using System;
using MoonSharp.Interpreter.Compatibility;

namespace MoonSharp.Interpreter.Interop
{
	/// <summary>
	/// Data descriptor used for proxy objects
	/// </summary>
	public sealed class ProxyUserDataDescriptor : IUserDataDescriptor
	{
		IUserDataDescriptor m_ProxyDescriptor;
		IProxyFactory m_ProxyFactory;

		internal ProxyUserDataDescriptor(IProxyFactory proxyFactory, IUserDataDescriptor proxyDescriptor, string friendlyName = null)
		{
			m_ProxyFactory = proxyFactory;
			Name = friendlyName ?? (proxyFactory.TargetType.Name + "::proxy");
			m_ProxyDescriptor = proxyDescriptor;
		}

		/// <summary>
		/// Gets the descriptor which describes the proxy object
		/// </summary>
		public IUserDataDescriptor InnerDescriptor
		{
			get { return m_ProxyDescriptor; }
		}

		/// <summary>
		/// Gets the name of the descriptor (usually, the name of the type described).
		/// </summary>
		public string Name
		{
			get;
			private set; 
		}

		/// <summary>
		/// Gets the type this descriptor refers to
		/// </summary>
		public Type Type
		{
			get { return m_ProxyFactory.TargetType; }
		}

		/// <summary>
		/// Proxies the specified object.
		/// </summary>
		/// <param name="obj">The object.</param>
		/// <returns></returns>
		private object Proxy(object obj)
		{
			return obj != null ? m_ProxyFactory.CreateProxyObject(obj) : null;
		}

		/// <summary>
		/// Performs an "index" "get" operation.
		/// </summary>
		/// <param name="script">The script originating the request</param>
		/// <param name="obj">The object (null if a static request is done)</param>
		/// <param name="index">The index.</param>
		/// <param name="isDirectIndexing">If set to true, it's indexed with a name, if false it's indexed through brackets.</param>
		/// <returns></returns>
		public DynValue Index(Script script, object obj, DynValue index, bool isDirectIndexing)
		{
			return m_ProxyDescriptor.Index(script, Proxy(obj), index, isDirectIndexing);
		}

		/// <summary>
		/// Performs an "index" "set" operation.
		/// </summary>
		/// <param name="script">The script originating the request</param>
		/// <param name="obj">The object (null if a static request is done)</param>
		/// <param name="index">The index.</param>
		/// <param name="value">The value to be set</param>
		/// <param name="isDirectIndexing">If set to true, it's indexed with a name, if false it's indexed through brackets.</param>
		/// <returns></returns>
		public bool SetIndex(Script script, object obj, DynValue index, DynValue value, bool isDirectIndexing)
		{
			return m_ProxyDescriptor.SetIndex(script, Proxy(obj), index, value, isDirectIndexing);
		}

		/// <summary>
		/// Converts this userdata to string
		/// </summary>
		/// <param name="obj">The object.</param>
		/// <returns></returns>
		public string AsString(object obj)
		{
			return m_ProxyDescriptor.AsString(Proxy(obj));
		}

		/// <summary>
		/// Gets a "meta" operation on this userdata. If a descriptor does not support this functionality,
		/// it should return "null" (not a nil).
		/// These standard metamethods can be supported (the return value should be a function accepting the
		/// classic parameters of the corresponding metamethod):
		/// __add, __sub, __mul, __div, __div, __pow, __unm, __eq, __lt, __le, __lt, __len, __concat,
		/// __pairs, __ipairs, __iterator, __call
		/// These standard metamethods are supported through other calls for efficiency:
		/// __index, __newindex, __tostring
		/// </summary>
		/// <param name="script">The script originating the request</param>
		/// <param name="obj">The object (null if a static request is done)</param>
		/// <param name="metaname">The name of the metamember.</param>
		/// <returns></returns>
		public DynValue MetaIndex(Script script, object obj, string metaname)
		{
			return m_ProxyDescriptor.MetaIndex(script, Proxy(obj), metaname);
		}

		/// <summary>
		/// Determines whether the specified object is compatible with the specified type.
		/// Unless a very specific behaviour is needed, the correct implementation is a
		/// simple " return type.IsInstanceOfType(obj); "
		/// </summary>
		/// <param name="type">The type.</param>
		/// <param name="obj">The object.</param>
		/// <returns></returns>
		public bool IsTypeCompatible(Type type, object obj)
		{
			return Framework.Do.IsInstanceOfType(type, obj);
		}
	}
}
