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

public class Block
{

    enum Cubeside { BOTTOM, TOP, LEFT, RIGHT, FRONT, BACK };
    public enum BlockType { GRASS, DIRT, STONE, SAND, DIAMOND, COAL, GOLD, BEDROCK, AIR };


    public BlockType bType;
    public bool isSolid;
    Chunk owner;
    GameObject parent;
    Vector3 position;

    Vector2[,] blockUVs = {
		/*grass top*/{new Vector2(0f,0.9375f),new Vector2(0.0625f,0.9375f),new Vector2(0f,1f),new Vector2(0.0625f,1f) },
      /*grass side*/{new Vector2(0.1875f,0.9375f),new Vector2(0.25f,0.9375f),new Vector2(0.1875f,1f),new Vector2(0.25f,1f)},
    /*dirt*/{new Vector2(0.5f,0.6875f),new Vector2(0.5625f,0.6875f),new Vector2(0.5f,0.75f),new Vector2(0.5625f,0.75f)},
/*stone*/{new Vector2(0f,0.8125f),new Vector2(0.0625f,0.8125f),new Vector2(0f,0.875f),new Vector2(0.0625f,0.875f)},
        /*sand*/{new Vector2(0f,0.25f),new Vector2(0.0625f,0.25f),new Vector2(0f,0.3125f),new Vector2(0.0625f,0.3125f)},
        /*diamond*/{new Vector2(0f,0.3125f),new Vector2(0.0625f,0.3125f),new Vector2(0f,0.375f),new Vector2(0.0625f,0.375f)},
        /*coal*/{new Vector2(0.125f,0.8125f),new Vector2(0.1875f,0.8125f),new Vector2(0.125f,0.875f),new Vector2(0.1875f,0.875f) },
        /*gold*/{ new Vector2(0.125f,0.75f),new Vector2(0.1875f,0.75f),new Vector2(0.125f,0.8125f),new Vector2(0.1875f,0.8125f)},
     /*bedrock*/{ new Vector2(0.4375f,0.3125f),new Vector2(0.5f,0.3125f),new Vector2(0.4375f,0.375f),new Vector2(0.5f,0.375f)}};

    public Block(BlockType b, Vector3 pos, GameObject p, Chunk o)
    {
        bType = b;
        owner = o;
        parent = p;
        position = pos;
        if (bType == BlockType.AIR)
            isSolid = false;
        else
            isSolid = true;
    }

    public Block(BlockType b, Vector3 pos, GameObject p)
    {
        bType = b;
        parent = p;
        position = pos;
        if (bType == BlockType.AIR)
            isSolid = false;
        else
            isSolid = true;
    }

    public void SetType(BlockType b)
    {
        bType = b;
        if (bType == BlockType.AIR)
            isSolid = false;
        else
            isSolid = true;
    }

    void CreateQuad(Cubeside side)
    {
        Mesh mesh = new Mesh();
        mesh.name = "ScriptedMesh" + side.ToString();

        Vector3[] vertices = new Vector3[4];
        Vector3[] normals = new Vector3[4];
        Vector2[] uvs = new Vector2[4];
        int[] triangles = new int[6];

        //all possible UVs
        Vector2 uv00;
        Vector2 uv10;
        Vector2 uv01;
        Vector2 uv11;

        if (bType == BlockType.GRASS && side == Cubeside.TOP)
        {
            uv00 = blockUVs[0, 0];
            uv10 = blockUVs[0, 1];
            uv01 = blockUVs[0, 2];
            uv11 = blockUVs[0, 3];
        }
        else if (bType == BlockType.GRASS && side == Cubeside.BOTTOM)
        {
            uv00 = blockUVs[(int)(BlockType.DIRT + 1), 0];
            uv10 = blockUVs[(int)(BlockType.DIRT + 1), 1];
            uv01 = blockUVs[(int)(BlockType.DIRT + 1), 2];
            uv11 = blockUVs[(int)(BlockType.DIRT + 1), 3];
        }
        else
        {
            uv00 = blockUVs[(int)(bType + 1), 0];
            uv10 = blockUVs[(int)(bType + 1), 1];
            uv01 = blockUVs[(int)(bType + 1), 2];
            uv11 = blockUVs[(int)(bType + 1), 3];
        }

        //all possible vertices
        Vector3 p0 = new Vector3(-0.5f, -0.5f, 0.5f);
        Vector3 p1 = new Vector3(0.5f, -0.5f, 0.5f);
        Vector3 p2 = new Vector3(0.5f, -0.5f, -0.5f);
        Vector3 p3 = new Vector3(-0.5f, -0.5f, -0.5f);
        Vector3 p4 = new Vector3(-0.5f, 0.5f, 0.5f);
        Vector3 p5 = new Vector3(0.5f, 0.5f, 0.5f);
        Vector3 p6 = new Vector3(0.5f, 0.5f, -0.5f);
        Vector3 p7 = new Vector3(-0.5f, 0.5f, -0.5f);

        switch (side)
        {
            case Cubeside.BOTTOM:
                vertices = new Vector3[] { p0, p1, p2, p3 };
                normals = new Vector3[] {Vector3.down, Vector3.down,
                                            Vector3.down, Vector3.down};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
            case Cubeside.TOP:
                vertices = new Vector3[] { p7, p6, p5, p4 };
                normals = new Vector3[] {Vector3.up, Vector3.up,
                                            Vector3.up, Vector3.up};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
            case Cubeside.LEFT:
                vertices = new Vector3[] { p7, p4, p0, p3 };
                normals = new Vector3[] {Vector3.left, Vector3.left,
                                            Vector3.left, Vector3.left};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
            case Cubeside.RIGHT:
                vertices = new Vector3[] { p5, p6, p2, p1 };
                normals = new Vector3[] {Vector3.right, Vector3.right,
                                            Vector3.right, Vector3.right};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
            case Cubeside.FRONT:
                vertices = new Vector3[] { p4, p5, p1, p0 };
                normals = new Vector3[] {Vector3.forward, Vector3.forward,
                                            Vector3.forward, Vector3.forward};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
            case Cubeside.BACK:
                vertices = new Vector3[] { p6, p7, p3, p2 };
                normals = new Vector3[] {Vector3.back, Vector3.back,
                                            Vector3.back, Vector3.back};
                uvs = new Vector2[] { uv11, uv01, uv00, uv10 };
                triangles = new int[] { 3, 1, 0, 3, 2, 1 };
                break;
        }

        mesh.vertices = vertices;
        mesh.normals = normals;
        mesh.uv = uvs;
        mesh.triangles = triangles;

        mesh.RecalculateBounds();

        GameObject quad = new GameObject("Quad");
        quad.transform.position = position;
        quad.transform.parent = this.parent.transform;

        MeshFilter meshFilter = (MeshFilter)quad.AddComponent(typeof(MeshFilter));
        meshFilter.mesh = mesh;

    }

    int ConvertBlockIndexToLocal(int i)
    {
        if (i == -1)
            i = World.chunkSize - 1;
        else if (i == World.chunkSize)
            i = 0;
        return i;
    }

    public bool HasSolidNeighbour(int x, int y, int z)
    {
        Block[,,] chunks;

        if (x < 0 || x >= World.chunkSize ||
           y < 0 || y >= World.chunkSize ||
           z < 0 || z >= World.chunkSize)
        {  //block in a neighbouring chunk

            Vector3 neighbourChunkPos = this.parent.transform.position +
                                        new Vector3((x - (int)position.x) * World.chunkSize,
                                            (y - (int)position.y) * World.chunkSize,
                                            (z - (int)position.z) * World.chunkSize);
            string nName = World.BuildChunkName(neighbourChunkPos);

            x = ConvertBlockIndexToLocal(x);
            y = ConvertBlockIndexToLocal(y);
            z = ConvertBlockIndexToLocal(z);

            Chunk nChunk;
            if (World.chunks.TryGetValue(nName, out nChunk))
            {
                chunks = nChunk.chunkData;
            }
            else
                return false;
        }  //block in this chunk
        else
            chunks = owner.chunkData;

        try
        {
            return chunks[x, y, z].isSolid;
        }
        catch (System.IndexOutOfRangeException) { }

        return false;
    }

    public void Draw()
    {
        if (bType == BlockType.AIR) return;

        if (!HasSolidNeighbour((int)position.x, (int)position.y, (int)position.z + 1))
            CreateQuad(Cubeside.FRONT);
        if (!HasSolidNeighbour((int)position.x, (int)position.y, (int)position.z - 1))
            CreateQuad(Cubeside.BACK);
        if (!HasSolidNeighbour((int)position.x, (int)position.y + 1, (int)position.z))
            CreateQuad(Cubeside.TOP);
        if (!HasSolidNeighbour((int)position.x, (int)position.y - 1, (int)position.z))
            CreateQuad(Cubeside.BOTTOM);
        if (!HasSolidNeighbour((int)position.x - 1, (int)position.y, (int)position.z))
            CreateQuad(Cubeside.LEFT);
        if (!HasSolidNeighbour((int)position.x + 1, (int)position.y, (int)position.z))
            CreateQuad(Cubeside.RIGHT);
    }
}