source: binary-improvements2/WebServer/src/Permissions/AdminWebModules.cs@ 418

using System.Collections.Generic;
using System.Xml;

namespace Webserver.Permissions {
        public class AdminWebModules : AdminSectionAbs {
                public static AdminWebModules Instance { get; private set; }

                public AdminWebModules (AdminTools _parent) : base (_parent, "webmodules") {
                        Instance = this;
                }

                private readonly Dictionary<string, WebModule> modules = new CaseInsensitiveStringDictionary<WebModule> ();


#region IO

                public override void Clear () {
                        modules.Clear ();
                }

                protected override void ParseElement (XmlElement _childElement) {
                        if (WebModule.TryParse (_childElement, out WebModule webModule)) {
                                modules [webModule.Name] = webModule;
                        }
                }

                public override void Save (XmlElement _root) {
                        XmlElement modulesElement = _root.AddXmlElement (SectionTypeName);
                        // modulesElement.AddXmlComment (" <module name=\"adminuser1\" secret=\"supersecrettoken\" permission_level=\"0\" /> ");

                        foreach ((string _, WebModule module) in modules) {
                                module.ToXml (modulesElement);
                        }
                }

#endregion


#region Runtime interaction


                public void AddModule (string _module, int _permissionLevel) {
                        WebModule p = new WebModule (_module, _permissionLevel, false);
                        lock (this) {
                                allModulesList.Clear ();
                                
                                modules [_module] = p;
                                Parent.Save ();
                        }
                }

                public bool RemoveModule (string _module) {
                        lock (this) {
                                allModulesList.Clear ();
                                
                                bool removed = modules.Remove (_module);
                                if (removed) {
                                        Parent.Save ();
                                }

                                return removed;
                        }
                }

                public List<WebModule> GetModules () {
                        lock (this) {
                                if (allModulesList.Count != 0) {
                                        return allModulesList;
                                }

                                foreach ((string moduleName, WebModule moduleDefaultPerm) in knownModules) {
                                        allModulesList.Add (modules.TryGetValue (moduleName, out WebModule modulePermission)
                                                ? modulePermission
                                                : moduleDefaultPerm);
                                }

                                return allModulesList;
                        }
                }

#endregion

                public readonly struct WebModule {
                        public readonly string Name;
                        public readonly int PermissionLevel;
                        public readonly bool IsDefault;

                        public WebModule (string _name, int _permissionLevel, bool _isDefault) {
                                Name = _name;
                                PermissionLevel = _permissionLevel;
                                IsDefault = _isDefault;
                        }
                        
                        public void ToXml (XmlElement _parent) {
                                _parent.AddXmlElement ("module")
                                                .SetAttrib ("name", Name)
                                                .SetAttrib ("permission_level", PermissionLevel.ToString ());
                        }

                        public static bool TryParse (XmlElement _element, out WebModule _result) {
                                _result = default;


                                if (!_element.TryGetAttribute ("name", out string name)) {
                                        Log.Warning ($"[Web] [Perms] Ignoring module-entry because of missing 'name' attribute: {_element.OuterXml}");
                                        return false;
                                }

                                if (!_element.TryGetAttribute ("permission_level", out string permissionLevelString)) {
                                        Log.Warning ($"[Web] [Perms] Ignoring module-entry because of missing 'permission_level' attribute: {_element.OuterXml}");
                                        return false;
                                }

                                if (!int.TryParse (permissionLevelString, out int permissionLevel)) {
                                        Log.Warning (
                                                $"[Web] [Perms] Ignoring module-entry because of invalid (non-numeric) value for 'permission_level' attribute: {_element.OuterXml}");
                                        return false;
                                }
                                
                                _result = new WebModule (name, permissionLevel, false);
                                return true;
                        }
                }


#region Specials

                /// <summary>
                /// Contains all registered modules and their default permission
                /// </summary>
                private readonly Dictionary<string, WebModule> knownModules = new CaseInsensitiveStringDictionary<WebModule> ();

                /// <summary>
                /// Public list of all modules, both those with custom permissions as well as those that do not with their default permission
                /// </summary>
                private readonly List<WebModule> allModulesList = new List<WebModule> ();

                public void AddKnownModule (string _module, int _defaultPermission) {
                        if (string.IsNullOrEmpty (_module)) {
                                return;
                        }

                        WebModule p = new WebModule (_module, _defaultPermission, true);

                        lock (this) {
                                allModulesList.Clear ();
                                knownModules [_module] = p;
                        }
                }

                public bool IsKnownModule (string _module) {
                        if (string.IsNullOrEmpty (_module)) {
                                return false;
                        }

                        lock (this) {
                                return knownModules.ContainsKey (_module);
                        }
                }

                public bool ModuleAllowedWithLevel (string _module, int _level) {
                        WebModule permInfo = GetModule (_module)!.Value;
                        return permInfo.PermissionLevel >= _level;
                }

                public WebModule? GetModule (string _module, bool _returnDefaults = true) {
                        if (modules.TryGetValue (_module, out WebModule result)) {
                                return result;
                        }

                        if (!_returnDefaults) {
                                return null;
                        }

                        return knownModules.TryGetValue (_module, out result) ? result : defaultModulePermission;
                }

                private readonly WebModule defaultModulePermission = new WebModule ("", 0, true);
                
#endregion
        }
}