using System;
using System.Diagnostics;
using FrostFS.Refs;

using FrostFS.SDK.Client;
using FrostFS.SDK.Cryptography;
using FrostFS.Session;

using Google.Protobuf;

namespace FrostFS.SDK;

public class FrostFsSessionToken
{
    private Guid _id;
    private ReadOnlyMemory<byte> _sessionKey;
    private readonly SessionToken.Types.Body _body;

    private FrostFsSessionToken()
    {
        ProtoId = ByteString.Empty;
        ProtoSessionKey = ByteString.Empty;
        _body = new SessionToken.Types.Body();
    }

    internal FrostFsSessionToken(SessionToken token)
    {
        ProtoId = token.Body.Id;
        ProtoSessionKey = token.Body.SessionKey;

        _body = token.Body;
    }

    public Guid Id
    {
        get
        {
            if (_id == Guid.Empty)
            {
                _id = ProtoId.ToUuid();
            }

            return _id;
        }
    }

    public ReadOnlyMemory<byte> SessionKey
    {
        get
        {
            if (_sessionKey.IsEmpty)
            {
                _sessionKey = ProtoSessionKey.Memory;
            }

            return _sessionKey;
        }
    }

    internal ByteString ProtoId { get; }

    internal ByteString ProtoSessionKey { get; }

    public SessionToken CreateContainerToken(ContainerID? containerId, ContainerSessionContext.Types.Verb verb, ClientKey key)
    {
        if (key is null)
        {
            throw new ArgumentNullException(nameof(key));
        }

        SessionToken sessionToken = new() { Body = _body.Clone() };

        sessionToken.Body.Container = new() { Verb = verb };

        if (containerId != null)
        {
            sessionToken.Body.Container.ContainerId = containerId;
        }
        else
        {
            sessionToken.Body.Container.Wildcard = true;
        }

        sessionToken.Body.SessionKey = key.PublicKeyProto;
        sessionToken.Signature = key.ECDsaKey.SignMessagePart(sessionToken.Body);

        return sessionToken;
    }

    public SessionToken CreateObjectTokenContext(Address address, ObjectSessionContext.Types.Verb verb, ClientKey key)
    {
        if (address is null)
        {
            throw new ArgumentNullException(nameof(address));
        }

        if (key is null)
        {
            throw new ArgumentNullException(nameof(key));
        }

        SessionToken sessionToken = new()
        {
            Body = _body.Clone()
        };

        ObjectSessionContext.Types.Target target = new() { Container = address.ContainerId };

        if (address.ObjectId != null)
        {
            target.Objects.Add(address.ObjectId);
        }

        sessionToken.Body.Object = new()
        {
            Target = target,
            Verb = verb
        };

        sessionToken.Signature = key.ECDsaKey.SignMessagePart(sessionToken.Body);

        return sessionToken;
    }
}