using System;
using System.Collections.Generic;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.ui;
using UnityEngine;

namespace Unity.UIWidgets.gestures {
    public delegate void PointerRoute(PointerEvent evt);

    public class PointerRouter {
        readonly Dictionary<int, Dictionary<PointerRoute, Matrix4>> _routeMap = new Dictionary<int, Dictionary<PointerRoute, Matrix4>>();

        readonly Dictionary<PointerRoute, Matrix4> _globalRoutes = new Dictionary<PointerRoute, Matrix4>();

        public void addRoute(int pointer, PointerRoute route, Matrix4 transform = null) {
            var routes = this._routeMap.putIfAbsent(
                pointer, 
                () => new Dictionary<PointerRoute, Matrix4>()
            );
            D.assert(!routes.ContainsKey(route));
            routes[route] = transform;
        }
        
        public void removeRoute(int pointer, PointerRoute route) {
            D.assert(this._routeMap.ContainsKey(pointer));
            var routes = this._routeMap[pointer];
            routes.Remove(route);
            if (routes.isEmpty()) {
                this._routeMap.Remove(pointer);
            }
        }
        
        public void addGlobalRoute(PointerRoute route, Matrix4 transform = null) {
            D.assert(!this._globalRoutes.ContainsKey(route));
            this._globalRoutes[route] = transform;
        }
        
        public void removeGlobalRoute(PointerRoute route) {
            D.assert(this._globalRoutes.ContainsKey(route));
            this._globalRoutes.Remove(route);
        }

        public bool acceptScroll() {
            return this._routeMap.Count == 0;
        }

        public void clearScrollRoute(int pointer) {
            if (this._routeMap.ContainsKey(pointer)) {
                this._routeMap.Remove(pointer);
            }
        }


        void _dispatch(PointerEvent evt, PointerRoute route, Matrix4 transform) {
            try {
                evt = evt.transformed(transform);
                route(evt);
            }
            catch (Exception ex) {
                D.logError("Error while routing a pointer event: ", ex);
            }
        }

        public void route(PointerEvent evt) {
            // TODO: update this to latest version
            Dictionary<PointerRoute, Matrix4> routes;
            this._routeMap.TryGetValue(evt.pointer, out routes);

            Dictionary<PointerRoute, Matrix4> copiedGlobalRoutes = new Dictionary<PointerRoute, Matrix4>(this._globalRoutes);

            if (routes != null) {
                this._dispatchEventToRoutes(
                    evt,
                    routes,
                    new Dictionary<PointerRoute, Matrix4>(routes)
                );
            }
            this._dispatchEventToRoutes(evt, this._globalRoutes, copiedGlobalRoutes);
        }
        
        public void _dispatchEventToRoutes(
            PointerEvent evt,
            Dictionary<PointerRoute, Matrix4> referenceRoutes,
            Dictionary<PointerRoute, Matrix4> copiedRoutes
        ) {
            foreach (var item in copiedRoutes) {
                var route = item.Key;
                var transform = item.Value;
                if (referenceRoutes.ContainsKey(route)) {
                    this._dispatch(evt, route, transform);
                }
            }
        }
    }
}

// TODO: FlutterErrorDetailsForPointerRouter