ------------------------------------------------------------------------------------------------
void XGLImporter::ReadWorld(XmlNode &node, TempScope &scope) {
    for (XmlNode &currentNode : node.children()) {
        const std::string &s = ai_stdStrToLower(currentNode.name());

		// XXX right now we'd skip <lighting> if it comes after
		// <object> or <mesh>
		if (s == "lighting") {
            ReadLighting(currentNode, scope);
		} else if (s == "object" || s == "mesh" || s == "mat") {
			break;
		}
	}

	aiNode *const nd = ReadObject(node, scope);
	if (!nd) {
		ThrowException("failure reading <world>");
	}
	if (nd->mName.length == 0) {
		nd->mName.Set("WORLD");
	}

	m_scene->mRootNode = nd;
}

// ------------------------------------------------------------------------------------------------
void XGLImporter::ReadLighting(XmlNode &node, TempScope &scope) {
    const std::string &s = ai_stdStrToLower(node.name());
	if (s == "directionallight") {
		scope.light = ReadDirectionalLight(node);
	} else if (s == "ambient") {
		LogWarn("ignoring <ambient> tag");
	} else if (s == "spheremap") {
		LogWarn("ignoring <spheremap> tag");
	}
}

// ------------------------------------------------------------------------------------------------
aiLight *XGLImporter::ReadDirectionalLight(XmlNode &node) {
	std::unique_ptr<aiLight> l(new aiLight());
	l->mType = aiLightSource_DIRECTIONAL;
	find_node_by_name_predicate predicate("directionallight");
	XmlNode child = node.find_child(std::move(predicate));
	if (child.empty()) {
		return nullptr;
	}

	const std::string &s = ai_stdStrToLower(child.name());
	if (s == "direction") {
		l->mDirection = ReadVec3(child);
	} else if (s == "diffuse") {
		l->mColorDiffuse = ReadCol3(child);
	} else if (s == "specular") {
		l->mColorSpecular = ReadCol3(child);
	}

	return l.release();
}

// ------------------------------------------------------------------------------------------------
aiNode *XGLImporter::ReadObject(XmlNode &node, TempScope &scope) {
	aiNode *nd = new aiNode;
	std::vector<aiNode *> children;
	std::vector<unsigned int> meshes;

	try {
		for (XmlNode &child : node.children()) {
			const std::string &s = ai_stdStrToLower(child.name());
			if (s == "mesh") {
				const size_t prev = scope.meshes_linear.size();
                bool empty;
				if (ReadMesh(child, scope, empty)) {
					const size_t newc = scope.meshes_linear.size();
					for (size_t i = 0; i < newc - prev; ++i) {
						meshes.push_back(static_cast<unsigned int>(i + prev));
					}
				}
			} else if (s == "mat") {
				ReadMaterial(child, scope);
			} else if (s == "object") {
				children.push_back(ReadObject(child, scope));
			} else if (s == "objectref") {
				// XXX
			} else if (s == "meshref") {
				const unsigned int id = static_cast<unsigned int>(ReadIndexFromText(child));

				std::multimap<unsigned int, aiMesh *>::iterator it = scope.meshes.find(id), end = scope.meshes.end();
				if (it == end) {
					ThrowException("<meshref> index out of range");
				}

				for (; it != end && (*it).first == id; ++it) {
					// ok, this is n^2 and should get optimized one day
					aiMesh *const m = it->second;
					unsigned int i = 0, mcount = static_cast<unsigned int>(scope.meshes_linear.size());
					for (; i < mcount; ++i) {
						if (scope.meshes_linear[i] == m) {
							meshes.push_back(i);
							break;
						}
					}

					ai_assert(i < mcount);
				}
			} else if (s == "transform") {
				nd->mTransformation = ReadTrafo(child);
			}
		}
	} catch (...) {
		for (aiNode *ch : children) {
			delete ch;
		}
		throw;
	}

	// FIX: since we used std::multimap<> to keep meshes by id, mesh order now depends on the behaviour
	// of the multimap implementation with respect to the ordering of entries with same values.
	// C++11 gives the guarantee that it uses insertion order, before it is implementation-specific.
	// Sort by material id to always guarantee a deterministic result.
	std::sort(meshes.begin(), meshes.end(), SortMeshByMaterialId(scope));

	// link meshes to node
	nd->mNumMeshes = static_cast<unsigned int>(meshes.size());
	if (0 != nd->mNumMeshes) {
		nd->mMeshes = new unsigned int[nd->mNumMeshes]();
		for (unsigned int i = 0; i < nd->mNumMeshes; ++i) {
			nd->mMeshes[i] = meshes[i];
		}
	}

	// link children to parent
	nd->mNumChildren = static_cast<unsigned int>(children.size());
	if (nd->mNumChildren) {
		nd->mChildren = new aiNode *[nd->mNumChildren]();
		for (unsigned int i = 0; i < nd->mNumChildren; ++i) {
			nd->mChildren[i] = children[i];
			children[i]->mParent = nd;
		}
	}

	return nd;
}

// ------------------------------------------------------------------------------------------------
aiMatrix4x4 XGLImporter::ReadTrafo(XmlNode &node) {
	aiVector3D forward, up, right, position;
	float scale = 1.0f;

	aiMatrix4x4 m;
	XmlNode child = node.child("TRANSFORM");
	if (child.empty()) {
		return m;
	}

	for (XmlNode &sub_child : child.children()) {
        const std::string &s = ai_stdStrToLower(sub_child.name());
		if (s == "forward") {
			forward = ReadVec3(sub_child);
		} else if (s == "up") {
			up = ReadVec3(sub_child);
		} else if (s == "position") {
			position = ReadVec3(sub_child);
		}
		if (s == "scale") {
			scale = ReadFloat(sub_child);
			if (scale < 0.f) {
				// this is wrong, but we can leave the value and pass it to the caller
				LogError("found negative scaling in <transform>, ignoring");
			}
		}
	}

    if (forward.SquareLength() < 1e-4 || up.SquareLength() < 1e-4) {
	    LogError("A direction vector in <transform> is zero, ignoring trafo");
	    return m;
    }

    forward.Normalize();
    up.Normalize();

    right = forward ^ up;
    if (std::fabs(up * forward) > 1e-4) {
	    // this is definitely wrong - a degenerate coordinate space ruins everything
	    // so substitute identity transform.
	    LogError("<forward> and <up> vectors in <transform> are skewing, ignoring trafo");
	    return m;
    }

    right *= scale;
    up *= scale;
    forward *= scale;

    m.a1 = right.x;
    m.b1 = right.y;
    m.c1 = right.z;

    m.a2 = up.x;
    m.b2 = up.y;
    m.c2 = up.z;

    m.a3 = forward.x;
    m.b3 = forward.y;
    m.c3 = forward.z;

    m.a4 = position.x;
    m.b4 = position.y;
    m.c4 = position.z;

	return m;
}

// ------------------------------------------------------------------------------------------------
aiMesh *XGLImporter::ToOutputMesh(const TempMaterialMesh &m) {
	std::unique_ptr<aiMesh> mesh(new aiMesh());

	mesh->mNumVertices = static_cast<unsigned int>(m.positions.size());
	mesh->mVertices = new aiVector3D[mesh->mNumVertices];
	std::copy(m.positions.begin(), m.positions.end(), mesh->mVertices);

	if (!m.normals.empty()) {
		mesh->mNormals = new aiVector3D[mesh->mNumVertices];
		std::copy(m.normals.begin(), m.normals.end(), mesh->mNormals);
	}

	if (!m.uvs.empty()) {
		mesh->mNumUVComponents[0] = 2;
		mesh->mTextureCoords[0] = new aiVector3D[mesh->mNumVertices];

		for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
			mesh->mTextureCoords[0][i] = aiVector3D(m.uvs[i].x, m.uvs[i].y, 0.f);
		}
	}

	mesh->mNumFaces = static_cast<unsigned int>(m.vcounts.size());
	mesh->mFaces = new aiFace[m.vcounts.size()];

	unsigned int idx = 0;
	for (unsigned int i = 0; i < mesh->mNumFaces; ++i) {
		aiFace &f = mesh->mFaces[i];
		f.mNumIndices = m.vcounts[i];
		f.mIndices = new unsigned int[f.mNumIndices];
		for (unsigned int c = 0; c < f.mNumIndices; ++c) {
			f.mIndices[c] = idx++;
		}
	}

	ai_assert(idx == mesh->mNumVertices);

	mesh->mPrimitiveTypes = m.pflags;
	mesh->mMaterialIndex = m.matid;

    return mesh.release();
}

// ------------------------------------------------------------------------------------------------
bool XGLImporter::ReadMesh(XmlNode &node, TempScope &scope, bool &empty) {
	TempMesh t;

	std::map<unsigned int, TempMaterialMesh> bymat;
    const unsigned int mesh_id = ReadIDAttr(node);
    bool empty_mesh = true;
	for (XmlNode &child : node.children()) {
        const std::string &s = ai_stdStrToLower(child.name());

		if (s == "mat") {
			ReadMaterial(child, scope);
		} else if (s == "p") {
			pugi::xml_attribute attr = child.attribute("ID");
			if (attr.empty()) {
				LogWarn("no ID attribute on <p>, ignoring");
			} else {
				int id = attr.as_int();
				t.points[id] = ReadVec3(child);
			}
		} else if (s == "n") {
			pugi::xml_attribute attr = child.attribute("ID");
			if (attr.empty()) {
				LogWarn("no ID attribute on <n>, ignoring");
			} else {
				int id = attr.as_int();
				t.normals[id] = ReadVec3(child);
			}
		} else if (s == "tc") {
			pugi::xml_attribute attr = child.attribute("ID");
			if (attr.empty()) {
				LogWarn("no ID attribute on <tc>, ignoring");
			} else {
				int id = attr.as_int();
				t.uvs[id] = ReadVec2(child);
			}
		} else if (s == "f" || s == "l" || s == "p") {
			const unsigned int vcount = s == "f" ? 3 : (s == "l" ? 2 : 1);

			unsigned int mid = ~0u;
			TempFace tf[3];
			bool has[3] = { false };
			for (XmlNode &sub_child : child.children()) {
                const std::string &scn = ai_stdStrToLower(sub_child.name());
                if (scn == "fv1" || scn == "lv1" || scn == "pv1") {
					ReadFaceVertex(sub_child, t, tf[0]);
					has[0] = true;
                } else if (scn == "fv2" || scn == "lv2") {
					ReadFaceVertex(sub_child, t, tf[1]);
					has[1] = true;
                } else if (scn == "fv3") {
					ReadFaceVertex(sub_child, t, tf[2]);
					has[2] = true;
                } else if (scn == "mat") {
					if (mid != ~0u) {
						LogWarn("only one material tag allowed per <f>");
					}
					mid = ResolveMaterialRef(sub_child, scope);
                } else if (scn == "matref") {
					if (mid != ~0u) {
						LogWarn("only one material tag allowed per <f>");
					}
					mid = ResolveMaterialRef(sub_child, scope);
				}
			}
            if (has[0] || has[1] || has[2]) {
                empty_mesh = false;
            }

			if (mid == ~0u) {
				ThrowException("missing material index");
			}

			bool nor = false;
			bool uv = false;
			for (unsigned int i = 0; i < vcount; ++i) {
				if (!has[i]) {
					ThrowException("missing face vertex data");
				}

				nor = nor || tf[i].has_normal;
				uv = uv || tf[i].has_uv;
			}

			if (mid >= (1 << 30)) {
				LogWarn("material indices exhausted, this may cause errors in the output");
			}
			unsigned int meshId = mid | ((nor ? 1 : 0) << 31) | ((uv ? 1 : 0) << 30);

			TempMaterialMesh &mesh = bymat[meshId];
			mesh.matid = mid;

			for (unsigned int i = 0; i < vcount; ++i) {
				mesh.positions.push_back(tf[i].pos);
				if (nor) {
					mesh.normals.push_back(tf[i].normal);
				}
				if (uv) {
					mesh.uvs.push_back(tf[i].uv);
				}

				mesh.pflags |= 1 << (vcount - 1);
			}

			mesh.vcounts.push_back(vcount);
		}
	}

	// finally extract output meshes and add them to the scope
	using pairt = std::pair<const unsigned int, TempMaterialMesh>;
	for (const pairt &p : bymat) {
		aiMesh *const m = ToOutputMesh(p.second);
		scope.meshes_linear.push_back(m);

		// if this is a definition, keep it on the stack
		if (mesh_id != ~0u) {
			scope.meshes.insert(std::pair<unsigned int, aiMesh *>(mesh_id, m));
		}
	}
    if (empty_mesh) {
        LogWarn("Mesh is empty, skipping.");
        empty = empty_mesh;
        return false;
    }

	// no id == not a reference, insert this mesh right *here*
	return mesh_id == ~0u;
}

// ----------------------------------------------------------------------------------------------
unsigned int XGLImporter::ResolveMaterialRef(XmlNode &node, TempScope &scope) {
	const std::string &s = node.name();
	if (s == "mat") {
		ReadMaterial(node, scope);
		return static_cast<unsigned int>(scope.materials_linear.size() - 1);
	}

	const int id = ReadIndexFromText(node);

	auto it = scope.materials.find(id), end = scope.materials.end();
	if (it == end) {
		ThrowException("<matref> index out of range");
	}

	// ok, this is n^2 and should get optimized one day
	aiMaterial *const m = it->second;

	unsigned int i = 0, mcount = static_cast<unsigned int>(scope.materials_linear.size());
	for (; i < mcount; ++i) {
		if (scope.materials_linear[i] == m) {
			return i;
		}
	}

	ai_assert(false);

	return 0;
}

// ------------------------------------------------------------------------------------------------
void XGLImporter::ReadMaterial(XmlNode &node, TempScope &scope) {
    const unsigned int mat_id = ReadIDAttr(node);

	auto *mat(new aiMaterial);
	for (XmlNode &child : node.children()) {
        const std::string &s = ai_stdStrToLower(child.name());
		if (s == "amb") {
			const aiColor3D c = ReadCol3(child);
			mat->AddProperty(&c, 1, AI_MATKEY_COLOR_AMBIENT);
		} else if (s == "diff") {
			const aiColor3D c = ReadCol3(child);
			mat->AddProperty(&c, 1, AI_MATKEY_COLOR_DIFFUSE);
		} else if (s == "spec") {
			const aiColor3D c = ReadCol3(child);
			mat->AddProperty(&c, 1, AI_MATKEY_COLOR_SPECULAR);
		} else if (s == "emiss") {
			const aiColor3D c = ReadCol3(child);
			mat->AddProperty(&c, 1, AI_MATKEY_COLOR_EMISSIVE);
		} else if (s == "alpha") {
			const float f = ReadFloat(child);
			mat->AddProperty(&f, 1, AI_MATKEY_OPACITY);
		} else if (s == "shine") {
			const float f = ReadFloat(child);
			mat->AddProperty(&f, 1, AI_MATKEY_SHININESS);
		}
	}

	scope.materials[mat_id] = mat;
	scope.materials_linear.push_back(mat);
}

// ----------------------------------------------------------------------------------------------
void XGLImporter::ReadFaceVertex(XmlNode &node, const TempMesh &t, TempFace &out) {
	bool havep = false;
	for (XmlNode &child : node.children()) {
        const std::string &s = ai_stdStrToLower(child.name());
		if (s == "pref") {
			const unsigned int id = ReadIndexFromText(child);
			std::map<unsigned int, aiVector3D>::const_iterator it = t.points.find(id);
			if (it == t.points.end()) {
				ThrowException("point index out of range");
			}

			out.pos = (*it).second;
			havep = true;
		} else if (s == "nref") {
			const unsigned int id = ReadIndexFromText(child);
			std::map<unsigned int, aiVector3D>::const_iterator it = t.normals.find(id);
			if (it == t.normals.end()) {
				ThrowException("normal index out of range");
			}

			out.normal = (*it).second;
			out.has_normal = true;
		} else if (s == "tcref") {
			const unsigned int id = ReadIndexFromText(child);
			std::map<unsigned int, aiVector2D>::const_iterator it = t.uvs.find(id);
			if (it == t.uvs.end()) {
				ThrowException("uv index out of range");
			}

			out.uv = (*it).second;
			out.has_uv = true;
		} else if (s == "p") {
			out.pos = ReadVec3(child);
		} else if (s == "n") {
			out.normal = ReadVec3(child);
		} else if (s == "tc") {
			out.uv = ReadVec2(child);
		}
	}

	if (!havep) {
		ThrowException("missing <pref> in <fvN> element");
	}
}

// ------------------------------------------------------------------------------------------------
unsigned int XGLImporter::ReadIDAttr(XmlNode &node) {
	for (pugi::xml_attribute attr : node.attributes()) {
		if (!ASSIMP_stricmp(attr.name(), "id")) {
			return attr.as_int();
		}
	}

	return ~0u;
}

// ------------------------------------------------------------------------------------------------
float XGLImporter::ReadFloat(XmlNode &node) {
    std::string v;
    XmlParser::getValueAsString(node, v);
    const char *s = v.c_str(), *se;
	if (!SkipSpaces(&s)) {
		LogError("unexpected EOL, failed to parse index element");
		return 0.f;
	}
	float t;
	se = fast_atoreal_move(s, t);
	if (se == s) {
		LogError("failed to read float text");
		return 0.f;
	}

	return t;
}

// ------------------------------------------------------------------------------------------------
unsigned int XGLImporter::ReadIndexFromText(XmlNode &node) {
    std::string v;
    XmlParser::getValueAsString(node, v);
    const char *s = v.c_str();
	if (!SkipSpaces(&s)) {
		LogError("unexpected EOL, failed to parse index element");
		return ~0u;
	}
	const char *se;
	const unsigned int t = strtoul10(s, &se);

	if (se == s) {
		LogError("failed to read index");
		return ~0u;
	}

	return t;
}

// ------------------------------------------------------------------------------------------------
aiVector2D XGLImporter::ReadVec2(XmlNode &node) {
	aiVector2D vec;
    std::string val;
    XmlParser::getValueAsString(node, val);
    const char *s = val.c_str();
    ai_real v[2] = {};
	for (int i = 0; i < 2; ++i) {
		if (!SkipSpaces(&s)) {
			LogError("unexpected EOL, failed to parse vec2");
			return vec;
		}

		v[i] = fast_atof(&s);

		SkipSpaces(&s);
		if (i != 1 && *s != ',') {
			LogError("expected comma, failed to parse vec2");
			return vec;
		}
		++s;
	}
	vec.x = v[0];
	vec.y = v[1];

	return vec;
}

// ------------------------------------------------------------------------------------------------
aiVector3D XGLImporter::ReadVec3(XmlNode &node) {
	aiVector3D vec;
    std::string v;
    XmlParser::getValueAsString(node, v);
	const char *s = v.c_str();
	for (int i = 0; i < 3; ++i) {
		if (!SkipSpaces(&s)) {
			LogError("unexpected EOL, failed to parse vec3");
			return vec;
		}
		vec[i] = fast_atof(&s);

		SkipSpaces(&s);
		if (i != 2 && *s != ',') {
			LogError("expected comma, failed to parse vec3");
			return vec;
		}
		++s;
	}

	return vec;
}

// ------------------------------------------------------------------------------------------------
aiColor3D XGLImporter::ReadCol3(XmlNode &node) {
	const aiVector3D &v = ReadVec3(node);
	if (v.x < 0.f || v.x > 1.0f || v.y < 0.f || v.y > 1.0f || v.z < 0.f || v.z > 1.0f) {
		LogWarn("color values out of range, ignoring");
	}
	return aiColor3D(v.x, v.y, v.z);
}

#endif // ASSIMP_BUILD_NO_XGL_IMPORTER
