#include "defines.h"
#include "Scene.h"
#include "Shader.h"
#include "Primitives.h"
#include "Visitor.h"
#include "GarbageVisitor.h"
#include "Log.h"
#include "GlmToolkit.h"
#include "SessionVisitor.h"

#include <glad/glad.h>

#include <glm/gtc/type_ptr.hpp>
#include <glm/gtc/matrix_access.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/random.hpp>

#include <chrono>
#include <ctime>
#include <algorithm>


// Node
Node::Node() : initialized_(false), visible_(true), refcount_(0)
{
    // create unique id
    auto duration = std::chrono::system_clock::now().time_since_epoch();
    id_ = std::chrono::duration_cast<std::chrono::nanoseconds>(duration).count() % 100000000;

    transform_ = glm::identity<glm::mat4>();
    scale_ = glm::vec3(1.f);
    rotation_ = glm::vec3(0.f);
    translation_ = glm::vec3(0.f);
}

Node::~Node ()
{

}

void Node::copyTransform(Node *other)
{
    if (!other)
        return;
    transform_ = glm::identity<glm::mat4>();
    scale_ = other->scale_;
    rotation_ = other->rotation_;
    translation_ = other->translation_;
}

void Node::update( float )
{
    // update transform matrix from attributes
    transform_ = GlmToolkit::transform(translation_, rotation_, scale_);
}

void Node::accept(Visitor& v)
{
    v.visit(*this);
}

// Primitive

Primitive::~Primitive()
{
    if ( vao_ )
        glDeleteVertexArrays ( 1, &vao_);
    if (shader_)
        delete shader_;
}

void Primitive::init()
{
    if ( vao_ )
        glDeleteVertexArrays ( 1, &vao_);

    // Vertex Array
    glGenVertexArrays( 1, &vao_ );
    // Create and initialize buffer objects
    uint arrayBuffer_;
    uint elementBuffer_;
    glGenBuffers( 1, &arrayBuffer_ );
    glGenBuffers( 1, &elementBuffer_);
    glBindVertexArray( vao_ );

    // compute the memory needs for points normals and indicies
    std::size_t sizeofPoints = sizeof(glm::vec3) * points_.size();
    std::size_t sizeofColors = sizeof(glm::vec4) * colors_.size();
    std::size_t sizeofTexCoords = sizeof(glm::vec2) * texCoords_.size();

    // setup the array buffers for vertices
    glBindBuffer( GL_ARRAY_BUFFER, arrayBuffer_ );
    glBufferData(GL_ARRAY_BUFFER, sizeofPoints + sizeofColors + sizeofTexCoords, NULL, GL_STATIC_DRAW);
    glBufferSubData( GL_ARRAY_BUFFER, 0, sizeofPoints, &points_[0] );
    glBufferSubData( GL_ARRAY_BUFFER, sizeofPoints, sizeofColors, &colors_[0] );
    if ( sizeofTexCoords )
        glBufferSubData( GL_ARRAY_BUFFER, sizeofPoints + sizeofColors, sizeofTexCoords, &texCoords_[0] );

    // setup the element array for the triangle indices
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementBuffer_);
    int sizeofIndices = indices_.size()*sizeof(uint);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeofIndices, &(indices_[0]), GL_STATIC_DRAW);

    // explain how to read attributes 0, 1 and 2 (for point, color and textcoord respectively)
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(glm::vec3), (void *)0 );
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(glm::vec4), (void *)(sizeofPoints) );
    glEnableVertexAttribArray(1);
    if ( sizeofTexCoords ) {
        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(glm::vec2), (void *)(sizeofPoints + sizeofColors) );
        glEnableVertexAttribArray(2);
    }

    // done
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);

    // drawing indications
    drawCount_ = indices_.size();

    // delete temporary buffers
    if ( arrayBuffer_ )
        glDeleteBuffers ( 1, &arrayBuffer_);
    if ( elementBuffer_ )
        glDeleteBuffers ( 1, &elementBuffer_);

    // compute AxisAlignedBoundingBox
    bbox_.extend(points_);

    // arrays of vertices are not needed anymore (STATIC DRAW of vertex object)
    points_.clear();
    colors_.clear();
    texCoords_.clear();
    indices_.clear();

    Node::init();
}

void Primitive::draw(glm::mat4 modelview, glm::mat4 projection)
{
    if ( !initialized() )
        init();

    if ( visible_ ) {
        //
        // prepare and use shader
        //
        if (shader_) {
            shader_->projection = projection;
            shader_->modelview  = modelview * transform_;
            shader_->use();
        }
        //
        // draw vertex array object
        //
        if (vao_) {
            glBindVertexArray( vao_ );
            glDrawElements( drawMode_, drawCount_, GL_UNSIGNED_INT, 0  );
            glBindVertexArray(0);
        }
    }
}

void Primitive::accept(Visitor& v)
{
    Node::accept(v);
    v.visit(*this);
}

void Primitive::replaceShader( Shader *newshader )
{
    if (newshader) {
        if (shader_)
            delete shader_;
        shader_ = newshader;
    }
}


// Group
Group::~Group()
{
    clear();
}

void Group::clear()
{
    for(NodeSet::iterator it = children_.begin(); it != children_.end(); ) {
        // one less ref to this node
        (*it)->refcount_--;
        // if this group was the only remaining parent
        if ( (*it)->refcount_ < 1 ) {
            // delete
            delete (*it);
        }
        // erase this iterator from the list
        it = children_.erase(it);
    }
}

void Group::attach(Node *child)
{
    children_.insert(child);
    child->refcount_++;
}


void Group::sort()
{
    // reorder list of nodes
    NodeSet ordered_children;
    for(auto it = children_.begin(); it != children_.end(); it++)
        ordered_children.insert(*it);
    children_.swap(ordered_children);
}

void Group::detatch(Node *child)
{
    // find the node with this id, and erase it out of the list of children
    // NB: do NOT delete with remove : this takes all nodes with same depth (i.e. equal depth in set)
    NodeSet::iterator it = std::find_if(children_.begin(), children_.end(), hasId(child->id()));
    if ( it != children_.end())  {
        // detatch child from group parent
        children_.erase(it);
        child->refcount_--;
    }

}

void Group::update( float dt )
{
    Node::update(dt);

    // update every child node
    for (NodeSet::iterator node = children_.begin();
         node != children_.end(); node++) {
        (*node)->update ( dt );
    }
}

void Group::draw(glm::mat4 modelview, glm::mat4 projection)
{
    if ( !initialized() )
        init();

    if ( visible_ ) {

        // append the instance transform to the ctm
        glm::mat4 ctm = modelview * transform_;

        // draw every child node
        for (NodeSet::iterator node = children_.begin();
             node != children_.end(); node++) {
            (*node)->draw ( ctm, projection );
        }
    }
}

void Group::accept(Visitor& v)
{
    Node::accept(v);
    v.visit(*this);
}

NodeSet::iterator Group::begin()
{
    return children_.begin();
}

NodeSet::iterator Group::end()
{
    return children_.end();
}


Node *Group::front()
{
    if (!children_.empty())
        return *children_.rbegin();
    return nullptr;
}

Node *Group::back()
{
    if (!children_.empty())
        return *children_.begin();
    return nullptr;
}

uint Group::numChildren() const
{
    return children_.size();
}

void Switch::update( float dt )
{
    Node::update(dt);

    // update active child node
    if (active_ != children_.end())
        (*active_)->update( dt );
}

void Switch::draw(glm::mat4 modelview, glm::mat4 projection)
{
    if ( !initialized() )
        init();

    if ( visible_ ) {
        // draw current child        
        if (active_ != children_.end())
            (*active_)->draw( modelview * transform_, projection);
    }
}

void Switch::accept(Visitor& v)
{
    Node::accept(v);
    v.visit(*this);
}

void Switch::attach(Node *child)
{
    Group::attach(child);
    setActiveChild(child);
}

void Switch::detatch(Node *child)
{
    Group::detatch(child);
    active_ = children_.begin();
}


void Switch::unsetActiveChild ()
{
    active_ = children_.end();
}

void Switch::setActiveChild(Node *child)
{
    setActiveChild( std::find_if(children_.begin(), children_.end(), hasId(child->id())) );
}

void Switch::setActiveChild(NodeSet::iterator n)
{
    if ( n != children_.end())
        active_ = n;
    else
        active_ = children_.begin();
}

NodeSet::iterator Switch::activeChild() const
{
    return active_;
}

void Switch::setIndexActiveChild(int index)
{
    int i = 0;
    for (NodeSet::iterator node = children_.begin();
         node != children_.end(); node++, i++) {
        if ( i == index ) {
            active_ = node;
            break;
        }
    }
}

int Switch::getIndexActiveChild() const
{
    int index = 0;
    for (NodeSet::iterator node = children_.begin();
         node != children_.end(); node++, index++) {
        if (node == active_)
            break;
    }
    return index;
}

void Animation::init()
{
    Group::init();

    animation_ = glm::identity<glm::mat4>();
//    animation_ = glm::translate(glm::identity<glm::mat4>(), glm::vec3(2.f, 0.f, 0.f));
}

void Animation::update( float dt )
{
    Group::update(dt);

    // incremental rotation
    animation_ = glm::rotate(animation_, speed_ * dt, axis_);

    // calculate translation of a point at distance radius_ after rotation by animation_
    static glm::vec3 any = glm::linearRand( glm::vec3(0.f, 0.f, 0.f), glm::vec3(1.f, 1.f, 1.f));
    glm::vec3 pos = glm::normalize( glm::cross(any, axis_) ) * radius_;
    glm::vec4 delta = glm::vec4(pos, 0.f) * animation_;

    // apply this translation to the Group transform
    transform_ *= glm::translate(glm::identity<glm::mat4>(), glm::vec3(delta.x, delta.y, 0.f));

}

void Animation::accept(Visitor& v)
{
    Group::accept(v);
    v.visit(*this);
}

Scene::Scene(): root_(nullptr), foreground_(nullptr), background_(nullptr)
{
    root_ = new Group;

    background_ = new Group;
    background_->translation_.z = 0;
    foreground_ = new Group;
    // TODO Verify depth for foreground
    foreground_->translation_.z = 1;

    root_->attach(background_);
    root_->attach(foreground_);
}

Scene::~Scene()
{
    // bg and fg are deleted as children of root
    delete root_;
}


void Scene::clear()
{
    clearForeground();
    clearBackground();
}

void Scene::clearForeground()
{
    foreground_->clear();
}

void Scene::clearBackground()
{
    background_->clear();
}

void Scene::update(float dt)
{
    root_->update( dt );
}

void Scene::accept(Visitor& v)
{
    v.visit(*this);
}