using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Tilemaps;
using System.Linq;
namespace Dragons.Lighting {
    public class FloodFill
    {
        private Dictionary<Vector2Int, float> blocksLight;
        private Dictionary<Vector2Int, float> backgroundsLight;
        private List<Vector2Int> lit;
        private Tilemap blocks;
        private Tilemap backgrounds;
        public struct LightMap {
            public Dictionary<Vector2Int, float> blocks;
            public Dictionary<Vector2Int, float> backgrounds;
        }
        public LightMap generateLightMap(Dictionary<Vector2Int, float> lightSources, float ambientIntensity, Tilemap blocks, Tilemap backgrounds, int lowestXBounds, int lowerYBounds, Vector2Int dimensions, Tile[] clearTiles) {
            this.blocks = blocks;
            this.backgrounds = backgrounds;
            LightMap finalMap = new LightMap();
            lit = new List<Vector2Int>();
            blocksLight = new Dictionary<Vector2Int, float>();
            backgroundsLight = new Dictionary<Vector2Int, float>();
            //Go through every block in light chunk and check if clear, if so, propagate light.
            for (int x = lowestXBounds; x < dimensions.x + lowestXBounds; x++) {
                for (int y = lowerYBounds; y > lowerYBounds - dimensions.y; y--) {
                    Vector2Int pos = new Vector2Int(x, y);
                    Vector2Int posX = new Vector2Int(pos.x + 1, pos.y);
                    Vector2Int negX = new Vector2Int(pos.x - 1, pos.y);
                    Vector2Int posY = new Vector2Int(pos.x, pos.y + 1);
                    Vector2Int negY = new Vector2Int(pos.x, pos.y - 1);
                    //Check if clear.
                    if (blocks.GetTile((Vector3Int) pos) == null && backgrounds.GetTile((Vector3Int) pos) == null) {
                        //Check if one or more blocks surrounding light are solid, else don't propagate.
                        if (blocks.GetTile((Vector3Int) posX) != null || backgrounds.GetTile((Vector3Int) posX) != null)
                            floodFill(pos, ambientIntensity);
                        else if (blocks.GetTile((Vector3Int) negX) != null || backgrounds.GetTile((Vector3Int) negX) != null)
                            floodFill(pos, ambientIntensity);
                        else if (blocks.GetTile((Vector3Int) posY) != null || backgrounds.GetTile((Vector3Int) posY) != null)
                            floodFill(pos, ambientIntensity);
                        else if (blocks.GetTile((Vector3Int) negY) != null || backgrounds.GetTile((Vector3Int) negY) != null)
                            floodFill(pos, ambientIntensity);
                    }
                }
            }
            //Go through every light source on map and check if in light chunk.
            for (int i = 0; i < lightSources.Count; i++) {
                var pair = lightSources.ElementAt(i);
                floodFill(pair.Key, pair.Value);
            }
            finalMap.backgrounds = backgroundsLight;
            finalMap.blocks = blocksLight;
            return finalMap;
        }
        //Internal
        private void floodFill(Vector2Int pos, float intensity) {
            //Check if intensity > 0.05 to prevent infinite loops
            //Else return.
            if (intensity > 0.05f) {
                float div = 1.5f;
                if (blocks.GetTile((Vector3Int) pos) != null) {
                    div = 2f;
                }
                //Get all propagation points.
                Vector2Int posX = new Vector2Int(pos.x + 1, pos.y);
                Vector2Int negX = new Vector2Int(pos.x - 1, pos.y);
                Vector2Int posY = new Vector2Int(pos.x, pos.y + 1);
                Vector2Int negY = new Vector2Int(pos.x, pos.y - 1);
                lit.Add(pos);
                //Light blocks.
                if (blocks.GetTile((Vector3Int) pos) != null || backgrounds.GetTile((Vector3Int) pos) != null) {
                    //Check if intensity is greater than previous intensity on block,
                    //or check if unlit.
                    if (!blocksLight.ContainsKey(pos)) 
                        blocksLight.Add(pos, intensity);
                    else
                        blocksLight[pos] = intensity;
                    if (!backgroundsLight.ContainsKey(pos)) 
                        backgroundsLight.Add(pos, intensity);
                    else
                        backgroundsLight[pos] = intensity;
                }
                float newIntensity = intensity / div;
                //Propagate light.
                if (!checkIfLit(posX, newIntensity))
                    floodFill(posX, newIntensity);
                if (!checkIfLit(negX, newIntensity))
                    floodFill(negX, newIntensity);
                if (!checkIfLit(posY, newIntensity))
                    floodFill(posY, newIntensity);
                if (!checkIfLit(negY, newIntensity))
                    floodFill(negY, newIntensity);
                return;
            } else {
                return;
            }
        }
        bool checkIfLit(Vector2Int pos, float intensity) {
            if (blocksLight.ContainsKey(pos) || backgroundsLight.ContainsKey(pos)) {
                return lit.Contains(pos) && (!(intensity > blocksLight[pos]) || !(intensity > backgroundsLight[pos]));
            }
            return lit.Contains(pos);
        }
    }
}