using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Threading.Tasks;

using FrostFS.Container;
using FrostFS.Refs;
using FrostFS.SDK.Client;
using FrostFS.SDK.Client.Mappers.GRPC;
using FrostFS.SDK.Cryptography;
using FrostFS.Session;

namespace FrostFS.SDK.Client;

internal sealed class ContainerServiceProvider(ContainerService.ContainerServiceClient service, ClientContext clientCtx) : ContextAccessor(clientCtx)
{
    private SessionProvider? sessions;

    public async ValueTask<FrostFsSessionToken> GetDefaultSession(ISessionToken args, CallContext ctx)
    {
        sessions ??= new(ClientContext);

        if (!ClientContext.SessionCache!.TryGetValue(ClientContext.SessionCacheKey, out var token))
        {
            var protoToken = await sessions.GetDefaultSession(args, ctx).ConfigureAwait(false);

            token = new FrostFsSessionToken(protoToken);

            ClientContext.SessionCache.SetValue(ClientContext.SessionCacheKey, token);
        }

        if (token == null)
        {
            throw new FrostFsException("Cannot create session");
        }

        return token;
    }

    internal async Task<FrostFsContainerInfo> GetContainerAsync(PrmContainerGet args, CallContext ctx)
    {
        GetRequest request = GetContainerRequest(args.Container.GetContainerID(), args.XHeaders, ClientContext.Key.ECDsaKey);

        var response = await service.GetAsync(request, null, ctx.GetDeadline(), ctx.CancellationToken);

        Verifier.CheckResponse(response);

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

    internal async IAsyncEnumerable<FrostFsContainerId> ListContainersAsync(PrmContainerGetAll args, CallContext ctx)
    {
        var request = new ListRequest
        {
            Body = new()
            {
                OwnerId = ClientContext.Owner.OwnerID
            }
        };

        request.AddMetaHeader(args.XHeaders);
        request.Sign(ClientContext.Key.ECDsaKey);

        var response = await service.ListAsync(request, null, ctx.GetDeadline(), ctx.CancellationToken);

        Verifier.CheckResponse(response);

        foreach (var cid in response.Body.ContainerIds)
        {
            yield return new FrostFsContainerId(Base58.Encode(cid.Value.Span));
        }
    }

    internal async Task<FrostFsContainerId> CreateContainerAsync(PrmContainerCreate args, CallContext ctx)
    {
        var grpcContainer = args.Container.GetContainer();

        grpcContainer.OwnerId ??= ClientContext.Owner.OwnerID;
        grpcContainer.Version ??= ClientContext.Version.VersionID;

        var request = new PutRequest
        {
            Body = new PutRequest.Types.Body
            {
                Container = grpcContainer,
                Signature = ClientContext.Key.ECDsaKey.SignRFC6979(grpcContainer)
            }
        };

        var sessionToken = (args.SessionToken ?? await GetDefaultSession(args, ctx).ConfigureAwait(false)) ?? throw new FrostFsException("Cannot create session token");

        var protoToken = sessionToken.CreateContainerToken(
            null,
            ContainerSessionContext.Types.Verb.Put,
            ClientContext.Key);

        request.AddMetaHeader(args.XHeaders, protoToken);

        request.Sign(ClientContext.Key.ECDsaKey);

        var response = await service.PutAsync(request, null, ctx.GetDeadline(), ctx.CancellationToken);

        Verifier.CheckResponse(response);

        await WaitForContainer(WaitExpects.Exists, response.Body.ContainerId, args.WaitParams, ctx).ConfigureAwait(false);

        return new FrostFsContainerId(response.Body.ContainerId);
    }

    internal async Task DeleteContainerAsync(PrmContainerDelete args, CallContext ctx)
    {
        var request = new DeleteRequest
        {
            Body = new DeleteRequest.Types.Body
            {
                ContainerId = args.ContainerId.ToMessage(),
                Signature = ClientContext.Key.ECDsaKey.SignRFC6979(args.ContainerId.ToMessage().Value)
            }
        };

        var sessionToken = args.SessionToken ?? await GetDefaultSession(args, ctx).ConfigureAwait(false);

        var protoToken = sessionToken.CreateContainerToken(
            request.Body.ContainerId,
            ContainerSessionContext.Types.Verb.Delete,
            ClientContext.Key);

        request.AddMetaHeader(args.XHeaders, protoToken);

        request.Sign(ClientContext.Key.ECDsaKey);

        var response = await service.DeleteAsync(request, null, ctx.GetDeadline(), ctx.CancellationToken);

        Verifier.CheckResponse(response);

        await WaitForContainer(WaitExpects.Removed, request.Body.ContainerId, args.WaitParams, ctx)
            .ConfigureAwait(false);

        Verifier.CheckResponse(response);
    }

    private static GetRequest GetContainerRequest(ContainerID id, string[] xHeaders, ECDsa key)
    {
        var request = new GetRequest
        {
            Body = new GetRequest.Types.Body
            {
                ContainerId = id
            }
        };

        request.AddMetaHeader(xHeaders);
        request.Sign(key);

        return request;
    }

    private enum WaitExpects
    {
        Exists,
        Removed
    }

    private async Task WaitForContainer(WaitExpects expect, ContainerID id, PrmWait waitParams, CallContext ctx)
    {
        var request = GetContainerRequest(id, [], ClientContext.Key.ECDsaKey);

        async Task action()
        {
            var response = await service.GetAsync(request, null, ctx.GetDeadline(), ctx.CancellationToken);
            Verifier.CheckResponse(response);
        }

        await WaitFor(action, expect, waitParams).ConfigureAwait(false);
    }

    private static async Task WaitFor(
        Func<Task> action,
        WaitExpects expect,
        PrmWait waitParams)
    {
        var deadLine = waitParams.GetDeadline();

        while (true)
        {
            try
            {
                await action().ConfigureAwait(false);

                if (expect == WaitExpects.Exists)
                    return;

                if (DateTime.UtcNow >= deadLine)
                    throw new TimeoutException();

                await Task.Delay(waitParams.PollInterval).ConfigureAwait(false);
            }
            catch (FrostFsResponseException ex)
            {
                if (DateTime.UtcNow >= deadLine)
                    throw new TimeoutException();

                if (ex.Status?.Code != FrostFsStatusCode.ContainerNotFound)
                    throw;

                if (expect == WaitExpects.Removed)
                    return;

                await Task.Delay(waitParams.PollInterval).ConfigureAwait(false);
            }
        }
    }
}