// Copyright (C) 2014-2015 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

#include "nv/formats/assimp_loader.hh"

#include "nv/interface/data_channel_access.hh"
#include "nv/stl/hash_store.hh"
#include "nv/lib/assimp.hh"

using namespace nv;

const unsigned MAX_BONES = 64;

struct assimp_plain_vtx 
{
	vec3 position;
	vec3 normal;
	vec2 texcoord;
	vec4 tangent;

	assimp_plain_vtx() {}
	assimp_plain_vtx( const vec3& v, const vec2& t, const vec3& n, const vec4& g )
	{
		position = v;
		texcoord = t;
		normal   = n;
		tangent  = g;
	}
};

struct assimp_skinned_vtx 
{
	vec3  position;
	vec3  normal;
	vec2  texcoord;
	vec4  tangent;
	ivec4 boneindex;
	vec4  boneweight;

	assimp_skinned_vtx() {}
	assimp_skinned_vtx( const vec3& v, const vec2& t, const vec3& n, const vec4& g )
	{
		position = v;
		texcoord = t;
		normal   = n;
		tangent  = g;
	}
};

struct assimp_key_p  { float time; vec3 translation; };
struct assimp_key_r  { float time; quat rotation; };
struct assimp_key_s  { float time; vec3 scale; };
struct assimp_key_tr { transform tform; };


nv::assimp_loader::assimp_loader( string_table* strings, const string_view& a_ext, uint32 a_assimp_flags /*= 0 */ )
	: mesh_loader( strings ), m_scene( nullptr ), m_mesh_count(0)
{
	m_ext   = a_ext;
	m_assimp_flags = a_assimp_flags;
	if ( m_assimp_flags == 0 )
	{
		m_assimp_flags = ( 
			aiProcess_CalcTangentSpace				|  
			aiProcess_GenSmoothNormals				|  
			aiProcess_JoinIdenticalVertices			|   
			aiProcess_ImproveCacheLocality			|  
			aiProcess_LimitBoneWeights				|  
			aiProcess_RemoveRedundantMaterials      |  
			aiProcess_SplitLargeMeshes				|  
			aiProcess_Triangulate					|  
			aiProcess_GenUVCoords                   |  
			aiProcess_SortByPType                   |  
			aiProcess_FindDegenerates               |  
			aiProcess_FindInvalidData               |  
			0 );
	}
}


bool nv::assimp_loader::load( stream& source )
{
	load_assimp_library();
	if ( m_scene != nullptr ) aiReleaseImport( reinterpret_cast<const aiScene*>( m_scene ) );
	m_scene = nullptr;
	m_mesh_count = 0;
	NV_LOG_NOTICE( "AssImp loading file..." );
	size_t size = source.size();
	char* data  = new char[ size ];
	source.read( data, size, 1 );
	const aiScene* scene = aiImportFileFromMemory( data, size, m_assimp_flags, m_ext.data() );

	if( !scene)
	{
		NV_LOG_ERROR( aiGetErrorString() );
		return false;
	}
	m_scene      = scene;
	m_mesh_count = scene->mNumMeshes;
	NV_LOG_NOTICE( "Loading successfull" );
	return true;
}

data_channel_set* nv::assimp_loader::release_mesh_data( size_t index /*= 0 */ )
{
	if ( index >= m_mesh_count ) return nullptr;
	data_channel_set* result = data_channel_set_creator::create_set( 2 );
	load_mesh_data( result, index );
	return result;
}
void nv::assimp_loader::load_mesh_data( data_channel_set* data, size_t index )
{
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	const aiMesh*  mesh  = scene->mMeshes[ index ];

	bool skinned = mesh->mNumBones > 0;

	data_descriptor desc;
	if ( skinned )
		desc.initialize< assimp_skinned_vtx >();
	else
		desc.initialize< assimp_plain_vtx >();
	data_channel_set_creator maccess( data );
	const char* name = mesh->mName.data;
	maccess.set_name( make_name( name ) );
	uint8*  cdata   = maccess.add_channel( desc, mesh->mNumVertices ).raw_data();
	uint16* indices = reinterpret_cast<uint16*>( maccess.add_channel< index_u16 >( mesh->mNumFaces * 3 ).raw_data() );

	if ( mesh->mTangents && mesh->mBitangents )
		for ( unsigned int i = 0; i < mesh->mNumVertices; i++ )
		{
			vec3 v = assimp_vec3_cast( mesh->mVertices[i] );
			vec3 n = math::normalize( assimp_vec3_cast( mesh->mNormals[i] ) );
			vec3 t = math::normalize( assimp_vec3_cast( mesh->mTangents[i] ) );
			vec3 b = math::normalize( assimp_vec3_cast( mesh->mBitangents[i] ) );
			vec2 s = assimp_st_cast( mesh->mTextureCoords[0][i] );

			vec3 t_i = math::normalize( t - n * math::dot( n, t ) );
			float det = ( math::dot( math::cross( n, t ), b ) );
			det = ( det < 0.0f ? -1.0f : 1.0f );
			nv::vec4 vt( t_i[0], t_i[1], t_i[2], det );
			if ( skinned )
				reinterpret_cast<assimp_skinned_vtx*>( cdata )[i] = assimp_skinned_vtx( v, s, n, vt );
			else
				reinterpret_cast<assimp_plain_vtx*>( cdata )[i] = assimp_plain_vtx( v, s, n, vt );
		}

	if ( skinned )
	{
		assimp_skinned_vtx* vtx = reinterpret_cast< assimp_skinned_vtx* >( cdata );
		for (unsigned int m=0; m<mesh->mNumBones; m++)
		{
			aiBone* bone  = mesh->mBones[m];
			for (unsigned int w=0; w<bone->mNumWeights; w++)
			{
				assimp_skinned_vtx& v = vtx[ bone->mWeights[w].mVertexId ];
				bool found = false;
				for ( int i = 0 ; i < 4; ++i )
				{
					if ( v.boneweight[i] <= 0.0f ) 
					{
						v.boneindex[i]  = int( m );
						v.boneweight[i] = bone->mWeights[w].mWeight;
						found = true;
						break;
					}
				}
				NV_ASSERT( found, "Too many weights!" );
			}
		}
	}

	for (unsigned int i=0; i<mesh->mNumFaces; i++)
	{
		const aiFace* face = &mesh->mFaces[i];
		for (unsigned int j=0; j<face->mNumIndices; j++)
		{
			indices[ i*3 + j ] = uint16( face->mIndices[j] );
		}
	}

}

nv::assimp_loader::~assimp_loader()
{
	if ( m_scene != nullptr ) aiReleaseImport( reinterpret_cast<const aiScene*>( m_scene ) );
}

bool nv::assimp_loader::load_bones( size_t index, array_ref< data_channel_set* > bones )
{
	if ( m_scene == nullptr ) return false;
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	const aiMesh*  mesh  = scene->mMeshes[ index ];

	for (unsigned int m=0; m<mesh->mNumBones; m++)
	{
		aiBone* bone   = mesh->mBones[m];
		mat4    offset = assimp_mat4_cast( bone->mOffsetMatrix );
		bones[m] = data_channel_set_creator::create_set( 0 );
		data_channel_set_creator access( bones[m] );
		const char* name = bone->mName.data;
		access.set_name( make_name( name ) );
		access.set_transform( offset );
	}
	return true;
}

void nv::assimp_loader::scene_report() const
{
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	if ( scene == nullptr ) return;

	NV_LOG_NOTICE( "------------------------" );
	NV_LOG_NOTICE( "Texture   count - ", scene->mNumTextures );
	NV_LOG_NOTICE( "Animation count - ", scene->mNumAnimations );
	NV_LOG_NOTICE( "Material  count - ", scene->mNumMaterials );
	NV_LOG_NOTICE( "Meshes    count - ", scene->mNumMeshes );
	NV_LOG_NOTICE( "------------------------" );

	aiNode* root = scene->mRootNode;
	if (root)
	{
		NV_LOG_NOTICE( "Root node  - ", root->mName.data );
		NV_LOG_NOTICE( "  meshes   - ", root->mNumMeshes );
		NV_LOG_NOTICE( "  children - ", root->mNumChildren );
	}
	else
	{
		NV_LOG_NOTICE( "No root node!" );
	}
	NV_LOG_NOTICE( "------------------------" );

	if ( scene->mNumMeshes > 0 )
	{
		for ( nv::uint32 mc = 0; mc < scene->mNumMeshes; mc++ )
		{
			aiMesh* mesh = scene->mMeshes[mc];

			NV_LOG_NOTICE( "Mesh #", mc, "   - ", string_view( static_cast<char*>( mesh->mName.data ) ) );
			NV_LOG_NOTICE( "  bones   - ", mesh->mNumBones );
			NV_LOG_NOTICE( "  uvs     - ", mesh->mNumUVComponents[0] );
			NV_LOG_NOTICE( "  verts   - ", mesh->mNumVertices );
			NV_LOG_NOTICE( "  faces   - ", mesh->mNumFaces );

			// 			NV_LOG_NOTICE(  "Bones:" );
			// 			for (unsigned int m=0; m<mesh->mNumBones; m++)
			// 			{
			// 				aiBone* bone  = mesh->mBones[m];
			// 				NV_LOG_NOTICE( bone->mName.C_Str() );
			// 			}
		}
	}
	else
	{
		NV_LOG_NOTICE( "No meshes!" );
	}
	NV_LOG_NOTICE( "------------------------" );


	// 	if ( scene->mNumMaterials > 0 )
	// 	{
	// 		for (unsigned int m=0; m < scene->mNumMaterials; m++)
	// 		{
	// 			int texIndex = 0;
	// 			aiReturn texFound = aiReturn_SUCCESS;
	// 			aiString path;	// filename
	//  			while (texFound == aiReturn_SUCCESS)
	//  			{
	// 				texFound = scene->mMaterials[m]->GetTexture(aiTextureType_DIFFUSE, texIndex, &path);
	// 				NV_LOG_NOTICE( "  material - ", path.data );
	// 				texIndex++;
	// 			}
	// 		}
	// 	}
	// 	else
	// 	{
	// 		NV_LOG_NOTICE( "No materials" );
	// 	}
	// 	NV_LOG_NOTICE( "------------------------" );

}

mesh_nodes_data* nv::assimp_loader::release_merged_bones( data_channel_set* meshes )
{
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	mesh_nodes_data* result = new mesh_nodes_data( make_name( "bones" ) );
	hash_store< shash64, uint16 > names;
	for ( unsigned int m = 0; m < m_mesh_count; ++m )
	{
		uint16 translate[MAX_BONES];
		vector< data_channel_set* > bones;
		const aiMesh*  mesh  = scene->mMeshes[ m ];
		if ( mesh->mNumBones != 0 )
		{
			bones.resize( mesh->mNumBones );
			load_bones( m, bones );
			for ( unsigned int b = 0; b < mesh->mNumBones; ++b )
			{

				data_channel_set* bone = bones[b];
				auto iname = names.find( bone->get_name() );
				if ( iname == names.end() )
				{
					NV_ASSERT( result->size() < MAX_BONES, "Too many bones to merge!" );
					uint16 index = uint16( result->size() );
					result->append( bone );
					names[ bone->get_name() ] = index;
					translate[b] = index;
				}
				else
				{
					translate[b] = iname->second;
				}
			}
			if ( m > 0 && bones.size() > 0 )
			{
				data_channel_access< assimp_skinned_vtx > channel( const_cast< raw_data_channel* >( meshes[m].get_channel(0) ) );
				for ( unsigned v = 0; v < channel.size(); ++v )
				{
					assimp_skinned_vtx& vertex = channel.data()[v];

					for ( int i = 0 ; i < 4; ++i)
					{
						if ( vertex.boneweight[i] > 0.0f ) 
						{
							vertex.boneindex[i] = int( translate[vertex.boneindex[i]] );
						}
					}
				}
			}
		}	
	}
	result->initialize();

	return result;
}

mesh_nodes_data* nv::assimp_loader::release_mesh_nodes_data( size_t index /*= 0*/ )
{
	if ( m_scene == nullptr ) return nullptr;
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	if ( scene->mRootNode == nullptr || scene->mAnimations == nullptr || scene->mAnimations[index] == nullptr) return nullptr;

	const aiNode*      root = scene->mRootNode;
	const aiAnimation* anim = scene->mAnimations[index];

	uint32 count = count_nodes( scene->mRootNode );

	uint16 frame_rate     = static_cast<uint16>( anim->mTicksPerSecond );
	uint16 duration       = static_cast<uint16>( anim->mDuration );
	bool   flat           = false;

	data_channel_set** temp = new data_channel_set*[ count ];
	array_ref< data_channel_set* > temp_ref( temp, count );
	load_node( index, temp_ref, root, 0, -1 );

	mesh_nodes_data* result = new mesh_nodes_data( make_name( static_cast<const char*>( anim->mName.data ) ), frame_rate, duration, flat );
	for ( auto set : temp_ref )
	{
		result->append( set );
	}
	result->initialize();
	delete temp;
	return result;
}

nv::uint32 nv::assimp_loader::count_nodes( const void* node ) const
{
	const aiNode* ainode = reinterpret_cast< const aiNode* >( node );
	nv::uint32 count = 1;
	for ( unsigned i = 0; i < ainode->mNumChildren; ++i )
	{
		count += count_nodes( ainode->mChildren[i] );
	}
	return count;
}

nv::sint16 nv::assimp_loader::load_node( uint32 anim_id, array_ref< data_channel_set* > nodes, const void* vnode, sint16 this_id, sint16 parent_id )
{
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	const aiNode*  node  = reinterpret_cast<const aiNode*>( vnode );
	string_view name( static_cast< const char* >( node->mName.data ) );
	const aiAnimation* anim  = scene->mAnimations[anim_id];
	const aiNodeAnim*  anode = nullptr;

	for ( unsigned i = 0 ; i < anim->mNumChannels ; i++ )
	{
		anode = anim->mChannels[i];
		if ( string_view( static_cast< const char* >( anode->mNodeName.data ) ) == name ) break;
		anode = nullptr;
	}

	nodes[ this_id ] = anode ? create_keys( anode ) : data_channel_set_creator::create_set( 0 );

	data_channel_set_creator access( nodes[this_id] );
	access.set_name( make_name( name ) );
	access.set_parent_id( parent_id );
	// This value is ignored by the create_transformed_keys, but needed by create_direct_keys!
	// TODO: find a common solution!
	//       This is bad because create_transformed_keys never uses node-transformations for
	//       node's without keys
	access.set_transform( nv::assimp_mat4_cast( node->mTransformation ) );
	if ( this_id == 0 ) access.set_transform( mat4() );

	nv::sint16 next = this_id + 1;
	for ( unsigned i = 0; i < node->mNumChildren; ++i )
	{
		next = load_node( anim_id, nodes, node->mChildren[i], next, this_id );
	}

	return next;
}

data_channel_set* nv::assimp_loader::create_keys( const void* vnode )
{
	const aiNodeAnim* node = reinterpret_cast< const aiNodeAnim* >( vnode );
	if ( node->mNumPositionKeys == 0 && node->mNumRotationKeys == 0 && node->mNumScalingKeys == 0 )
	{
		return data_channel_set_creator::create_set( 0 );
	}
	
	data_channel_set* set = data_channel_set_creator::create_set( 2 );
	data_channel_set_creator key_set( set );

	assimp_key_p* pchannel = key_set.add_channel< assimp_key_p >( node->mNumPositionKeys ).data();
	assimp_key_r* rchannel = key_set.add_channel< assimp_key_r >( node->mNumRotationKeys ).data();
//	assimp_key_s* schannel = key_set.add_channel< assimp_key_s >( node->mNumScalingKeys ).data();

	for ( unsigned np = 0; np < node->mNumPositionKeys; ++np )
	{
		pchannel[np].time        = static_cast<float>( node->mPositionKeys[np].mTime );
		pchannel[np].translation = assimp_vec3_cast(node->mPositionKeys[np].mValue);
	}
	for ( unsigned np = 0; np < node->mNumRotationKeys; ++np )
	{
		rchannel[np].time     = static_cast<float>( node->mRotationKeys[np].mTime );
		rchannel[np].rotation = assimp_quat_cast(node->mRotationKeys[np].mValue );
	}
// 	if ( node->mNumScalingKeys > 0 )
// 	{
// 		vec3 scale_vec0 = assimp_vec3_cast( node->mScalingKeys[0].mValue );
// 		float scale_value   = math::length( math::abs( scale_vec0 - vec3(1,1,1) ) );
// 		if ( node->mNumScalingKeys > 1 || scale_value > 0.001 ) 
// 		{
// 			NV_LOG( nv::LOG_WARNING, "scale key significant!" );
// 			for ( unsigned np = 0; np < node->mNumRotationKeys; ++np )
// 			{
// 				schannel[np].time  = (float)node->mScalingKeys[np].mTime;
// 				schannel[np].scale = assimp_vec3_cast(node->mScalingKeys[np].mValue);
// 			}
// 		}
// 		else 
// 		{
// 			schannel[0].time  = (float)node->mScalingKeys[0].mTime;
// 			schannel[0].scale = assimp_vec3_cast(node->mScalingKeys[0].mValue);
// 		}
// 	}
	return set;
}

mesh_data_pack* nv::assimp_loader::release_mesh_data_pack()
{
	if ( m_scene == nullptr || m_mesh_count == 0 ) return nullptr;
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	bool has_bones = false;
	data_channel_set* meshes = data_channel_set_creator::create_set_array( m_mesh_count, 2 );
	for ( size_t m = 0; m < m_mesh_count; ++m )
	{
		const aiMesh* mesh = scene->mMeshes[ m ];
		data_channel_set_creator( &meshes[m] ).set_name( make_name( static_cast<const char*>( mesh->mName.data ) ) );
		if ( mesh->mNumBones > 0 ) has_bones = true;
		load_mesh_data(&meshes[m],m);
	}

	mesh_nodes_data* nodes = ( has_bones ? release_merged_bones( meshes ) : release_mesh_nodes_data(0) );
	return new mesh_data_pack( m_mesh_count, meshes, nodes );
}

nv::size_t nv::assimp_loader::get_nodes_data_count() const
{
	if ( m_scene == nullptr ) return 0;
	const aiScene* scene = reinterpret_cast<const aiScene*>( m_scene );
	return scene->mNumAnimations;	
}