using System;
using System.Collections.Generic;
using System.Linq;
using FOU.Scripts.Elements;
using Godot;

namespace FOU.Scripts;

public class Chunk {
    public Element[,] Elements;
    public int Index = -1;
    public Chunk NeighborN = null;
    public Chunk NeighborE = null;
    public Chunk NeighborS = null;
    public Chunk NeighborW = null;

    private readonly Image image;
    private readonly int sizeX;
    private readonly int sizeY;
    private readonly HashSet<Element> activeElements;

    public Chunk(int x, int y, int index) {
        Index = index;
        sizeX = x;
        sizeY = y;

        Elements = new Element[x, y];
        for (int i = 0; i < sizeX; i++) {
            for (int j = 0; j < sizeY; j++) {
                Elements[i,j] = new Element(i, j, this);
            }
        }

        activeElements = new HashSet<Element>(sizeX * sizeY);

        image = Image.Create(sizeX, sizeY, false, Image.Format.Rgb8);
        image.Fill(Colors.Black);
    }

    public void Update() {
        // for (int x = 0; x < sizeX; x++) {
        //     for (int y = 0; y < sizeY; y++) {
        //         if (Elements[x,y] != null)
        //             Elements[x,y].Update();
        //     }
        // }
        foreach (Element e in activeElements) {
            e.Update();
        }
    }

    public void WritePixel<T>(int x, int y, int size) {
        int halfsize = size/2;

        Type type = typeof(T);

        for (int i = -halfsize; i <= halfsize; i++) {
            for (int j = -halfsize; j <= halfsize; j++) {
                int X = Mathf.Clamp(x + i, 0, sizeX-1);
                int Y = Mathf.Clamp(y + j, 0, sizeY-1);
                object o = Activator.CreateInstance(type, X, Y, this);

                if (Elements[X,Y].GetType() != type) {
                    Elements[X, Y] = o as Element;
                    Elements[X, Y].Active = true;
                }
            }
        }
    }

    // TODO: use this function and stitch together partial images in Level
    public Image DrawLevel() {
        for (int x = 0; x < sizeX; x++) {
            for (int y = 0; y < sizeY; y++) {
                image.SetPixel(x,y, Elements[x,y].Color);
            }
        }
        return image;
    }

    public void SetElementActive(Element e, bool active) {
        if (e.Active == active) return;

        GD.Print($"setting {e} to {active}");
        if (active && e.GetType() != typeof(Element))
            activeElements.Add(e);
        else
            activeElements.Remove(e);
    }

    public int ActiveElemetnsCount() {
        return activeElements.Count;
    }

    public void Swap(Element what, Vector2I pos) {
        Swap(what, Get(pos));
    }

    public Element Get(Vector2I pos) {
        Element e = null;

        if (pos.Y < 0) {
            if (NeighborN != null)
                e = NeighborN.Get(pos.X, NeighborN.sizeY + pos.Y);

        } else if (pos.Y >= sizeY) {
            if (NeighborS != null)
                e = NeighborS.Get(pos.X, sizeY - pos.Y);

        } else if (pos.X < 0) {
            if (NeighborE != null)
                e = NeighborE.Get(NeighborE.sizeX + pos.X, pos.Y);

        } else if (pos.X >= sizeX) {
            if (NeighborW != null)
                e = NeighborW.Get(sizeX - pos.X, pos.Y);

        } else e = Get(pos.X, pos.Y);

        return e;
    }

    private Element Get(int x, int y) {
        if (x < 0 || x >= sizeX) return null;
        if (y < 0 || y >= sizeY) return null;

        return Elements[x,y];
    }

    public bool IsEmpty(Vector2I pos) {
        return Get(pos)?.GetType() == typeof(Element);
    }

    private void Swap(Element what, Element swapTo) {
        if (what == null || swapTo == null) {
            GD.PrintErr("Trying to swap null");
            return;
        }
        Element temp = new Element(what);

        what.Position = swapTo.Position;
        what.Chunk = swapTo.Chunk;
        what.Chunk.Elements[what.Position.X, what.Position.Y] = what;

        swapTo.Position = temp.Position;
        swapTo.Chunk = temp.Chunk;
        swapTo.Chunk.Elements[swapTo.Position.X, swapTo.Position.Y] = swapTo;

        what.Active = true;
        swapTo.Active = true;
    }
}