// Copyright (c) The LEGO Group. All rights reserved.

namespace LEGO.AsyncAPI.Readers

{

using System.IO;

using System.Linq;

using System.Text.Json;

using System.Text.Json.Nodes;

using System.Threading;

using System.Threading.Tasks;

using LEGO.AsyncAPI.Models;

using LEGO.AsyncAPI.Models.Interfaces;

using LEGO.AsyncAPI.Readers.Interface;

using YamlDotNet.RepresentationModel;

/// <summary>

/// Service class for converting contents of TextReader into AsyncApiDocument instances.

/// </summary>

public class AsyncApiTextReader : IAsyncApiReader<TextReader, AsyncApiDiagnostic>

{

private readonly AsyncApiReaderSettings settings;

/// <summary>

/// Create stream reader with custom settings if desired.

/// </summary>

/// <param name="settings"></param>

public AsyncApiTextReader(AsyncApiReaderSettings settings = null)

{

this.settings = settings ?? new AsyncApiReaderSettings();

}

/// <summary>

/// Reads the stream input and parses it into an AsyncApi document.

/// </summary>

/// <param name="input">TextReader containing AsyncApi description to parse.</param>

/// <param name="diagnostic">Returns diagnostic object containing errors detected during parsing.</param>

/// <returns>Instance of newly created AsyncApiDocument.</returns>

public AsyncApiDocument Read(TextReader input, out AsyncApiDiagnostic diagnostic)

{

JsonNode jsonNode;

// Parse the YAML/JSON text in the TextReader into the YamlDocument

try

{

jsonNode = LoadYamlDocument(input, this.settings);

}

catch (JsonException ex)

{

diagnostic = new AsyncApiDiagnostic();

diagnostic.Errors.Add(new AsyncApiError($"#line={ex.LineNumber}", ex.Message));

return new AsyncApiDocument();

}

return new AsyncApiJsonDocumentReader(this.settings).Read(jsonNode, out diagnostic);

}

/// <summary>

/// Reads the content of the TextReader.

/// </summary>

/// <param name="input">TextReader containing AsyncApi description to parse.</param>

/// <param name="cancellationToken">The cancellation token.</param>

/// <returns>

/// A ReadResult instance that contains the resulting AsyncApiDocument and a diagnostics instance.

/// </returns>

public async Task<ReadResult> ReadAsync(TextReader input, CancellationToken cancellationToken)

{

JsonNode jsonNode;

// Parse the YAML/JSON text in the TextReader into the YamlDocument

try

{

jsonNode = LoadYamlDocument(input, this.settings);

}

catch (JsonException ex)

{

var diagnostic = new AsyncApiDiagnostic();

diagnostic.Errors.Add(new AsyncApiError($"#line={ex.LineNumber}", ex.Message));

return new ReadResult

{

AsyncApiDocument = null,

AsyncApiDiagnostic = diagnostic,

};

}

return await new AsyncApiJsonDocumentReader(this.settings).ReadAsync(jsonNode, cancellationToken);

}

/// <summary>

/// Reads the stream input and parses the fragment of an AsyncApi description into an AsyncApi Element.

/// </summary>

/// <param name="input">TextReader containing AsyncApi description to parse.</param>

/// <param name="version">Version of the AsyncApi specification that the fragment conforms to.</param>

/// <param name="diagnostic">Returns diagnostic object containing errors detected during parsing.</param>

/// <returns>Instance of newly created AsyncApiDocument.</returns>

public T ReadFragment<T>(TextReader input, AsyncApiVersion version, out AsyncApiDiagnostic diagnostic)

where T : IAsyncApiElement

{

JsonNode jsonNode;

// Parse the YAML/JSON

try

{

jsonNode = LoadYamlDocument(input, this.settings);

}

catch (JsonException ex)

{

diagnostic = new AsyncApiDiagnostic();

diagnostic.Errors.Add(new AsyncApiError($"#line={ex.LineNumber}", ex.Message));

return default;

}

return new AsyncApiJsonDocumentReader(this.settings).ReadFragment<T>(jsonNode, version,

out diagnostic);

}

/// <summary>

/// Helper method to turn streams into YamlDocument.

/// </summary>

/// <param name="input">Stream containing YAML formatted text.</param>

/// <returns>Instance of a YamlDocument.</returns>

static JsonNode LoadYamlDocument(TextReader input, AsyncApiReaderSettings settings)

{

var yamlStream = new YamlStream();

yamlStream.Load(input);

return yamlStream.Documents.First().ToJsonNode(settings.CultureInfo);

}

}

}