using System;
using System.Collections.Generic;
using System.Linq;
using Godot;
using VirtualChemDemo.Concepts;
using VirtualChemistry.Chemistry.Atoms.Implements;
using VirtualChemistry.Chemistry.Atoms.Resolver;
using VirtualChemistry.Chemistry.Bonds.Implements;
using VirtualChemistry.Chemistry.Compounds.Implements;
using VirtualChemistry.Chemistry.Mixtures.Implements;

public partial class CompoundConstructor : Panel
{
	private HeterogeneousMixture HeterogeneousMixture { get; set; }
	public HomogeneousMixture HomogeneousMixture { get; set; }
	public HashSet<Atom> Atoms { get; set; } = new();
	public BaseBond ConnectPending { get; set; } = BaseBond.Null;
	public Atom PendingAtom { get; set; }
	public Dictionary<Atom, HashSet<Bond2D>> BondMap { get; set; } = new();
	private Viewer PanelViewer { get; set; }

	public override void _Ready()
	{
		GlobalScene.CompoundConstructor = this;
		HeterogeneousMixture = new();
		HomogeneousMixture = HeterogeneousMixture.AddLayer();
		PanelViewer = GetNode<Viewer>("Viewer");
	}

	private static class AtomPositionFixMemory
	{
		public static Atom[] SavedAtoms { get; set; } = null;
		private static int I { get; set; }
		private static int J { get; set; }
		public static int Max => SavedAtoms.Length;

		public static void Reset()
		{
			SavedAtoms = null;
			I = 0;
			J = 0;
		}

		public static void OneStep()
		{
			if (J >= Max)
			{
				J = 0;
				I++;
			}
			if (I >= Max)
			{
				Reset();
				return;
			}

			if (I == J)
			{
				J++;
				return;
			}

			Atom a1 = SavedAtoms[I];
			Atom a2 = SavedAtoms[J];

			if ((a1.Position - a2.Position).Length() < 64)
			{
				Vector2 pd = a1.Position - a2.Position;
				if (pd == Vector2.Zero)
					pd = new Vector2(J % 3 - 2, I % 3 - 1);
				a1.Position += pd;
				a2.Position -= pd;
				if (GlobalScene.CompoundConstructor.BondMap.TryGetValue(a1, out var bonds1))
					foreach (Bond2D b1 in bonds1)
						b1.BondUpdate();					
				if(GlobalScene.CompoundConstructor.BondMap.TryGetValue(a2, out var bonds2))
					foreach (Bond2D b2 in bonds2)
						b2.BondUpdate();
			}
			J++;
		}
	}
	
	public override void _Process(double delta)
	{
		if (AtomPositionFixMemory.SavedAtoms == null)
			AtomPositionFixMemory.SavedAtoms = Atoms.ToArray();
		AtomPositionFixMemory.OneStep();
	}

	public override bool _CanDropData(Vector2 atPosition, Variant data)
	{
		return true;
	}

	public override void _DropData(Vector2 atPosition, Variant data)
	{
		Atom a = data.As<Atom>(); 
		a.Position = atPosition;
		if(BondMap.ContainsKey(a))
			foreach (Bond2D b in BondMap[a])
				b.BondUpdate();
	}

	public void AddAtomOf(int idx)
	{
		BaseAtom a = AtomResolver.Resolve(idx);
		Compound c = a.GrabCompound;
		c.Amount = 1;
		a.Compound = c;
		Atom at = ResourceLoader.Load<PackedScene>("res://Scenes/Atom.tscn").Instantiate<Atom>();
		at.BaseAtom = a;
		AddChild(at);
		at.Position = new(500, 500);
		HomogeneousMixture.AddCompound(c, true, true);
		Atoms.Add(at);
		AtomPositionFixMemory.Reset();
	}

	public void RemoveAtomOf(Atom atom)
	{
		foreach (BaseBond b in atom.BaseAtom.ConnectedBonds)
			b.Disconnect();

		Bond2D[] toRemove = Array.Empty<Bond2D>();
		if (BondMap.TryGetValue(atom, out HashSet<Bond2D> value))
			toRemove = value.ToArray();
		
		foreach (Bond2D b in toRemove)
		{
			BondMap[b.AtomFrom].Remove(b);
			BondMap[b.AtomTo].Remove(b);
			RemoveChild(b);
		}

		atom.BaseAtom.Compound.HomogeneousMixture.Compounds.Remove(atom.BaseAtom.Compound);
		atom.BaseAtom.Compound.HomogeneousMixture = HomogeneousMixture.Null;
		atom.BaseAtom.Compound = Compound.Null;
		RemoveChild(atom);
		Atoms.Remove(atom);
		AtomPositionFixMemory.Reset();
	}

	public void ConnectAtoms(Atom a, BaseBond b)
	{
		b.Connect(ConnectPending);
		Bond2D bond = Bond2D.Resolve(b, ConnectPending);
		bond.AtomFrom = PendingAtom;
		bond.AtomTo = a;
		bond.BondFrom = ConnectPending;
		bond.BondTo = b;
		
		if (!BondMap.ContainsKey(a))
			BondMap[a] = new HashSet<Bond2D>();
		BondMap[a].Add(bond);
		if (!BondMap.ContainsKey(PendingAtom!))
			BondMap[PendingAtom] = new HashSet<Bond2D>();
		BondMap[PendingAtom].Add(bond);
		ConnectPending = BaseBond.Null;
		a.AtomActions.BuildMenu();
		PendingAtom.AtomActions.BuildMenu();
		PendingAtom = null;
		AddChild(bond);
		foreach (Bond2D bd in BondMap[a])
			bd.BondUpdate();
		
	}

	private void Back()
	{
		GlobalScene.MainScene.SwitchToDemo();
	}

	private void Build()
	{
		if(HomogeneousMixture.Compounds.Count==0)
			return;
		HeterogeneousMixture.Container = GlobalScene.Demo.SelectedBottle;
		GlobalScene.Demo.SelectedBottle.Content = HeterogeneousMixture;
		GlobalScene.Demo.SelectedBottle.BuildMenu();
		
		Clear();
		Back();
	}

	private void Clear(bool save = true)
	{
		if (!save)
		{
			foreach (Atom atom in Atoms)
				RemoveAtomOf(atom);
			return;
		}

		HashSet<Bond2D> removedBonds = new();
		foreach (Atom atom in Atoms)
		{
			RemoveChild(atom);
			if (!BondMap.ContainsKey(atom))
				continue;
			foreach (Bond2D bond in BondMap[atom])
			{
				if (!removedBonds.Contains(bond))
					RemoveChild(bond);
				removedBonds.Add(bond);
			}
		}

		Atoms = new();
		BondMap = new();
		HeterogeneousMixture = new HeterogeneousMixture();
		HomogeneousMixture = HeterogeneousMixture.AddLayer();
	}

	private void ForceClear() => Clear(false);
	private void BackToCenter() => PanelViewer.BackToCenter();
}