using System;
using System.Collections.Generic;
using SepCore.Definition;
using UnityEngine;

namespace SepCore.Battle
{
    /// <summary>
    /// 单个属性实例容器。
    /// 维护基础值、修饰器列表，通过脏标记（Dirty Flag）缓存计算结果，并基于 StatConfig 进行边界钳制。
    /// </summary>
    public sealed class CharacterStat
    {
        private readonly List<StatModifier> _modifiers = new();
        private float _baseValue;
        private bool _isBaseValueExplicitlySet;
        private bool _isDirty = true;
        private float _cachedValue;
        private StatConfig _config;

        public StatType Type { get; }

        public StatConfig Config
        {
            get
            {
                if (_config == null && GameEntry.Luban != null && GameEntry.Luban.IsReady)
                {
                    _config = GameEntry.Luban.Get<StatConfig>((int)Type);
                    if (!_isBaseValueExplicitlySet && _config != null)
                    {
                        _baseValue = _config.DefaultBaseValue;
                        _isDirty = true;
                    }
                }

                return _config;
            }
            set
            {
                _config = value;
                if (!_isBaseValueExplicitlySet && _config != null)
                {
                    _baseValue = _config.DefaultBaseValue;
                }
                _isDirty = true;
            }
        }

        public float BaseValue
        {
            get
            {
                if (!_isBaseValueExplicitlySet)
                {
                    if (Config != null)
                    {
                        _baseValue = Config.DefaultBaseValue;
                    }
                    else if (Type is StatType.DamagePercent or StatType.AttackSpeed)
                    {
                        _baseValue = 1.0f;
                    }
                }

                return _baseValue;
            }
            set
            {
                _isBaseValueExplicitlySet = true;
                if (Math.Abs(_baseValue - value) > 1e-6f)
                {
                    _baseValue = value;
                    _isDirty = true;
                }
            }
        }

        public float Value
        {
            get
            {
                if (_isDirty)
                {
                    _cachedValue = CalculateFinalValue();
                    _isDirty = false;
                }

                return _cachedValue;
            }
        }

        public IReadOnlyList<StatModifier> Modifiers => _modifiers;

        public CharacterStat(StatType type, float baseValue = 0f, StatConfig config = null)
        {
            Type = type;
            _config = config;
            if (Math.Abs(baseValue) > 1e-6f)
            {
                _baseValue = baseValue;
                _isBaseValueExplicitlySet = true;
            }
            else if (_config != null)
            {
                _baseValue = _config.DefaultBaseValue;
                _isBaseValueExplicitlySet = true;
            }
            else if (type is StatType.DamagePercent or StatType.AttackSpeed)
            {
                _baseValue = 1.0f;
            }
            _isDirty = true;
        }

        public void AddModifier(StatModifier modifier)
        {
            if (modifier == null)
            {
                throw new ArgumentNullException(nameof(modifier));
            }

            _modifiers.Add(modifier);
            _isDirty = true;
        }

        public bool RemoveModifier(StatModifier modifier)
        {
            if (modifier == null)
            {
                return false;
            }

            if (_modifiers.Remove(modifier))
            {
                _isDirty = true;
                return true;
            }

            return false;
        }

        public int RemoveAllModifiersFromSource(object source)
        {
            if (source == null)
            {
                return 0;
            }

            int removed = _modifiers.RemoveAll(m => ReferenceEquals(m.Source, source) || Equals(m.Source, source));
            if (removed > 0)
            {
                _isDirty = true;
            }

            return removed;
        }

        public void ClearModifiers()
        {
            if (_modifiers.Count > 0)
            {
                _modifiers.Clear();
                _isDirty = true;
            }
        }

        public void MarkDirty()
        {
            _isDirty = true;
        }

        private float CalculateFinalValue()
        {
            float sumFlat = 0f;
            float sumPercentAdd = 0f;
            float prodPercentMult = 1f;

            for (int i = 0; i < _modifiers.Count; i++)
            {
                StatModifier mod = _modifiers[i];
                switch (mod.Type)
                {
                    case ModifierType.Flat:
                        sumFlat += mod.Value;
                        break;
                    case ModifierType.PercentAdd:
                        sumPercentAdd += mod.Value;
                        break;
                    case ModifierType.PercentMult:
                        prodPercentMult *= mod.Value;
                        break;
                }
            }

            float finalValue;
            if (Type is StatType.CritChance or StatType.Dodge or StatType.LifeSteal)
            {
                // 概率/比率型属性（暴击率、闪避率、生命窃取）：底数通常为 0~1 的小数概率。
                // 无论是 Flat（如道具填 0.27）还是 PercentAdd（如升级奖励填 0.30），本质上均为点数直接加算（+30% 概率）。
                // 若沿用标量乘法公式，由于 BaseValue 为 0，会导致 (0 + 0) * (1 + 0.30) = 0，从而百分比奖励完全失效。
                finalValue = (BaseValue + sumFlat + sumPercentAdd) * prodPercentMult;
            }
            else
            {
                // 标量属性与倍率属性（MaxHp、MoveSpeed、DamagePercent、AttackSpeed 等）：
                // (Base + Flat) * (1 + PercentAdd) * PercentMult
                finalValue = ((BaseValue + sumFlat) * (1f + sumPercentAdd)) * prodPercentMult;
            }

            return ClampStat(finalValue);
        }

        private float ClampStat(float value)
        {
            StatConfig config = Config;
            if (config != null)
            {
                if (config.HasMin && value < config.MinValue)
                {
                    value = config.MinValue;
                }

                if (config.HasMax && value > config.MaxValue)
                {
                    value = config.MaxValue;
                }
            }

            return value;
        }
    }
}