using Qrakhen.Qamp.Core.Collections;
using Qrakhen.Qamp.Core.Values.Objects;

namespace Qrakhen.Qamp.Core.Values;

public delegate Value ExtensionDelegate(Value target, Value[] parameters);

public class NativeExtension(
    ValueType targetType,
    string name,
    ExtensionDelegate callback,
    string[] parameters)
{
   private static readonly Register<ValueType, Register<string, NativeExtension>> _register = new();

   public readonly string Name = name;
   public readonly ValueType TargetType = targetType;
   public readonly ExtensionDelegate Callback = callback;
   public readonly string[] Parameters = parameters.ToArray();

   public static NativeExtension? Get(ValueType targetType, string name)
   {
      if (!_register.Has(targetType))
         return null;
      if (!_register[targetType].Has(name))
         return null;
      return _register[targetType][name];
   }

   public static void Register(ValueType targetType,
                               string name,
                               ExtensionDelegate callback,
                               params string[] parameters)
   {
      if (!_register.Has(targetType))
         _register.Add(targetType, new());
      if (_register[targetType].Has(name))
         throw new QampException($"Extension {name} already exists for type {targetType}.");
      _register[targetType].Add(name, new NativeExtension(targetType, name, callback, parameters));
   }

   static NativeExtension()
   {
      Register(ValueType.String, "Length", (v, p) => new Value((long)v.Ptr.As<Objects.String>()!.Value!.Length), []);
      Register(ValueType.String, "IndexOf", (v, p) => new Value((long)v.Ptr.As<Objects.String>()!.Value!.IndexOf(p[0].Ptr.As<Objects.String>()!.Value!)), ["needle"]);
   }

   public override string ToString()
   {
      return $"{TargetType}.{Name}({string.Join(", ", Parameters)}) (NativeExtension)";
   }
}