using Newtonsoft.Json;
using System.Collections;
using System.Net;
using System.Reflection;

namespace SimpleHttpServer.Internal;

internal class HttpEndpointHandler {
    private static readonly DefaultAuthorizer defaultAuth = new();

    private readonly IAuthorizer _auth;
    private readonly MethodInfo _handler;
    private readonly Dictionary<string, (int pindex, Type type, int pparamIdx)> _params;
    private readonly Func<Exception, HttpResponseBuilder> _errorPageBuilder;

    public HttpEndpointHandler() {
        _auth = defaultAuth;
    }

    public HttpEndpointHandler(IAuthorizer auth) {

    }

    public virtual void Handle(HttpListenerContext ctx) {
        try {
            var (isAuth, authData) = _auth.IsAuthenticated(ctx);
            if (!isAuth) {
                throw new HttpHandlingException(401, "Authorization required!");
            }

            // collect parameters
            var invokeParams = new object?[_params.Count + 1];
            var set = new BitArray(_params.Count);
            invokeParams[0] = ctx;

            // read pparams

            // read qparams
            var qst = ctx.Request.QueryString;
            foreach (var qelem in ctx.Request.QueryString.AllKeys) {
                if (_params.ContainsKey(qelem!)) {
                    var (pindex, type, isPParam) = _params[qelem!];
                    if (type == typeof(string)) {
                        invokeParams[pindex] = ctx.Request.QueryString[qelem!];
                        set.Set(pindex - 1, true);
                    } else {
                        var elem = JsonConvert.DeserializeObject(ctx.Request.QueryString[qelem!]!, type);
                        if (elem != null) {
                            invokeParams[pindex] = elem;
                            set.Set(pindex - 1, true);
                        }
                    }
                }
            }

            // fill with defaults
            foreach (var p in _params) {
                if (!set.Get(p.Value.pindex)) {
                    invokeParams[p.Value.pindex] = p.Value.type.IsValueType ? Activator.CreateInstance(p.Value.type) : null;
                }
            }


            var builder = _handler.Invoke(null, invokeParams) as HttpResponseBuilder;
            builder!.SendResponse(ctx.Response);
        } catch (Exception e) {
            if (e is TargetInvocationException tex) {
                e = tex.InnerException!;
            }
            _errorPageBuilder(e).SendResponse(ctx.Response);
        }
    }
}