using System;
using System.Collections.Generic;
using System.Reflection;

namespace NTERA.Engine.Runtime.Base
{
	public static class Functions
	{
		private class FunctionAttribute : Attribute
		{
			public string Name { get; }

			public FunctionAttribute(string name)
			{
				Name = name;
			}
		}

		public static Dictionary<string, Func<EraRuntime, StackFrame, IList<Value>, Value>> StaticFunctions { get; } = _getFunctions();

		private static Dictionary<string, Func<EraRuntime, StackFrame, IList<Value>, Value>> _getFunctions()
		{
			var output = new Dictionary<string, Func<EraRuntime, StackFrame, IList<Value>, Value>>();

			foreach (MethodInfo method in typeof(Functions).GetMethods(BindingFlags.Public | BindingFlags.Static))
			{
				var function = method.GetCustomAttribute<FunctionAttribute>();

				if (function != null)
					output[function.Name] = (runtime, set, parameters) => (Value)method.Invoke(null, new object[] { runtime, set, parameters });
			}

			return output;
		}

		[Function("__FORMAT")]
		public static Value Format(EraRuntime runtime, StackFrame context, IList<Value> parameters)
		{
			if (parameters.Count == 1)
				return parameters[0].String;

			throw new NotImplementedException("Advanced formatting hasn't been implemented yet");
		}

		[Function("TOSTR")]
		public static Value ToStr(EraRuntime runtime, StackFrame context, IList<Value> parameters)
		{
			if (parameters.Count == 1)
				return parameters[0].ToString();

			if (parameters.Count == 2)
				return ((int)parameters[0]).ToString(parameters[1].String);

			throw new EraRuntimeException("Invalid amount of parameters");
		}

		private static Random _random = new Random();

		[Function("RAND")]
		public static Value Rand(EraRuntime runtime, StackFrame context, IList<Value> parameters)
		{
			return _random.Next((int)parameters[0].Real, (int)parameters[1].Real);
		}
	}
}