using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace game.PlayerDataStorage
{
    public sealed class KVPlayerSaveStore : IPlayerSaveStore, IDisposable
    {
        private PlayerKVGameSessionHandle handle;
        private CancellationToken lifetime;
        private bool bound, disposed;
        private readonly object receiptsGate = new object();
        public bool IsCurrent => bound && !disposed && !lifetime.IsCancellationRequested && handle.Status != PlayerKVSyncStatus.Closed;

        internal void Bind(PlayerKVGameSessionHandle original, CancellationToken loginLifetime)
        {
            if (bound || disposed || original == null || loginLifetime.IsCancellationRequested)
                throw new InvalidOperationException("Player save store cannot be rebound.");
            // This also checks the load guard before permitting business use.
            if (!KVMgr.ReadKV(original, "LastLoginTimeUtc").Success)
                throw new InvalidOperationException("Player save handle is not ready.");
            handle = original;
            lifetime = loginLifetime;
            bound = true;
        }

        internal void ReleaseFailedBinding(PlayerKVGameSessionHandle original)
        {
            lock (receiptsGate)
            {
                if (!bound)
                {
                    return;
                }
                if (disposed || !ReferenceEquals(handle, original) || original.Status != PlayerKVSyncStatus.Closed)
                {
                    throw new InvalidOperationException("Failed save binding has not closed.");
                }
                handle = null;
                bound = false;
            }
        }

        public PlayerSaveReadResult Read(string key)
        {
            if (!IsCurrent) return new PlayerSaveReadResult("StaleOrNotReady");
            var result = KVMgr.ReadKV(handle, key);
            return result.Success ? new PlayerSaveReadResult(result.Found.Value, result.Value) :
                new PlayerSaveReadResult(result.Error.ToString());
        }

        public PlayerSaveWriteResult Write(string key, string value, bool remoteStore = true)
        {
            lock (receiptsGate)
            {
                if (!IsCurrent)
                {
                    var rejected = new PlayerSaveWriteResult("StaleOrNotReady");
                    return rejected;
                }
                var result = KVMgr.WriteKV(handle, key, value, remoteStore);
                var write = result.Accepted ? new PlayerSaveWriteResult(new PlayerSaveReceipt(this, result.Ticket)) :
                    new PlayerSaveWriteResult(result.StateResult.Error.ToString());
                return write;
            }
        }

        public async Task<bool> SyncDataImmidiate(string key, string value)
        {
            PlayerKVGameSessionHandle original;
            CancellationToken originalLifetime;
            Task<bool> save;
            lock (receiptsGate)
            {
                if (!IsCurrent)
                {
                    return false;
                }
                // Preserve the former current-store dictionary lookup's null-key behavior.
                if (key == null)
                {
                    throw new ArgumentNullException(nameof(key));
                }
                original = handle;
                originalLifetime = lifetime;
                save = KVMgr.SyncDataImmidiate(original, key, value);
            }
            var success = await save;
            lock (receiptsGate)
            {
                return success && IsCurrent && !originalLifetime.IsCancellationRequested && ReferenceEquals(handle, original);
            }
        }

        internal async Task<bool> SyncDataImmidiate(IReadOnlyDictionary<string, string> values)
        {
            PlayerKVGameSessionHandle original;
            CancellationToken originalLifetime;
            Task<bool> save;
            lock (receiptsGate)
            {
                if (!IsCurrent || values == null || values.Count == 0)
                {
                    return false;
                }
                var data = values.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal);
                original = handle;
                originalLifetime = lifetime;
                save = KVMgr.SyncDataImmidiate(original, data);
            }
            var success = await save;
            lock (receiptsGate)
            {
                return success && IsCurrent && !originalLifetime.IsCancellationRequested && ReferenceEquals(handle, original);
            }
        }

        internal Task<PlayerKVFlushResult> SyncDataAsync()
        {
            lock (receiptsGate)
            {
                var original = handle;
                if (!IsCurrent)
                {
                    return Task.FromResult(new PlayerKVFlushResult(0, 0, 1, 0, PlayerKVError.Cancelled,
                        original == null ? PlayerKVSyncStatus.NotLoaded : original.Status));
                }
                return KVMgr.SyncKVAsync(original);
            }
        }

        public void Dispose()
        {
            lock (receiptsGate)
            {
                disposed = true;
            }
        }
    }

    public sealed class PlayFabPlayerSaveStore : IPlayerSaveStore
    {
        public Task<bool> SyncDataImmidiate(string key, string value)
        {
            return manager.SyncDataImmidiate(key, value);
        }

        readonly PlayFabMgr manager;
        readonly CancellationToken lifetime;
        public PlayFabPlayerSaveStore(IUserService user) : this(PlayFabMgr.Instance, user.LoginLifetime) { }
        internal PlayFabPlayerSaveStore(PlayFabMgr manager, CancellationToken lifetime)
        { this.manager = manager; this.lifetime = lifetime; }
        public bool IsCurrent => manager != null && !lifetime.IsCancellationRequested;

        public PlayerSaveReadResult Read(string key)
        {
            if (!IsCurrent) return new PlayerSaveReadResult("StaleOrNotReady");
            try
            {
                var value = manager.GetLocalData(key);
                return new PlayerSaveReadResult(value != null, value);
            }
            catch (Exception ex) { return new PlayerSaveReadResult(ex.GetType().Name); }
        }

        public PlayerSaveWriteResult Write(string key, string value, bool remoteStore = true)
        {
            if (!IsCurrent) return new PlayerSaveWriteResult("StaleOrNotReady");
            try
            {
                manager.UpdateUserDataValue(key, value, remoteStore);
                return new PlayerSaveWriteResult(new PlayerSaveReceipt(this, remoteStore ? (object)true : null));
            }
            catch (Exception ex) { return new PlayerSaveWriteResult(ex.GetType().Name); }
        }

    }
}