Add exporter base and json exporter

README.md

@@ -21,6 +21,19 @@ Make sure to read the [docs](https://sarcasticmoose.github.io/mcda-toolkit-docs)
 - [Math.Net Numerics](https://numerics.mathdotnet.com/)
 - [Light Results](https://github.com/jscarle/LightResults)
 
+## Extensions
+
+### McdaToolkit.Exporters.Abstraction
+
+Provides common interfaces and base contracts for exporting results generated by **McdaToolkit**.  
+It enables a consistent and extensible export mechanism, allowing different output formats to be implemented independently of the core library.
+
+More in the [docs](src/lib/McdaToolkit.Exporters.Abstraction/README.md)
+
+### Available extensions
+
+#### [McdaToolkit.Exporters.Json](src/lib/McdaToolkit.Exporters.Json/README.md)
+
 ## Quick Example
 
 Here's a simple example to show how to prepare and structure your data for an MCDA calculation using the MCDA Toolkit.

src/McdaToolkit.slnx

@@ -0,0 +1,6 @@
+<Solution>
+  <Project Path="lib/McdaToolkit.Exporters.Abstraction/McdaToolkit.Exporters.Abstraction.csproj" />
+  <Project Path="lib/McdaToolkit.Exporters.Json/McdaToolkit.Exporters.Json.csproj" />
+  <Project Path="lib/McdaToolkit/McdaToolkit.csproj" />
+  <Project Path="tests/McdaToolkit.UnitTests/McdaToolkit.UnitTests.csproj" />
+</Solution>

src/lib/McdaToolkit.Exporters.Abstraction/FileFormat/IFileFormat.cs

@@ -0,0 +1,7 @@
+namespace McdaToolkit.Exporters.Abstraction.FileFormat
+{
+    public interface IFileFormat
+    {
+        string Format { get; }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileName/Generators/DateTimeFileNameGenerator.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace McdaToolkit.Exporters.Abstraction.FileName.Generators
+{
+    public sealed class DateTimeFileNameGenerator : FileNameGeneratorBase
+    {
+        protected override string GenerateUniqueName()
+        {
+            return DateTime.Now.ToString("yyyy-MM-dd-HH-mm-ss");
+        }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileName/Generators/FileNameGeneratorBase.cs

@@ -0,0 +1,18 @@
+using System.Text;
+
+namespace McdaToolkit.Exporters.Abstraction.FileName.Generators
+{
+    public abstract class FileNameGeneratorBase : IFileNameGenerator
+    {
+        protected abstract string GenerateUniqueName();
+
+        public string Generate()
+        {
+            return new StringBuilder()
+                .Append(StaticNames.FileFirstSegment)
+                .Append('_')
+                .Append(GenerateUniqueName())
+                .ToString();
+        }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileName/IFileNameGenerator.cs

@@ -0,0 +1,7 @@
+namespace McdaToolkit.Exporters.Abstraction.FileName
+{
+    public interface IFileNameGenerator
+    {
+        public string Generate();
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/IFileWriter.cs

@@ -0,0 +1,17 @@
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using LightResults;
+using McdaToolkit.Exporters.Abstraction.FileWriter.Results.Success;
+using McdaToolkit.Exporters.Abstraction.Path;
+
+namespace McdaToolkit.Exporters.Abstraction.FileWriter
+{
+    public interface IFileWriter
+    {
+        ValueTask<Result<ISuccessFileOperation>> WriteToFile(
+            Stream stream, 
+            OutputPath outputPath,
+            CancellationToken ct = default);
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/InternalFileWriter.cs

@@ -0,0 +1,65 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using LightResults;
+using McdaToolkit.Exporters.Abstraction.FileWriter.Results.Errors;
+using McdaToolkit.Exporters.Abstraction.FileWriter.Results.Success;
+using McdaToolkit.Exporters.Abstraction.Path;
+
+namespace McdaToolkit.Exporters.Abstraction.FileWriter
+{
+    internal sealed class InternalFileWriter : IFileWriter
+    {
+        private readonly int _bufferSize;
+
+        public InternalFileWriter(int bufferSize = 8192)
+        {
+            _bufferSize = bufferSize;
+        }
+
+        public async ValueTask<Result<ISuccessFileOperation>> WriteToFile(
+            Stream stream, 
+            OutputPath outputPath,
+            CancellationToken ct = default)
+        {
+            if(outputPath is null) throw new ArgumentNullException(nameof(outputPath));
+            if(stream is null) throw new ArgumentNullException(nameof(stream));
+
+            stream.Position = 0;
+            stream.Seek(0, SeekOrigin.Begin);
+
+            try
+            {
+                await using var fileStream = new FileStream(
+                    outputPath.ToString(),
+                    FileMode.Create,
+                    FileAccess.ReadWrite,
+                    FileShare.None,
+                    _bufferSize);
+
+                fileStream.Position = 0;
+                fileStream.Seek(0, SeekOrigin.Begin);
+
+                var buffer = new byte[_bufferSize];
+                var totalWritedBytes = 0;
+                var currentReadBytes = 0;
+
+                while ((currentReadBytes = await stream.ReadAsync(buffer, 0, _bufferSize, ct)) > 0)
+                {
+                    await fileStream.WriteAsync(buffer.AsMemory(0, currentReadBytes), ct);
+                    totalWritedBytes += currentReadBytes;
+                }
+                if (totalWritedBytes == 0) return new NoneDataWrited();
+
+                await fileStream.FlushAsync(ct);
+                await stream.FlushAsync(ct);
+                return new DataWrited(totalWritedBytes);
+            }
+            catch (IOException ex)
+            {
+                return new IoError(ex);
+            }
+        }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/Results/Errors/IoError.cs

@@ -0,0 +1,12 @@
+using System;
+using LightResults;
+
+namespace McdaToolkit.Exporters.Abstraction.FileWriter.Results.Errors
+{
+    public class IoError : Error
+    {
+        public IoError(Exception exception) : base(exception.Message)
+        {
+        }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/Results/Success/DataWrited.cs

@@ -0,0 +1,9 @@
+namespace McdaToolkit.Exporters.Abstraction.FileWriter.Results.Success
+{
+    public class DataWrited : ISuccessFileOperation
+    {
+        public DataWrited(int writedBytes)
+        {
+        }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/Results/Success/ISuccessFileOperation.cs

@@ -0,0 +1,4 @@
+namespace McdaToolkit.Exporters.Abstraction.FileWriter.Results.Success
+{
+    public interface ISuccessFileOperation {}
+}

src/lib/McdaToolkit.Exporters.Abstraction/FileWriter/Results/Success/NoneDataWrited.cs

@@ -0,0 +1,4 @@
+namespace McdaToolkit.Exporters.Abstraction.FileWriter.Results.Success
+{
+    public class NoneDataWrited : ISuccessFileOperation {}
+}

src/lib/McdaToolkit.Exporters.Abstraction/IExporter.cs

@@ -0,0 +1,26 @@
+using System.Threading;
+using System.Threading.Tasks;
+using LightResults;
+using McdaToolkit.Data;
+
+namespace McdaToolkit.Exporters.Abstraction
+{
+    public interface IExporter
+    {
+        /// <summary>
+        /// Asynchronously exports the provided execution details.
+        /// </summary>
+        /// <param name="details">
+        /// The <see cref="ExecutionDetails"/> containing the results of an MCDA method execution,
+        /// including rankings, criteria, and any metadata.
+        /// </param>
+        /// <param name="ct">A <see cref="CancellationToken"/> to observe while performing the export.</param>
+        /// <returns>
+        /// A <see cref="ValueTask"/> representing the asynchronous operation.
+        /// The <see cref="IResult"/> indicates whether the export succeeded or failed.
+        /// </returns>
+        ValueTask<IResult> ExportAsync(
+            ExecutionDetails details,
+            CancellationToken ct);
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/IExporterSettings.cs

@@ -0,0 +1,9 @@
+using McdaToolkit.Exporters.Abstraction.Path;
+
+namespace McdaToolkit.Exporters.Abstraction
+{
+    internal interface IExporterSettings
+    {
+        public OutputPath Path { get; }
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/McdaToolkit.Exporters.Abstraction.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <Nullable>enable</Nullable>
+        <Version>1.0.0</Version>
+        <PackageReadmeFile>README.md</PackageReadmeFile>
+        <TargetFrameworks>netstandard2.1;net6.0</TargetFrameworks>
+        <Copyright>© 2026 Jakub Tokarczyk</Copyright>
+        <PackageLicenseExpression>MIT</PackageLicenseExpression>
+        <RepositoryUrl>https://github.com/SarcasticMoose/mcda-toolkit</RepositoryUrl>
+        <PackageIcon>icon.png</PackageIcon>
+        <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    </PropertyGroup>
+
+    <ItemGroup Label="Resources">
+        <None Include="README.md" Pack="true" PackagePath="\" />
+        <None Include="..\..\..\images\icon.png" Pack="true" PackagePath="\" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\McdaToolkit\McdaToolkit.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <InternalsVisibleTo Include="McdaToolkit.Exporters.Json.UnitTests" />
+        <InternalsVisibleTo Include="McdaToolkit.Exporters.Json" />
+    </ItemGroup>
+
+</Project>

src/lib/McdaToolkit.Exporters.Abstraction/Path/IOutputPathBuilder.cs

@@ -0,0 +1,11 @@
+using McdaToolkit.Exporters.Abstraction.FileName;
+
+namespace McdaToolkit.Exporters.Abstraction.Path
+{
+    public interface IOutputPathBuilder
+    {
+        IOutputPathBuilder WithDirectory(string directory);
+        IOutputPathBuilder WithFileNameGenerator(IFileNameGenerator fileNameGenerator);
+        OutputPath Build();
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/Path/OutputPath.cs

@@ -0,0 +1,21 @@
+using System;
+
+namespace McdaToolkit.Exporters.Abstraction.Path
+{
+    public class OutputPath
+    {
+        private readonly string _fullPath;
+
+        internal OutputPath(string fullPath)
+        {
+            _fullPath = fullPath;
+        }
+
+        public override string ToString()
+        {
+            return _fullPath;
+        }
+
+        public static OutputPath Default => new OutputPath(System.IO.Path.Join(Environment.CurrentDirectory, ""));
+    }
+}

src/lib/McdaToolkit.Exporters.Abstraction/Path/OutputPathBuilder.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Text;
+using McdaToolkit.Exporters.Abstraction.FileFormat;
+using McdaToolkit.Exporters.Abstraction.FileName;
+using McdaToolkit.Exporters.Abstraction.FileName.Generators;
+
+namespace McdaToolkit.Exporters.Abstraction.Path
+{
+    public abstract class OutputPathBuilder<TFileFormat>  : 
+        IOutputPathBuilder
+        where TFileFormat : IFileFormat, new()
+    {
+        private IFileNameGenerator? _fileNameGenerator;
+        private IFileFormat _fileFormat = new TFileFormat();
+        private string? _directory;
+
+        public IOutputPathBuilder WithDirectory(string directory)
+        {
+            _directory = directory;
+            return this;
+        }
+
+        public IOutputPathBuilder WithFileNameGenerator(IFileNameGenerator fileNameGenerator)
+        {
+            _fileNameGenerator = fileNameGenerator;
+            return this;
+        }
+
+        public OutputPath Build()
+        {
+            _fileNameGenerator ??= new DateTimeFileNameGenerator();
+            _directory ??= Environment.CurrentDirectory;
+
+            var fileName = new StringBuilder();
+            fileName.Append(_fileNameGenerator.Generate());
+            fileName.Append('.');
+            fileName.Append(_fileFormat.Format);
+
+            return new OutputPath(System.IO.Path.Join(_directory, fileName.ToString()));
+        }
+    }
+}