#include "graphics/chunkmesh.h"

#include "world.h"
#include "chunk.h"

#include <vector>
#include <GL/glew.h>
#include <GL/gl.h>
#include <iostream>


namespace vtk {

ChunkMesh::ChunkMesh(World& world, glm::ivec3 chunkPos) :
	mLinkedWorld(world),
	mLinkedChunkPos(chunkPos),
	mLocked(false)
{
	glGenBuffers(1, &mGeometryTexVBO);
	glGenBuffers(1, &mLightVBO);

	glGenVertexArrays(1, &mVAO);

	glBindVertexArray(mVAO);

	glBindBuffer(GL_ARRAY_BUFFER, mGeometryTexVBO);


	//vertices
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6*sizeof(float), NULL);
	glEnableVertexAttribArray(0);

	//tex uv coords
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6*sizeof(float), (void*)(3*sizeof(float)));
	glEnableVertexAttribArray(1);
}

void ChunkMesh::rebuildChunkGeometry() {
	if (mLocked) return;
	mLocked = true;
	//get the chunk from position
	auto chunk = mLinkedWorld.getChunk(mLinkedChunkPos); 

	//temporary until I finish mesh providers
	float texUV [] = {
		0.0f, 1.0f,
		1.0f, 1.0f,
		0.0f, 0.0f,
		1.0f, 0.0f,
		0.0f, 0.0f,
		1.0f, 1.0f
	};
	float topModel [] = {
		//x     y     z    
		0.0f, 1.0f, 0.0f, //tl
		1.0f, 1.0f, 0.0f, //tr
		0.0f, 1.0f, 1.0f, //bl
		1.0f, 1.0f, 1.0f, //br
		0.0f, 1.0f, 1.0f, //bl
		1.0f, 1.0f, 0.0f //tr
	};
	float bottomModel [] = {
		//x     y     z     u     v
		0.0f, 0.0f, 1.0f, //tl
		1.0f, 0.0f, 1.0f, //tr
		0.0f, 0.0f, 0.0f, //bl
		1.0f, 0.0f, 0.0f, //br
		0.0f, 0.0f, 0.0f, //bl
		1.0f, 0.0f, 1.0f //tr
	};
	float northModel [] = {
		//x     y     z     u     v
		0.0f, 1.0f, 1.0f, //tl
		1.0f, 1.0f, 1.0f, //tr
		0.0f, 0.0f, 1.0f, //bl
		1.0f, 0.0f, 1.0f, //br
		0.0f, 0.0f, 1.0f, //bl
		1.0f, 1.0f, 1.0f //tr
	};
	float southModel [] = {
		//x     y     z     u     v
		1.0f, 1.0f, 0.0f, //tl
		0.0f, 1.0f, 0.0f, //tr
		1.0f, 0.0f, 0.0f, //bl
		0.0f, 0.0f, 0.0f, //br
		1.0f, 0.0f, 0.0f, //bl
		0.0f, 1.0f, 0.0f //tr
	};
	float eastModel [] = {
		//x     y     z     u     v
		1.0f, 1.0f, 1.0f, //tl
		1.0f, 1.0f, 0.0f, //tr
		1.0f, 0.0f, 1.0f, //bl
		1.0f, 0.0f, 0.0f, //br
		1.0f, 0.0f, 1.0f, //bl
		1.0f, 1.0f, 0.0f //tr
	};
	float westModel [] = {
		//x     y     z     u     v
		0.0f, 1.0f, 0.0f, //tl
		0.0f, 1.0f, 1.0f, //tr
		0.0f, 0.0f, 0.0f, //bl
		0.0f, 0.0f, 1.0f, //br
		0.0f, 0.0f, 0.0f, //bl
		0.0f, 1.0f, 1.0f //tr
	};

	// geometry format: x,y,z,u,v,i
	geometry.clear();
	mFaceCount = 0;
	int chunkSize = 16; // TODO: make this not hardcoded

	for (int i = 0; i < chunkSize; ++i) {
		for (int j = 0; j < chunkSize; ++j) {
			for (int k = 0; k < chunkSize; ++k) {
				//for each voxel in the chunk...
				// TODO: move this code into a mesh provider system

				//top
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i, j + 1, k)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(topModel[(l * 3)] + (float)i);
							geometry.push_back(topModel[(l * 3) + 1] + (float)j);
							geometry.push_back(topModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}

				//bottom
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i, j - 1, k)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(bottomModel[(l * 3)] + (float)i);
							geometry.push_back(bottomModel[(l * 3) + 1] + (float)j);
							geometry.push_back(bottomModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}

				//north
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i, j, k + 1)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(northModel[(l * 3)] + (float)i);
							geometry.push_back(northModel[(l * 3) + 1] + (float)j);
							geometry.push_back(northModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}
				//south
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i, j, k - 1)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(southModel[(l * 3)] + (float)i);
							geometry.push_back(southModel[(l * 3) + 1] + (float)j);
							geometry.push_back(southModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}
				//east
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i + 1, j, k)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(eastModel[(l * 3)] + (float)i);
							geometry.push_back(eastModel[(l * 3) + 1] + (float)j);
							geometry.push_back(eastModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}

				//west
				if (chunk->isVoxelSolid(i,j,k)) { //check that it's solid
					if (!chunk->isVoxelSolid(i - 1, j, k)) {
						++mFaceCount;
						for (int l = 0; l < 6; ++l) {
							geometry.push_back(westModel[(l * 3)] + (float)i);
							geometry.push_back(westModel[(l * 3) + 1] + (float)j);
							geometry.push_back(westModel[(l * 3) + 2] + (float)k);
							geometry.push_back(texUV[l*2]);
							geometry.push_back(texUV[(l*2)+1]);
							geometry.push_back(mLinkedWorld.voxelInfo.getTexIndexFromID(2, Face3D::TOP));
						}
					} 
				}
			}
		}
	}

	mUpdated = true;
	mLocked = false;
}

void ChunkMesh::rebuildChunkLighting() {
	//this doesn't do anything yet
}

void ChunkMesh::draw() {
	updateGeometry();
	glBindVertexArray(mVAO);
	glDrawArrays(GL_TRIANGLES, 0, mGeometryFaceCount * 6);
}

bool ChunkMesh::updateGeometry() {
	if (mUpdated) {
		mUpdated = false;
		glBindBuffer(GL_ARRAY_BUFFER, mGeometryTexVBO);
		glBufferData(GL_ARRAY_BUFFER, sizeof(float) * geometry.size(), geometry.data(), GL_STATIC_DRAW);
		mGeometryFaceCount = mFaceCount;
		return true;
	}
	return false;
}

} //namespace vtk