PocoAdapter.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Dynamic;
using System.Linq;
using System.Reflection;
using System.Text.Json;
using System.Text.Json.Nodes;
using SystemTextJsonPatch.Internal.Proxies;

namespace SystemTextJsonPatch.Internal;

/// <summary>
/// This API supports infrastructure and is not intended to be used
/// directly from your code. This API may change or be removed in future releases.
/// </summary>
public sealed class PocoAdapter : IAdapter
{
	public bool TryAdd(object target, string segment, JsonSerializerOptions options, object? value, out string? errorMessage)
	{
		if (!TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
			return false;
		}

		if (!jsonProperty!.CanWrite)
		{
			errorMessage = Resources.FormatCannotUpdateProperty(segment);
			return false;
		}

		if (!ConversionResultProvider.TryConvertTo(value, jsonProperty.PropertyType, options, out var convertedValue, out var conversionErrorMessage))
		{
			errorMessage = conversionErrorMessage ?? Resources.FormatInvalidValueForProperty(value);
			return false;
		}

		jsonProperty.SetValue(target, convertedValue);

		errorMessage = null;
		return true;
	}

	public bool TryGet(object target, string segment, JsonSerializerOptions options, out object? value, out string? errorMessage)
	{
		if (!TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
			value = null;
			return false;
		}

		if (!jsonProperty!.CanRead)
		{
			errorMessage = Resources.FormatCannotReadProperty(segment);
			value = null;
			return false;
		}

		value = jsonProperty.GetValue(target);
		errorMessage = null;
		return true;
	}

	public bool TryRemove(object target, string segment, JsonSerializerOptions options, out string? errorMessage)
	{
		if (!TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
			return false;
		}

		if (!jsonProperty!.CanWrite)
		{
			errorMessage = Resources.FormatCannotUpdateProperty(segment);
			return false;
		}

		jsonProperty.RemoveValue(target);

		errorMessage = null;
		return true;
	}

	public bool TryReplace(object target, string segment, JsonSerializerOptions options, object? value, out string? errorMessage)
	{
		if (!TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
			return false;
		}

		if (!jsonProperty!.CanWrite)
		{
			errorMessage = Resources.FormatCannotUpdateProperty(segment);
			return false;
		}

		if (!ConversionResultProvider.TryConvertTo(value, jsonProperty.PropertyType, options, out var convertedValue, out var conversionErrorMessage))
		{
			errorMessage = conversionErrorMessage ?? Resources.FormatInvalidValueForProperty(value);
			return false;
		}

		jsonProperty.SetValue(target, convertedValue);

		errorMessage = null;
		return true;
	}

	public bool TryTest(object target, string segment, JsonSerializerOptions options, object? value, out string? errorMessage)
	{
		if (!TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
			return false;
		}

		if (!jsonProperty!.CanRead)
		{
			errorMessage = Resources.FormatCannotReadProperty(segment);
			return false;
		}

		if (!ConversionResultProvider.TryConvertTo(value, jsonProperty.PropertyType, options, out var convertedValue, out var conversionErrorMessage))
		{
			errorMessage = conversionErrorMessage ?? Resources.FormatInvalidValueForProperty(value);
			return false;
		}

		var currentValue = jsonProperty.GetValue(target);

		// all numeric values are handled as decimals
		if (ConversionResultProvider.IsNumericType(currentValue))
		{
			if (!Equals(currentValue, convertedValue))
			{
				errorMessage = Resources.FormatValueNotEqualToTestValue(JsonSerializer.SerializeToNode(currentValue)?.ToString(), value, segment);
				return false;
			}
		}
		else if (!ByteHelper.BytesEquals(JsonSerializer.SerializeToUtf8Bytes(currentValue), JsonSerializer.SerializeToUtf8Bytes(convertedValue)))
		{
			errorMessage = Resources.FormatValueNotEqualToTestValue(JsonSerializer.SerializeToNode(currentValue)?.ToString(), value, segment);
			return false;
		}

		errorMessage = null;
		return true;
	}

	public bool TryTraverse(object? target, string segment, JsonSerializerOptions options, out object? nextTarget, out string? errorMessage)
	{
		if (target == null)
		{
			nextTarget = null;
			errorMessage = null;
			return false;
		}

		if (TryGetJsonProperty(target, segment, options, out var jsonProperty))
		{
			nextTarget = jsonProperty!.GetValue(target);
			errorMessage = null;
			return true;
		}

		nextTarget = null;
		errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
		return false;
	}

	private static bool TryGetJsonProperty(object target, string segment, JsonSerializerOptions options, out IPropertyProxy? jsonProperty)
	{
		jsonProperty = FindPropertyByName(segment, target, options);

		return jsonProperty != null;
	}

	private static IPropertyProxy? FindPropertyByName(string name, object target, JsonSerializerOptions options)
	{
		var propertyName = options.PropertyNamingPolicy != null ? options.PropertyNamingPolicy.ConvertName(name) : name;

		if (target is DynamicObject dyObj)
		{
			return new DynamicObjectPropertyProxy(dyObj, propertyName);
		}

		var genericDictionaryType = target.GetType().GetInterfaces()
			.FirstOrDefault(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IDictionary<,>));
		if (genericDictionaryType is not null)
		{
			var args = genericDictionaryType.GetGenericArguments();
			var keyType = args[0];
			var valueType = args[1];
			var converter = TypeDescriptor.GetConverter(keyType);
			if (converter.CanConvertFrom(typeof(string)))
			{
				var key = converter.ConvertFromInvariantString(propertyName);
				var proxyType = typeof(DictionaryTypedPropertyProxy<,>).MakeGenericType(keyType, valueType);
				return (IPropertyProxy)Activator.CreateInstance(
					proxyType,
					BindingFlags.NonPublic | BindingFlags.Instance,
					null,
					[target, key],
					null)!;
			}
		}

		if (target is IDictionary dictionary)
		{
			return new DictionaryPropertyProxy(dictionary, propertyName);
		}

		if (target is JsonArray jsonArray)
		{
			return new JsonArrayProxy(jsonArray, propertyName);
		}

		if (target is JsonNode jsonElement)
		{
			return new JsonNodeProxy(jsonElement, propertyName);
		}

		return PropertyProxyCache.GetPropertyProxy(target.GetType(), propertyName, options.PropertyNamingPolicy, options.PropertyNameCaseInsensitive);
	}
}