/** Implementation of the Collada parser helper*/
/*
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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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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
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*/

#include "AssimpPCH.h"
#include "ColladaParser.h"
#include "fast_atof.h"
#include "ParsingUtils.h"

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
ColladaParser::ColladaParser( const std::string& pFile)
	: mFileName( pFile)
{
	mRootNode = NULL;
	mUnitSize = 1.0f;
	mUpDirection = UP_Z;

	// generate a XML reader for it
	mReader = irr::io::createIrrXMLReader( pFile.c_str());
	if( !mReader)
		ThrowException( "Unable to open file.");

	// start reading
	ReadContents();
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
ColladaParser::~ColladaParser()
{
	delete mReader;
	for( NodeLibrary::iterator it = mNodeLibrary.begin(); it != mNodeLibrary.end(); ++it)
		delete it->second;
}

// ------------------------------------------------------------------------------------------------
// Reads the contents of the file
void ColladaParser::ReadContents()
{
	while( mReader->read())
	{
		// handle the root element "COLLADA"
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			if( IsElement( "COLLADA"))
			{
				ReadStructure();
			} else
			{
				DefaultLogger::get()->debug( boost::str( boost::format( "Ignoring global element \"%s\".") % mReader->getNodeName()));
				SkipElement();
			}
		} else
		{
			// skip everything else silently
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Reads the structure of the file
void ColladaParser::ReadStructure()
{
	while( mReader->read())
	{
		// beginning of elements
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			if( IsElement( "asset"))
				ReadAssetInfo();
			else if( IsElement( "library_geometries"))
				ReadGeometryLibrary();
			else if( IsElement( "library_visual_scenes"))
				ReadSceneLibrary();
			else if( IsElement( "scene"))
				ReadScene();
			else
				SkipElement();
		} 
		else if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
		{
			break;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Reads asset informations such as coordinate system informations and legal blah
void ColladaParser::ReadAssetInfo()
{
	while( mReader->read())
	{
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			if( IsElement( "unit"))
			{
				// read unit data from the element's attributes
				int attrIndex = GetAttribute( "meter");
				mUnitSize = mReader->getAttributeValueAsFloat( attrIndex);

				// consume the trailing stuff
				if( !mReader->isEmptyElement())
					SkipElement();
			} 
			else if( IsElement( "up_axis"))
			{
				// read content, strip whitespace, compare
				const char* content = GetTextContent();
				if( strncmp( content, "X_UP", 4) == 0)
					mUpDirection = UP_X;
				else if( strncmp( content, "Y_UP", 4) == 0)
					mUpDirection = UP_Y;
				else
					mUpDirection = UP_Z;

				// check element end
				TestClosing( "up_axis");
			} else
			{
				SkipElement();
			}
		} 
		else if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
		{
			break;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Reads the geometry library contents
void ColladaParser::ReadGeometryLibrary()
{
	SkipElement();
}

// ------------------------------------------------------------------------------------------------
// Reads the library of node hierarchies and scene parts
void ColladaParser::ReadSceneLibrary()
{
	while( mReader->read())
	{
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			// a visual scene - generate root node under its ID and let ReadNode() do the recursive work
			if( IsElement( "visual_scene"))
			{
				// read ID. Is optional according to the spec, but how on earth should a scene_instance refer to it then?
				int indexID = GetAttribute( "id");
				const char* attrID = mReader->getAttributeValue( indexID);

				// read name if given. 
				int indexName = TestAttribute( "name");
				const char* attrName = "unnamed";
				if( indexName > -1)
					attrName = mReader->getAttributeValue( indexName);

				// TODO: (thom) support SIDs
				assert( TestAttribute( "sid") == -1);

				// create a node and store it in the library under its ID
				Node* node = new Node;
				node->mID = attrID;
				node->mName = attrName;
				mNodeLibrary[node->mID] = node;

				ReadSceneNode( node);
			} else
			{
				// ignore the rest
				SkipElement();
			}
		}
		else if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
		{
			break;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Reads a scene node's contents including children and stores it in the given node
void ColladaParser::ReadSceneNode( Node* pNode)
{
	// quit immediately on <bla/> elements
	if( mReader->isEmptyElement())
		return;

	while( mReader->read())
	{
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			if( IsElement( "lookat"))
				ReadNodeTransformation( pNode, TF_LOOKAT);
			else if( IsElement( "matrix"))
				ReadNodeTransformation( pNode, TF_MATRIX);
			else if( IsElement( "rotate"))
				ReadNodeTransformation( pNode, TF_ROTATE);
			else if( IsElement( "scale"))
				ReadNodeTransformation( pNode, TF_SCALE);
			else if( IsElement( "skew"))
				ReadNodeTransformation( pNode, TF_SKEW);
			else if( IsElement( "translate"))
				ReadNodeTransformation( pNode, TF_TRANSLATE);
			else if( IsElement( "node"))
			{
				Node* child = new Node;
				int attrID = TestAttribute( "id");
				if( attrID > -1)
					child->mID = mReader->getAttributeValue( attrID);

				int attrName = TestAttribute( "name");
				if( attrName > -1)
					child->mName = mReader->getAttributeValue( attrName);

				// TODO: (thom) support SIDs
				assert( TestAttribute( "sid") == -1);

				pNode->mChildren.push_back( child);
				child->mParent = pNode;

				// read on recursively from there
				ReadSceneNode( child);
			} else if( IsElement( "instance_node"))
			{
				// test for it, in case we need to implement it
				assert( false);
				SkipElement();
			} else
			{
				// skip everything else for the moment
				SkipElement();
			}
		} 
		else if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
		{
			break;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Reads a node transformation entry of the given type and adds it to the given node's transformation list.
void ColladaParser::ReadNodeTransformation( Node* pNode, TransformType pType)
{
	std::string tagName = mReader->getNodeName();

	// how many parameters to read per transformation type
	static const unsigned int sNumParameters[] = { 9, 4, 3, 3, 7, 16 };
	const char* content = GetTextContent();

	// read as many parameters and store in the transformation
	Transform tf;
	tf.mType = pType;
	for( unsigned int a = 0; a < sNumParameters[pType]; a++)
	{
		// read a number
		content = fast_atof_move( content, tf.f[a]);
		// skip whitespace after it
		SkipSpacesAndLineEnd( &content);
	}

	// place the transformation at the queue of the node
	pNode->mTransforms.push_back( tf);

	// and consum the closing tag
	TestClosing( tagName.c_str());
}

// ------------------------------------------------------------------------------------------------
// Reads the collada scene
void ColladaParser::ReadScene()
{
	while( mReader->read())
	{
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT)
		{
			if( IsElement( "instance_visual_scene"))
			{
				// should be the first and only occurence
				if( mRootNode)
					ThrowException( "Invalid scene containing multiple root nodes");

				// read the url of the scene to instance. Should be of format "#some_name"
				int urlIndex = GetAttribute( "url");
				const char* url = mReader->getAttributeValue( urlIndex);
				if( url[0] != '#')
					ThrowException( "Unknown reference format");

				// find the referred scene, skip the leading # 
				NodeLibrary::const_iterator sit = mNodeLibrary.find( url+1);
				if( sit == mNodeLibrary.end())
					ThrowException( boost::str( boost::format( "Unable to resolve visual_scene reference \"%s\".") % url));
				mRootNode = sit->second;
			} else
			{
				SkipElement();
			}
		} 
		else if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
		{
			break;
		} 
	}
}

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

// ------------------------------------------------------------------------------------------------
// Skips all data until the end node of the current element
void ColladaParser::SkipElement()
{
	// nothing to skip if it's an <element />
	if( mReader->isEmptyElement())
		return;

	// copy the current node's name because it'a pointer to the reader's internal buffer, 
	// which is going to change with the upcoming parsing 
	std::string element = mReader->getNodeName();
	while( mReader->read())
	{
		if( mReader->getNodeType() == irr::io::EXN_ELEMENT_END)
			if( mReader->getNodeName() == element)
				break;
	}
}

// ------------------------------------------------------------------------------------------------
// Tests for the closing tag of the given element, throws an exception if not found
void ColladaParser::TestClosing( const char* pName)
{
	// read closing tag
	if( !mReader->read())
		ThrowException( boost::str( boost::format( "Unexpected end of file while reading end of \"%s\" element.") % pName));
	if( mReader->getNodeType() != irr::io::EXN_ELEMENT_END || strcmp( mReader->getNodeName(), pName) != 0)
		ThrowException( boost::str( boost::format( "Expected end of \"%s\" element.") % pName));
}

// ------------------------------------------------------------------------------------------------
// Returns the index of the named attribute or -1 if not found. Does not throw, therefore useful for optional attributes
int ColladaParser::GetAttribute( const char* pAttr) const
{
	int index = TestAttribute( pAttr);
	if( index != -1)
		return index;

	// attribute not found -> throw an exception
	ThrowException( boost::str( boost::format( "Expected attribute \"%s\" at element \"%s\".") % pAttr % mReader->getNodeName()));
	return -1;
}

// ------------------------------------------------------------------------------------------------
// Tests the present element for the presence of one attribute, returns its index or throws an exception if not found
int ColladaParser::TestAttribute( const char* pAttr) const
{
	for( int a = 0; a < mReader->getAttributeCount(); a++)
		if( strcmp( mReader->getAttributeName( a), pAttr) == 0)
			return a;

	return -1;
}

// ------------------------------------------------------------------------------------------------
// Reads the text contents of an element, throws an exception if not given. Skips leading whitespace.
const char* ColladaParser::GetTextContent()
{
	// present node should be the beginning of an element
	if( mReader->getNodeType() != irr::io::EXN_ELEMENT || mReader->isEmptyElement())
		ThrowException( "Expected opening element");

	// read contents of the element
	if( !mReader->read())
		ThrowException( "Unexpected end of file while reading asset up_axis element.");
	if( mReader->getNodeType() != irr::io::EXN_TEXT)
		ThrowException( "Invalid contents in element \"up_axis\".");

	// skip leading whitespace
	const char* text = mReader->getNodeData();
	SkipSpacesAndLineEnd( &text);

	return text;
}

// ------------------------------------------------------------------------------------------------
// Calculates the resulting transformation fromm all the given transform steps
aiMatrix4x4 ColladaParser::CalculateResultTransform( const std::vector<Transform>& pTransforms) const
{
	aiMatrix4x4 res;

	for( std::vector<Transform>::const_iterator it = pTransforms.begin(); it != pTransforms.end(); ++it)
	{
		const Transform& tf = *it;
		switch( tf.mType)
		{
			case TF_LOOKAT:
				// TODO: (thom)
				assert( false);
				break;
			case TF_ROTATE:
			{
				aiMatrix4x4 rot;
				aiMatrix4x4::Rotation( tf.f[3], aiVector3D( tf.f[0], tf.f[1], tf.f[2]), rot);
				res *= rot;
				break;
			}
			case TF_TRANSLATE:
			{
				aiMatrix4x4 trans;
				aiMatrix4x4::Translation( aiVector3D( tf.f[0], tf.f[1], tf.f[2]), trans);
				res *= trans;
				break;
			}
			case TF_SCALE:
			{
				aiMatrix4x4 scale( tf.f[0], 0.0f, 0.0f, 0.0f, 0.0f, tf.f[1], 0.0f, 0.0f, 0.0f, 0.0f, tf.f[2], 0.0f, 
					0.0f, 0.0f, 0.0f, 1.0f);
				res *= scale;
				break;
			}
			case TF_SKEW:
				// TODO: (thom)
				assert( false);
				break;
			case TF_MATRIX:
			{
				aiMatrix4x4 mat( tf.f[0], tf.f[1], tf.f[2], tf.f[3], tf.f[4], tf.f[5], tf.f[6], tf.f[7],
					tf.f[8], tf.f[9], tf.f[10], tf.f[11], tf.f[12], tf.f[13], tf.f[14], tf.f[15]);
				res *= mat;
				break;
			}
			default: 
				assert( false);
				break;
		}
	}

	return res;
}