adas-core/adas-core.Infrastructure/Utils/PatientPumpObservationConverter.cs

using System.Reflection;
using adas_core.Domain.Models;
using adas_core.Domain.Models.Pumps;
using MongoDB.Bson.Serialization;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json.Linq;
using JsonConverterAttribute = Newtonsoft.Json.JsonConverterAttribute;

namespace adas_core.Infrastructure.Utils;

/// <summary>
/// Provides JSON conversion for <see cref="PumpObservation"/> instances and supports BSON serialization through the <see cref="IBsonSerializer"/> interface.
/// </summary>
public class PatientPumpObservationConverter : JsonConverter<PumpObservation>, IBsonSerializer
{
    /// <summary>
    /// Deserializes a BSON value into a .NET object using the provided deserialization context and arguments.
    /// </summary>
    /// <param name="context">The BSON deserialization context that provides access to the reader and configuration.</param>
    /// <param name="args">The deserialization arguments containing additional settings for the operation.</param>
    /// <returns>The deserialized object.</returns>
    /// <exception cref="NotImplementedException">Thrown when the method is invoked, as the deserialization logic has not been implemented.</exception>
    public object Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
        {
            throw new NotImplementedException();
        }

    /// <summary>
    /// Serializes the specified value into BSON format using the provided serialization context and arguments.
    /// This method is not yet implemented and currently throws an exception when invoked.
    /// </summary>
    /// <param name="context">The BSON serialization context that provides the writer and configuration for the operation.</param>
    /// <param name="args">The BSON serialization arguments that influence the serialization behavior.</param>
    /// <param name="value">The object to be serialized into BSON.</param>
    /// <exception cref="NotImplementedException">Thrown because the method has not been implemented.</exception>
    public void Serialize(BsonSerializationContext context, BsonSerializationArgs args, object value)
        {
            throw new NotImplementedException();
        }

    public Type ValueType => typeof(PatientObservationAlarm);

    /// <summary>
    /// Deserializes a JSON representation into a <see cref="PumpObservation"/> instance.
    /// This implementation is not yet provided and always throws an exception.
    /// </summary>
    /// <param name="reader">The <see cref="JsonReader"/> to read JSON from.</param>
    /// <param name="objectType">The type of the object to deserialize.</param>
    /// <param name="existingValue">The existing value of the object being read, or <c>null</c> if there is no existing value.</param>
    /// <param name="hasExistingValue">A value indicating whether <paramref name="existingValue"/> has a value.</param>
    /// <param name="serializer">The <see cref="JsonSerializer"/> used for deserialization.</param>
    /// <returns>A <see cref="PumpObservation"/> instance reconstructed from the JSON data.</returns>
    /// <exception cref="NotImplementedException">Thrown because the method has not been implemented yet.</exception>
    public override PumpObservation ReadJson(JsonReader reader, Type objectType,
            PumpObservation? existingValue,
            bool hasExistingValue, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }

    /// <summary>
    /// Serializes the specified value to JSON, applying string enum conversion to the Event, Status, PumpMode, InfusingStatus, and AlarmMode properties. No output is written when the value is null.
    /// </summary>
    /// <param name="writer">The JSON writer to which the serialized object is written.</param>
    /// <param name="value">The object to serialize; if null, the method does nothing.</param>
    /// <param name="serializer">The JSON serializer used as context for the conversion.</param>
    public new void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
        {
            if (value != null)
            {
                var jo = JObject.FromObject(value);
    
                // Add [JsonConverter(typeof(StringEnumConverter))] attribute to specified properties
                AddStringEnumConverterAttribute(value, "Event");
                AddStringEnumConverterAttribute(value, "Status");
                AddStringEnumConverterAttribute(value, "PumpMode");
                AddStringEnumConverterAttribute(value, "InfusingStatus");
                AddStringEnumConverterAttribute(value, "AlarmMode");
    
                jo.WriteTo(writer);
            }
        }

    /// <summary>
    /// Serializes a <see cref="PumpObservation"/> instance to JSON. This override is not yet implemented and will always throw.
    /// </summary>
    /// <param name="writer">The JSON writer used to emit the serialized output.</param>
    /// <param name="value">The <see cref="PumpObservation"/> to serialize, or <see langword="null"/> if no value is available.</param>
    /// <param name="serializer">The <see cref="JsonSerializer"/> providing serialization context and options.</param>
    /// <exception cref="NotImplementedException">Always thrown because the method has not been implemented.</exception>
    public override void WriteJson(JsonWriter writer, PumpObservation? value, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }

    /// <summary>
    /// Adds a <see cref="JsonConverterAttribute"/> of type <see cref="StringEnumConverter"/> to the specified property, ensuring that enum values are serialized as their string names rather than numeric values. If the property already has a <see cref="JsonConverterAttribute"/> applied, no changes are made.
    /// </summary>
    /// <param name="value">The object instance whose property will be inspected for the attribute.</param>
    /// <param name="propertyName">The name of the property to which the converter attribute will be added.</param>
    private static void AddStringEnumConverterAttribute(object value, string propertyName)
        {
            var prop = value.GetType().GetProperty(propertyName);
            var attr = new JsonConverterAttribute(typeof(StringEnumConverter));
    
            if (prop != null)
            {
                var attrs = prop.GetCustomAttributes(false);
    
                // Check if the attribute is not already applied
                if (Array.Find(attrs, a => a is JsonConverterAttribute) == null)
                {
                    // Create a new array that includes the existing attributes and the new one
                    var newAttrs = new object[attrs.Length + 1];
                    Array.Copy(attrs, newAttrs, attrs.Length);
                    newAttrs[attrs.Length] = attr;
    
                    // Use reflection to set the new attributes array
                    var field = typeof(PropertyInfo).GetField("m_customAttributes",
                        BindingFlags.Instance | BindingFlags.NonPublic);
                    field?.SetValue(prop, newAttrs);
                }
            }
        }
}

/*How to use it:
    BsonSerializer.RegisterSerializer(new PatientObservationAlarmConverter());
    JsonConvert.DefaultSettings = () => new JsonSerializerSettings
    {
        Converters = { new PatientObservationAlarmConverter() }
    };
*/