/*
    QGLView
    Copyright (C) 2019  Ivan Pelipenko peri4ko@yandex.ru

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "loader_assimp.h"
#include "glscene.h"
#include "glmesh.h"
#include "glmaterial.h"
#include "globject.h"
#include <assimp/Importer.hpp>
#include <assimp/postprocess.h>
#include <assimp/scene.h>
#include <assimp/mesh.h>
#include <assimp/material.h>

QVector3D  fromAiVector3D(const aiVector3D & v) {return QVector3D(v.x, v.y, v.z);}
 Vector3i  fromAiFace    (const aiFace & v) {return Vector3i(v.mIndices[0], v.mIndices[1], v.mIndices[2]);}
QMatrix4x4 fromAiMatrix4D(const aiMatrix4x4 & v) {return QMatrix4x4(v.a1, v.a2, v.a3, v.a4,
																	v.b1, v.b2, v.b3, v.b4,
																	v.c1, v.c2, v.c3, v.c4,
																	v.d1, v.d2, v.d3, v.d4);}
bool isAiMeshTriangles(const aiMesh * m) {return (m->mPrimitiveTypes & aiPrimitiveType_TRIANGLE) == aiPrimitiveType_TRIANGLE;}


Mesh * assimpMesh(const aiMesh * m) {
	if (!m) return 0;
	if (!isAiMeshTriangles(m)) return 0;
	Mesh * ret = new Mesh();
	int vcnt = m->mNumVertices, tcnt = m->mNumFaces;

	QVector<QVector3D> & v(ret->vertices());  v.resize(vcnt);
	QVector<QVector2D> & t(ret->texcoords()); t.resize(vcnt);
	QVector< Vector3i> & ind(ret->indices());

	for (int i = 0; i < vcnt; ++i)
		v[i] = fromAiVector3D(m->mVertices[i]);

	if (m->HasNormals()) {
		QVector<QVector3D> & n(ret->normals());
		n.resize(vcnt);
		for (int i = 0; i < vcnt; ++i)
			n[i] = fromAiVector3D(m->mNormals[i]);
	}

	if (m->HasTextureCoords(0)) {
		for (int i = 0; i < vcnt; ++i)
			t[i] = fromAiVector3D(m->mTextureCoords[0][i]).toVector2D();
	}

	if (m->HasFaces()) {
		ind.resize(tcnt);
		for (int i = 0; i < tcnt; ++i)
			ind[i] = fromAiFace(m->mFaces[i]);
	} else {
		tcnt = vcnt / 3;
		ind.resize(tcnt);
		int si = 0;
		for (int i = 0; i < tcnt; ++i) {
			si = i+i+i;
			ind[i] = Vector3i(si, si+1, si+2);
		}
	}

	//qDebug() << "add mesh" << v.size() << ret->normals().size() << ret->texcoords().size() << ret->indices().size();

	return ret;
}


ObjectBase * assimpObject(const aiNode * n, const QVector<Mesh * > & meshes) {
	if (!n) return 0;
	ObjectBase * ret = new ObjectBase();
	ret->setName(n->mName.C_Str());
	ret->setTransform(fromAiMatrix4D(n->mTransformation));
	//qDebug() << "add object" << ret << ret->name();
	for (uint i = 0; i < n->mNumMeshes; ++i) {
		int mi = n->mMeshes[i];
		if (meshes[mi]) {
			ret->setMesh(meshes[mi]);
			//qDebug() << "set mesh" << mi << ret->mesh();
			break;
		}
	}
	for (uint i = 0; i < n->mNumChildren; ++i) {
		ObjectBase * co = assimpObject(n->mChildren[i], meshes);
		if (co) ret->addChild(co);
	}

	return ret;
}


Scene * loadScene(const QString & filepath) {
	if (filepath.isEmpty()) return 0;
	qDebug() << "[Loader Assimp] Import" << filepath << "...";
	Assimp::Importer importer;
	const aiScene * ais = importer.ReadFile(filepath.toUtf8(), aiProcess_Triangulate |
																aiProcess_SortByPType |
																aiProcess_GenUVCoords |
																aiProcess_TransformUVCoords);
	if (!ais) {
		qDebug() << "[Loader Assimp] Error: \"" + QString(importer.GetErrorString()) + "\"";
		return 0;
	}
	qDebug() << "[Loader Assimp] Imported" << ais->mNumMeshes << "meshes";
	QVector<Mesh * > meshes;
	for (uint i = 0; i < ais->mNumMeshes; ++i)
		meshes << assimpMesh(ais->mMeshes[i]);

	ObjectBase * root = assimpObject(ais->mRootNode, meshes);
	if (!root) return 0;

	Scene * scene = new Scene();
	scene->setName(root->name());
	foreach (ObjectBase * o, root->children())
		scene->addObject(o);

	return scene;
}