/** Implementation of the BVH loader */
/*
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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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*/

#include "AssimpPCH.h"
#include "../include/aiAnim.h"
#include "BVHLoader.h"
#include "fast_atof.h"
#include "SkeletonMeshBuilder.h"

using namespace Assimp;

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

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

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file. 
bool BVHLoader::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 == ".bvh")
		return true;

	return false;
}

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

	// read file into memory
	boost::scoped_ptr<IOStream> file( pIOHandler->Open( pFile));
	if( file.get() == NULL)
		throw new ImportErrorException( "Failed to open file " + pFile + ".");

	size_t fileSize = file->FileSize();
	if( fileSize == 0)
		throw new ImportErrorException( "File is too small.");

	mBuffer.resize( fileSize);
	file->Read( &mBuffer.front(), 1, fileSize);

	// start reading
	mReader = mBuffer.begin();
	mLine = 1;
	ReadStructure( pScene);

	// build a dummy mesh for the skeleton so that we see something at least
	SkeletonMeshBuilder meshBuilder( pScene);

	// construct an animation from all the motion data we read
	CreateAnimation( pScene);
}

// ------------------------------------------------------------------------------------------------
// Reads the file
void BVHLoader::ReadStructure( aiScene* pScene)
{
	// first comes hierarchy
	std::string header = GetNextToken();
	if( header != "HIERARCHY")
		ThrowException( "Expected header string \"HIERARCHY\".");
	ReadHierarchy( pScene);

	// then comes the motion data
	std::string motion = GetNextToken();
	if( motion != "MOTION")
		ThrowException( "Expected beginning of motion data \"MOTION\".");
	ReadMotion( pScene);
}

// ------------------------------------------------------------------------------------------------
// Reads the hierarchy
void BVHLoader::ReadHierarchy( aiScene* pScene)
{
	std::string root = GetNextToken();
	if( root != "ROOT")
		ThrowException( "Expected root node \"ROOT\".");

	// Go read the hierarchy from here
	pScene->mRootNode = ReadNode();
}

// ------------------------------------------------------------------------------------------------
// Reads a node and recursively its childs and returns the created node;
aiNode* BVHLoader::ReadNode()
{
	// first token is name
	std::string nodeName = GetNextToken();
	if( nodeName.empty() || nodeName == "{")
		ThrowException( boost::str( boost::format( "Expected node name, but found \"%s\".") % nodeName));

	// then an opening brace should follow
	std::string openBrace = GetNextToken();
	if( openBrace != "{")
		ThrowException( boost::str( boost::format( "Expected opening brace \"{\", but found \"%s\".") % openBrace));

	// Create a node
	aiNode* node = new aiNode( nodeName);
	std::vector<aiNode*> childNodes;

	// and create an bone entry for it
	mNodes.push_back( Node( node));
	Node& internNode = mNodes.back();

	// now read the node's contents
	while( 1)
	{
		std::string token = GetNextToken();

		// node offset to parent node
		if( token == "OFFSET")
			ReadNodeOffset( node);
		else if( token == "CHANNELS")
			ReadNodeChannels( internNode);
		else if( token == "JOINT")
		{
			// child node follows
			aiNode* child = ReadNode();
			child->mParent = node;
			childNodes.push_back( child);
		} 
		else if( token == "End")
		{
			// The real symbol is "End Site". Second part comes in a separate token
			std::string siteToken = GetNextToken();
			if( siteToken != "Site")
				ThrowException( boost::str( boost::format( "Expected \"End Site\" keyword, but found \"%s %s\".") % token % siteToken));

			aiNode* child = ReadEndSite( nodeName);
			child->mParent = node;
			childNodes.push_back( child);
		} 
		else if( token == "}")
		{
			// we're done with that part of the hierarchy
			break;
		} else
		{
			// everything else is a parse error
			ThrowException( boost::str( boost::format( "Unknown keyword \"%s\".") % token));
		}
	}

	// add the child nodes if there are any
	if( childNodes.size() > 0)
	{
		node->mNumChildren = childNodes.size();
		node->mChildren = new aiNode*[node->mNumChildren];
		std::copy( childNodes.begin(), childNodes.end(), node->mChildren);
	}

	// and return the sub-hierarchy we built here
	return node;
}

// ------------------------------------------------------------------------------------------------
// Reads an end node and returns the created node.
aiNode* BVHLoader::ReadEndSite( const std::string& pParentName)
{
	// check opening brace
	std::string openBrace = GetNextToken();
	if( openBrace != "{")
		ThrowException( boost::str( boost::format( "Expected opening brace \"{\", but found \"%s\".") % openBrace));

	// Create a node
	aiNode* node = new aiNode( "EndSite_" + pParentName);

	// now read the node's contents. Only possible entry is "OFFSET"
	while( 1)
	{
		std::string token = GetNextToken();

		// end node's offset
		if( token == "OFFSET")
		{
			ReadNodeOffset( node);
		} 
		else if( token == "}")
		{
			// we're done with the end node
			break;
		} else
		{
			// everything else is a parse error
			ThrowException( boost::str( boost::format( "Unknown keyword \"%s\".") % token));
		}
	}

	// and return the sub-hierarchy we built here
	return node;
}
// ------------------------------------------------------------------------------------------------
// Reads a node offset for the given node
void BVHLoader::ReadNodeOffset( aiNode* pNode)
{
	// Offset consists of three floats to read
	aiVector3D offset;
	offset.x = GetNextTokenAsFloat();
	offset.y = GetNextTokenAsFloat();
	offset.z = GetNextTokenAsFloat();

	// build a transformation matrix from it
	pNode->mTransformation = aiMatrix4x4( 1.0f, 0.0f, 0.0f, offset.x, 0.0f, 1.0f, 0.0f, offset.y,
		0.0f, 0.0f, 1.0f, offset.z, 0.0f, 0.0f, 0.0f, 1.0f);
}

// ------------------------------------------------------------------------------------------------
// Reads the animation channels for the given node
void BVHLoader::ReadNodeChannels( BVHLoader::Node& pNode)
{
	// number of channels. Use the float reader because we're lazy
	float numChannelsFloat = GetNextTokenAsFloat();
	unsigned int numChannels = (unsigned int) numChannelsFloat;

	for( unsigned int a = 0; a < numChannels; a++)
	{
		std::string channelToken = GetNextToken();

		if( channelToken == "Xposition")
			pNode.mChannels.push_back( Channel_PositionX);
		else if( channelToken == "Yposition")
			pNode.mChannels.push_back( Channel_PositionY);
		else if( channelToken == "Zposition")
			pNode.mChannels.push_back( Channel_PositionZ);
		else if( channelToken == "Xrotation")
			pNode.mChannels.push_back( Channel_RotationX);
		else if( channelToken == "Yrotation")
			pNode.mChannels.push_back( Channel_RotationY);
		else if( channelToken == "Zrotation")
			pNode.mChannels.push_back( Channel_RotationZ);
		else
			ThrowException( boost::str( boost::format( "Invalid channel specifier \"%s\".") % channelToken));
	}
}

// ------------------------------------------------------------------------------------------------
// Reads the motion data
void BVHLoader::ReadMotion( aiScene* pScene)
{
	// Read number of frames
	std::string tokenFrames = GetNextToken();
	if( tokenFrames != "Frames:")
		ThrowException( boost::str( boost::format( "Expected frame count \"Frames:\", but found \"%s\".") % tokenFrames));

	float numFramesFloat = GetNextTokenAsFloat();
	mAnimNumFrames = (unsigned int) numFramesFloat;

	// Read frame duration
	std::string tokenDuration1 = GetNextToken();
	std::string tokenDuration2 = GetNextToken();
	if( tokenDuration1 != "Frame" || tokenDuration2 != "Time:")
		ThrowException( boost::str( boost::format( "Expected frame duration \"Frame Time:\", but found \"%s %s\".") % tokenDuration1 % tokenDuration2));

	mAnimTickDuration = GetNextTokenAsFloat();

	// resize value vectors for each node
	for( std::vector<Node>::iterator it = mNodes.begin(); it != mNodes.end(); ++it)
		it->mChannelValues.reserve( it->mChannels.size() * mAnimNumFrames);

	// now read all the data and store it in the corresponding node's value vector
	for( unsigned int frame = 0; frame < mAnimNumFrames; ++frame)
	{
		// on each line read the values for all nodes
		for( std::vector<Node>::iterator it = mNodes.begin(); it != mNodes.end(); ++it)
		{
			// get as many values as the node has channels
			for( unsigned int c = 0; c < it->mChannels.size(); ++c)
				it->mChannelValues.push_back( GetNextTokenAsFloat());
		}

		// after one frame worth of values for all nodes there should be a newline, but we better don't rely on it
	}
}

// ------------------------------------------------------------------------------------------------
// Retrieves the next token
std::string BVHLoader::GetNextToken()
{
	// skip any preceeding whitespace
	while( mReader != mBuffer.end())
	{
		if( !isspace( *mReader))
			break;

		// count lines
		if( *mReader == '\n')
			mLine++;

		++mReader;
	}

	// collect all chars till the next whitespace. BVH is easy in respect to that.
	std::string token;
	while( mReader != mBuffer.end())
	{
		if( isspace( *mReader))
			break;

		token.push_back( *mReader);
		++mReader;

		// little extra logic to make sure braces are counted correctly
		if( token == "{" || token == "}")
			break;
	}

	// empty token means end of file, which is just fine
	return token;
}

// ------------------------------------------------------------------------------------------------
// Reads the next token as a float
float BVHLoader::GetNextTokenAsFloat()
{
	std::string token = GetNextToken();
	if( token.empty())
		ThrowException( "Unexpected end of file while trying to read a float");

	// check if the float is valid by testing if the atof() function consumed every char of the token
	const char* ctoken = token.c_str();
	float result = 0.0f;
	ctoken = fast_atof_move( ctoken, result);

	if( ctoken != token.c_str() + token.length())
		ThrowException( boost::str( boost::format( "Expected a floating point number, but found \"%s\".") % token));

	return result;
}

// ------------------------------------------------------------------------------------------------
// Aborts the file reading with an exception
void BVHLoader::ThrowException( const std::string& pError)
{
	throw new ImportErrorException( boost::str( boost::format( "%s:%d - %s") % mFileName % mLine % pError));
}

// ------------------------------------------------------------------------------------------------
// Constructs an animation for the motion data and stores it in the given scene
void BVHLoader::CreateAnimation( aiScene* pScene)
{
	// create the animation
	pScene->mNumAnimations = 1;
	pScene->mAnimations = new aiAnimation*[1];
	aiAnimation* anim = new aiAnimation;
	pScene->mAnimations[0] = anim;

	// put down the basic parameters
	anim->mName.Set( "Motion");
	anim->mTicksPerSecond = 1.0 / double( mAnimTickDuration);
	anim->mDuration = double( mAnimNumFrames - 1);

	// now generate the tracks for all nodes
	anim->mNumChannels = mNodes.size();
	anim->mChannels = new aiNodeAnim*[anim->mNumChannels];
	for( unsigned int a = 0; a < anim->mNumChannels; a++)
	{
		const Node& node = mNodes[a];
		const char* nodeName = node.mNode->mName.data;
		aiNodeAnim* nodeAnim = new aiNodeAnim;
		anim->mChannels[a] = nodeAnim;
		nodeAnim->mNodeName.Set( std::string( nodeName));

		// translational part, if given
		if( node.mChannels.size() == 6)
		{
			if( node.mChannels[0] != Channel_PositionX || node.mChannels[1] != Channel_PositionY
				|| node.mChannels[2] != Channel_PositionZ)
			{
				throw new ImportErrorException( boost::str( boost::format( "Unexpected animation "
					"channel setup at node \"%s\".") % nodeName));
			}

			nodeAnim->mNumPositionKeys = mAnimNumFrames;
			nodeAnim->mPositionKeys = new aiVectorKey[mAnimNumFrames];
			aiVectorKey* poskey = nodeAnim->mPositionKeys;
			for( unsigned int fr = 0; fr < mAnimNumFrames; ++fr)
			{
				poskey->mTime = double( fr);
				poskey->mValue.x = node.mChannelValues[fr * node.mChannels.size() + 0];
				poskey->mValue.z = node.mChannelValues[fr * node.mChannels.size() + 1];
				poskey->mValue.y = node.mChannelValues[fr * node.mChannels.size() + 2];
				++poskey;
			}
		} else
		{
			// if no translation part is given, put a default sequence
			aiVector3D nodePos( node.mNode->mTransformation.a4, node.mNode->mTransformation.b4, node.mNode->mTransformation.c4);
			nodeAnim->mNumPositionKeys = 1;
			nodeAnim->mPositionKeys = new aiVectorKey[1];
			nodeAnim->mPositionKeys[0].mTime = 0.0;
			nodeAnim->mPositionKeys[0].mValue = nodePos;
		}

		// rotation part. Always present. First find value offsets
		{
			unsigned int rotOffset = 0;
			if( node.mChannels.size() == 6)
			{
				if( node.mChannels[3] != Channel_RotationZ || node.mChannels[4] != Channel_RotationX
					|| node.mChannels[5] != Channel_RotationY)
				{
					throw new ImportErrorException( boost::str( boost::format( "Unexpected animation "
						"channel setup at node \"%s\".") % nodeName));
				}
				rotOffset = 3;
			} else
			{
				if( node.mChannels[0] != Channel_RotationZ || node.mChannels[1] != Channel_RotationX
					|| node.mChannels[2] != Channel_RotationY || node.mChannels.size() != 3)
				{
					throw new ImportErrorException( boost::str( boost::format( "Unexpected animation "
						"channel setup at node \"%s\".") % nodeName));
				}
			}

			// Then create the number of rotation keys
			nodeAnim->mNumRotationKeys = mAnimNumFrames;
			nodeAnim->mRotationKeys = new aiQuatKey[mAnimNumFrames];
			aiQuatKey* rotkey = nodeAnim->mRotationKeys;
			for( unsigned int fr = 0; fr < mAnimNumFrames; ++fr)
			{
				// translate ZXY euler angels into a quaternion
				float angleZ = node.mChannelValues[fr * node.mChannels.size() + rotOffset + 0] * float( AI_MATH_PI) / 180.0f;
				float angleX = node.mChannelValues[fr * node.mChannels.size() + rotOffset + 1] * float( AI_MATH_PI) / 180.0f;
				float angleY = node.mChannelValues[fr * node.mChannels.size() + rotOffset + 2] * float( AI_MATH_PI) / 180.0f;
				aiMatrix4x4 temp;
				aiMatrix3x3 rotMatrix;
				aiMatrix4x4::RotationZ( angleZ, temp); rotMatrix *= aiMatrix3x3( temp);
				aiMatrix4x4::RotationX( angleX, temp); rotMatrix *= aiMatrix3x3( temp);
				aiMatrix4x4::RotationY( angleY, temp); rotMatrix *= aiMatrix3x3( temp);

				rotkey->mTime = double( fr);
				rotkey->mValue = aiQuaternion( rotMatrix);
				++rotkey;
			}
		}

		// scaling part. Always just a default track
		{
			nodeAnim->mNumScalingKeys = 1;
			nodeAnim->mScalingKeys = new aiVectorKey[1];
			nodeAnim->mScalingKeys[0].mTime = 0.0;
			nodeAnim->mScalingKeys[0].mValue.Set( 1.0f, 1.0f, 1.0f);
		}
	}
}
