using Godot;
using System;
using System.Collections.Generic;
using System.Linq;
using static GameData;

public partial class World : Node3D
{
	public Dictionary<string, MeshInstance3D> tileMeshes;
	PackedScene layerPrefab = ResourceLoader.LoadLayerPrefab();
	private Dictionary<string, MultiMeshInstance3D> multiMeshes = new();
	private Dictionary<string, Mesh> meshLibrary = new();
	Layer[] map;
	Layer layerNode;
	// Called when the node enters the scene tree for the first time.
	public override void _Ready()
	{
		WFC.FillAdjacencies();
		tileMeshes = ResourceLoader.LoadTiles();
		foreach (var kvp in tileMeshes)
		{
			var temp = kvp.Value;
			meshLibrary[kvp.Key] = temp.Mesh;
			temp.QueueFree();
		}
		foreach (var kvp in meshLibrary)
		{
			var mm = new MultiMesh();
			mm.Mesh = kvp.Value;
			mm.TransformFormat = MultiMesh.TransformFormatEnum.Transform3D;

			var instance = new MultiMeshInstance3D();
			instance.Multimesh = mm;

			AddChild(instance);
			multiMeshes[kvp.Key] = instance;
		}
		map = new Layer[ruinSize];
		GenerateWorld();
		GD.Print("World generated");
		BuildMeshesForLayer(0);
	}

	// Called every frame. 'delta' is the elapsed time since the previous frame.
	public override void _Process(double delta)
	{
		if (Input.IsActionJustPressed("layer_up") && currentLayer > 0) currentLayer--;
		if (Input.IsActionJustPressed("layer_down") && currentLayer < ruinSize - 1) currentLayer++;
		if (currentLayer != visibleLayer)
		{
			BuildMeshesForLayer(currentLayer);
			visibleLayer = currentLayer;
		}
	}

	private void GenerateWorld()
	{
		DateTime now = DateTime.Now;
		for (int layer = 0; layer < ruinSize; layer++)
		{
			layerNode = layerPrefab.Instantiate<Layer>();
			AddChild(layerNode);
			layerNode.SetupLayer(layerSize, layer, tileMeshes);
			map[layer] = layerNode;
		}
		GD.Print("Time for map generation: " + (DateTime.Now - now).Seconds);
	}

	private void BuildMeshesForLayer(int layerIndex)
	{
		foreach (MultiMeshInstance3D mm in multiMeshes.Values)
		{
			mm.Multimesh.InstanceCount = 0;
		}

		Layer layer = map[layerIndex];

		Dictionary<string, List<Transform3D>> batches = new();

		for (int x = 0; x < layerSize; x++)
		{
			for (int y = 0; y < layerSize; y++)
			{
				Tile tile = layer.tiles[x, y];
				string key = tile.collapsedMesh;

				if (!batches.ContainsKey(key))
					batches[key] = new List<Transform3D>();

				batches[key].Add(new Transform3D(
					Basis.Identity,
					tile.Position
				));
			}
		}

		foreach (var kvp in batches)
		{
			MultiMesh mm = multiMeshes[kvp.Key].Multimesh;
			List<Transform3D> list = kvp.Value;

			mm.InstanceCount = list.Count;

			for (int i = 0; i < list.Count; i++)
			{
				mm.SetInstanceTransform(i, list[i]);
			}
		}
	}
}