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

namespace GeometryTD.UI
{
    public class RewardSelectFormUseCase : IUIUseCase
    {
        private readonly List<RewardSelectItemRawData> _rewardPool = new List<RewardSelectItemRawData>();

        private RewardSelectFormRawData _currentModel;
        private Action<RewardSelectItemRawData> _onRewardSelected;
        private Action _onGiveUp;

        private int _displayCount = 3;
        private int _refreshCost;
        private bool _allowRotateOnce = true;
        private bool _allowGiveUp = true;
        private bool _hasRotated;
        private int _selectionOffset;
        private string _tipText = "Select one reward";

        // RewardSelectForm keeps a fixed reward pool for the current node.
        // The "refresh" action only rotates which slice of that pool is shown so save/load
        // can reopen the same node with the exact same reward contents.
        public void ConfigureRewardPool(
            IReadOnlyList<RewardSelectItemRawData> rewardPool,
            int displayCount = 3,
            int refreshCost = 0,
            bool allowRotateOnce = true,
            bool allowGiveUp = true,
            string tipText = null)
        {
            _rewardPool.Clear();
            if (rewardPool != null)
            {
                foreach (var item in rewardPool)
                {
                    if (item == null)
                    {
                        continue;
                    }

                    _rewardPool.Add(item);
                }
            }

            _displayCount = Mathf.Max(1, displayCount);
            _refreshCost = Mathf.Max(0, refreshCost);
            _allowRotateOnce = allowRotateOnce;
            _allowGiveUp = allowGiveUp;
            _tipText = string.IsNullOrWhiteSpace(tipText) ? "Select one reward" : tipText;
            _hasRotated = false;
            _selectionOffset = 0;
            _currentModel = null;
        }

        public void ConfigureRewardCandidates(
            IReadOnlyList<TowerCompItemData> rewardCandidates,
            int displayCount = 3,
            int refreshCost = 0,
            bool allowRotateOnce = true,
            bool allowGiveUp = true,
            string tipText = null)
        {
            _rewardPool.Clear();
            if (rewardCandidates != null)
            {
                foreach (var item in rewardCandidates)
                {
                    if (item == null)
                    {
                        continue;
                    }

                    _rewardPool.Add(RewardSelectItemRawDataBuilder.Build(item));
                }
            }

            _displayCount = Mathf.Max(1, displayCount);
            _refreshCost = Mathf.Max(0, refreshCost);
            _allowRotateOnce = allowRotateOnce;
            _allowGiveUp = allowGiveUp;
            _tipText = string.IsNullOrWhiteSpace(tipText) ? "Select one reward" : tipText;
            _hasRotated = false;
            _selectionOffset = 0;
            _currentModel = null;
        }

        public void SetCallbacks(Action<RewardSelectItemRawData> onRewardSelected, Action onGiveUp = null)
        {
            _onRewardSelected = onRewardSelected;
            _onGiveUp = onGiveUp;
        }

        public RewardSelectFormRawData CreateInitialModel()
        {
            _hasRotated = false;
            _currentModel = BuildModel();
            return _currentModel;
        }

        public RewardSelectFormRawData TryRotateSelection()
        {
            if (_currentModel == null)
            {
                return null;
            }

            if (!CanRotateSelectionInternal())
            {
                return _currentModel;
            }

            if (!TryConsumeRotateCost())
            {
                _currentModel.CanRefresh = false;
                return _currentModel;
            }

            _hasRotated = true;
            if (_rewardPool.Count > 0)
            {
                _selectionOffset = (_selectionOffset + _displayCount) % _rewardPool.Count;
            }

            _currentModel = BuildModel();
            return _currentModel;
        }

        public RewardSelectFormRawData SelectReward(int selectedIndex)
        {
            if (_currentModel?.RewardItems == null || _currentModel.RewardItems.Length <= 0)
            {
                return null;
            }

            if (selectedIndex < 0 || selectedIndex >= _currentModel.RewardItems.Length)
            {
                return _currentModel;
            }

            RewardSelectItemRawData selectedReward = _currentModel.RewardItems[selectedIndex];
            _onRewardSelected?.Invoke(selectedReward);

            _currentModel = null;
            return null;
        }

        public bool TryGiveUp()
        {
            if (!_allowGiveUp)
            {
                return false;
            }

            _onGiveUp?.Invoke();
            _currentModel = null;
            return true;
        }

        private RewardSelectFormRawData BuildModel()
        {
            RewardSelectItemRawData[] selectedRewards = SelectRewards();

            return new RewardSelectFormRawData
            {
                TipText = _tipText,
                RewardItems = selectedRewards,
                RefreshCost = _refreshCost,
                CanRefresh = selectedRewards.Length > 0 && CanRotateSelectionInternal(),
                CanGiveUp = _allowGiveUp
            };
        }

        private RewardSelectItemRawData[] SelectRewards()
        {
            if (_rewardPool.Count <= 0)
            {
                return Array.Empty<RewardSelectItemRawData>();
            }

            int finalCount = Mathf.Clamp(_displayCount, 1, _rewardPool.Count);
            RewardSelectItemRawData[] results = new RewardSelectItemRawData[finalCount];
            for (int i = 0; i < finalCount; i++)
            {
                int sourceIndex = (_selectionOffset + i) % _rewardPool.Count;
                RewardSelectItemRawData source = _rewardPool[sourceIndex];
                results[i] = source;
            }

            return results;
        }

        private bool CanRotateSelectionInternal()
        {
            if (!_allowRotateOnce || _hasRotated)
            {
                return false;
            }

            return CanPayRotateCost();
        }

        private bool CanPayRotateCost()
        {
            if (_refreshCost <= 0)
            {
                return true;
            }

            if (GameEntry.PlayerInventory == null)
            {
                return true;
            }

            return GameEntry.PlayerInventory.Gold >= _refreshCost;
        }

        private bool TryConsumeRotateCost()
        {
            if (_refreshCost <= 0)
            {
                return true;
            }

            if (GameEntry.PlayerInventory == null)
            {
                return true;
            }

            return GameEntry.PlayerInventory.TryConsumeGold(_refreshCost);
        }
    }
}