using System;
using NewLife.Reflection;

namespace NewLife.Http
{
    /// <summary>Http处理器</summary>
    public interface IHttpHandler
    {
        /// <summary>处理请求</summary>
        /// <param name="context"></param>
        void ProcessRequest(IHttpContext context);
    }

    /// <summary>Http请求处理委托</summary>
    /// <param name="context"></param>
    public delegate void HttpProcessDelegate(IHttpContext context);

    /// <summary>委托Http处理器</summary>
    public class DelegateHandler : IHttpHandler
    {
        /// <summary>委托</summary>
        public Delegate Callback { get; set; }

        /// <summary>处理请求</summary>
        /// <param name="context"></param>
        public virtual void ProcessRequest(IHttpContext context)
        {
            var handler = Callback;
            if (handler is HttpProcessDelegate httpHandler)
            {
                httpHandler(context);
            }
            else
            {
                var result = OnInvoke(handler, context);
                context.Response.SetResult(result);
            }
        }

        /// <summary>复杂调用</summary>
        /// <param name="handler"></param>
        /// <param name="context"></param>
        /// <returns></returns>
        protected virtual Object OnInvoke(Delegate handler, IHttpContext context)
        {
            var mi = handler.Method;
            var pis = mi.GetParameters();
            if (pis.Length == 0) return handler.DynamicInvoke();

            var parameters = context.Parameters;

            var args = new Object[pis.Length];
            for (var i = 0; i < pis.Length; i++)
            {
                if (parameters.TryGetValue(pis[i].Name, out var v))
                    args[i] = v.ChangeType(pis[i].ParameterType);
            }

            return handler.DynamicInvoke(args);
        }
    }
}