using System;
using System.Collections;
using System.Linq;
using TransportGame.Generator;
using TransportGame.Model;
using TransportGame.Unity;
using TransportGame.Utils;
using UnityEngine;

public class TerrainGeneratorScript : MonoBehaviour
{
	private Map map = null;

	public int TerrainWidth = 1024;
	public int TerrainHeight = 1024;
	public GameObject WaterObject;
    public Texture2D[] TerrainTextures;
    public Texture2D[] BuildingTextures;
    public Material RoadMaterial;
    public Material BuildingMaterial;

	// Use this for initialization
	void Start()
	{
		StartCoroutine(GenerateMap());
	}

	private void GenerateTerrainThread()
	{
		CityGenerator generator = new CityGenerator();
		map = generator.Generate(TerrainWidth, TerrainHeight);
	}
    
	private Mesh GenerateWater()
	{
		Mesh water = new Mesh();
		water.name = "water";
		water.vertices = new[] { 
			new Vector3(0, map.WaterLevel, 0), 
			new Vector3(0, map.WaterLevel, map.Height), 
			new Vector3(map.Width, map.WaterLevel, 0), 
			new Vector3(map.Width, map.WaterLevel, map.Height)
		};
		water.triangles = new[] { 0, 1, 2, 2, 1, 3 };
		water.uv = new[] {
			new UnityEngine.Vector2(0, 0),
			new UnityEngine.Vector2(0, 1),
			new UnityEngine.Vector2(1, 0),
			new UnityEngine.Vector2(1, 1)
		};
		water.RecalculateNormals();

		return water;
	}

	private IEnumerator GenerateMap()
	{
		// Generate terrain
		foreach (var i in Task.Await(GenerateTerrainThread))
			yield return i;

		// Generate terrain data
		TerrainData terrainData = new TerrainData();
		terrainData.heightmapResolution = Mathf.Max(map.Height, map.Width) + 1;
		terrainData.size = new Vector3(map.Width, map.Biome.Height, map.Height);
		terrainData.SetDetailResolution(1024, 8);
		terrainData.SetHeights(0, 0, map.Heightmap);
		terrainData.name = "Generated Terrain Data";
        yield return null;
        
        if (map.Biome.Textures != null)
        {
            SplatPrototype[] prototypes = new SplatPrototype[map.Biome.Textures.Length];
            
            for (int i = 0; i < map.Biome.Textures.Length; i++)
            {
                Texture2D texture = TerrainTextures.FirstOrDefault(tex => tex != null && tex.name == map.Biome.Textures[i].Source);

                if (texture == null)
                    throw new Exception("Texture " + map.Biome.Textures[i].Source + " not found!");

                prototypes[i] = new SplatPrototype();
                prototypes[i].texture = texture;
            }

            terrainData.splatPrototypes = prototypes;

            yield return null;
        }

		// Create terrain object
		GameObject terrain = Terrain.CreateTerrainGameObject(terrainData);
		terrain.name = "Generated Terrain";
		yield return null;

		Terrain terrainComp = terrain.GetComponent<Terrain>();
		terrainComp.heightmapPixelError = 1;
		yield return null;

		// Set water
		if (WaterObject != null)
		{
			MeshFilter waterMesh = WaterObject.GetComponent<MeshFilter>();
			waterMesh.mesh = GenerateWater();
		}
        yield return null;

        // Set up textures
        Logger.Info("Setting up textures...");
        BeginSetupSplatmaps(terrainData);

        foreach (var lot in map.BuildingLots)
        {
            for (int i = 0; i < lot.Points.Length; i++)
            {
                int j = (i + 1) % lot.Points.Length;

                if (!map.IsInside(lot.Points[i]))
                {
                    Logger.Warning("Generated point not inside: {0}", lot.Points[i]);
                    continue;
                }
                if (!map.IsInside(lot.Points[j]))
                {
                    Logger.Warning("Generated point not inside: {0}", lot.Points[j]);
                    continue;
                }

                Debug.DrawLine(
                    new Vector3(lot.Points[i].Y, map.GetHeight((int)lot.Points[i].X, (int)lot.Points[i].Y) + 0.5f, lot.Points[i].X),
                    new Vector3(lot.Points[j].Y, map.GetHeight((int)lot.Points[j].X, (int)lot.Points[j].Y) + 0.5f, lot.Points[j].X),
                    Color.yellow, 10000);
            }
        }

        // Generate road & building mesh (we run the loops in parallel), and apply textures
        Logger.Info("Generating buildings and roads...");

        BuildingMeshGenerator buildingMeshGenerator = new BuildingMeshGenerator();
        buildingMeshGenerator.BuildingMaterial = BuildingMaterial;
        buildingMeshGenerator.Textures = BuildingTextures;

        RoadMeshGenerator roadMeshGenerator = new RoadMeshGenerator();
        roadMeshGenerator.RoadMaterial = RoadMaterial;

        foreach (var i in Task.InParallel(buildingMeshGenerator.Generate(map), roadMeshGenerator.Generate(map), EndSetupSplatmaps(terrainData)))
            yield return i;
	}

    private float[,,] GenerateSplatData(int alphaWidth, int alphaHeight, int alphaLayers)
    {
        float[, ,] splatData = new float[alphaWidth, alphaHeight, alphaLayers];
        Expression[] expressions = new Expression[alphaLayers];

        for (int y = 0; y < alphaHeight; y++)
            for (int x = 0; x < alphaWidth; x++)
            {
                float y_01 = (float)y / (float)alphaHeight;
                float x_01 = (float)x / (float)alphaWidth;

                int ix = Mathf.RoundToInt(x_01 * TerrainWidth);
                int iy = Mathf.RoundToInt(y_01 * TerrainHeight);

                // Get height
                float height = map.GetHeight(ix, iy);

                // Get steepness
                float steepness = map.GetSteepness(ix, iy);

                // Go through each texture layer
                float[] weights = new float[alphaLayers];
                float sum = 0;

                for (int t = 0; t < alphaLayers; t++)
                {
                    // Set up expression
                    if (expressions[t] == null)
                    {
                        expressions[t] = new Expression(map.Biome.Textures[t].Expression);
                        expressions[t].ParseExpression();
                    }

                    expressions[t].Variables["height"] = height;
                    expressions[t].Variables["steepness"] = steepness;
                    expressions[t].Variables["maxHeight"] = map.Biome.Height;
                    expressions[t].Variables["waterLevel"] = map.WaterLevel - 1f;

                    // Obtain weight
                    weights[t] = expressions[t].Evaluate();
                    sum += weights[t];
                }

                // Normalize and copy weights
                for (int t = 0; t < alphaLayers; t++)
                {
                    splatData[x, y, t] = weights[t] / sum;
                }
            }

        return splatData;
    }

    float[, ,] splatData = null;
    private Task splatmapsTask = null;

    private void BeginSetupSplatmaps(TerrainData terrainData)
    {
        int alphaW = terrainData.alphamapWidth;
        int alphaH = terrainData.alphamapHeight;
        int alphaL = terrainData.alphamapLayers;

        splatmapsTask = Task.RunAsync(() => splatData = GenerateSplatData(alphaW, alphaH, alphaL));
    }

    private IEnumerable EndSetupSplatmaps(TerrainData terrainData)
    {
        foreach (var i in splatmapsTask.Await())
            yield return i;

        terrainData.SetAlphamaps(0, 0, splatData);
    }

	// Update is called once per frame
	void Update()
	{
	}

    void OnGUI()
    {
        Event e = Event.current;
        if (e.type == EventType.KeyDown)
        {
            if (e.keyCode == KeyCode.Home)
            {
                Logger.Warning("Writing to file...");
                Logger.DumpMap(map, "map.map");
                Logger.Warning("Wrote map to file.");
            }
        }
    }
}