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

namespace Heroes.Battle
{
    /// <summary>
    /// Container of all obstacles and per-terrain background sprites used by
    /// the generator and the view. Generator reads it as pure data; view uses
    /// it to resolve sprites during deployment.
    /// </summary>
    [CreateAssetMenu(menuName = "Heroes/Battle/Obstacle Database", fileName = "ObstacleDatabase")]
    public sealed class ObstacleDatabase : ScriptableObject
    {
        [Tooltip("All known obstacles. Filtered by allowed terrain at generation time.")]
        public List<ObstacleDefinition> obstacles = new List<ObstacleDefinition>();

        [Tooltip("Background sprite variants for each terrain. Generator picks one at random.")]
        public List<TerrainBackground> backgrounds = new List<TerrainBackground>();

        [Header("Generation")]
        [Tooltip("Inclusive minimum number of usual obstacles to attempt.")]
        [Min(0)]
        public int minObstacles = 5;

        [Tooltip("Inclusive maximum number of usual obstacles to attempt.")]
        [Min(0)]
        public int maxObstacles = 15;

        [Tooltip("Placement retry attempts per obstacle. H3 gives up after a handful of tries.")]
        [Min(1)]
        public int placementAttemptsPerObstacle = 20;

        [Tooltip("Probability (0..1) of placing an absolute obstacle when one is available for the terrain.")]
        [Range(0f, 1f)]
        public float absoluteObstacleChance = 0.5f;

        public IEnumerable<ObstacleDefinition> GetObstaclesForTerrain(TerrainType terrain)
        {
            return GetObstaclesForTerrain(terrain, null);
        }

        public IEnumerable<ObstacleDefinition> GetObstaclesForTerrain(TerrainType terrain, ObstacleType? typeFilter)
        {
            if (obstacles == null) yield break;
            foreach (var o in obstacles)
            {
                if (o == null) continue;
                if (typeFilter.HasValue && o.type != typeFilter.Value) continue;
                if (o.allowedTerrains == null || o.allowedTerrains.Count == 0) continue;
                if (o.allowedTerrains.Contains(terrain)) yield return o;
            }
        }

        public TerrainBackground FindBackgrounds(TerrainType terrain)
        {
            if (backgrounds == null) return null;
            foreach (var b in backgrounds)
            {
                if (b != null && b.terrain == terrain) return b;
            }
            return null;
        }

        public ObstacleDefinition FindById(string obstacleId)
        {
            if (obstacles == null || string.IsNullOrEmpty(obstacleId)) return null;
            foreach (var o in obstacles)
            {
                if (o != null && o.ResolveId() == obstacleId) return o;
            }
            return null;
        }
    }

    [Serializable]
    public sealed class TerrainBackground
    {
        public TerrainType terrain;

        [Tooltip("One or more sprite variants. Generator picks one at random.")]
        public List<Sprite> variants = new List<Sprite>();

        public string ResolveVariantId(int index)
        {
            if (variants == null || variants.Count == 0) return terrain.ToString();
            index = Mathf.Clamp(index, 0, variants.Count - 1);
            var s = variants[index];
            return s != null ? s.name : $"{terrain}#{index}";
        }

        public Sprite GetVariantById(string id)
        {
            if (variants == null) return null;
            foreach (var s in variants)
            {
                if (s != null && s.name == id) return s;
            }
            return variants.Count > 0 ? variants[0] : null;
        }
    }
}