using System.Collections.Generic;
using UnityEngine;

public class TargetFinder
{
    HashSet<string> filterTags = new HashSet<string>();

    public TargetFinder(params string[] filterTags)
    {
        for(int i = 0; i < filterTags.Length; i++)
        {
            this.filterTags.Add(filterTags[i]);
        }
    }

    public IList<Vector2> GetRandom(Bounds bounds, int maxCount)
    {
        var areaSize = BattleMgr.SGetBgSize();

        var result = new List<Vector2>();
        for(int i = 0; i < maxCount; i++)
        {
            float rndX = Random.Range(bounds.min.x, bounds.max.x);
            float rndY = Random.Range(bounds.min.y, bounds.max.y);

            rndX = Mathf.Clamp(rndX, areaSize.bounds.min.x, areaSize.bounds.max.x);
            rndY = Mathf.Clamp(rndY, areaSize.bounds.min.y, areaSize.bounds.max.y);

            result.Add(new Vector2(rndX, rndY));
        }

        return result;
    }

    public IList<CreatureBase> GetNearests(Vector2 pivot, int maxCount, ICollection<CreatureBase> except = null)
    {
        var heap = new SimpleHeap<CreatureBase>((a, b) =>
        {
            float distA = (pivot - (Vector2)a.transform.position).sqrMagnitude;
            float distB = (pivot - (Vector2)b.transform.position).sqrMagnitude;

            return distA < distB;
        });

        if(except is null)
        {
            BattleMgr.LoopAllCreatures((creature) =>
            {
                if (filterTags.Contains(creature.tag))
                {
                    heap.Push(creature);
                }
                return true;
            });
        }
        else
        {
            BattleMgr.LoopAllCreatures((creature) =>
            {
                if (filterTags.Contains(creature.tag) && !except.Contains(creature))
                {
                    heap.Push(creature);
                }
                return true;
            });
        }

        var result = new List<CreatureBase>();
        while (heap.Count > 0 && result.Count < maxCount)
        {
            result.Add(heap.Pop());
        }

        return result;
    }

    public bool TryFindNearest(Vector2 pivot, out CreatureBase result, ICollection<CreatureBase> except = null, bool ignoreExcepIfNoTarget = false)
    {
        CreatureBase minDistCreature = null;
        float minSqrtDist = float.MaxValue;

        if(except is null)
        {
            BattleMgr.LoopAllCreatures((creature) =>
            {
                if (filterTags.Contains(creature.tag))
                {
                    float sqrtDist = (pivot - (Vector2)creature.transform.position).sqrMagnitude;
                    if (sqrtDist < minSqrtDist)
                    {
                        minSqrtDist = sqrtDist;
                        minDistCreature = creature;
                    }
                }

                return true;
            });
        }
        else if(!ignoreExcepIfNoTarget)
        {
            BattleMgr.LoopAllCreatures((creature) =>
            {
                if (filterTags.Contains(creature.tag) && !except.Contains(creature))
                {
                    float sqrtDist = (pivot - (Vector2)creature.transform.position).sqrMagnitude;
                    if (sqrtDist < minSqrtDist)
                    {
                        minSqrtDist = sqrtDist;
                        minDistCreature = creature;
                    }
                }

                return true;
            });
        }
        else
        {
            var targetCandidates = new List<CreatureBase>();
            BattleMgr.LoopAllCreatures((creature) =>
            {
                if (filterTags.Contains(creature.tag) && !except.Contains(creature))
                {
                    float sqrtDist = (pivot - (Vector2)creature.transform.position).sqrMagnitude;
                    if (sqrtDist < minSqrtDist)
                    {
                        minSqrtDist = sqrtDist;
                        minDistCreature = creature;
                    }
                }

                targetCandidates.Add(creature);
                return true;
            });

            if(minDistCreature is null && targetCandidates.Count > 0)
            {
                minDistCreature = targetCandidates[Random.Range(0, targetCandidates.Count)];
            }
        }

        result = minDistCreature;
        return minDistCreature != null;
    }
}