using System;
using Godot;
using VirtualChemDemo.Concepts;

public partial class SingleBond : Bond2D
{
	private static int BIndex(int index, int multi)
	{
		if (multi == 1)
			return 0;
		if (multi % 2 == 1)
		{
			int center = multi / 2 + 1;
			return center - index;
		}

		if (multi % 2 == 0)
		{
			double center = multi / 2 + 0.5;
			return (int)(center > index ? Math.Ceiling(center - index) : Math.Floor(center - index));
		}

		return 0;
	}
	private void MakeCurve(float curveRate=20f, int cDir = 1)
	{
		Vector2 Start = AtomFrom.Position + new Vector2(32, 32);;
		Vector2 End = AtomTo.Position + new Vector2(32, 32);;
		Vector2[] xs = new Vector2[17];
		int[] x2 = new[] { 4, 12 };
		int[] x3 = new[] { 2, 6, 10, 14};
		int[] x4 = new[] { 1, 3, 5, 7, 9, 11, 13, 15 };
		Vector2 vd = End - Start;
		Vector2 nor = vd.Rotated(Mathf.Pi / 2 * cDir);
		Vector2 center = vd / 2 + 4f * nor / curveRate;
		xs[0] = Start;
		xs[16] = End;
		xs[8] = center + xs[0];
		foreach (int i in x2)
		{
			Vector2 v = xs[i + 4] - xs[i - 4];
			Vector2 n = v.Rotated(Mathf.Pi / 2 * cDir);
			Vector2 w = v / 2 + 2f * n / curveRate;
			xs[i] = w + xs[i - 4];
		}

		foreach (int i in x3)
		{
			Vector2 v = xs[i + 2] - xs[i - 2];
			Vector2 n = v.Rotated(Mathf.Pi / 2 * cDir);
			Vector2 w = v / 2 + n / curveRate;
			xs[i] = w + xs[i - 2];
		}

		foreach (int i in x4)
		{
			Vector2 v = xs[i + 1] - xs[i - 1];
			Vector2 n = v.Rotated(Mathf.Pi / 2 * cDir);
			Vector2 w = v / 2 + n / curveRate;
			xs[i] = w + xs[i - 1];
		}
		BondTypeA.Position = xs[10];
		BondTypeB.Position = xs[6];
		Points = xs;
	}

	public override void BondUpdate()
	{
		Reindex();
		int bindex = BIndex(Index, Multi);
		if (bindex == 0)
		{
			Vector2 v1 = AtomFrom.Position + new Vector2(32, 32);
			Vector2 v2 = AtomTo.Position + new Vector2(32, 32);
			Vector2 m = (v1 + v2) / 2;
			Points = new[] { v1, m, v2 };
			BondTypeA.Position = m - new Vector2(10, 10);
			BondTypeB.Position = m + new Vector2(10, 10);
		}
		else
		{
			float curveRate = 25 - Math.Abs(bindex)*5;
			int cDir = bindex > 0 ? 1 : -1;
			MakeCurve(curveRate, cDir);
		}

		

		BondTypeA.Text = BondFrom.BondType;
		BondTypeB.Text = BondTo.BondType;
	}

	// Called every frame. 'delta' is the elapsed time since the previous frame.
	public override void _Process(double delta)
	{
	}
}