using System;
using System.Linq;

using Scriban;

namespace EnumSerializer.Generator {


  public static class SourceGenerationHelper {
    internal const string ConverterTemplate = @"//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by the EnumSerializer.Generator source generator
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

#nullable enable

using System;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System.Runtime.CompilerServices;

{{~ if enum_namespace ~}}
namespace {{ enum_namespace }}{
{{~ end ~}}

  internal partial class {{ enum_name }}Converter : JsonConverter<{{ enum_name }}>
  {
      public override void WriteJson(JsonWriter writer, {{ enum_name }} value, JsonSerializer serializer) =>
          writer.WriteValue(value switch
          {
          {{~ for enum_member in enum_members ~}}
              {{ enum_name }}.{{enum_member.key}} => ""{{ enum_member.value }}"",
          {{~ end ~}}
          {{~ if has_unknown_member ~}}
              _ => throw new NotSupportedException(),
          {{~ else ~}}
              ({{ enum_name }})0 => ""unknown"",
              _ => throw new NotSupportedException(),
          {{~ end ~}}
          });

      public override {{ enum_name }} ReadJson(
          JsonReader reader,
          Type objectType,
      {{ enum_name }} existingValue,
          bool hasExistingValue,
          JsonSerializer serializer
      ) =>
          JToken.ReadFrom(reader).Value<string>() switch
          {
          {{~ for enum_member in enum_members ~}}
              ""{{ enum_member.value }}"" => {{ enum_name }}.{{ enum_member.key }},
          {{~ end ~}}
          {{~ if has_unknown_member ~}}
              _ => {{ enum_name }}.Unknown,
          {{~ else ~}}
              _ => 0,
          {{~ end ~}}
          };
}}";

    public static string GenerateConverterClass(Template template, EnumInfo enumToGenerate) {
      var hasUnknownMember = enumToGenerate.Members.Any(
          e => string.Equals(e.Value, "Unknown", StringComparison.OrdinalIgnoreCase)
      );

      var result = template.Render(new {
        EnumNamespace = enumToGenerate.Namespace,
        EnumName = enumToGenerate.Name,
        EnumMembers = enumToGenerate.Members,
        HasUnknownMember = hasUnknownMember
      });

      return result;
    }
  }
}