using System;
using Newtonsoft.Json.Bson;
using System.Globalization;
using Newtonsoft.Json.Utilities;

namespace Newtonsoft.Json.Converters
{
  /// <summary>
  /// Converts a <see cref="BsonObjectId"/> to and from JSON and BSON.
  /// </summary>
  public class BsonObjectIdConverter : JsonConverter
  {
    /// <summary>
    /// Writes the JSON representation of the object.
    /// </summary>
    /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
    /// <param name="value">The value.</param>
    /// <param name="serializer">The calling serializer.</param>
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
      BsonObjectId objectId = (BsonObjectId) value;

      BsonWriter bsonWriter = writer as BsonWriter;
      if (bsonWriter != null)
      {
        bsonWriter.WriteObjectId(objectId.Value);
      }
      else
      {
        writer.WriteValue(objectId.Value);
      }
    }

    /// <summary>
    /// Reads the JSON representation of the object.
    /// </summary>
    /// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
    /// <param name="objectType">Type of the object.</param>
    /// <param name="existingValue">The existing value of object being read.</param>
    /// <param name="serializer">The calling serializer.</param>
    /// <returns>The object value.</returns>
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
      if (reader.TokenType != JsonToken.Bytes)
        throw new JsonSerializationException("Expected Bytes but got {0}.".FormatWith(CultureInfo.InvariantCulture, reader.TokenType));

      byte[] value = (byte[])reader.Value;

      return new BsonObjectId(value);
    }

    /// <summary>
    /// Determines whether this instance can convert the specified object type.
    /// </summary>
    /// <param name="objectType">Type of the object.</param>
    /// <returns>
    /// 	<c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
    /// </returns>
    public override bool CanConvert(Type objectType)
    {
      return (objectType == typeof (BsonObjectId));
    }
  }
}