using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Chunk : MonoBehaviour {

	public MeshRenderer meshRenderer;
	public MeshFilter meshFilter;

	int vertexIndex = 0;
	List<Vector3> vertices = new List<Vector3> ();
	List<int> triangles = new List<int> ();
	List<Vector2> uvs = new List<Vector2> ();

	byte[,,] voxelMap = new byte[VoxelData.ChunkWidth, VoxelData.ChunkHeight, VoxelData.ChunkWidth];

	World world;

	void Start () {

		world = GameObject.Find("World").GetComponent<World>();

		PopulateVoxelMap ();
		CreateMeshData ();
		CreateMesh ();

	}

	void PopulateVoxelMap () {

		for (int y = 0; y < VoxelData.ChunkHeight; y++) {
			for (int x = 0; x < VoxelData.ChunkWidth; x++) {
				for (int z = 0; z < VoxelData.ChunkWidth; z++) {

					voxelMap [x, y, z] = 0;

				}
			}
		}
	}

	void CreateMeshData() {

		for (int y = 0; y < VoxelData.ChunkHeight; y++) {
			for (int x = 0; x < VoxelData.ChunkWidth; x++) {
				for (int z = 0; z < VoxelData.ChunkWidth; z++) {

					AddVoxelDataToChunk (new Vector3(x, y, z));

				}
			}
		}
	}

	bool CheckVoxel (Vector3 pos) {

		int x = Mathf.FloorToInt (pos.x);
		int y = Mathf.FloorToInt (pos.y);
		int z = Mathf.FloorToInt (pos.z);

		if (x < 0 || x > VoxelData.ChunkWidth - 1 || y < 0 || y > VoxelData.ChunkHeight - 1 || z < 0 || z > VoxelData.ChunkWidth - 1)
			return false;

		return world.blocktypes[voxelMap [x, y, z]].isSolid;

	}

	void AddVoxelDataToChunk (Vector3 pos) {

		for (int p = 0; p < 6; p++) {

			if (!CheckVoxel(pos + VoxelData.faceChecks[p])) {

				vertices.Add (pos + VoxelData.voxelVerts[VoxelData.voxelTris[p, 0]]);
				vertices.Add (pos + VoxelData.voxelVerts[VoxelData.voxelTris[p, 1]]);
				vertices.Add (pos + VoxelData.voxelVerts[VoxelData.voxelTris[p, 2]]);
				vertices.Add (pos + VoxelData.voxelVerts[VoxelData.voxelTris[p, 3]]);

				AddTexture(0);

				triangles.Add (vertexIndex);
				triangles.Add (vertexIndex + 1);
				triangles.Add (vertexIndex + 2);
				triangles.Add (vertexIndex + 2);
				triangles.Add (vertexIndex + 1);
				triangles.Add (vertexIndex + 3);
				vertexIndex += 4;

			}
		}

	}

	void CreateMesh () {

		Mesh mesh = new Mesh ();
		mesh.vertices = vertices.ToArray ();
		mesh.triangles = triangles.ToArray ();
		mesh.uv = uvs.ToArray ();

		mesh.RecalculateNormals ();

		meshFilter.mesh = mesh;
	}

	void AddTexture (int textureID) {

		float y = textureID / VoxelData.TextureAtlasSizeInBlocks;
		float x = textureID - (y * VoxelData.TextureAtlasSizeInBlocks);

		x *= VoxelData.NormalizedBlockTextureSize;
		y *= VoxelData.NormalizedBlockTextureSize;

		y = 1f - y - VoxelData.NormalizedBlockTextureSize;

		uvs.Add(new Vector2(x, y));
		uvs.Add(new Vector2(x, y + VoxelData.NormalizedBlockTextureSize));
		uvs.Add(new Vector2(x + VoxelData.NormalizedBlockTextureSize, y));
		uvs.Add(new Vector2(x + VoxelData.NormalizedBlockTextureSize, y + VoxelData.NormalizedBlockTextureSize));

	}

}