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

namespace Cielonos.MainGame.AttackArea
{
    public static class AttackAreaDistributionHelper
    {
        /// <summary>
        /// 在圆形范围内生成不重叠的随机位置列表，并自动吸附到 NavMesh 上。
        /// </summary>
        /// <param name="center">生成范围的中心点</param>
        /// <param name="spawnRadius">允许生成的最大范围半径</param>
        /// <param name="exclusionDistance">两个点之间的最小安全距离（防止重叠）</param>
        /// <param name="count">需要生成的点位数量</param>
        /// <param name="prePlacedPositions">已经预先放置好的点位（新生成的点位会避开这些点）</param>
        /// <param name="maxAttemptsPerPoint">每个点位的最大尝试次数（防止死循环）</param>
        /// <param name="navMeshSampleDistance">NavMesh 投影搜索的最大距离</param>
        /// <returns>成功生成的随机点位列表</returns>
        public static List<Vector3> GenerateNonOverlappingInCircle(
            Vector3 center, 
            float spawnRadius, 
            float exclusionDistance, 
            int count, 
            List<Vector3> prePlacedPositions = null,
            int maxAttemptsPerPoint = 30,
            float navMeshSampleDistance = 10f)
        {
            List<Vector3> results = new List<Vector3>();
            List<Vector3> occupiedPositions = new List<Vector3>();
            if (prePlacedPositions != null)
            {
                occupiedPositions.AddRange(prePlacedPositions);
            }

            float minSqrDistance = exclusionDistance * exclusionDistance;

            for (int i = 0; i < count; i++)
            {
                Vector3 bestPos = Vector3.zero;
                bool found = false;

                for (int attempt = 0; attempt < maxAttemptsPerPoint; attempt++)
                {
                    Vector2 randomOffset = Random.insideUnitCircle * spawnRadius;
                    Vector3 candidatePos = center + new Vector3(randomOffset.x, 0f, randomOffset.y);
                    
                    // NavMesh projection
                    if (NavMesh.SamplePosition(candidatePos, out NavMeshHit hit, navMeshSampleDistance, NavMesh.AllAreas))
                    {
                        candidatePos = hit.position;
                    }

                    if (IsValidPosition(candidatePos, occupiedPositions, minSqrDistance))
                    {
                        bestPos = candidatePos;
                        found = true;
                        break;
                    }
                }

                if (found)
                {
                    results.Add(bestPos);
                    occupiedPositions.Add(bestPos);
                }
            }

            return results;
        }

        /// <summary>
        /// 在矩形范围内生成不重叠的随机位置列表，并自动吸附到 NavMesh 上。
        /// </summary>
        /// <param name="center">生成范围的中心点</param>
        /// <param name="extents">矩形的半长宽 (x对应X轴, y对应Z轴)</param>
        /// <param name="exclusionDistance">两个点之间的最小安全距离（防止重叠）</param>
        /// <param name="count">需要生成的点位数量</param>
        /// <param name="prePlacedPositions">已经预先放置好的点位（新生成的点位会避开这些点）</param>
        /// <param name="maxAttemptsPerPoint">每个点位的最大尝试次数（防止死循环）</param>
        /// <param name="navMeshSampleDistance">NavMesh 投影搜索的最大距离</param>
        /// <returns>成功生成的随机点位列表</returns>
        public static List<Vector3> GenerateNonOverlappingInRect(
            Vector3 center, 
            Vector2 extents, 
            float exclusionDistance, 
            int count, 
            List<Vector3> prePlacedPositions = null,
            int maxAttemptsPerPoint = 30,
            float navMeshSampleDistance = 10f)
        {
            List<Vector3> results = new List<Vector3>();
            List<Vector3> occupiedPositions = new List<Vector3>();
            if (prePlacedPositions != null)
            {
                occupiedPositions.AddRange(prePlacedPositions);
            }

            float minSqrDistance = exclusionDistance * exclusionDistance;

            for (int i = 0; i < count; i++)
            {
                Vector3 bestPos = Vector3.zero;
                bool found = false;

                for (int attempt = 0; attempt < maxAttemptsPerPoint; attempt++)
                {
                    float randomX = Random.Range(-extents.x, extents.x);
                    float randomZ = Random.Range(-extents.y, extents.y);
                    Vector3 candidatePos = center + new Vector3(randomX, 0f, randomZ);
                    
                    // NavMesh projection
                    if (NavMesh.SamplePosition(candidatePos, out NavMeshHit hit, navMeshSampleDistance, NavMesh.AllAreas))
                    {
                        candidatePos = hit.position;
                    }

                    if (IsValidPosition(candidatePos, occupiedPositions, minSqrDistance))
                    {
                        bestPos = candidatePos;
                        found = true;
                        break;
                    }
                }

                if (found)
                {
                    results.Add(bestPos);
                    occupiedPositions.Add(bestPos);
                }
            }

            return results;
        }

        private static bool IsValidPosition(Vector3 candidatePos, List<Vector3> occupiedPositions, float minSqrDistance)
        {
            foreach (var pos in occupiedPositions)
            {
                // 为了防止在楼上楼下的重叠，我们使用 3D 距离，但在大多数平面场景下也等同于 2D 距离
                if ((candidatePos - pos).sqrMagnitude < minSqrDistance)
                {
                    return false;
                }
            }
            return true;
        }
    }
}