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

using Google.Protobuf;

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(ObjectService.ObjectServiceClient client, ClientEnvironment ctx) : ContextAccessor(ctx)
{
    readonly ObjectTools tools = new(ctx);

    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 client!.HeadAsync(request, null, ctx.Deadline, ctx.CancellationToken);
        
        Verifier.CheckResponse(response);

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

    internal async Task<FrostFsObject> 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);

        return await GetObject(request, ctx);
    }

    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 client.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());
        }
    }

    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(FrostFsObject modelObject, Context ctx)
    {
        var sessionToken = await GetOrCreateSession(ctx);
    
        var grpcObject = tools.CreateObject(modelObject);

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

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

        request.Sign(Context.Key);

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

        Verifier.CheckResponse(response);
        
        return ObjectId.FromHash(grpcObject.ObjectId.Value.ToByteArray());
    }
 
    private async Task<ObjectId> PutClientCutObject(PutObjectParameters parameters, Context ctx)
    {
        var payloadStream = parameters.Payload!;
        var header = parameters.Header!;

        ObjectId? objectId;
        List<ObjectId> sentObjectIds = [];
        
        FrostFsObject? currentObject;

        var networkSettings = await Context.Client.GetNetworkSettingsAsync(ctx);

        var objectSize = (int)networkSettings.MaxObjectSize;

        var fullLength = header.PayloadLength;

        if (payloadStream.CanSeek)
        {
            objectSize = (int)Math.Min(objectSize, payloadStream.Length);

            if (fullLength == 0)
                fullLength = (ulong)payloadStream.Length;
        }
        
        if (fullLength == 0)
            throw new ArgumentException("Payload stream must be able to seek or PayloadLength must be specified");
        
        var buffer = new byte[objectSize];      

        var largeObject = new LargeObject(header.ContainerId);

        var split = new Split();
           
        while (true)
        {
            var bytesCount = await payloadStream.ReadAsync(buffer, 0, objectSize);

            split.Previous = sentObjectIds.LastOrDefault();

            largeObject.AppendBlock(buffer, bytesCount);

            currentObject = new FrostFsObject(header.ContainerId, bytesCount < objectSize ? buffer[..bytesCount] : buffer)
                .SetSplit(split);

            if (largeObject.PayloadLength == fullLength)
                break;

            objectId = await PutSingleObjectAsync(currentObject, ctx);

            sentObjectIds.Add(objectId!);
        }

        if (sentObjectIds.Count != 0)
        {
            largeObject.AddAttributes(parameters.Header!.Attributes);
            largeObject.CalculateHash();

            currentObject.SetParent(largeObject);

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

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

            linkObject.Header.Attributes.Clear();

            _ = await PutSingleObjectAsync(linkObject, ctx);

            return tools.CalculateObjectId(largeObject.Header);
        }

        currentObject.AddAttributes(parameters.Header!.Attributes);
        
        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 initRequest = new PutRequest
        {
            Body = new PutRequest.Types.Body
            {
                Init = new PutRequest.Types.Body.Types.Init
                {
                    Header = hdr
                }
            }
        };

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

        initRequest.Sign(Context.Key);

        using var stream = await PutObjectInit(initRequest, ctx);

        var bufferSize = parameters.BufferMaxSize > 0 ? parameters.BufferMaxSize : Constants.ObjectChunkSize;

        if (payload.CanSeek)
        {
            bufferSize = (int)Math.Min(payload.Length, bufferSize);
        }
        else if (header.PayloadLength > 0)
        {
            bufferSize = (int)Math.Min((long)header.PayloadLength, bufferSize);
        }

        var buffer = new byte[bufferSize];

        while (true)
        {
            var bytesCount = await payload.ReadAsync(buffer, 0, bufferSize, ctx.CancellationToken);

            if (bytesCount == 0)
                break;

            var chunkRequest = new PutRequest(initRequest)
            {
                Body = new PutRequest.Types.Body
                {
                    Chunk = ByteString.CopyFrom(buffer[..bytesCount]),
                },
                VerifyHeader = null
            };

            chunkRequest.Sign(Context.Key);
            await stream.Write(chunkRequest);
        }

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

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

    private async Task<FrostFsObject> GetObject(GetRequest request, Context ctx)
    {
        var reader = GetObjectInit(request, ctx);
      
        var grpcObject = await reader.ReadHeader();
        var modelObject = grpcObject.ToModel();
      
        modelObject.ObjectReader = reader;

        return modelObject;       
    }

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

        var call = client.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 = client.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 = client.Search(initRequest, null, ctx.Deadline, ctx.CancellationToken);
    
        return new SearchReader(call);
    }   

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