/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Data Visualization module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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****************************************************************************/

#include "meshloader_p.h"
#include "vertexindexer_p.h"
#include "objecthelper_p.h"

QT_BEGIN_NAMESPACE

ObjectHelper::ObjectHelper(const QString &objectFile)
    : m_objectFile(objectFile)
{
    load();
}

struct ObjectHelperRef {
    int refCount;
    ObjectHelper *obj;
};

// The "Abstract3DRenderer *" key identifies the renderer
static QHash<const Abstract3DRenderer *, QHash<QString, ObjectHelperRef *> *> cacheTable;

ObjectHelper::~ObjectHelper()
{
}

void ObjectHelper::resetObjectHelper(const Abstract3DRenderer *cacheId, ObjectHelper *&obj,
                                     const QString &meshFile)
{
    Q_ASSERT(cacheId);

    if (obj) {
        const QString &oldFile = obj->objectFile();
        if (meshFile == oldFile)
            return; // same file, do nothing
        releaseObjectHelper(cacheId, obj);
    }
    obj = getObjectHelper(cacheId, meshFile);
}

void ObjectHelper::releaseObjectHelper(const Abstract3DRenderer *cacheId, ObjectHelper *&obj)
{
    Q_ASSERT(cacheId);

    if (obj) {
        QHash<QString, ObjectHelperRef *> *objectTable = cacheTable.value(cacheId, 0);
        if (objectTable) {
            // Delete object if last reference is released
            ObjectHelperRef *objRef = objectTable->value(obj->m_objectFile, 0);
            if (objRef) {
                objRef->refCount--;
                if (objRef->refCount <= 0) {
                    objectTable->remove(obj->m_objectFile);
                    delete objRef->obj;
                    delete objRef;
                }
            }
            if (objectTable->isEmpty()) {
                // Remove the entire cache if last object was removed
                cacheTable.remove(cacheId);
                delete objectTable;
            }
        } else {
            // Just delete the object if unknown cache
            delete obj;
        }
        obj = 0;
    }
}

ObjectHelper *ObjectHelper::getObjectHelper(const Abstract3DRenderer *cacheId,
                                            const QString &objectFile)
{
    if (objectFile.isEmpty())
        return 0;

    QHash<QString, ObjectHelperRef *> *objectTable = cacheTable.value(cacheId, 0);
    if (!objectTable) {
        objectTable = new QHash<QString, ObjectHelperRef *>;
        cacheTable.insert(cacheId, objectTable);
    }

    // Check if object helper for this mesh already exists
    ObjectHelperRef *objRef = objectTable->value(objectFile, 0);
    if (!objRef) {
        objRef = new ObjectHelperRef;
        objRef->refCount = 0;
        objRef->obj = new ObjectHelper(objectFile);
        objectTable->insert(objectFile, objRef);
    }
    objRef->refCount++;
    return objRef->obj;
}

void ObjectHelper::load()
{
    if (m_meshDataLoaded) {
        // Delete old data
        glDeleteBuffers(1, &m_vertexbuffer);
        glDeleteBuffers(1, &m_uvbuffer);
        glDeleteBuffers(1, &m_normalbuffer);
        glDeleteBuffers(1, &m_elementbuffer);
        m_indices.clear();
        m_indexedVertices.clear();
        m_indexedUVs.clear();
        m_indexedNormals.clear();
        m_vertexbuffer = 0;
        m_uvbuffer = 0;
        m_normalbuffer = 0;
        m_elementbuffer = 0;
    }
    QList<QVector3D> vertices;
    QList<QVector2D> uvs;
    QList<QVector3D> normals;
    bool loadOk = MeshLoader::loadOBJ(m_objectFile, vertices, uvs, normals);
    if (!loadOk)
        qFatal("loading failed");

    // Index vertices
    VertexIndexer::indexVBO(vertices, uvs, normals, m_indices, m_indexedVertices, m_indexedUVs,
                            m_indexedNormals);

    m_indexCount = m_indices.size();

    glGenBuffers(1, &m_vertexbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, m_vertexbuffer);
    glBufferData(GL_ARRAY_BUFFER, m_indexedVertices.size() * sizeof(QVector3D),
                 &m_indexedVertices.at(0),
                 GL_STATIC_DRAW);

    glGenBuffers(1, &m_normalbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, m_normalbuffer);
    glBufferData(GL_ARRAY_BUFFER, m_indexedNormals.size() * sizeof(QVector3D),
                 &m_indexedNormals.at(0),
                 GL_STATIC_DRAW);

    glGenBuffers(1, &m_uvbuffer);
    glBindBuffer(GL_ARRAY_BUFFER, m_uvbuffer);
    glBufferData(GL_ARRAY_BUFFER, m_indexedUVs.size() * sizeof(QVector2D),
                 &m_indexedUVs.at(0), GL_STATIC_DRAW);

    glGenBuffers(1, &m_elementbuffer);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_elementbuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, m_indices.size() * sizeof(GLuint),
                 &m_indices.at(0), GL_STATIC_DRAW);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

    m_meshDataLoaded = true;
}

QT_END_NAMESPACE
