using System;
using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class FogOverlay : MonoBehaviour
{
    private const int fogTextureResolution = 256;
    private const int fogTextureSize = fogTextureResolution * fogTextureResolution;

    public Color fogColor = new Color(1, 1, 1, .3f);
    public Color noFogColor = new Color(1, 1, 1, 0);
    public float radius = 1;
    public int minFogZoom = 15;

    private Texture2D defaultFog;
    private List<Vector2> points;

    private void ApplyPointToTiles(Vector2 newLocation)
    {
        lock (OnlineMapsTile.tiles)
        {
            foreach (OnlineMapsTile tile in OnlineMapsTile.tiles)
            {
                Texture2D texture = tile.overlayBackTexture;
                if (texture == null) continue;

                double r = radius * (1 << tile.zoom) / (1 << 20);
                double r2 = r * r * 256 * 256;

                int tilex = tile.x * 256;
                int tiley = tile.y * 256;

                double tx, ty;
                OnlineMaps.instance.projection.CoordinatesToTile(newLocation.x, newLocation.y, tile.zoom, out tx, out ty);
                double stx = tx - r;
                double sty = ty - r;
                double etx = tx + r;
                double ety = ty + r;

                if ((int)stx <= tile.x && (int)sty <= tile.y && (int)etx >= tile.x && (int)ety >= tile.y)
                {
                    int sx = (int)((stx - tile.x) * fogTextureResolution);
                    if (sx < 0) sx = 0;
                    else if (sx >= fogTextureResolution) continue;

                    int sy = (int)((sty - tile.y) * fogTextureResolution);
                    if (sy < 0) sy = 0;
                    else if (sy >= fogTextureResolution) continue;

                    int ex = (int)((etx - tile.x) * fogTextureResolution);
                    if (ex >= fogTextureResolution) ex = fogTextureResolution - 1;
                    else if (ex < 0) continue;

                    int ey = (int)((ety - tile.y) * fogTextureResolution);
                    if (ey >= fogTextureResolution) ey = fogTextureResolution - 1;
                    else if (ey < 0) continue;

                    int itx = (int)(tx * 256) - tilex;
                    int ity = (int)(ty * 256) - tiley;

                    Color[] colors = texture.GetPixels();

                    for (int y = sy; y < ey + 1; y++)
                    {
                        int cy = (fogTextureResolution - y - 1) * fogTextureResolution;
                        double dy = ity - y;
                        double dy2 = dy * dy;
                        if (dy2 >= r2) continue;

                        for (int x = sx; x < ex + 1; x++)
                        {
                            double dx = itx - x;
                            if (dx * dx + dy2 < r2)
                            {
                                colors[cy + x] = noFogColor;
                            }
                        }
                    }

                    texture.SetPixels(colors);
                    texture.Apply();
                }
            }
        }
    }

    private void ApplyPointsToTile(OnlineMapsTile tile)
    {
        Texture2D texture = tile.overlayBackTexture;
        Color[] colors = texture.GetPixels();
        bool textureChanged = false;

        double r = radius * (1 << tile.zoom) / (1 << 20);
        double r2 = r * r * 256 * 256;

        int tilex = tile.x * 256;
        int tiley = tile.y * 256;

        foreach (Vector2 point in points)
        {
            double tx, ty;
            OnlineMaps.instance.projection.CoordinatesToTile(point.x, point.y, tile.zoom, out tx, out ty);
            double stx = tx - r;
            double sty = ty - r;
            double etx = tx + r;
            double ety = ty + r;

            if ((int)stx <= tile.x && (int)sty <= tile.y && (int)etx >= tile.x && (int)ety >= tile.y)
            {
                int sx = (int)((stx - tile.x) * fogTextureResolution);
                if (sx < 0) sx = 0;
                else if (sx >= fogTextureResolution) continue;

                int sy = (int)((sty - tile.y) * fogTextureResolution);
                if (sy < 0) sy = 0;
                else if (sy >= fogTextureResolution) continue;

                int ex = (int)((etx - tile.x) * fogTextureResolution);
                if (ex >= fogTextureResolution) ex = fogTextureResolution - 1;
                else if (ex < 0) continue;

                int ey = (int)((ety - tile.y) * fogTextureResolution);
                if (ey >= fogTextureResolution) ey = fogTextureResolution - 1;
                else if (ey < 0) continue;

                textureChanged = true;

                int itx = (int) (tx * 256) - tilex;
                int ity = (int) (ty * 256) - tiley;

                for (int y = sy; y < ey + 1; y++)
                {
                    int cy = (fogTextureResolution - y - 1) * fogTextureResolution;
                    double dy = ity - y;
                    double dy2 = dy * dy;
                    if (dy2 >= r2) continue;

                    for (int x = sx; x < ex + 1; x++)
                    {
                        double dx = itx - x;
                        if (dx * dx + dy2 < r2)
                        {
                            colors[cy + x] = noFogColor;
                        }
                    }
                }
            }
        }

        if (textureChanged)
        {
            texture.SetPixels(colors);
            texture.Apply();
        }
    }

    private void OnLocationChanged(Vector2 newLocation)
    {
        points.Add(newLocation);
        ApplyPointToTiles(newLocation);
    }

    private void OnStartDownloadTile(OnlineMapsTile tile)
    {
        if (tile.zoom >= minFogZoom)
        {
            tile.overlayBackTexture = Instantiate(defaultFog) as Texture2D;
            tile.overlayBackTexture.name = tile.zoom + "x" + tile.x + "x" + tile.y;
            ApplyPointsToTile(tile);
        }
        OnlineMaps.instance.StartDownloadTile(tile);
    }

    private void Start()
    {
        points = new List<Vector2>();

        defaultFog = new Texture2D(fogTextureResolution, fogTextureResolution, TextureFormat.ARGB32, false);
        defaultFog.wrapMode = TextureWrapMode.Clamp;
        Color[] defaultFogColors = new Color[fogTextureSize];
        for (int i = 0; i < fogTextureSize; i++) defaultFogColors[i] = fogColor;
        defaultFog.SetPixels(defaultFogColors);
        defaultFog.Apply();

        OnlineMaps.instance.OnStartDownloadTile += OnStartDownloadTile;
        OnlineMapsLocationService.instance.OnLocationChanged += OnLocationChanged;
    }
}