using System;
using System.Collections.Generic;
using GeometryTD.DataTable;
using GeometryTD.Definition;
using UnityEngine;
using Random = System.Random;

namespace GeometryTD.CustomComponent
{
    public sealed class RewardCandidateBuilder
    {
        private readonly DropPoolRoller _dropPoolRoller;

        public RewardCandidateBuilder(DropPoolRoller dropPoolRoller)
        {
            _dropPoolRoller = dropPoolRoller;
        }

        public IReadOnlyList<TowerCompItemData> BuildCandidates(
            int displayPhaseIndex,
            LevelThemeType themeType,
            int candidateCount,
            Func<InventoryGenerationRandomContext> createRandomContext,
            Func<DROutGameDropPool, RarityType, InventoryGenerationRandomContext, TowerCompItemData> buildRewardItem)
        {
            int resolvedCount = Mathf.Max(0, candidateCount);
            if (resolvedCount <= 0)
            {
                return Array.Empty<TowerCompItemData>();
            }

            List<TowerCompItemData> candidates = new List<TowerCompItemData>(resolvedCount);
            HashSet<long> selectedPoolEntryKeys = new HashSet<long>();
            int maxAttempts = Mathf.Max(resolvedCount * 6, resolvedCount);
            int phaseIndex = Mathf.Max(1, displayPhaseIndex);

            int attempts = 0;
            while (candidates.Count < resolvedCount && attempts < maxAttempts)
            {
                attempts++;
                InventoryGenerationRandomContext randomContext = createRandomContext();
                Random random = randomContext.CreateRandom();
                if (!_dropPoolRoller.TryRollRow(
                        phaseIndex,
                        themeType,
                        random,
                        out DROutGameDropPool selectedRow,
                        out RarityType selectedRarity) || selectedRow == null)
                {
                    break;
                }

                if (!selectedPoolEntryKeys.Add(BuildSelectionKey(selectedRow.Id, selectedRarity)))
                {
                    continue;
                }

                TowerCompItemData candidate = buildRewardItem(selectedRow, selectedRarity, randomContext);
                if (candidate == null)
                {
                    continue;
                }

                candidates.Add(candidate);
            }

            attempts = 0;
            while (candidates.Count < resolvedCount && attempts < maxAttempts)
            {
                attempts++;
                InventoryGenerationRandomContext randomContext = createRandomContext();
                Random random = randomContext.CreateRandom();
                if (!_dropPoolRoller.TryRollRow(
                        phaseIndex,
                        themeType,
                        random,
                        out DROutGameDropPool selectedRow,
                        out RarityType selectedRarity) || selectedRow == null)
                {
                    break;
                }

                TowerCompItemData candidate = buildRewardItem(selectedRow, selectedRarity, randomContext);
                if (candidate == null)
                {
                    continue;
                }

                candidates.Add(candidate);
            }

            return candidates;
        }

        private static long BuildSelectionKey(int rowId, RarityType rarity)
        {
            return ((long)rowId << 32) | (uint)rarity;
        }
    }
}