/*
    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->indicesTriangles());

	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;
}


QColor aiMatColor(const aiMaterial * m, const char * key, uint s0, uint s1, const QColor & def = Qt::white) {
	aiColor4D col;
	aiReturn r = m->Get(key, s0, s1, col);
	//qDebug() << key << r << col.r << col.g << col.b;
	if (r != aiReturn_SUCCESS) return def;
	return QColor::fromRgbF(col.r, col.g, col.b);
}
float aiMatFloat(const aiMaterial * m, const char * key, uint s0, uint s1, float def = 0.f) {
	float ret;
	aiReturn r = m->Get(key, s0, s1, ret);
	if (r != aiReturn_SUCCESS) return def;
	return ret;
}
QString aiMatMap(const aiMaterial * m, aiTextureType texture) {
	aiString p;
	aiReturn r = const_cast<aiMaterial*>(m)->GetTexture(texture, 0, &p);
	if (r != aiReturn_SUCCESS) return QString(p.C_Str());
	return QString();
}
Material * assimpMaterial(const aiMaterial * m) {
	if (!m) return 0;
	Material * ret = new Material();
	ret->name = const_cast<aiMaterial*>(m)->GetName().C_Str();
	//qDebug() << "mat" << ret->name;
	//for (int i = 0; i < m->mNumProperties; ++i)
	//	qDebug()<< m->mProperties[i]->mKey.C_Str();
	ret->color_diffuse  = aiMatColor(m, AI_MATKEY_COLOR_DIFFUSE);
	ret->color_specular = aiMatColor(m, AI_MATKEY_COLOR_SPECULAR);
	ret->color_emission = aiMatColor(m, AI_MATKEY_COLOR_EMISSIVE);
	ret->map_diffuse  .bitmap_path = aiMatMap(m, aiTextureType_DIFFUSE);
	ret->map_normal   .bitmap_path = aiMatMap(m, aiTextureType_NORMALS);
	ret->map_specular .bitmap_path = aiMatMap(m, aiTextureType_SPECULAR);
	ret->map_roughness.bitmap_path = aiMatMap(m, aiTextureType_DIFFUSE_ROUGHNESS);
	ret->map_emission .bitmap_path = aiMatMap(m, aiTextureType_EMISSIVE);
	ret->transparency = 1.f - aiMatFloat(m, AI_MATKEY_OPACITY, 1.f);
	ret->setTypes();
	return ret;
}


Light * assimpLight(const aiLight * l) {
	if (!l) return 0;
	Light * ret = new Light();
	ret->setName(l->mName.C_Str());
	ret->setPos(fromAiVector3D(l->mPosition));
	ret->setDirection(fromAiVector3D(l->mDirection));
	ret->decay_const     = l->mAttenuationConstant ;
	ret->decay_linear    = l->mAttenuationLinear   ;
	ret->decay_quadratic = l->mAttenuationQuadratic;
	ret->angle_start = l->mAngleInnerCone * rad2deg;
	ret->angle_end   = l->mAngleOuterCone * rad2deg;
	if (l->mType == aiLightSource_SPOT)
		ret->light_type = Light::Cone;
	QVector3D col(l->mColorDiffuse.r, l->mColorDiffuse.g, l->mColorDiffuse.b);
	ret->intensity = col.length();
	col /= ret->intensity;
	ret->setColor(QColor::fromRgbF(col[0], col[1], col[2]));
	return ret;
}


ObjectBase * assimpObject(const aiNode * n, const QVector<Mesh * > & meshes, aiMesh ** ai_meshes,
						  const QVector<Material*> & materials,
						  const QMap<QString, Light * > & light_by_name, QVector<Light*> & out_lights) {
	if (!n) return 0;
	ObjectBase * ret = 0;
	QString name = n->mName.C_Str();
	Light * light = light_by_name.value(name, 0);
	if (light) {
		ret = light->clone();
		out_lights << (Light*)ret;
	} else
		ret = new ObjectBase();
	ret->setName(name);
	ret->setMatrix(fromAiMatrix4D(n->mTransformation));
	//qDebug() << "add object" << ret << ret->name();
	if (!light) {
		//qDebug() << name << "has" << n->mNumMeshes << "meshes";
		for (uint i = 0; i < n->mNumMeshes; ++i) {
			int mi = n->mMeshes[i];
			if (meshes[mi]) {
				if (!ret->mesh()) {
					ret->setMesh(new Mesh());
					int mati = ai_meshes[mi]->mMaterialIndex;
					if (mati >= 0 || mati < materials.size())
						ret->setMaterial(materials[mati]);
				}
				ret->mesh()->append(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, ai_meshes, materials, light_by_name, out_lights);
		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]);
	QVector<Material * > materials;
	for (uint i = 0; i < ais->mNumMaterials; ++i)
		materials << assimpMaterial(ais->mMaterials[i]);
	QVector<Light * > lights;
	for (uint i = 0; i < ais->mNumLights; ++i)
		lights << assimpLight(ais->mLights[i]);
	QMap<QString, Light * > light_by_name;
	foreach (Light * l, lights)
		light_by_name[l->name()] = l;

	QVector<Light*> out_lights;
	ObjectBase * root = assimpObject(ais->mRootNode, meshes, ais->mMeshes, materials, light_by_name, out_lights);
	if (!root) return 0;

	ObjectBaseList rcl = root->children(true);
	foreach (ObjectBase * c, rcl) {
		foreach (Light * l, out_lights) {
			if (c->name() == (l->name() + ".Target")) {
				l->setAim((l->worldTransform().inverted() * QVector4D(c->worldPos(), 1)).toVector3D());
				delete c;
				break;
			}
		}
	}

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

	return scene;
}