using System;
using System.Collections.Generic;
using System.Linq;
namespace ProjectI.Runs
{
    public sealed class RunRewardService
    {
        private sealed class Queue
        {
            public readonly int[] Counts=new int[4], Deferred=new int[4];
            public UpgradeOffer Offer;
            public CoreCategoryOffer Category;
            public CoreAwardReceipt Receipt;
            public ulong DeferredStage;
            public readonly Dictionary<CoreCategory,int[]> Pools=new Dictionary<CoreCategory,int[]>();
            public readonly Dictionary<long,CoreAwardReceipt> Receipts=new Dictionary<long,CoreAwardReceipt>();
            public UpgradeEligibility Eligibility;
            public long Stream;
        }
        private readonly Dictionary<ulong,Queue> queues=new Dictionary<ulong,Queue>();
        private readonly HashSet<ulong> deaths=new HashSet<ulong>();
        private readonly Random random;
        private int drought; private long nextOffer;
        public RunRewardService(int seed) { random=new Random(seed); }
        public void BeginStage() { deaths.Clear(); }
        public bool RollDeath(ulong target,bool elite,bool boss,out UpgradeTier tier)
        {
            tier=UpgradeTier.Common; if(!deaths.Add(target))return false;
            bool drop=boss || drought>=15 || random.NextDouble()<(elite?.25:.08);
            if(!drop){drought++;return false;} drought=0;
            double roll=random.NextDouble();
            tier=boss?(roll<.50?UpgradeTier.Common:roll<.80?UpgradeTier.Uncommon:roll<.98?UpgradeTier.Rare:UpgradeTier.Legendary)
                :(roll<.65?UpgradeTier.Common:roll<.90?UpgradeTier.Uncommon:roll<.99?UpgradeTier.Rare:UpgradeTier.Legendary);
            return true;
        }
        public void Bank(IEnumerable<ulong> owners,UpgradeTier tier)
        { foreach(var owner in owners) { var q=Get(owner); if(q.Counts[(int)tier]<int.MaxValue)q.Counts[(int)tier]++; } }
        public int[] PendingCoreCounts(ulong owner)
        {
            if(!queues.TryGetValue(owner,out var q))return new int[4];
            var counts=(int[])q.Counts.Clone();
            if(q.Offer!=null&&counts[(int)q.Offer.Tier]<int.MaxValue)counts[(int)q.Offer.Tier]++;
            if(q.Category!=null&&counts[(int)q.Category.Tier]<int.MaxValue)counts[(int)q.Category.Tier]++;
            for(int i=0;i<4;i++)counts[i]=(int)Math.Min(int.MaxValue,(long)counts[i]+q.Deferred[i]);
            return counts;
        }
        public int Pending(ulong owner) { if(!queues.TryGetValue(owner,out var q))return 0; long total=q.Offer!=null||q.Category!=null?1:0;foreach(var n in q.Counts)total+=n;foreach(var n in q.Deferred)total+=n;return (int)Math.Min(int.MaxValue,total); }
        public UpgradeOffer Locked(ulong owner)=>queues.TryGetValue(owner,out var q)?q.Offer:null;
        public CoreCategoryOffer LockedCategory(ulong owner)=>queues.TryGetValue(owner,out var q)?q.Category:null;
        public CoreAwardReceipt LockedReceipt(ulong owner)=>queues.TryGetValue(owner,out var q)?q.Receipt:null;
        public int DeferredPending(ulong owner)
        {if(!queues.TryGetValue(owner,out var q))return 0;return (int)Math.Min(int.MaxValue,q.Deferred.Sum(x=>(long)x));}
        private static void AdvanceDeferred(Queue q,ulong stage)
        {
            if(q.DeferredStage==stage)return;
            for(int i=0;i<4;i++){q.Counts[i]=(int)Math.Min(int.MaxValue,(long)q.Counts[i]+q.Deferred[i]);q.Deferred[i]=0;}
            foreach(var id in q.Receipts.Where(x=>x.Value.StageId!=stage).Select(x=>x.Key).ToArray())q.Receipts.Remove(id);
            q.DeferredStage=stage;
        }
        public int BlockingPending(ulong owner,ulong stage)
        {
            if(!queues.TryGetValue(owner,out var q))return 0;
            AdvanceDeferred(q,stage);long total=q.Offer!=null||q.Category!=null?1:0;
            if(q.Receipt!=null)total++;
            foreach(var n in q.Counts)total+=n;
            return (int)Math.Min(int.MaxValue,total);
        }
        public int PeekBlockingPending(ulong owner,ulong stage)
        {
            if(!queues.TryGetValue(owner,out var q))return 0;
            long total=q.Offer!=null||q.Category!=null?1:0;if(q.Receipt!=null)total++;
            foreach(int count in q.Counts)total+=count;
            if(q.DeferredStage!=stage)foreach(int count in q.Deferred)total+=count;
            return (int)Math.Min(int.MaxValue,total);
        }
        public int NextTier(ulong owner,ulong stage)
        {
            var q=Get(owner);AdvanceDeferred(q,stage);
            if(q.Receipt!=null)return -1;
            if(q.Offer!=null)return (int)q.Offer.Tier;
            if(q.Category!=null)return (int)q.Category.Tier;
            return Array.FindIndex(q.Counts,x=>x>0);
        }
        public CoreCategoryOffer OpenCategoryOffer(ulong owner,ulong run,ulong stage,RunInventory inventory,UpgradeEligibility eligibility)
        {
            if(inventory==null||eligibility==null||run==0)return null;
            var q=Get(owner);AdvanceDeferred(q,stage);
            if(q.Receipt!=null||q.Offer!=null)return null;
            if(q.Category!=null)return q.Category.RunId==run&&q.Category.StageId==stage?q.Category:null;
            if(nextOffer==long.MaxValue)return null;
            int tier=Array.FindIndex(q.Counts,x=>x>0);if(tier<=0)return null;
            var options=CoreCategoryRules.EligibleCategories((UpgradeTier)tier,inventory,eligibility).ToList();
            var categories=new List<CoreCategory>();q.Pools.Clear();
            while(options.Count>0&&categories.Count<3)
            {
                int chosen=random.Next(options.Count);var category=options[chosen];options.RemoveAt(chosen);categories.Add(category);
                q.Pools[category]=CoreCategoryRules.EligibleIds(category,(UpgradeTier)tier,inventory,eligibility);
            }
            q.Counts[tier]--;q.Eligibility=SnapshotEligibility(eligibility);
            q.Category=new CoreCategoryOffer {RunId=run,StageId=stage,RewardId=checked(++nextOffer),Tier=(UpgradeTier)tier,Categories=categories.ToArray(),Exhausted=categories.Count==0};
            return q.Category;
        }
        public bool TrySelectCategory(ulong owner,ulong run,long rewardId,CoreCategory category,RunInventory inventory,out CoreAwardReceipt receipt)
            => TrySelectCategory(owner,run,rewardId,category,inventory,out receipt,out _);
        public bool TrySelectCategory(ulong owner,ulong run,long rewardId,CoreCategory category,RunInventory inventory,out CoreAwardReceipt receipt,out bool awarded)
            => TrySelectCategory(owner,run,rewardId,category,inventory,null,out receipt,out awarded);
        public bool TrySelectCategory(ulong owner,ulong run,long rewardId,CoreCategory category,RunInventory inventory,UpgradeEligibility currentEligibility,out CoreAwardReceipt receipt,out bool awarded)
        {
            receipt=null;awarded=false;if(!queues.TryGetValue(owner,out var q))return false;
            if(q.Receipts.TryGetValue(rewardId,out var cached))
            {if(cached.RunId!=run||cached.Category!=category)return false;receipt=cached;return true;}
            var offer=q.Category;
            if(offer==null||offer.RunId!=run||offer.RewardId!=rewardId||!offer.Categories.Contains(category))return false;
            var eligibility=currentEligibility??q.Eligibility;
            // Preserve the original locked IDs, but never award an effect whose prerequisite or
            // party/loadout compatibility vanished before this first claim. No IDs are added.
            foreach(var original in q.Pools.ToArray())
            {
                var compatible=original.Value.Where(id=>CoreCategoryRules.IsEligible(UpgradeCatalog.Get(id),inventory,eligibility)).ToArray();
                if(compatible.Length==0)q.Pools.Remove(original.Key);else q.Pools[original.Key]=compatible;
            }
            offer.Categories=offer.Categories.Where(x=>q.Pools.ContainsKey(x)).ToArray();offer.Exhausted=offer.Categories.Length==0;
            if(!q.Pools.TryGetValue(category,out var pool)||pool.Length==0)return false;
            // Sampling an ID first prevents ability-specific recipients or multiple tags increasing its draw weight.
            int id=pool[random.Next(pool.Length)],ability=0;string name=null;
            if(id==(int)UpgradeId.ReserveCell)
            {
                var targets=eligibility.ActiveAbilities.Where(x=>x>0&&inventory.Rank(UpgradeId.ReserveCell,x)<long.MaxValue).Distinct().ToArray();
                if(targets.Length==0)return false;ability=targets[random.Next(targets.Length)];
                int index=Array.IndexOf(eligibility.ActiveAbilities,ability);
                name=index>=0&&index<eligibility.ActiveNames.Length?eligibility.ActiveNames[index]:"Normal ability";
            }
            if(!inventory.Add(id,ability))return false;
            receipt=new CoreAwardReceipt {RunId=run,StageId=offer.StageId,RewardId=rewardId,UpgradeId=id,AbilityId=ability,AbilityName=name,NewRank=inventory.Rank((UpgradeId)id,ability),Tier=offer.Tier,Category=category};
            q.Receipts[rewardId]=receipt;q.Receipt=receipt;q.Category=null;q.Pools.Clear();awarded=true;return true;
        }
        private static UpgradeEligibility SnapshotEligibility(UpgradeEligibility value)
            => new UpgradeEligibility {ActiveAbilities=(int[])value.ActiveAbilities.Clone(),ActiveNames=(string[])value.ActiveNames.Clone(),DamagingAbilities=(int[])value.DamagingAbilities.Clone(),EchoAbilities=(int[])value.EchoAbilities.Clone(),EchoEligibilitySpecified=value.EchoEligibilitySpecified,MaxHealth=value.MaxHealth,MaxNormalShield=value.MaxNormalShield,ExtraJump=value.ExtraJump,MovementAbility=value.MovementAbility,StatusAbility=value.StatusAbility,MarkAbility=value.MarkAbility,SupportAbility=value.SupportAbility,HasTeammates=value.HasTeammates};
        public bool AcknowledgeReceipt(ulong owner,ulong run,long rewardId)
        {
            if(!queues.TryGetValue(owner,out var q)||q.Receipt==null||q.Receipt.RunId!=run||q.Receipt.RewardId!=rewardId)return false;
            q.Receipt=null;return true;
        }
        public bool DeferCategoryOffer(ulong owner,ulong run,ulong stage,long rewardId)
        {
            if(!queues.TryGetValue(owner,out var q)||q.Category==null||q.Category.RunId!=run||q.Category.StageId!=stage||q.Category.RewardId!=rewardId||!q.Category.Exhausted)return false;
            int tier=(int)q.Category.Tier;if(q.Deferred[tier]<int.MaxValue)q.Deferred[tier]++;
            q.DeferredStage=stage;q.Category=null;q.Pools.Clear();return true;
        }
        public UpgradeOffer Open(ulong owner,RunInventory inventory,UpgradeEligibility eligibility)
        {
            var q=Get(owner); if(q.Offer!=null)return q.Offer;if(q.Category!=null||q.Receipt!=null||nextOffer==long.MaxValue)return null;
            int tier=Array.FindIndex(q.Counts,x=>x>0); if(tier<0)return null; q.Counts[tier]--;
            var cards=new List<UpgradeCard>(); var options=new List<UpgradeCard>();
            for(int t=tier;t>=0 && cards.Count<3;t--)
            {
                options.Clear();
                foreach(var d in UpgradeCatalog.All.Where(x=>(int)x.Tier==t))
                {
                    if(d.Id==(int)UpgradeId.CrimsonCascade && inventory.Rank(UpgradeId.SerratedPayload)==0)continue;
                    if(d.Id==(int)UpgradeId.EchoCast && eligibility.DamagingAbilities.Length==0)continue;
                    if(d.Id==(int)UpgradeId.ReserveCell)
                    {
                        for(int i=0;i<eligibility.ActiveAbilities.Length;i++) AddOption(options,d,inventory,eligibility.ActiveAbilities[i],i<eligibility.ActiveNames.Length?eligibility.ActiveNames[i]:"Active ability",eligibility);
                    }
                    else AddOption(options,d,inventory,0,null,eligibility);
                }
                while(options.Count>0 && cards.Count<3) { int choice=random.Next(options.Count);cards.Add(options[choice]);options.RemoveAt(choice); }
            }
            foreach(var card in cards)if((int)card.Tier<tier)card.Description="Compatibility fallback: "+card.Description;
            q.Stream++; q.Offer=new UpgradeOffer { RewardId=++nextOffer,Tier=(UpgradeTier)tier,Cards=cards.ToArray(),Exhausted=cards.Count==0 }; return q.Offer;
        }
        private static void AddOption(List<UpgradeCard> list,UpgradeDefinition d,RunInventory inventory,int ability,string abilityName,UpgradeEligibility eligibility)
        {
            long rank=inventory.Rank((UpgradeId)d.Id,ability);
            // The last representable rank cannot accept another copy. This is a storage boundary,
            // not an authored stacking cap; lower ranks remain eligible, including the final copy.
            if(rank==long.MaxValue)return;
            list.Add(new UpgradeCard { UpgradeId=d.Id,AbilityId=ability,Name=d.Name+(ability>0?" · "+abilityName:""),Tier=d.Tier,CurrentRank=rank,MaxRank=d.MaxRank,Description=UpgradeEffectResolver.Describe((UpgradeId)d.Id,rank,eligibility.MaxHealth,eligibility.MaxNormalShield),Restriction=d.Restriction });
        }
        public bool Select(ulong owner,long rewardId,int upgradeId,int ability,RunInventory inventory)
        {
            var q=Get(owner);if(q.Offer==null||q.Offer.RewardId!=rewardId||!q.Offer.Cards.Any(x=>x.UpgradeId==upgradeId&&x.AbilityId==ability))return false;
            if(!inventory.Add(upgradeId,ability))return false; q.Offer=null;return true;
        }
        public bool Dismiss(ulong owner,long rewardId)
        {var q=Get(owner);if(q.Offer==null||q.Offer.RewardId!=rewardId||!q.Offer.Exhausted)return false;q.Offer=null;return true;}
        public void Remove(ulong owner)=>queues.Remove(owner);
        public void Clear(){queues.Clear();deaths.Clear();drought=0;} // Preserve process-local reward identity across runs.
        private Queue Get(ulong owner){if(!queues.TryGetValue(owner,out var q)){q=new Queue();queues.Add(owner,q);}return q;}
    }
}