#include "planet/PlanetFace.h"
#include <time.h>
#include <math.h>

PlanetFaceNode::PlanetFaceNode(
	PlanetFace* face,
	PlanetFaceNode* parent,
	const unsigned int index
) :
	m_planetFace(face),
	m_quadrant(index),
	m_level(parent ? parent->m_level + 1 : 0),
	m_generated(false),
	m_dirty(true),
	m_leaf(true),
	m_parent(parent),
	m_children(),
	m_neighbors(),
	neighborDetailDifferences()
{
	generate();
}

PlanetFaceNode::~PlanetFaceNode()
{
	for (unsigned int i = 0; i < 4; i++)
	{
		if (m_neighbors[i])
		{
			m_neighbors[i]->setNeighbor(mirrorSide(i), 0);
		}
	}

	if (!m_leaf)
	{
		for (int i = 0; i < 4; i++)
		{
			delete m_children[i];
		}
	}
}

unsigned int PlanetFaceNode::mirrorSide(const unsigned int side) const
{
  // If no neighbor; use default mirroring
  if (!m_neighbors[side])
    return MIRROR(side);

  // Get source and destination faces
  const unsigned int f0 = m_planetFace->getFace();
  const unsigned int f1 = m_neighbors[side]->m_planetFace->getFace();

  // If within the same face or faces with equal properties
  if (f0 == f1 || (f0 < 4 && f1 < 4))
    return MIRROR(side);

  // Source face
  switch (f0)
  {
    // Top face; always end up north
    case FACE_TOP:
      return TOP;
    // Source bottom; always end up south
    case FACE_BOTTOM:
      return BOTTOM;
  }

  // Destination face
  switch (f1)
  {
    // Top face; rotate to the source face
    case FACE_TOP:
      return MIRROR(f0);
    // Bottom face; rotate to the source face
    case FACE_BOTTOM:
      return (4 - f0) % 4;
  }

  return MIRROR(side);
}

unsigned int PlanetFaceNode::mirrorQuadrant(const unsigned int side, const unsigned int quadrant) const
{
  // If mirroring within the parent node
  if (!ADJACENT(side, quadrant))
    return REFLECT(side, quadrant);

  // If no parent or parent neighbor
  if (!m_parent || !m_parent->m_neighbors[side])
    return REFLECT(side, quadrant);

  // Get source and destination faces
  const unsigned int f0 = m_planetFace->getFace();
  const unsigned int f1 = m_parent->m_neighbors[side]->m_planetFace->getFace();

  // If within the same face or faces with equal properties
  if (f0 == f1 || (f0 < 4 && f1 < 4))
    return REFLECT(side, quadrant);

  // Source face
  switch (f0)
  {
    case FACE_FRONT:
      return REFLECT(side, quadrant);
    case FACE_LEFT:
      switch(quadrant)
      {
        case TOP_RIGHT:
        case BOTTOM_LEFT:
          return BOTTOM_LEFT;
        case TOP_LEFT:
        case BOTTOM_RIGHT:
          return TOP_LEFT;
      }
			return REFLECT(side, quadrant);
    case FACE_BACK:
      switch (quadrant)
      {
        case TOP_RIGHT:
          return TOP_LEFT;
        case TOP_LEFT:
          return TOP_RIGHT;
        case BOTTOM_RIGHT:
          return BOTTOM_LEFT;
        case BOTTOM_LEFT:
          return BOTTOM_RIGHT;
      }
			return REFLECT(side, quadrant);
    case FACE_RIGHT:
      switch (quadrant)
      {
        case TOP_RIGHT:
        case BOTTOM_LEFT:
          return TOP_RIGHT;
        case TOP_LEFT:
        case BOTTOM_RIGHT:
          return BOTTOM_RIGHT;
      }
			return REFLECT(side, quadrant);
    case FACE_TOP:
      switch (quadrant)
      {
        case TOP_RIGHT:
        case BOTTOM_LEFT:
          return (side == TOP || side == BOTTOM) ? TOP_LEFT : TOP_RIGHT;
        case TOP_LEFT:
        case BOTTOM_RIGHT:
          return (side == TOP || side == BOTTOM) ? TOP_RIGHT : TOP_LEFT;
      }
			return REFLECT(side, quadrant);
    case FACE_BOTTOM:
      switch (quadrant)
      {
        case TOP_RIGHT:
        case BOTTOM_LEFT:
          return (side == TOP || side == BOTTOM) ? BOTTOM_RIGHT : BOTTOM_LEFT;
        case TOP_LEFT:
        case BOTTOM_RIGHT:
          return (side == TOP || side == BOTTOM) ? BOTTOM_LEFT : BOTTOM_RIGHT;
      }
  }

  return REFLECT(side, quadrant);
}

void PlanetFaceNode::setNeighbor(const unsigned int side, PlanetFaceNode *neighbor)
{
  // Connect the nodes and update neighbor detail differences
  m_neighbors[side] = neighbor;
  if (neighbor)
  {
    const unsigned int sideMirrored = mirrorSide(side);
    neighbor->m_neighbors[sideMirrored] = this;
    neighbor->updateNeighborDetailDifferences(sideMirrored);
  }
  updateNeighborDetailDifferences(side);	
}

// Returns the neighbor of equal depth if it exists; otherwise its youngest ancestor
const PlanetFaceNode* PlanetFaceNode::getEqualOrHigherNeighbor(const unsigned int side) const
{
  // Find the youngest ancestor with a neighbor in the given direction
  for (const PlanetFaceNode *node = this; node != 0; node = node->m_parent)
	{
    if (node->m_neighbors[side])
		{
      return node->m_neighbors[side];
		}
	}
  return 0;
}

void PlanetFaceNode::findNeighbor(const unsigned int side)
{
  // If the current node has no neighbor in the given direction, but its parent does
  if (!m_neighbors[side] && m_parent && m_parent->m_neighbors[side])
  {
    // If a valid neighbor is found (child of the parent's neighbor); use it
    if (PlanetFaceNode *neighbor = m_parent->m_neighbors[side]->m_children[mirrorQuadrant(side, m_quadrant)])
      setNeighbor(side, neighbor);
    else
      return;
  }

  // If no leaf node; find child node neighbors
  if (!isLeaf())
    for (unsigned int i = 0; i < 4; i++)
      if (ADJACENT(side, i))
        m_children[i]->findNeighbor(side);
}

void PlanetFaceNode::updateNeighborDetailDifferences(const unsigned int side)
{
  // Update neighbor detail differences
  for (unsigned int i = 0; i < 4; i++)
	{
    if (const PlanetFaceNode *neighbor = getEqualOrHigherNeighbor(i)) {
      neighborDetailDifferences[i] = std::min(m_level - neighbor->m_level, (unsigned int)4); // 4 max difference
		}
	}

  // Force child nodes on the updated side to redraw
  if (!isLeaf())
	{
    for (unsigned int i = 0; i < 4; i++)
    {
		  if (ADJACENT(side, i))
			{
        m_children[i]->updateNeighborDetailDifferences(side);
			}
		}
	}
}

// Returns the neighbor detail (depth) difference [0,MAX_DETAIL_DIFFERENCE]
unsigned int PlanetFaceNode::getNeighborDetailDifference(const unsigned int side) const
{
  return neighborDetailDifferences[side];
}

void PlanetFaceNode::tick(Camera* camera, GLfloat dtime)
{
	glm::mat4 transform = m_planetFace->getPlanet()->getTransformation();
	glm::transpose(transform);
	glm::vec3 campos = glm::vec3(transform * glm::vec4(camera->getPosition(), 1.0f));
	float camToOrigin = glm::distance(campos, (m_center));

	if (camToOrigin < m_radius * 2.0 && m_leaf) {
		this->subdivide();
	} else if (camToOrigin > m_radius * 2.0 && !m_leaf) {
		this->merge();
		return;
	}

	if (!m_leaf)
	{
		for (int i = 0; i < 4; i++)
		{
			m_children[i]->tick(camera, dtime);
		}
		return;
	}
}

void PlanetFaceNode::draw(Camera* camera, Shader* shader)
{
	// TODO: occlusion culling
	if (!m_leaf)
	{
		for (int i = 0; i < 4; i++)
		{
			m_children[i]->draw(camera, shader);
		}
		return;
	}

	if (!m_generated)
		return;

	PlanetIndexBuffer* buffers = m_planetFace->getPlanet()->getIndexBuffer(
		getNeighborDetailDifference(TOP),
		getNeighborDetailDifference(RIGHT),
		getNeighborDetailDifference(BOTTOM),
		getNeighborDetailDifference(LEFT)
	);

	shader->setBuffers(m_vao, m_vbo, buffers->getIbo());
	shader->use();

	camera->shaderViewProjection(*shader);
	shader->setUniform("modelMatrix", m_planetFace->getPlanet()->getTransformation());

	glDrawElements(GL_TRIANGLES, buffers->getVertexCount(), GL_UNSIGNED_SHORT, nullptr);
}

void PlanetFaceNode::generate()
{
	if (m_generated)
		return;

	int vertexCount = RESOLUTION * RESOLUTION;
	Vertex vertices[vertexCount];

	float divisionLevel = 1.0f / (float)pow(2.0, m_level);
	float radius = m_planetFace->getPlanet()->getRadius();
	float halfRes = (RESOLUTION - 1) / 2.f;
	glm::vec2 rpos = getPosition();
	for (int i = 0; i < RESOLUTION; i++)
	{
		for (int j = 0; j < RESOLUTION; j++)
		{
			// Get vertex position in the quadtree
			glm::vec2 treePos = (glm::vec2(i, j) - halfRes) * divisionLevel / halfRes + rpos;
			glm::vec3 vertex = glm::vec3(treePos, 1.0f);
			// Orient the vertex to the face
			vertex = glm::vec3(glm::vec4(vertex, 1.0f) * m_planetFace->getOrientation());

			// Normalize and multiply by radius to create a spherical mesh (unit sphere)
			float x2 = vertex.x * vertex.x;
			float y2 = vertex.y * vertex.y;
			float z2 = vertex.z * vertex.z;
			glm::vec3 point = glm::vec3(
				vertex.x * sqrt(1.0f - ((y2 + z2) / 2.0f) + ((y2 * z2) / 3.0f)),
				vertex.y * sqrt(1.0f - ((z2 + x2) / 2.0f) + ((z2 * x2) / 3.0f)),
				vertex.z * sqrt(1.0f - ((x2 + y2) / 2.0f) + ((x2 * y2) / 3.0f))
			);

			// Get noise height and multiply by radius
			float height = m_planetFace->getPlanet()->getNoise().fractal(8, point.x, point.y, point.z) * 20.0f;
			glm::vec3 pos = (height + radius) * point;

			// Texture coordinate
			glm::vec2 texCoord = glm::vec2(i, j) / (float)(RESOLUTION - 1);
			texCoord = texCoord * (1.0f - (1.0f / 128.f)) + 0.5f * (1.0f / 128.f);

			// Add vertex
			vertices[INDEX1D(i, j)].position = pos;
			vertices[INDEX1D(i, j)].normal = point;
			vertices[INDEX1D(i, j)].uv = texCoord;

			// Set center
			if ((i == RESOLUTION / 2 && j == RESOLUTION / 2))
				m_center = pos;
		}
	}

	glGenVertexArrays(1, &m_vao);
	glBindVertexArray(m_vao);

	glGenBuffers(1, &m_vbo);

	glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertexCount, vertices, GL_STATIC_DRAW);

  glm::vec3 boundingSphereCenterF = glm::vec3(0.0, 0.0, 0.0);
  float boundingSphereRadiusF = 0.0;

  // Calculate mean position and use as bounding sphere center
  for (int i = 0; i < vertexCount; i++)
	{
    boundingSphereCenterF += vertices[i].position;
	}
  boundingSphereCenterF /= (float)vertexCount;

  // Find the largest distance from the center to a vertex
  for (int i = 0; i < vertexCount; i++)
	{
		glm::vec3 length = (vertices[i].position - boundingSphereCenterF);
    boundingSphereRadiusF = std::max(boundingSphereRadiusF, glm::dot(length, length));
	}
  boundingSphereRadiusF = std::sqrt(boundingSphereRadiusF);

	m_center = boundingSphereCenterF;
	m_radius = boundingSphereRadiusF;

	m_generated = true;
}

bool PlanetFaceNode::subdivide()
{
	if (m_level == 8 || !m_planetFace->hasSplitsLeft() || !m_leaf)
		return false;
	
	m_children[TOP_LEFT]     = new PlanetFaceNode(m_planetFace, this, TOP_LEFT);
	m_children[TOP_RIGHT]    = new PlanetFaceNode(m_planetFace, this, TOP_RIGHT);
	m_children[BOTTOM_RIGHT] = new PlanetFaceNode(m_planetFace, this, BOTTOM_RIGHT);
	m_children[BOTTOM_LEFT]  = new PlanetFaceNode(m_planetFace, this, BOTTOM_LEFT);
	
	// Connect the children
	m_children[TOP_LEFT]->setNeighbor(RIGHT, m_children[TOP_RIGHT]);
	m_children[TOP_RIGHT]->setNeighbor(BOTTOM, m_children[BOTTOM_RIGHT]);
	m_children[BOTTOM_RIGHT]->setNeighbor(LEFT, m_children[BOTTOM_LEFT]);
	m_children[BOTTOM_LEFT]->setNeighbor(TOP, m_children[TOP_LEFT]);

	// Connect neighbors
  for (int i = 0; i < 4; i++)
	{
    if (m_neighbors[i] && !m_neighbors[i]->isLeaf())
		{
      m_neighbors[i]->findNeighbor(mirrorSide(i));
		}
	}

	// No longer leaf
	m_leaf = false;

	this->dispose();

	return true;
}
glm::vec2 PlanetFaceNode::getPosition()
{
	return m_parent ? m_parent->getPosition() + glm::vec2(ADJACENT(RIGHT, m_quadrant) ? 1.0 : -1.0, ADJACENT(TOP, m_quadrant) ? 1.0 : -1.0) * (1.0f / (1 << m_level)) : glm::vec2(0.0, 0.0);
}

bool PlanetFaceNode::merge()
{
	// Leaves don't ever need to be merged
	if (m_leaf)
		return false;

	// Merge and dispose the children
	for (int i = 0; i < 4; i++)
	{
		m_children[i]->dispose();
		delete m_children[i];
		m_children[i] = 0;
	}

	// We're a leaf now
	m_leaf = true;
	generate();
	return true;
}

void PlanetFaceNode::dispose()
{
	m_generated = false;
}

bool PlanetFaceNode::isLeaf()
{
	return m_leaf;
}

glm::vec3 PlanetFaceNode::getAbsolutePosition()
{
	return m_planetFace->getPlanet()->getPosition();
}

PlanetFace::PlanetFace(
	Planet* planet,
	const unsigned int face
) : 
	m_planet(planet),
	m_face(face)
{
	if (face < 4)
	{
    m_orientation = glm::rotate(glm::mat4(1.0f), (float)((double)face * -0.5 * M_PI), glm::vec3(0.0f, -1.0f, 0.0f));
	}
	else
	{
    m_orientation = glm::rotate(glm::mat4(1.0f), (float)((face == FACE_BOTTOM ? 0.5 : -0.5) * M_PI), glm::vec3(-1.0f, 0.0f, 0.0f));
	}

	m_lod = new PlanetFaceNode(this, 0, 0);
}

PlanetFace::~PlanetFace()
{
	delete m_lod;
}

void PlanetFace::draw(Camera* camera, Shader* shader)
{
	m_lod->draw(camera, shader);
}

void PlanetFace::tick(Camera* camera, GLfloat dtime)
{
	m_splits = MAX_SPLITS_PER_UPDATE;
	m_lod->tick(camera, dtime);
}

void PlanetFace::connect(const unsigned int side, PlanetFace* face)
{
	if (m_lod && face->getLODRoot()) {
		m_lod->setNeighbor(side, face->getLODRoot());
	}
}

bool PlanetFace::hasSplitsLeft()
{
	if (m_splits == 0)
	{
		return false;
	}

	m_splits--;
	return true;
}