// Copyright 2014-2017 ClassicalSharp | Licensed under BSD-3
using System;
using ClassicalSharp.GraphicsAPI;
using OpenTK;

namespace ClassicalSharp.Selections {

	public class SelectionBox {
		
		public byte ID;
		public Vector3I Min, Max;
		public FastColour Colour;
		public float MinDist, MaxDist;
		
		public SelectionBox(Vector3I start, Vector3I end, FastColour col) {	
			Min = Vector3I.Min(start, end);
			Max = Vector3I.Max(start, end);
			Colour = col;
		}
		
		public void Render(double delta, VertexP3fC4b[] vertices, VertexP3fC4b[] lineVertices,
		                  ref int index, ref int lineIndex) {
			float offset = MinDist < 32 * 32 ? 1/32f : 1/16f;
			Vector3 p1 = (Vector3)Min - new Vector3(offset, offset, offset);
			Vector3 p2 = (Vector3)Max + new Vector3(offset, offset, offset);		
			int col = Colour.Pack();
			
			HorQuad(vertices, ref index, col, p1.X, p1.Z, p2.X, p2.Z, p1.Y); // bottom
			HorQuad(vertices, ref index, col, p1.X, p1.Z, p2.X, p2.Z, p2.Y); // top		
			VerQuad(vertices, ref index, col, p1.X, p1.Y, p1.Z, p2.X, p2.Y, p1.Z); // sides
			VerQuad(vertices, ref index, col, p1.X, p1.Y, p2.Z, p2.X, p2.Y, p2.Z);
			VerQuad(vertices, ref index, col, p1.X, p1.Y, p1.Z, p1.X, p2.Y, p2.Z);
			VerQuad(vertices, ref index, col, p2.X, p1.Y, p1.Z, p2.X, p2.Y, p2.Z);
			
			col = new FastColour((byte)~Colour.R, (byte)~Colour.G, (byte)~Colour.B).Pack();
			// bottom face
			Line(lineVertices, ref lineIndex, p1.X, p1.Y, p1.Z, p2.X, p1.Y, p1.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p1.Y, p1.Z, p2.X, p1.Y, p2.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p1.Y, p2.Z, p1.X, p1.Y, p2.Z, col);
			Line(lineVertices, ref lineIndex, p1.X, p1.Y, p2.Z, p1.X, p1.Y, p1.Z, col);
			// top face
			Line(lineVertices, ref lineIndex, p1.X, p2.Y, p1.Z, p2.X, p2.Y, p1.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p2.Y, p1.Z, p2.X, p2.Y, p2.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p2.Y, p2.Z, p1.X, p2.Y, p2.Z, col);
			Line(lineVertices, ref lineIndex, p1.X, p2.Y, p2.Z, p1.X, p2.Y, p1.Z, col);
			// side faces
			Line(lineVertices, ref lineIndex, p1.X, p1.Y, p1.Z, p1.X, p2.Y, p1.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p1.Y, p1.Z, p2.X, p2.Y, p1.Z, col);
			Line(lineVertices, ref lineIndex, p2.X, p1.Y, p2.Z, p2.X, p2.Y, p2.Z, col);
			Line(lineVertices, ref lineIndex, p1.X, p1.Y, p2.Z, p1.X, p2.Y, p2.Z, col);
		}
		
		internal static void VerQuad(VertexP3fC4b[] vertices, ref int index, int col,
		                           float x1, float y1, float z1, float x2, float y2, float z2) {
			vertices[index++] = new VertexP3fC4b(x1, y1, z1, col);
			vertices[index++] = new VertexP3fC4b(x1, y2, z1, col);
			vertices[index++] = new VertexP3fC4b(x2, y2, z2, col);
			vertices[index++] = new VertexP3fC4b(x2, y1, z2, col);
		}
		
		internal static void HorQuad(VertexP3fC4b[] vertices, ref int index, int col, 
		                           float x1, float z1, float x2, float z2, float y) {
			vertices[index++] = new VertexP3fC4b(x1, y, z1, col);
			vertices[index++] = new VertexP3fC4b(x1, y, z2, col);
			vertices[index++] = new VertexP3fC4b(x2, y, z2, col);
			vertices[index++] = new VertexP3fC4b(x2, y, z1, col);
		}
		
		static void Line(VertexP3fC4b[] vertices, ref int index, float x1, float y1, float z1, 
		          float x2, float y2, float z2, int col) {
			vertices[index++] = new VertexP3fC4b(x1, y1, z1, col);
			vertices[index++] = new VertexP3fC4b(x2, y2, z2, col);
		}
	}
}