using System;
using System.Collections.Generic;
using System.Linq;


using Google.Protobuf;

using System.Threading.Tasks;

using FrostFS.Object;
using FrostFS.Refs;
using FrostFS.SDK.ClientV2.Mappers.GRPC;
using FrostFS.SDK.Cryptography;
using FrostFS.Session;
using FrostFS.SDK.ModelsV2;
using FrostFS.SDK.ClientV2.Extensions;

namespace FrostFS.SDK.ClientV2;

internal class ObjectServiceProvider : ContextAccessor
{
    private readonly ObjectService.ObjectServiceClient objectServiceClient;
    
    internal ObjectServiceProvider(ObjectService.ObjectServiceClient objectServiceClient, ClientEnvironment context)
        : base (context)
    {
        this.objectServiceClient = objectServiceClient;
    }

    internal async Task<ObjectHeader> GetObjectHeadAsync(ContainerId cid, ObjectId oid, Context ctx)
    {
        var request = new HeadRequest
        {
            Body = new HeadRequest.Types.Body
            {
                Address = new Address
                {
                    ContainerId = cid.ToGrpcMessage(),
                    ObjectId = oid.ToGrpcMessage()
                }
            }
        };

        request.AddMetaHeader();
        request.Sign(Context.Key);

        var response = await objectServiceClient!.HeadAsync(request, null, ctx.Deadline, ctx.CancellationToken);
        
        Verifier.CheckResponse(response);

        return response.Body.Header.Header.ToModel();
    }

    internal async Task<ModelsV2.Object> GetObjectAsync(ContainerId cid, ObjectId oid, Context ctx)
    {
        var sessionToken = await GetOrCreateSession(ctx);

        var request = new GetRequest
        {
            Body = new GetRequest.Types.Body
            {
                Address = new Address
                {
                    ContainerId = cid.ToGrpcMessage(),
                    ObjectId = oid.ToGrpcMessage()
                }
            }
        };

        request.AddMetaHeader();
        request.AddObjectSessionToken(
            sessionToken,
            cid.ToGrpcMessage(),
            oid.ToGrpcMessage(),
            ObjectSessionContext.Types.Verb.Get,
            Context.Key
        );

        request.Sign(Context.Key);

        var obj = await GetObject(request, ctx);

        return obj;
    }

    internal Task<ObjectId> PutObjectAsync(PutObjectParameters parameters, Context ctx)
    {
        if (parameters.Header == null)
            throw new ArgumentException("Value cannot be null", nameof(parameters.Header));
        
        if (parameters.Payload == null)
            throw new ArgumentException("Value cannot be null", nameof(parameters.Payload));
        
        if (parameters.ClientCut)
            return PutClientCutObject(parameters, ctx);
        else 
            return PutStreamObject(parameters, ctx);
    }
   
    internal async Task<ObjectId> PutSingleObjectAsync(ModelsV2.Object @object, Context ctx)
    {
        var sessionToken = await GetOrCreateSession(ctx);
    
        var obj = CreateObject(@object);

        var request = new PutSingleRequest
        {
            Body = new PutSingleRequest.Types.Body()
            {
                 Object = obj 
            }
        };

        request.AddMetaHeader();
        request.AddObjectSessionToken(
            sessionToken,
            obj.Header.ContainerId,
            obj.ObjectId,
            ObjectSessionContext.Types.Verb.Put,
            Context.Key
        );

        request.Sign(Context.Key);

        var response = await objectServiceClient!.PutSingleAsync(request, null, ctx.Deadline, ctx.CancellationToken);

        Verifier.CheckResponse(response);
        
        return ObjectId.FromHash(obj.ObjectId.Value.ToByteArray());
    }

    internal ObjectId CalculateObjectId(ObjectHeader header)
    { 
        var grpcHeader = CreateHeader(header, []);

        return new ObjectID { Value = grpcHeader.Sha256() }.ToModel();        
    }
    
    internal async Task DeleteObjectAsync(ContainerId cid, ObjectId oid, Context ctx)
    {
        var request = new DeleteRequest
        {
            Body = new DeleteRequest.Types.Body
            {
                Address = new Address
                {
                    ContainerId = cid.ToGrpcMessage(),
                    ObjectId = oid.ToGrpcMessage()
                }
            }
        };

        request.AddMetaHeader();
        request.Sign(Context.Key);

        var response = await objectServiceClient!.DeleteAsync(request, null, ctx.Deadline, ctx.CancellationToken);
        
        Verifier.CheckResponse(response);
    }

    internal async IAsyncEnumerable<ObjectId> SearchObjectsAsync(
        ContainerId cid, 
        IEnumerable<ObjectFilter> filters, 
        Context ctx)
    {
        var request = new SearchRequest
        {
            Body = new SearchRequest.Types.Body
            {
                ContainerId = cid.ToGrpcMessage(),
                Filters = { },
                Version = 1  // TODO: clarify this param
            }
        };

        request.Body.Filters.AddRange(filters.Select(f => f.ToGrpcMessage()));
        
        request.AddMetaHeader();
        request.Sign(Context.Key);

        var objectsIds = SearchObjects(request, ctx);

        await foreach (var oid in objectsIds)
        {
            yield return ObjectId.FromHash(oid.Value.ToByteArray());
        }
    }

    private async Task<ObjectId> PutClientCutObject(PutObjectParameters parameters, Context ctx)
    {
        var payloadStream = parameters.Payload!;
        var header = parameters.Header!;

        ObjectId? objectId;
        List<ObjectId> sentObjectIds = [];
        ModelsV2.Object? currentObject;

        var networkSettings = await Context.NetmapService!.GetNetworkSettingsAsync(ctx);

        var partSize = (int)networkSettings.MaxObjectSize;
        var buffer = new byte[partSize];      

        var largeObject = new LargeObject(header.ContainerId);

        var split = new Split();
        
        var fullLength = (ulong)payloadStream.Length;
   
        while (true)
        {
            var bytesCount = await payloadStream.ReadAsync(buffer, 0, partSize);

            split.Previous = sentObjectIds.LastOrDefault();

            largeObject.AppendBlock(buffer, bytesCount);

            currentObject = new ModelsV2.Object(header.ContainerId, bytesCount < partSize ? buffer.Take(bytesCount).ToArray() : buffer)
                .AddAttributes(header.Attributes)
                .SetSplit(split);

            if (largeObject.PayloadLength == fullLength)
                break;

            objectId = await PutSingleObjectAsync(currentObject, ctx);

            sentObjectIds.Add(objectId!);
        }

        if (sentObjectIds.Count != 0)
        {
            largeObject.CalculateHash();

            currentObject.SetParent(largeObject);

            objectId = await PutSingleObjectAsync(currentObject, ctx);
            sentObjectIds.Add(objectId);

            var linkObject = new LinkObject(header.ContainerId, split.SplitId, largeObject)
                .AddChildren(sentObjectIds);

            _ = await PutSingleObjectAsync(linkObject, ctx);

            return CalculateObjectId(largeObject.Header);
        }

        return await PutSingleObjectAsync(currentObject, ctx);
    }

    private async Task<ObjectId> PutStreamObject(PutObjectParameters parameters, Context ctx)
    {
        var payload = parameters.Payload!;
        var header = parameters.Header!;

        var sessionToken = await GetOrCreateSession(ctx);

        var hdr = header.ToGrpcMessage();
        hdr.OwnerId = Context.Owner.ToGrpcMessage();
        hdr.Version = Context.Version.ToGrpcMessage();

        var oid = new ObjectID
        {
            Value = hdr.Sha256()
        };

        var request = new PutRequest
        {
            Body = new PutRequest.Types.Body
            {
                Init = new PutRequest.Types.Body.Types.Init
                {
                    Header = hdr
                },
            }
        };

        request.AddMetaHeader();
        request.AddObjectSessionToken(
            sessionToken,
            hdr.ContainerId,
            oid,
            ObjectSessionContext.Types.Verb.Put,
            Context.Key
        );

        request.Sign(Context.Key);

        using var stream = await PutObjectInit(request, ctx);
        var buffer = new byte[Constants.ObjectChunkSize];

        while (true)
        {
            var bufferLength = await payload.ReadAsync(buffer, 0, Constants.ObjectChunkSize, ctx.CancellationToken);

            if (bufferLength == 0)
                break;

            request.Body = new PutRequest.Types.Body
            {
                Chunk = ByteString.CopyFrom(buffer[..bufferLength]),
            };

            request.VerifyHeader = null;
            request.Sign(Context.Key);
            await stream.Write(request);
        }

        var response = await stream.Close();
        Verifier.CheckResponse(response);

        return ObjectId.FromHash(response.Body.ObjectId.Value.ToByteArray());
    }

    // TODO: add implementation with stream writer!
    private async Task<ModelsV2.Object> GetObject(GetRequest request, Context ctx)
    {
        var reader = GetObjectInit(request, ctx);
      
        var obj = await reader.ReadHeader();

        var @object = obj.ToModel();

        @object.ObjectReader = reader;

        return @object;
       
        // obj.

        // return obj.ToModel();

        // var payload = new byte[obj.Header.PayloadLength];
        // var offset = 0L;
        // var chunk = await stream.ReadChunk();

        // while (chunk is not null && (ulong)offset < obj.Header.PayloadLength)
        // {
        //     var length = Math.Min((long)obj.Header.PayloadLength - offset, chunk.Length);

        //     Array.Copy(chunk, 0, payload, offset, length);
        //     offset += chunk.Length;
        //     chunk = await stream.ReadChunk();
        // }

        // obj.Payload = ByteString.CopyFrom(payload);

        // return obj;
    }

    private ObjectReader GetObjectInit(GetRequest initRequest, Context ctx)
    {
        if (initRequest is null)
            throw new ArgumentNullException(nameof(initRequest));

        var call = objectServiceClient!.Get(initRequest, null, ctx.Deadline, ctx.CancellationToken);
 
        return new ObjectReader(call);
    }

    private async Task<ObjectStreamer> PutObjectInit(PutRequest initRequest, Context ctx)
    {
        if (initRequest is null)
        {
            throw new ArgumentNullException(nameof(initRequest));
        }

        var call = objectServiceClient!.Put(null, ctx.Deadline, ctx.CancellationToken);

        await call.RequestStream.WriteAsync(initRequest);

        return new ObjectStreamer(call);
    }

    private async IAsyncEnumerable<ObjectID> SearchObjects(SearchRequest request, Context ctx)
    {
        using var stream = GetSearchReader(request, ctx);
       
        while (true)
        {
            var ids = await stream.Read(ctx.CancellationToken);

            if (ids == null)
                break;
                
            foreach (var oid in ids)
            {
                yield return oid;
            }
        }
    }

    private SearchReader GetSearchReader(SearchRequest initRequest, Context ctx)
    {
        if (initRequest is null)
        {
            throw new ArgumentNullException(nameof(initRequest));
        }

        var call = objectServiceClient!.Search(initRequest, null, ctx.Deadline, ctx.CancellationToken);
    
        return new SearchReader(call);
    }
    
    private Object.Object CreateObject(ModelsV2.Object @object)
    {
        var grpcHeader = @object.Header.ToGrpcMessage();
       
        grpcHeader.OwnerId = Context.Owner.ToGrpcMessage();
        grpcHeader.Version = Context.Version.ToGrpcMessage();

        if (@object.Payload != null)
        {
            grpcHeader.PayloadLength = (ulong)@object.Payload.Length;
            grpcHeader.PayloadHash = Sha256Checksum(@object.Payload);
        }

        var split = @object.Header.Split;
        if (split != null)
        {
            grpcHeader.Split = new Header.Types.Split
            {
                SplitId = split.SplitId != null ? ByteString.CopyFrom(split.SplitId.ToBinary()) : null                    
            };

            if (split.Children != null && split.Children.Count != 0)
                grpcHeader.Split.Children.AddRange(split.Children.Select(id => id.ToGrpcMessage()));

            if (split.ParentHeader is not null)
            {
                var grpcParentHeader = CreateHeader(split.ParentHeader, []);

                grpcHeader.Split.Parent = new ObjectID { Value = grpcParentHeader.Sha256() };
                grpcHeader.Split.ParentHeader = grpcParentHeader;
                grpcHeader.Split.ParentSignature = new Refs.Signature
                {
                    Key = ByteString.CopyFrom(Context.Key.PublicKey()),
                    Sign = ByteString.CopyFrom(Context.Key.SignData(grpcHeader.Split.Parent.ToByteArray())),
                };

                split.Parent = grpcHeader.Split.Parent.ToModel();
            }

            grpcHeader.Split.Previous = split.Previous?.ToGrpcMessage(); 
        }

        var obj = new Object.Object
        {
            Header = grpcHeader,
            ObjectId = new ObjectID { Value = grpcHeader.Sha256() },
            Payload = ByteString.CopyFrom(@object.Payload)
        };

        obj.Signature = new Refs.Signature
        {
            Key = ByteString.CopyFrom(Context.Key.PublicKey()),
            Sign = ByteString.CopyFrom(Context.Key.SignData(obj.ObjectId.ToByteArray())),
        };        
      
        return obj;
    }

    private Header CreateHeader(ObjectHeader header, byte[]? payload)
    {
        var grpcHeader = header.ToGrpcMessage();
       
        grpcHeader.OwnerId = Context.Owner.ToGrpcMessage();
        grpcHeader.Version = Context.Version.ToGrpcMessage();

        if (header.PayloadCheckSum != null)
            grpcHeader.PayloadHash = Sha256Checksum(header.PayloadCheckSum);
        else if (payload != null)    
            grpcHeader.PayloadHash = Sha256Checksum(payload);
       
        return grpcHeader;
    }

    private static Checksum Sha256Checksum(byte[] data)
    {
        return new Checksum
        {
            Type = ChecksumType.Sha256,
            Sum =  ByteString.CopyFrom(data.Sha256())
        };
    }

    private async Task<Session.SessionToken> GetOrCreateSession(Context ctx)
    {
        if (string.IsNullOrEmpty(ctx.SessionToken))
        { 
            return await Context.SessionService!.CreateSessionAsync(uint.MaxValue, ctx);
        }
        
        return Convert.FromBase64String(ctx.SessionToken).DeserializeSessionToken();
    }
}