using System.Collections.Generic;
using UnityEngine;

namespace EerieVillage.Progression
{
    /// <summary>
    /// JSON 영역 레벨업 EXP 테이블 로더. Resources.Load + JsonUtility 활용.
    /// 정적 캐시 — 첫 호출 시점 1회 로드 (게임 영역 1회).
    /// SOT: Assets/Resources/Progression/level_xp_table.json (balance-designer SOT).
    /// PD 직접 지시 2026-05-08 — 코드 산식 폐기·JSON 테이블 영역 관리.
    /// </summary>
    public static class LevelXPTableLoader
    {
        [System.Serializable]
        public class LevelXPEntry
        {
            public int level;
            public int xp_to_next;
        }

        [System.Serializable]
        public class LevelXPTable
        {
            public string version;
            public string description;
            public string fallback_formula;
            public int max_level_in_table;
            public LevelXPEntry[] table;
        }

        const string RESOURCE_PATH = "Progression/level_xp_table";
        const int FALLBACK_BASE = 100;
        const int FALLBACK_INCREMENT = 20;

        static Dictionary<int, int> _cache;
        static int _maxLevelInTable;
        static int _lastTableXP;

        public static void EnsureLoaded()
        {
            if (_cache != null) return;

            _cache = new Dictionary<int, int>();
            _maxLevelInTable = 0;
            _lastTableXP = FALLBACK_BASE;

            var ta = Resources.Load<TextAsset>(RESOURCE_PATH);
            if (ta == null)
            {
                Debug.LogWarning($"[LevelXPTableLoader] Resources/{RESOURCE_PATH}.json 부재 — fallback 활성");
                return;
            }

            try
            {
                var data = JsonUtility.FromJson<LevelXPTable>(ta.text);
                if (data == null || data.table == null)
                {
                    Debug.LogWarning("[LevelXPTableLoader] JSON 파싱 실패 — fallback 활성");
                    return;
                }
                _maxLevelInTable = data.max_level_in_table;
                foreach (var entry in data.table)
                {
                    _cache[entry.level] = entry.xp_to_next;
                    if (entry.level == _maxLevelInTable) _lastTableXP = entry.xp_to_next;
                }
            }
            catch (System.Exception e)
            {
                Debug.LogError($"[LevelXPTableLoader] 파싱 예외 — {e.Message}");
            }
        }

        /// <summary>
        /// 지정 level → 다음 레벨 도달 EXP. 테이블 미정의 영역 = fallback (last_xp + 20 × overflow).
        /// </summary>
        public static int GetXPToNextLevel(int level)
        {
            EnsureLoaded();
            if (level <= 0) return FALLBACK_BASE;
            if (_cache.TryGetValue(level, out int xp)) return xp;
            if (_maxLevelInTable > 0 && level > _maxLevelInTable)
            {
                return _lastTableXP + FALLBACK_INCREMENT * (level - _maxLevelInTable);
            }
            return FALLBACK_BASE + level * FALLBACK_INCREMENT;
        }

        /// <summary>테이블 재로드 (Editor 영역 hot-reload 용).</summary>
        public static void Reload()
        {
            _cache = null;
            EnsureLoaded();
        }
    }
}