using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace YLErp.Web.App
{
    /// <summary>
    /// 
    /// </summary>
    public class AntiXssConverter : JsonConverter<string>
    {
        public override string Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            return reader.GetString();
        }

        public override void Write(Utf8JsonWriter writer, string value, JsonSerializerOptions options)
        {
            if (value != null)
            {
                var needEscape = false;

                foreach (var ch in value)
                {
                    if (ch == '<' || ch == '>')
                    {
                        needEscape = true;
                        break;
                    }
                }

                if (needEscape)
                {
                    var sb = new StringBuilder(value.Length + 30);

                    foreach (var c in value)
                    {
                        if (c == '<')
                        {
                            sb.Append("&lt;");
                        }
                        else if (c == '>')
                        {
                            sb.Append("&gt;");
                        }
                        else if (c == '&')
                        {
                            sb.Append("&amp;");
                        }
                        else
                        {
                            sb.Append(c);
                        }
                    }

                    value = sb.ToString();
                }
            }

            writer.WriteStringValue(value);
        }
    }
}