/*
* Copyright (c) 2023 Vaughn Nugent
* 
* Library: VNLib
* Package: Emails.Transactional
* File: MinioStorage.cs 
*
* MinioStorage.cs is part of Emails.Transactional which is part of the larger 
* VNLib collection of libraries and utilities.
*
* Emails.Transactional is free software: you can redistribute it and/or modify 
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation, either version 2 of the License,
* or (at your option) any later version.
*
* Emails.Transactional is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License 
* along with Emails.Transactional. If not, see http://www.gnu.org/licenses/.
*/


using System.IO;
using System.Threading;
using System.Threading.Tasks;

using VNLib.Utils.IO;
using VNLib.Utils.Memory;
using VNLib.Utils.Logging;
using VNLib.Utils.Extensions;
using VNLib.Plugins;
using VNLib.Plugins.Extensions.Loading;


using Minio;
using Minio.Handlers;
using Minio.DataModel;
using Minio.DataModel.Args;
using Minio.DataModel.Tracing;

namespace Emails.Transactional
{

    [ConfigurationName("s3_config")]
    internal sealed class MinioStorage : ISimpleFilesystem, IAsyncConfigurable
    {
        private readonly MinioClient Client;
        private readonly S3Config Config;

        public MinioStorage(PluginBase plugin, IConfigScope s3Config)
        {
            //Deserialize the config
            Config = s3Config.Deserialze<S3Config>();
            Client = new();

            Client.WithEndpoint(Config.ServerAddress)
                .WithSSL(Config.UseSsl.HasValue && Config.UseSsl.Value)
                .WithTimeout(10 * 1000);

            //Accept optional region
            if (!string.IsNullOrWhiteSpace(Config.Region))
            {
                Client.WithRegion(Config.Region);
            }

            //Setup debug trace
            if (plugin.IsDebug())
            {
                Client.SetTraceOn(new ReqLogger(plugin.Log));
            }
        }


        public string GetExternalFilePath(string filePath)
        {
            string path = Path.Combine(Config.BaseBucket!, filePath);
            //force forward only slashes
            return path.Replace('\\', '/');
        }

        ///<inheritdoc/>
        public async Task ConfigureServiceAsync(PluginBase plugin)
        {
            using ISecretResult? secret = await plugin.GetSecretAsync("s3_secret");

            //Build client
            Client.WithCredentials(Config.ClientId, secret.Result.ToString())
                .Build();
        }

        ///<inheritdoc/>
        public Task DeleteFileAsync(string filePath, CancellationToken cancellation)
        {
            string fullPath = GetExternalFilePath(filePath);

            RemoveObjectArgs args = new();
            args.WithBucket(Config.BaseBucket)
                .WithObject(fullPath);

            //Remove the object
            return Client.RemoveObjectAsync(args, cancellation);
        }

        ///<inheritdoc/>
        public Task WriteFileAsync(string filePath, Stream data, string ct, CancellationToken cancellation)
        {
            string fullPath = GetExternalFilePath(filePath);

            PutObjectArgs args = new();
            args.WithBucket(Config.BaseBucket)
                .WithContentType(ct)
                .WithObject(fullPath)
                .WithObjectSize(data.Length)
                .WithStreamData(data);

            //Upload the object
            return Client.PutObjectAsync(args, cancellation);
        }

        ///<inheritdoc/>
        public async Task<long> ReadFileAsync(string filePath, Stream output, CancellationToken cancellation)
        {
            string fullPath = GetExternalFilePath(filePath);

            //Get the item
            GetObjectArgs args = new();
            args.WithBucket(Config.BaseBucket)
            .WithObject(fullPath)
            .WithCallbackStream(async (stream, cancellation) =>
            {
                //Read the objec to memory
                await stream.CopyToAsync(output, 4096, MemoryUtil.Shared, cancellation);
            });
            try
            {
                //Get the post content file 
                ObjectStat stat = await Client.GetObjectAsync(args, cancellation);
            }
            catch (Minio.Exceptions.ObjectNotFoundException)
            {
                //File not found
                return -1;
            }
            return output.Position;
        }


        internal class ReqLogger : IRequestLogger
        {
            private readonly ILogProvider logProvider;

            public ReqLogger(ILogProvider log)
            {
                logProvider = log;
            }

            public void LogRequest(RequestToLog requestToLog, ResponseToLog responseToLog, double durationMs)
            {
                logProvider.Debug("S3 result\n{method} {uri} HTTP {ms}ms\nHTTP {status} {message}\n{content}",
                    requestToLog.Method, requestToLog.Resource, durationMs,
                    responseToLog.StatusCode, responseToLog.ErrorMessage, responseToLog.Content
                    );
            }
        }
    }
}