using System;
using System.Collections.Generic;
using UnityEngine.UIElements;
using Random = System.Random;

namespace DungeonGenerator
{
    public class EvenDisperser
    {
        private List<Point> _samples = new List<Point>(){new Point(1,1)};
        private List<Point> _availablePoints;
        
        public EvenDisperser(int xLength, int yLength, List<Point> excludedPoints = null)
        {
            _availablePoints = GenerateAvailablePoints(xLength, yLength, excludedPoints ?? new List<Point>());
        }

        private List<Point> GenerateAvailablePoints(int xLength, int yLength, List<Point> excludedPoints)
        {
            List<Point> availablePoints = new List<Point>();
            for (var x = 0; x < xLength; x++)
            {
                for (var y = 0; y < yLength; y++)
                {
                    if (!excludedPoints.Contains(new Point(x, y)))
                    {
                        availablePoints.Add(new Point(x, y));
                    }
                }
            }

            return availablePoints;
        }
        
        // Can place point so that the x lengt hand y length go out of bounds to the right and down.
        public Point GetPoint(int xLength, int yLength)
        {
            int numCandidates = 50; // Increasing improves results but greatly effects performance.
            Random rnd = new Random();
            int randomIndex = rnd.Next(0, _availablePoints.Count);
            Point bestCandidate = new Point(Int32.MaxValue, Int32.MaxValue);
            int bestDistance = 0;
            for (var i = 0; i < numCandidates; i++)
            {
                var candidate = _availablePoints[randomIndex];
                var distance = candidate.ManhattanDistance(FindClosest(_samples, candidate));
                if (distance > bestDistance)
                {
                    RemoveArea(candidate, xLength, yLength, _availablePoints);
                    bestCandidate = candidate;
                    bestDistance = distance;
                }
            }
            
            _samples.Add(bestCandidate);
            return bestCandidate;
        }
    
        private Point FindClosest(List<Point> options, Point reference)
        {
            Point closest = options[0];
            foreach (var option in options)
            {
                if (reference.ManhattanDistance(option) < reference.ManhattanDistance(closest))
                {
                    closest = option;
                }
            }

            return closest;
        }

        private void RemoveArea(Point topLeft, int xLength, int yLength, List<Point> availablePoints)
        {
            for (var x = topLeft.X; x < topLeft.X + xLength; x++)
            {
                for (var y = topLeft.Y; y < topLeft.Y + yLength; y++)
                {
                    availablePoints.Remove(new Point(x, y));
                }
            }
        }
    }
}