/*
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Open Asset Import Library (ASSIMP)
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Copyright (c) 2006-2008, ASSIMP Development Team

All rights reserved.

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*/

/** @file Implementation of the Collada loader */

#include "AssimpPCH.h"
#include "../include/aiAnim.h"
#include "ColladaLoader.h"
#include "ColladaParser.h"

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
ColladaLoader::ColladaLoader()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
ColladaLoader::~ColladaLoader()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file. 
bool ColladaLoader::CanRead( const std::string& pFile, IOSystem* pIOHandler) const
{
	// check file extension 
	std::string::size_type pos = pFile.find_last_of('.');
	// no file extension - can't read
	if( pos == std::string::npos)
		return false;
	std::string extension = pFile.substr( pos);
	for( std::string::iterator it = extension.begin(); it != extension.end(); ++it)
		*it = tolower( *it);

	if( extension == ".dae")
		return true;

	// XML - too generic, we need to open the file and search for typical keywords
	if( extension == ".xml")	{
		/*  If CanRead() is called in order to check whether we
		 *  support a specific file extension in general pIOHandler
		 *  might be NULL and it's our duty to return true here.
		 */
		if (!pIOHandler)return true;
		const char* tokens[] = {"collada"};
		return SearchFileHeaderForToken(pIOHandler,pFile,tokens,1);
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure. 
void ColladaLoader::InternReadFile( const std::string& pFile, aiScene* pScene, IOSystem* pIOHandler)
{
	mFileName = pFile;

	// parse the input file
	ColladaParser parser( pFile);

	if( !parser.mRootNode)
		throw new ImportErrorException( "File came out empty. Something is wrong here.");

	// create the materials first, for the meshes to find
	BuildMaterials( parser, pScene);

	// build the node hierarchy from it
	pScene->mRootNode = BuildHierarchy( parser, parser.mRootNode);

	// Convert to Z_UP, if different orientation
	if( parser.mUpDirection == ColladaParser::UP_X)
		pScene->mRootNode->mTransformation *= aiMatrix4x4( 
			 0, -1,  0,  0, 
			 0,  0, -1,  0,
			 1,  0,  0,  0,
			 0,  0,  0,  1);
	else if( parser.mUpDirection == ColladaParser::UP_Y)
		pScene->mRootNode->mTransformation *= aiMatrix4x4( 
			 1,  0,  0,  0, 
			 0,  0, -1,  0,
			 0,  1,  0,  0,
			 0,  0,  0,  1);

	// store all meshes
	StoreSceneMeshes( pScene);
}

// ------------------------------------------------------------------------------------------------
// Recursively constructs a scene node for the given parser node and returns it.
aiNode* ColladaLoader::BuildHierarchy( const ColladaParser& pParser, const Collada::Node* pNode)
{
	// create a node for it
	aiNode* node = new aiNode( pNode->mName);
	
	// calculate the transformation matrix for it
	node->mTransformation = pParser.CalculateResultTransform( pNode->mTransforms);

	// add children
	node->mNumChildren = pNode->mChildren.size();
	node->mChildren = new aiNode*[node->mNumChildren];
	for( unsigned int a = 0; a < pNode->mChildren.size(); a++)
	{
		node->mChildren[a] = BuildHierarchy( pParser, pNode->mChildren[a]);
		node->mChildren[a]->mParent = node;
	}

	// construct meshes
	BuildMeshesForNode( pParser, pNode, node);

	return node;
}

// ------------------------------------------------------------------------------------------------
// Builds meshes for the given node and references them
void ColladaLoader::BuildMeshesForNode( const ColladaParser& pParser, const Collada::Node* pNode, aiNode* pTarget)
{
	// accumulated mesh references by this node
	std::vector<size_t> newMeshRefs;

	// for the moment we simply ignore all material tags and transfer the meshes one by one
	BOOST_FOREACH( const Collada::MeshInstance& mid, pNode->mMeshes)
	{
		// find the referred mesh
		ColladaParser::MeshLibrary::const_iterator srcMeshIt = pParser.mMeshLibrary.find( mid.mMesh);
		if( srcMeshIt == pParser.mMeshLibrary.end())
		{
			DefaultLogger::get()->warn( boost::str( boost::format( "Unable to find geometry for ID \"%s\". Skipping.") % mid.mMesh));
			continue;
		}
		const Collada::Mesh* srcMesh = srcMeshIt->second;

		// build a mesh for each of its subgroups
		size_t vertexStart = 0, faceStart = 0;
		for( size_t sm = 0; sm < srcMesh->mSubMeshes.size(); ++sm)
		{
			const Collada::SubMesh& submesh = srcMesh->mSubMeshes[sm];
			// find material assigned to this submesh
			std::map<std::string, std::string>::const_iterator meshMatIt = mid.mMaterials.find( submesh.mMaterial);
			std::string meshMaterial;
			if( meshMatIt != mid.mMaterials.end())
				meshMaterial = meshMatIt->second;
			else
				DefaultLogger::get()->warn( boost::str( boost::format( "No material specified for subgroup \"%s\" in geometry \"%s\".") % submesh.mMaterial % mid.mMesh));

			// built lookup index of the Mesh-Submesh-Material combination
			ColladaMeshIndex index( mid.mMesh, sm, meshMaterial);

			// if we already have the mesh at the library, just add its index to the node's array
			std::map<ColladaMeshIndex, size_t>::const_iterator dstMeshIt = mMeshIndexByID.find( index);
			if( dstMeshIt != mMeshIndexByID.end())
			{
				newMeshRefs.push_back( dstMeshIt->second);
			} else
			{
				// else we have to add the mesh to the collection and store its newly assigned index at the node
				aiMesh* dstMesh = new aiMesh;

				// count the vertices addressed by its faces
				size_t numVertices = 
					std::accumulate( srcMesh->mFaceSize.begin() + faceStart, srcMesh->mFaceSize.begin() + faceStart + submesh.mNumFaces, 0);

				// copy positions
				dstMesh->mNumVertices = numVertices;
				dstMesh->mVertices = new aiVector3D[numVertices];
				std::copy( srcMesh->mPositions.begin() + vertexStart, srcMesh->mPositions.begin() + vertexStart + numVertices, dstMesh->mVertices);

				// normals, if given. HACK: (thom) Due to the fucking Collada spec we never know if we have the same
				// number of normals as there are positions. So we also ignore any vertex attribute if it has a different count
				if( srcMesh->mNormals.size() == srcMesh->mPositions.size())
				{
					dstMesh->mNormals = new aiVector3D[numVertices];
					std::copy( srcMesh->mNormals.begin() + vertexStart, srcMesh->mNormals.begin() + vertexStart + numVertices, dstMesh->mNormals);
				}

				// same for texturecoords, as many as we have
				for( size_t a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; a++)
				{
					if( srcMesh->mTexCoords[a].size() == srcMesh->mPositions.size())
					{
						dstMesh->mTextureCoords[a] = new aiVector3D[numVertices];
						for( size_t b = vertexStart; b < vertexStart + numVertices; ++b)
							dstMesh->mTextureCoords[a][b].Set( srcMesh->mTexCoords[a][b].x, srcMesh->mTexCoords[a][b].y, 0.0f);
						dstMesh->mNumUVComponents[a] = 2;
					}
				}

				// same for vertex colors, as many as we have
				for( size_t a = 0; a < AI_MAX_NUMBER_OF_COLOR_SETS; a++)
				{
					if( srcMesh->mColors[a].size() == srcMesh->mPositions.size())
					{
						dstMesh->mColors[a] = new aiColor4D[numVertices];
						std::copy( srcMesh->mColors[a].begin() + vertexStart, srcMesh->mColors[a].begin() + vertexStart + numVertices, dstMesh->mColors[a]);
					}
				}

				// create faces. Due to the fact that each face uses unique vertices, we can simply count up on each vertex
				size_t vertex = 0;
				dstMesh->mNumFaces = submesh.mNumFaces;
				dstMesh->mFaces = new aiFace[dstMesh->mNumFaces];
				for( size_t a = 0; a < dstMesh->mNumFaces; ++a)
				{
					size_t s = srcMesh->mFaceSize[ faceStart + a];
					aiFace& face = dstMesh->mFaces[a];
					face.mNumIndices = s;
					face.mIndices = new unsigned int[s];
					for( size_t b = 0; b < s; ++b)
						face.mIndices[b] = vertex++;
				}

				// store the mesh, and store its new index in the node
				newMeshRefs.push_back( mMeshes.size());
				mMeshIndexByID[index] = mMeshes.size();
				mMeshes.push_back( dstMesh);
				vertexStart += numVertices; faceStart += submesh.mNumFaces;

				// assign the material index
				std::map<std::string, size_t>::const_iterator matIt = mMaterialIndexByName.find( meshMaterial);
				if( matIt != mMaterialIndexByName.end())
					dstMesh->mMaterialIndex = matIt->second;
				else
					dstMesh->mMaterialIndex = 0;
			}
		}
	}

	// now place all mesh references we gathered in the target node
	pTarget->mNumMeshes = newMeshRefs.size();
	if( newMeshRefs.size())
	{
		pTarget->mMeshes = new unsigned int[pTarget->mNumMeshes];
		std::copy( newMeshRefs.begin(), newMeshRefs.end(), pTarget->mMeshes);
	}
}

// ------------------------------------------------------------------------------------------------
// Stores all meshes in the given scene
void ColladaLoader::StoreSceneMeshes( aiScene* pScene)
{
	pScene->mNumMeshes = mMeshes.size();
	if( mMeshes.size() > 0)
	{
		pScene->mMeshes = new aiMesh*[mMeshes.size()];
		std::copy( mMeshes.begin(), mMeshes.end(), pScene->mMeshes);
	}
}

// ------------------------------------------------------------------------------------------------
// Constructs materials from the collada material definitions
void ColladaLoader::BuildMaterials( const ColladaParser& pParser, aiScene* pScene)
{
	std::vector<aiMaterial*> newMats;

	for( ColladaParser::MaterialLibrary::const_iterator matIt = pParser.mMaterialLibrary.begin(); matIt != pParser.mMaterialLibrary.end(); ++matIt)
	{
		const Collada::Material& material = matIt->second;
		// a material is only a reference to an effect
		ColladaParser::EffectLibrary::const_iterator effIt = pParser.mEffectLibrary.find( material.mEffect);
		if( effIt == pParser.mEffectLibrary.end())
			continue;
		const Collada::Effect& effect = effIt->second;

		// create material
		Assimp::MaterialHelper* mat = new Assimp::MaterialHelper;
		aiString name( matIt->first);
		mat->AddProperty( &name, AI_MATKEY_NAME);

		int shadeMode;
		switch( effect.mShadeType)
		{
			case Collada::Shade_Constant: shadeMode = aiShadingMode_NoShading; break;
			case Collada::Shade_Lambert: shadeMode = aiShadingMode_Gouraud; break;
			case Collada::Shade_Blinn: shadeMode = aiShadingMode_Blinn; break;
			default: shadeMode = aiShadingMode_Phong; break;
		}
		mat->AddProperty<int>( &shadeMode, 1, AI_MATKEY_SHADING_MODEL);

		mat->AddProperty( &effect.mAmbient, 1, AI_MATKEY_COLOR_AMBIENT);
		mat->AddProperty( &effect.mDiffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
		mat->AddProperty( &effect.mSpecular, 1, AI_MATKEY_COLOR_SPECULAR);
		mat->AddProperty( &effect.mEmissive, 1, AI_MATKEY_COLOR_EMISSIVE);
		mat->AddProperty( &effect.mShininess, 1, AI_MATKEY_SHININESS);
		mat->AddProperty( &effect.mRefractIndex, 1, AI_MATKEY_REFRACTI);
		
		// add textures, if given
		if( !effect.mTexAmbient.empty())
			mat->AddProperty( &FindFilenameForEffectTexture( pParser, effect, effect.mTexAmbient), AI_MATKEY_TEXTURE_AMBIENT( 0));
		if( !effect.mTexDiffuse.empty())
			mat->AddProperty( &FindFilenameForEffectTexture( pParser, effect, effect.mTexDiffuse), AI_MATKEY_TEXTURE_DIFFUSE( 0));
		if( !effect.mTexEmissive.empty())
			mat->AddProperty( &FindFilenameForEffectTexture( pParser, effect, effect.mTexEmissive), AI_MATKEY_TEXTURE_EMISSIVE( 0));
		if( !effect.mTexSpecular.empty())
			mat->AddProperty( &FindFilenameForEffectTexture( pParser, effect, effect.mTexSpecular), AI_MATKEY_TEXTURE_SPECULAR( 0));

		// store the material
		mMaterialIndexByName[matIt->first] = newMats.size();
		newMats.push_back( mat);
	}

	// store a dummy material if none were given
	if( newMats.size() == 0)
	{
		Assimp::MaterialHelper* mat = new Assimp::MaterialHelper;
		aiString name( std::string( "dummy"));
		mat->AddProperty( &name, AI_MATKEY_NAME);

		int shadeMode = aiShadingMode_Phong;
		mat->AddProperty<int>( &shadeMode, 1, AI_MATKEY_SHADING_MODEL);
		aiColor4D colAmbient( 0.2f, 0.2f, 0.2f, 1.0f), colDiffuse( 0.8f, 0.8f, 0.8f, 1.0f), colSpecular( 0.5f, 0.5f, 0.5f, 0.5f);
		mat->AddProperty( &colAmbient, 1, AI_MATKEY_COLOR_AMBIENT);
		mat->AddProperty( &colDiffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
		mat->AddProperty( &colSpecular, 1, AI_MATKEY_COLOR_SPECULAR);
		float specExp = 5.0f;
		mat->AddProperty( &specExp, 1, AI_MATKEY_SHININESS);
	}

	// store the materials in the scene
	pScene->mNumMaterials = newMats.size();
	pScene->mMaterials = new aiMaterial*[pScene->mNumMaterials];
	std::copy( newMats.begin(), newMats.end(), pScene->mMaterials);
}

// ------------------------------------------------------------------------------------------------
// Resolves the texture name for the given effect texture entry
const aiString& ColladaLoader::FindFilenameForEffectTexture( const ColladaParser& pParser, const Collada::Effect& pEffect, const std::string& pName)
{
	// recurse through the param references until we end up at an image
	std::string name = pName;
	while( 1)
	{
		// the given string is a param entry. Find it
		Collada::Effect::ParamLibrary::const_iterator it = pEffect.mParams.find( name);
		// if not found, we're at the end of the recursion. The resulting string should be the image ID
		if( it == pEffect.mParams.end())
			break;

		// else recurse on
		name = it->second.mReference;
	}

	// find the image referred by this name in the image library of the scene
	ColladaParser::ImageLibrary::const_iterator imIt = pParser.mImageLibrary.find( name);
	if( imIt == pParser.mImageLibrary.end())
		throw new ImportErrorException( boost::str( boost::format( "Unable to resolve effect texture entry \"%s\", ended up at ID \"%s\".") % pName % name));

	static aiString result;
	result.Set( imIt->second.mFileName);
	return result;
}