using System;

using System.Threading.Tasks;

using JSONAPI.Documents;

using Newtonsoft.Json;

namespace JSONAPI.Json

{

/// <summary>

/// Default implementation of ILinkFormatter

/// </summary>

public class LinkFormatter : ILinkFormatter

{

private IMetadataFormatter _metadataFormatter;

private const string HrefKeyName = "href";

private const string MetaKeyName = "meta";

/// <summary>

/// Constructs a LinkFormatter

/// </summary>

public LinkFormatter()

{

}

/// <summary>

/// Constructs a LinkFormatter

/// </summary>

/// <param name="metadataFormatter"></param>

public LinkFormatter(IMetadataFormatter metadataFormatter)

{

_metadataFormatter = metadataFormatter;

}

/// <summary>

/// The formatter to use for metadata on the link object

/// </summary>

/// <exception cref="InvalidOperationException"></exception>

public IMetadataFormatter MetadataFormatter

{

get

{

return _metadataFormatter ?? (_metadataFormatter = new MetadataFormatter());

}

set

{

if (_metadataFormatter != null) throw new InvalidOperationException("This property can only be set once.");

_metadataFormatter = value;

}

}

public Task Serialize(ILink link, JsonWriter writer)

{

if (link.Metadata == null)

{

writer.WriteValue(link.Href);

}

else

{

writer.WriteStartObject();

writer.WritePropertyName(HrefKeyName);

writer.WriteValue(link.Href);

writer.WritePropertyName(MetaKeyName);

MetadataFormatter.Serialize(link.Metadata, writer);

writer.WriteEndObject();

}

return Task.FromResult(0);

}

public Task<ILink> Deserialize(JsonReader reader, string currentPath)

{

// The client should never be sending us links.

throw new NotSupportedException();

}

}

}