source: TFP-WebServer/WebServer/src/WebAPI/APIs/Permissions/WebUsers.cs@ 467

using System.Collections.Generic;
using System.Net;
using JetBrains.Annotations;
using Utf8Json;
using Webserver.Permissions;

namespace Webserver.WebAPI.APIs.Permissions {
        [UsedImplicitly]
        public class WebUsers : AbsRestApi {
                private const string propertyName = "name";
                private const string propertyPassword = "password";
                private const string propertyPlatformUserId = "platformUserId";
                private const string propertyCrossplatformUserId = "crossplatformUserId";

                private static readonly byte[] jsonKeyName = JsonWriter.GetEncodedPropertyNameWithBeginObject (propertyName);
                private static readonly byte[] jsonKeyPlatformUserId = JsonWriter.GetEncodedPropertyNameWithPrefixValueSeparator (propertyPlatformUserId);
                private static readonly byte[] jsonKeyCrossplatformUserId = JsonWriter.GetEncodedPropertyNameWithPrefixValueSeparator (propertyCrossplatformUserId);

                private static AdminWebUsers WebUsersInstance => AdminWebUsers.Instance;

                protected override void HandleRestGet (RequestContext _context) {
                        string id = _context.RequestPath;

                        PrepareEnvelopedResult (out JsonWriter writer);

                        if (string.IsNullOrEmpty (id)) {
                                writer.WriteBeginArray ();

                                bool first = true;
                                foreach ((_, AdminWebUsers.WebUser user) in WebUsersInstance.GetUsers ()) {
                                        if (!first) {
                                                writer.WriteValueSeparator ();
                                        }

                                        first = false;

                                        writeUserJson (ref writer, user);
                                }

                                writer.WriteEndArray ();

                                SendEnvelopedResult (_context, ref writer);
                                return;
                        }

                        writer.WriteRaw (WebUtils.JsonEmptyData);
                        SendEnvelopedResult (_context, ref writer, HttpStatusCode.BadRequest);
                }

                private void writeUserJson (ref JsonWriter _writer, AdminWebUsers.WebUser _user) {
                        _writer.WriteRaw (jsonKeyName);
                        _writer.WriteString (_user.Name ?? "");
                        _writer.WriteRaw (jsonKeyPlatformUserId);
                        JsonCommons.WritePlatformUserIdentifier (ref _writer, _user.PlatformUser);
                        _writer.WriteRaw (jsonKeyCrossplatformUserId);
                        JsonCommons.WritePlatformUserIdentifier (ref _writer, _user.CrossPlatformUser);
                        _writer.WriteEndObject ();
                }

                protected override void HandleRestPost (RequestContext _context, IDictionary<string, object> _jsonInput, byte[] _jsonInputData) {
                        if (!TryParseName (_context, _jsonInputData, out string userName)) {
                                return;
                        }

                        if (!JsonCommons.TryGetJsonField (_jsonInput, propertyPassword, out string password)) {
                                SendEmptyResponse (_context, HttpStatusCode.BadRequest, _jsonInputData, "NO_OR_INVALID_PASSWORD");
                                return;
                        }

                        if (!JsonCommons.TryGetJsonField (_jsonInput, propertyPlatformUserId, out IDictionary<string, object> userIdField)) {
                                SendEmptyResponse (_context, HttpStatusCode.BadRequest, _jsonInputData, "NO_PLATFORM_USER_ID");
                                return;
                        }

                        if (!JsonCommons.TryReadPlatformUserIdentifier (userIdField, out PlatformUserIdentifierAbs platformUserId)) {
                                SendEmptyResponse (_context, HttpStatusCode.BadRequest, _jsonInputData, "INVALID_PLATFORM_USER_ID");
                                return;
                        }

                        PlatformUserIdentifierAbs crossplatformUserId = null;
                        
                        if (JsonCommons.TryGetJsonField (_jsonInput, propertyCrossplatformUserId, out userIdField)) {
                                if (!JsonCommons.TryReadPlatformUserIdentifier (userIdField, out crossplatformUserId)) {
                                        SendEmptyResponse (_context, HttpStatusCode.BadRequest, _jsonInputData, "INVALID_CROSSPLATFORM_USER_ID");
                                        return;
                                }
                        }

                        WebUsersInstance.AddUser (userName, password, platformUserId, crossplatformUserId);

                        SendEmptyResponse (_context, HttpStatusCode.Created);
                }

                protected override void HandleRestDelete (RequestContext _context) {
                        if (!TryParseName (_context, null, out string userName)) {
                                return;
                        }

                        bool removed = WebUsersInstance.RemoveUser (userName);

                        SendEmptyResponse (_context, removed ? HttpStatusCode.NoContent : HttpStatusCode.NotFound);
                }

                private bool TryParseName (RequestContext _context, byte[] _jsonInputData, out string _userName) {
                        string id = _context.RequestPath;
                        _userName = default;

                        if (string.IsNullOrEmpty (id)) {
                                SendEmptyResponse (_context, HttpStatusCode.BadRequest, _jsonInputData, "NO_USERNAME");
                                return false;
                        }

                        _userName = id;
                        return true;
                }

                protected override bool AllowPostWithId => true;

                public override int[] DefaultMethodPermissionLevels () => new[] {
                        AdminWebModules.MethodLevelNotSupported,
                        AdminWebModules.MethodLevelInheritGlobal,
                        AdminWebModules.MethodLevelInheritGlobal,
                        AdminWebModules.MethodLevelNotSupported,
                        AdminWebModules.MethodLevelInheritGlobal
                };
        }
}