using System;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
using ln.json;
using ln.json.mapping;
using ln.type;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace ln.http
{
    public abstract class HttpEndpointController : HttpRouter, IDisposable
    {
        private HttpRouter _httpRouter;
        
        public HttpEndpointController():this(null){}
        public HttpEndpointController(HttpRouter httpRouter)
        {
            _httpRouter = httpRouter;
            MapAttribute mapAttribute = GetType().GetCustomAttribute<MapAttribute>();
            if (mapAttribute is not null)
            {
                HttpMethod = mapAttribute.Method != HttpMethod.NONE ? mapAttribute.Method : HttpMethod.ANY;
                Route = mapAttribute.Path is not null ? new Regex(mapAttribute.Path) : null;
            }
            
            Initialize();
            
            _httpRouter?.Map(this);
        }
        
        void Initialize()
        {
            foreach (MethodInfo methodInfo in GetType().GetMethods(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
            {
                foreach (MapAttribute mapAttribute in methodInfo.GetCustomAttributes<MapAttribute>())
                {
                    MappedEndpoint mappedEndpoint = CreateMapping(mapAttribute, methodInfo);
                    Map(mappedEndpoint.HttpMethod, mappedEndpoint.Path, mappedEndpoint.Route);
                }
            }
        }

        MappedEndpoint CreateMapping(MapAttribute mapAttribute, MethodInfo methodInfo)
        {
            if (methodInfo.ReturnType == typeof(void))
                return new MappedEndpoint.VoidEndpoint(this, mapAttribute, methodInfo);
            return new MappedEndpoint.NonVoidEndpoint(this, mapAttribute, methodInfo);
        }

        public abstract class MappedEndpoint
        {
            public HttpMethod HttpMethod { get; }
            public string Path { get; }
            private HttpEndpointController EndpointController; 

            public MethodInfo MethodInfo { get; }

            private ParameterInfo[] _parameterInfos;
            private HttpArgumentSourceAttribute[] _argumentSourceAttributes;
            private Type _returnType;

            private RequiresAttribute[] _requiresAttributes;

            public MappedEndpoint(HttpEndpointController endpointController, MapAttribute mapAttribute, MethodInfo methodInfo)
            {
                EndpointController = endpointController;
                HttpMethod = mapAttribute.Method;
                Path = mapAttribute.Path;
                MethodInfo = methodInfo;
                _parameterInfos = MethodInfo.GetParameters();
                _returnType = MethodInfo.ReturnType;
                _argumentSourceAttributes = _parameterInfos
                    .Select((pi) => pi.GetCustomAttribute<HttpArgumentSourceAttribute>()).ToArray();
                _requiresAttributes = methodInfo.GetCustomAttributes<RequiresAttribute>().ToArray();
            }

            public bool Route(HttpRequestContext httpContext, string routePath)
            {
                if (_requiresAttributes.Length > 0){
                    if (httpContext.AuthenticatedPrincipal is HttpPrincipal)
                    {
                        foreach (var requiresAttribute in _requiresAttributes)
                        {
                            if (requiresAttribute.Roles.All((role) =>
                                    httpContext.AuthenticatedPrincipal.Roles.Contains(role)))
                            {
                                return Route2(httpContext, routePath);
                            }
                        }
                    }
                    httpContext.Response = HttpResponse.Unauthorized();
                    return true;
                }
                return Route2(httpContext, routePath);
            }

            public abstract bool Route2(HttpRequestContext httpContext, string routePath);

            bool TryFindParameterValue(HttpRequestContext context, ParameterInfo parameterInfo, out object value)
            {
                if (parameterInfo.GetCustomAttribute<JsonBodyAttribute>() is JsonBodyAttribute jsonBodyAttribute)
                {
                    if (jsonBodyAttribute.Property is null)
                    {
                        value = context.Request.Json(parameterInfo.ParameterType);
                        return true;
                    }
                    else if (context.Request.Json().TryGetValue(jsonBodyAttribute.Property, out JToken property))
                    {
                            value = property.ToObject(parameterInfo.ParameterType);
                            return true;
                    }
                }

                if ((parameterInfo.GetCustomAttribute<RouteAttribute>() is RouteAttribute routeAttribute) &&
                    context.TryGetParameter(routeAttribute.Name ?? parameterInfo.Name, out string pvalue))
                {
                    value = pvalue;
                    return true;
                }

                if ((parameterInfo.GetCustomAttribute<QueryAttribute>() is QueryAttribute queryAttribute) &&
                    context.Request.Query.TryGetValue(queryAttribute.Name ?? parameterInfo.Name, out string svalue))
                {
                    value = svalue;
                    return true;
                }

                if (parameterInfo.ParameterType.Equals(typeof(Stream)))
                {
                    value = context.Request.ContentStream;
                    return true;
                }

                if (parameterInfo.ParameterType.Equals(typeof(HttpRequestContext)))
                {
                    value = context;
                    return true;
                }

                if (parameterInfo.ParameterType.Equals(typeof(HttpRequest)))
                {
                    value = context.Request;
                    return true;
                }

                if (parameterInfo.ParameterType.Equals(typeof(HttpPrincipal)))
                {
                    value = context.AuthenticatedPrincipal;
                    return true;
                }
                
                value = null;
                return false;
            }
            
            bool TryApplyParameters(HttpRequestContext requestContext, out object[] parameters)
            {
                parameters = new object[_parameterInfos.Length];

                for (int n = 0; n < _parameterInfos.Length; n++)
                {
                    ParameterInfo parameterInfo = _parameterInfos[n];

                    if (!TryFindParameterValue(requestContext, parameterInfo, out parameters[n]))
                        parameters[n] = parameterInfo.DefaultValue;

                    if ((parameters[n] != null) &&
                        (!parameterInfo.ParameterType.IsAssignableFrom(parameters[n].GetType())))
                    {
                        if (!Cast.To(parameters[n], _parameterInfos[n].ParameterType, out parameters[n]))
                        {
                            parameters[n] = TypeDescriptor
                                .GetConverter(parameterInfo.ParameterType)
                                .ConvertFrom(parameters[n]);
                        }
                    }
                    
                    if ((parameters[n] == null) && (parameterInfo.ParameterType.IsValueType))
                        return false;
                    
                }
                return true;
            }

            private object InvokeMethod(HttpRequestContext httpContext)
            {
                object[] parameters = null;
                try
                {
                    if (!TryApplyParameters(httpContext, out parameters))
                        return HttpResponse.InternalServerError().Content("could not apply parameters");
                    else
                    {
                        return MethodInfo.Invoke(EndpointController, parameters);
                    }
                }
                finally
                {
                    DisposeParameters(parameters);    
                }
            }

            public class NonVoidEndpoint : MappedEndpoint
            {
                public NonVoidEndpoint(HttpEndpointController endpointController, MapAttribute mapAttribute, MethodInfo methodInfo)
                    : base(endpointController, mapAttribute, methodInfo)
                {
                }

                public override bool Route2(HttpRequestContext httpContext, string routePath)
                {
                    object returnedValue = InvokeMethod(httpContext);

                    if (returnedValue is HttpResponse httpResponse)
                        httpContext.Response = httpResponse;
                    else if ((returnedValue is JSONValue jsonResult) || (JSONMapper.DefaultMapper.Serialize(returnedValue, out jsonResult)))
                        httpContext.Response = HttpResponse.Default(httpContext.Request.Method)
                            .Content(jsonResult);
                    else
                        httpContext.Response = HttpResponse.InternalServerError().Content("Method result could not be serialized");
                    return true;

                }
            }
            
            public class VoidEndpoint : MappedEndpoint
            {
                public VoidEndpoint(HttpEndpointController endpointController, MapAttribute mapAttribute, MethodInfo methodInfo)
                    : base(endpointController, mapAttribute, methodInfo)
                {
                }

                public override bool Route2(HttpRequestContext httpContext, string routePath)
                {
                    object returnedValue = InvokeMethod(httpContext);
                    if (returnedValue is HttpResponse httpResponse)
                        httpContext.Response = httpResponse;
                    else
                        httpContext.Response ??= HttpResponse.Default(httpContext.Request.Method);
                    
                    return true;
                }
            }

            private void DisposeParameters(object[] parameters)
            {
                if (parameters is null)
                    return;
                
                foreach (var o in parameters)
                {
                    if (o is IDisposable disposable)
                        disposable.Dispose();
                }
            }
        }

        public void Dispose()
        {
            _httpRouter?.Dispose();
            base.Dispose();
        }
    }
}