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using System.Globalization;
using System.Text.Json;
using System.Text.Json.Serialization;
namespace Cepis;
/// <summary>
/// Reads the <c>geo</c> block, yielding <see langword="null"/> for anything it
/// cannot make sense of.
/// </summary>
/// <remarks>
/// A malformed coordinate is not worth losing the whole address over: the rest
/// of the response is still useful, and an address with no coordinate is a
/// shape callers already handle, since about 43% of CEPs have none.
/// </remarks>
internal sealed class GeoConverter : JsonConverter<Geo?>
{
public override Geo? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
using var document = JsonDocument.ParseValue(ref reader);
var root = document.RootElement;
if (root.ValueKind != JsonValueKind.Object)
{
return null;
}
var lat = ReadDouble(root, "lat");
var lon = ReadDouble(root, "lon");
var raio = ReadDouble(root, "raio_m");
var precisao = ReadString(root, "precisao");
if (lat is null || lon is null || raio is null || precisao is null)
{
return null;
}
return new Geo
{
Lat = lat.Value,
Lon = lon.Value,
RaioM = (int)Math.Round(raio.Value),
Precisao = precisao,
};
}
public override void Write(Utf8JsonWriter writer, Geo? value, JsonSerializerOptions options)
{
ArgumentNullException.ThrowIfNull(writer);
if (value is null)
{
writer.WriteNullValue();
return;
}
writer.WriteStartObject();
writer.WriteNumber("lat", value.Lat);
writer.WriteNumber("lon", value.Lon);
writer.WriteNumber("raio_m", value.RaioM);
writer.WriteString("precisao", value.Precisao);
writer.WriteEndObject();
}
private static double? ReadDouble(JsonElement owner, string name)
{
if (!owner.TryGetProperty(name, out var element))
{
return null;
}
return element.ValueKind switch
{
JsonValueKind.Number => element.TryGetDouble(out var number) ? number : null,
JsonValueKind.String => double.TryParse(
element.GetString(),
NumberStyles.Float,
CultureInfo.InvariantCulture,
out var parsed)
? parsed
: null,
_ => null,
};
}
private static string? ReadString(JsonElement owner, string name) =>
owner.TryGetProperty(name, out var element) && element.ValueKind == JsonValueKind.String
? element.GetString()
: null;
}
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