// Copyright (C) 2014 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of NV Libraries.
// For conditions of distribution and use, see copyright notice in nv.hh

#include "nv/formats/assimp_loader.hh"
#include <unordered_map>
#include <glm/gtx/transform.hpp>
#include "nv/io/std_stream.hh"
#include "nv/lib/assimp.hh"

using namespace nv;

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

	if( !scene)
	{
		NV_LOG( nv::LOG_ERROR, aiGetErrorString() );
		return false;
	}
	m_scene      = scene;
	m_mesh_count = scene->mNumMeshes;
	NV_LOG( nv::LOG_NOTICE, "Loading successfull" );
	return true;
}

mesh_data* nv::assimp_loader::release_mesh_data( size_t index /*= 0 */ )
{
	if ( index >= m_mesh_count ) return nullptr;
	mesh_data* result = new mesh_data();
	const aiScene* scene = (const aiScene*)m_scene;
	const aiMesh*  mesh  = scene->mMeshes[ index ];

	mat3 scaled_rotatation = glm::mat3( glm::scale( m_scale, m_scale, m_scale ) * m_rotate_transform );
	vec3 vertex_offset     = glm::vec3(); 
	mat3 vertex_transform  = glm::mat3( glm::transpose( scaled_rotatation ) );
	mat3 normal_transform  = glm::mat3( glm::transpose( glm::inverse( scaled_rotatation ) ) );
	mat4 bone_transform    = glm::scale( 1.0f/m_scale, 1.0f/m_scale, 1.0f/m_scale ) * m_rotate_transform;

	bool skinned = mesh->mNumBones > 0;
	mesh_raw_channel* channel = nullptr;
	if ( skinned )
		channel = mesh_raw_channel::create< assimp_skinned_vtx >( mesh->mNumVertices );
	else
		channel = mesh_raw_channel::create< assimp_plain_vtx >( mesh->mNumVertices );

	result->add_channel( channel );
	for (unsigned int i=0; i<mesh->mNumVertices; i++)
	{
		vec3 v = vertex_transform * assimp_vec3_cast( mesh->mVertices[ i ] ) + vertex_offset;
		vec3 n = glm::normalize( normal_transform * assimp_vec3_cast( mesh->mNormals[ i ] ) );
		vec3 t = glm::normalize( normal_transform * assimp_vec3_cast( mesh->mTangents[ i ] ) );
		vec3 b = glm::normalize( normal_transform * assimp_vec3_cast( mesh->mBitangents[ i ] ) );
		vec2 s = assimp_st_cast( mesh->mTextureCoords[ 0 ][ i ] );

		glm::vec3 t_i = glm::normalize (t - n * glm::dot (n, t));
		float det = (glm::dot (glm::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 )
			((assimp_skinned_vtx*)channel->data)[i] = assimp_skinned_vtx( v, s, n, vt );
		else
			((assimp_plain_vtx*)channel->data)[i] = assimp_plain_vtx( v, s, n, vt );
	}

	if ( skinned )
	{
		assimp_skinned_vtx* vtx = (assimp_skinned_vtx*)channel->data;
		for (unsigned int m=0; m<mesh->mNumBones; m++)
		{
			aiBone* bone  = mesh->mBones[m];
			nv::mat4 offset = nv::assimp_mat4_cast( bone->mOffsetMatrix ) * bone_transform;
			for (unsigned int w=0; w<bone->mNumWeights; w++)
			{
				assimp_skinned_vtx& v = vtx[ bone->mWeights[w].mVertexId ];
				bool found = false;
				for (nv::uint32 i = 0 ; i < 4; ++i)
				{
					if ( v.boneweight[i] <= 0.0f ) 
					{
						v.boneindex[i] = m;
						v.boneweight[i] = bone->mWeights[w].mWeight;
						found = true;
						break;
					}
				}
				NV_ASSERT( found, "Too many weights!" );
			}
		}
	}

	mesh_raw_index_channel* ichannel = mesh_raw_index_channel::create( USHORT, mesh->mNumFaces * 3 );
	result->set_index_channel( ichannel );
	uint16* indices = (uint16*)ichannel->data;
	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];
		}
	}

	return result;
}

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

bool nv::assimp_loader::load_bones( size_t index, std::vector< assimp_bone >& bones )
{
	if ( m_scene == nullptr ) return false;
	const aiScene* scene = (const aiScene*)m_scene;
	const aiMesh*  mesh  = scene->mMeshes[ index ];
	if ( mesh->mNumBones == 0 ) return false;

	mat4 bone_transform    = glm::scale( 1.0f/m_scale, 1.0f/m_scale, 1.0f/m_scale ) * m_rotate_transform;

	for (unsigned int m=0; m<mesh->mNumBones; m++)
	{
		aiBone* bone   = mesh->mBones[m];
		mat4    offset = assimp_mat4_cast( bone->mOffsetMatrix ) * bone_transform;
		bones.emplace_back( bone->mName.data, offset );
	}
	return true;
}

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

	NV_LOG( nv::LOG_NOTICE, "------------------------" );
	NV_LOG( nv::LOG_NOTICE, "Texture   count - " << scene->mNumTextures );
	NV_LOG( nv::LOG_NOTICE, "Animation count - " << scene->mNumAnimations );
	NV_LOG( nv::LOG_NOTICE, "Material  count - " << scene->mNumMaterials );
	NV_LOG( nv::LOG_NOTICE, "Meshes    count - " << scene->mNumMeshes );
	NV_LOG( nv::LOG_NOTICE, "------------------------" );

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

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

			NV_LOG( nv::LOG_NOTICE, "Mesh #"<<mc<<"   - " << mesh->mName.data );
			NV_LOG( nv::LOG_NOTICE, "  bones   - " << mesh->mNumBones );
			NV_LOG( nv::LOG_NOTICE, "  uvs     - " << mesh->mNumUVComponents[0] );
			NV_LOG( nv::LOG_NOTICE, "  verts   - " << mesh->mNumVertices );
			NV_LOG( nv::LOG_NOTICE, "  faces   - " << mesh->mNumFaces );

			// 			NV_LOG( nv::LOG_NOTICE, "Bones:" );
			// 			for (unsigned int m=0; m<mesh->mNumBones; m++)
			// 			{
			// 				aiBone* bone  = mesh->mBones[m];
			// 				NV_LOG( nv::LOG_DEBUG, bone->mName.C_Str() );
			// 			}
		}
	}
	else
	{
		NV_LOG( nv::LOG_NOTICE, "No meshes!" );
	}
	NV_LOG( 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( nv::LOG_NOTICE, "  material - " << path.data );
	// 				texIndex++;
	// 			}
	// 		}
	// 	}
	// 	else
	// 	{
	// 		NV_LOG( nv::LOG_NOTICE, "No materials" );
	// 	}
	// 	NV_LOG( nv::LOG_NOTICE, "------------------------" );

}

assimp_model* nv::assimp_loader::release_merged_model()
{
	if ( m_scene == nullptr || m_mesh_count == 0 ) return nullptr;
	assimp_model* model = new assimp_model;

	for ( size_t m = 0; m < m_mesh_count; ++m )
	{
		model->meshes.push_back( release_mesh_data(m) );
	}

	std::unordered_map< std::string, uint16 > names;
	for ( unsigned int m = 0; m < model->meshes.size(); ++m )
	{
		nv::sint16 translate[64];
		std::vector< assimp_bone > bones;
		load_bones( m, bones );
		for ( unsigned int b = 0; b < bones.size(); ++b )
		{

			nv::assimp_bone& bone = bones[b];
			auto iname = names.find( bone.name );
			if ( iname == names.end() )
			{
				NV_ASSERT( model->bones.size() < 64, "Too many bones to merge!" );
				nv::sint16 index = (nv::sint16)model->bones.size();
				model->bones.push_back( bone );
				names[ bone.name ] = index;
				translate[b] = index;
			}
			else
			{
				translate[b] = (nv::sint16)iname->second;
			}
		}
		if ( m > 0 )
		{
			mesh_data* mesh = model->meshes[m];
			nv::mesh_raw_channel* channel = mesh->get_channel_data()[0];
			nv::assimp_skinned_vtx* va = (nv::assimp_skinned_vtx*)channel->data;
			for ( unsigned v = 0; v < channel->count; ++v )
			{
				nv::assimp_skinned_vtx& vertex = va[v];

				for (nv::uint32 i = 0 ; i < 4; ++i)
				{
					if ( vertex.boneweight[i] > 0.0f ) 
					{
						vertex.boneindex[i] = translate[vertex.boneindex[i]];
					}
				}
			}
		}
	}
	return model;
}