ConfigManager.cs

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using Microsoft.Xna.Framework;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using Terraria.ID;
using Terraria.ModLoader.Config.UI;
using Terraria.ModLoader.Exceptions;
using Terraria.ModLoader.UI;
using Terraria.UI;
 
namespace Terraria.ModLoader.Config
{
    public static class ConfigManager
    {
        // These are THE active configs.
        internal static readonly IDictionary<Mod, List<ModConfig>> Configs = new Dictionary<Mod, List<ModConfig>>();
        // Configs should never violate reload required.
        // Menu save should force reload
 
        // This copy of Configs stores instances present during load. Its only use in detecting if a reload is needed.
        private static readonly IDictionary<Mod, List<ModConfig>> LoadTimeConfigs = new Dictionary<Mod, List<ModConfig>>();
 
        public static readonly JsonSerializerSettings serializerSettings = new JsonSerializerSettings
        {
            Formatting = Formatting.Indented,
            DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate,
            ObjectCreationHandling = ObjectCreationHandling.Replace,
            NullValueHandling = NullValueHandling.Ignore,
            Converters = converters,
            ContractResolver = new ReferenceDefaultsPreservingResolver()
        };
 
        internal static readonly JsonSerializerSettings serializerSettingsCompact = new JsonSerializerSettings
        {
            Formatting = Formatting.None,
            DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate,
            ObjectCreationHandling = ObjectCreationHandling.Replace,
            NullValueHandling = NullValueHandling.Ignore,
            Converters = converters,
            ContractResolver = serializerSettings.ContractResolver
        };
 
        private static readonly IList<JsonConverter> converters = new List<JsonConverter>() {
            new Newtonsoft.Json.Converters.VersionConverter(),
            //new ColorJsonConverter(),
        };
 
        public static readonly string ModConfigPath = Path.Combine(Main.SavePath, "Mod Configs");
        public static readonly string ServerModConfigPath = Path.Combine(Main.SavePath, "Mod Configs", "Server");
 
        internal static void Add(ModConfig config)
        {
            ConfigManager.Load(config);
 
            List<ModConfig> configList;
            if (!Configs.TryGetValue(config.mod, out configList))
                Configs.Add(config.mod, configList = new List<ModConfig>());
            configList.Add(config);
 
            FieldInfo instance = config.GetType().GetField("Instance", BindingFlags.Static | BindingFlags.Public);
            if (instance != null) {
                instance.SetValue(null, config);
            }
            config.OnLoaded();
            config.OnChanged();
 
            // Maintain a backup of LoadTime Configs.
            List<ModConfig> configList2;
            if (!LoadTimeConfigs.TryGetValue(config.mod, out configList2))
                LoadTimeConfigs.Add(config.mod, configList2 = new List<ModConfig>());
            configList2.Add(GeneratePopulatedClone(config));
        }
 
        // This method for refreshing configs (ServerSide mostly) after events that could change configs: Multiplayer play.
        internal static void LoadAll()
        {
            foreach (var activeConfigs in ConfigManager.Configs)
            {
                foreach (var activeConfig in activeConfigs.Value)
                {
                    Load(activeConfig);
                }
            }
        }
 
        internal static void OnChangedAll() {
            foreach (var activeConfigs in ConfigManager.Configs) {
                foreach (var activeConfig in activeConfigs.Value) {
                    activeConfig.OnChanged();
                }
            }
        }
 
        internal static void Load(ModConfig config)
        {
            string filename = config.mod.Name + "_" + config.Name + ".json";
            string path = Path.Combine(ModConfigPath, filename);
            if (config.Mode == ConfigScope.ServerSide && ModNet.NetReloadActive) // #999: Main.netMode isn't 1 at this point due to #770 fix.
            {
                string netJson = ModNet.pendingConfigs.Single(x => x.modname == config.mod.Name && x.configname == config.Name).json;
                JsonConvert.PopulateObject(netJson, config, serializerSettingsCompact);
                return;
            }
            bool jsonFileExists = File.Exists(path);
            string json = jsonFileExists ? File.ReadAllText(path) : "{}";
            try {
                JsonConvert.PopulateObject(json, config, serializerSettings);
            }
            catch (Exception e) when (jsonFileExists && (e is JsonReaderException || e is JsonSerializationException)) {
                Logging.tML.Warn($"Then config file {config.Name} from the mod {config.mod.Name} located at {path} failed to load. The file was likely corrupted somehow, so the defaults will be loaded and the file deleted.");
                File.Delete(path);
                JsonConvert.PopulateObject("{}", config, serializerSettings);
            }
        }
 
        internal static void Reset(ModConfig pendingConfig)
        {
            string json = "{}";
            JsonConvert.PopulateObject(json, pendingConfig, serializerSettings);
        }
 
        internal static void Save(ModConfig config)
        {
            Directory.CreateDirectory(ModConfigPath);
            string filename = config.mod.Name + "_" + config.Name + ".json";
            string path = Path.Combine(ModConfigPath, filename);
            string json = JsonConvert.SerializeObject(config, serializerSettings);
            File.WriteAllText(path, json);
        }
 
        internal static void Unload()
        {
            serializerSettings.ContractResolver = new ReferenceDefaultsPreservingResolver();
            serializerSettingsCompact.ContractResolver = serializerSettings.ContractResolver;
 
            Configs.SelectMany(configList => configList.Value).ToList().ForEach(config => {
                FieldInfo instance = config.GetType().GetField("Instance", BindingFlags.Static | BindingFlags.Public);
                if (instance != null) {
                    instance.SetValue(null, null);
                }
            });
            Configs.Clear();
            LoadTimeConfigs.Clear();
 
            Interface.modConfig.Unload();
            Interface.modConfigList.Unload();
        }
 
        internal static bool AnyModNeedsReload() => ModLoader.Mods.Any(ModNeedsReload);
 
        internal static bool ModNeedsReload(Mod mod)
        {
            if (Configs.ContainsKey(mod))
            {
                var configs = Configs[mod];
                var loadTimeConfigs = LoadTimeConfigs[mod];
                for (int i = 0; i < configs.Count; i++)
                {
                    if (loadTimeConfigs[i].NeedsReload(configs[i]))
                    {
                        return true;
                    }
                }
            }
            return false;
        }
 
        // GetConfig...returns the config instance
        internal static ModConfig GetConfig(ModNet.NetConfig netConfig) => ConfigManager.GetConfig(ModLoader.GetMod(netConfig.modname), netConfig.configname);
        internal static ModConfig GetConfig(Mod mod, string config)
        {
            List<ModConfig> configs;
            if (Configs.TryGetValue(mod, out configs))
            {
                return configs.Single(x => x.Name == config);
            }
            throw new MissingResourceException("Missing config named " + config + " in mod " + mod.Name);
        }
 
        internal static ModConfig GetLoadTimeConfig(Mod mod, string config) {
            List<ModConfig> configs;
            if (LoadTimeConfigs.TryGetValue(mod, out configs)) {
                return configs.Single(x => x.Name == config);
            }
            throw new MissingResourceException("Missing config named " + config + " in mod " + mod.Name);
        }
 
        internal static void HandleInGameChangeConfigPacket(BinaryReader reader, int whoAmI)
        {
            if (Main.netMode == NetmodeID.MultiplayerClient)
            {
                bool success = reader.ReadBoolean();
                string message = reader.ReadString();
                if (success)
                {
                    string modname = reader.ReadString();
                    string configname = reader.ReadString();
                    string json = reader.ReadString();
                    ModConfig activeConfig = GetConfig(ModLoader.GetMod(modname), configname);
                    JsonConvert.PopulateObject(json, activeConfig, serializerSettingsCompact);
                    activeConfig.OnChanged();
 
                    Main.NewText($"Shared config changed: Message: {message}, Mod: {modname}, Config: {configname}");
                    if (Main.InGameUI.CurrentState == Interface.modConfig)
                    {
                        Main.InGameUI.SetState(Interface.modConfig);
                        Interface.modConfig.SetMessage("Server response: " + message, Color.Green);
                    }
                }
                else
                {
                    // rejection only sent back to requester.
                    // Update UI with message
 
                    Main.NewText("Changes Rejected: " + message);
                    if (Main.InGameUI.CurrentState == Interface.modConfig)
                    {
                        Interface.modConfig.SetMessage("Server rejected changes: " + message, Color.Red);
                        //Main.InGameUI.SetState(Interface.modConfig);
                    }
 
                }
            }
            else
            {
                // no bool in request.
                string modname = reader.ReadString();
                string configname = reader.ReadString();
                string json = reader.ReadString();
                ModConfig config = GetConfig(ModLoader.GetMod(modname), configname);
                ModConfig loadTimeConfig = GetLoadTimeConfig(ModLoader.GetMod(modname), configname);
                ModConfig pendingConfig = GeneratePopulatedClone(config);
                JsonConvert.PopulateObject(json, pendingConfig, serializerSettingsCompact);
                bool success = true;
                string message = "Accepted";
                if (loadTimeConfig.NeedsReload(pendingConfig))
                {
                    success = false;
                    message = "Can't save because changes would require a reload.";
                }
                if (!config.AcceptClientChanges(pendingConfig, whoAmI, ref message))
                {
                    success = false;
                }
                if (success)
                {
                    // Apply to Servers Config
                    ConfigManager.Save(pendingConfig);
                    JsonConvert.PopulateObject(json, config, ConfigManager.serializerSettingsCompact);
                    config.OnChanged();
                    // Send new config to all clients
                    var p = new ModPacket(MessageID.InGameChangeConfig);
                    p.Write(true);
                    p.Write(message);
                    p.Write(modname);
                    p.Write(configname);
                    p.Write(json);
                    p.Send();
                }
                else
                {
                    // Send rejections message back to client who requested change
                    var p = new ModPacket(MessageID.InGameChangeConfig);
                    p.Write(false);
                    p.Write(message);
                    p.Send(whoAmI);
                }
 
            }
            return;
        }
 
        public static IEnumerable<PropertyFieldWrapper> GetFieldsAndProperties(object item)
        {
            PropertyInfo[] properties = item.GetType().GetProperties(
                //BindingFlags.DeclaredOnly |
                BindingFlags.Public |
                BindingFlags.Instance);
 
            FieldInfo[] fields = item.GetType().GetFields(
                //BindingFlags.DeclaredOnly |
                BindingFlags.Public |
                BindingFlags.Instance);
 
            return fields.Select(x => new PropertyFieldWrapper(x)).Concat(properties.Select(x => new PropertyFieldWrapper(x)));
        }
 
        public static ModConfig GeneratePopulatedClone(ModConfig original) {
            string json = JsonConvert.SerializeObject(original, ConfigManager.serializerSettings);
            ModConfig properClone = original.Clone();
            JsonConvert.PopulateObject(json, properClone, ConfigManager.serializerSettings);
            return properClone;
        }
 
        public static object AlternateCreateInstance(Type type)
        {
            if (type == typeof(string))
                return "";
            return Activator.CreateInstance(type);
        }
 
        // Gets an Attribute from a property or field. Attribute defined on Member has highest priority, 
        // followed by the containing data structure, followed by attribute defined on the Class. 
        public static T GetCustomAttribute<T>(PropertyFieldWrapper memberInfo, object item, object array) where T : Attribute {
            // Class
            T attribute = (T)Attribute.GetCustomAttribute(memberInfo.Type, typeof(T), true);
            if (array != null)
            {
                // item null?
            //  attribute = (T)Attribute.GetCustomAttribute(item.GetType(), typeof(T), true) ?? attribute; // TODO: is this wrong?
            }
            // Member
            attribute = (T)Attribute.GetCustomAttribute(memberInfo.MemberInfo, typeof(T)) ?? attribute;
            return attribute;
            // TODO: allow for inheriting from parent's parent? (could get attribute from parent ConfigElement)
        }
 
        public static T GetCustomAttribute<T>(PropertyFieldWrapper memberInfo, Type type) where T : Attribute {
            // Class
            T attribute = (T)Attribute.GetCustomAttribute(memberInfo.Type, typeof(T), true);
 
            attribute = (T)Attribute.GetCustomAttribute(type, typeof(T), true) ?? attribute;
 
            // Member
            attribute = (T)Attribute.GetCustomAttribute(memberInfo.MemberInfo, typeof(T)) ?? attribute;
            return attribute;
        }
 
        public static Tuple<UIElement, UIElement> WrapIt(UIElement parent, ref int top, PropertyFieldWrapper memberInfo, object item, int order, object list = null, Type arrayType = null, int index = -1) 
        {
            // public api for modders.
            return UIModConfig.WrapIt(parent, ref top, memberInfo, item, order, list, arrayType, index);
        }
 
        public static void SetPendingChanges(bool changes = true) {
            // public api for modders.
            Interface.modConfig.SetPendingChanges(changes);
        }
 
        // TODO: better home?
        public static bool ObjectEquals(object a, object b) {
            if (ReferenceEquals(a, b)) return true;
            if (a == null || b == null) return false;
            if (a is IEnumerable && b is IEnumerable && !(a is string) && !(b is string))
                return EnumerableEquals((IEnumerable)a, (IEnumerable)b);
            return a.Equals(b);
        }
 
        public static bool EnumerableEquals(IEnumerable a, IEnumerable b) {
            IEnumerator enumeratorA = a.GetEnumerator();
            IEnumerator enumeratorB = b.GetEnumerator();
            bool hasNextA = enumeratorA.MoveNext();
            bool hasNextB = enumeratorB.MoveNext();
            while (hasNextA && hasNextB) {
                if (!ObjectEquals(enumeratorA.Current, enumeratorB.Current)) return false;
                hasNextA = enumeratorA.MoveNext();
                hasNextB = enumeratorB.MoveNext();
            }
            return !hasNextA && !hasNextB;
        }
    }
 
    class ReferenceDefaultsPreservingResolver : DefaultContractResolver
    {
        // This approach largely based on https://stackoverflow.com/a/52684798. 
        public abstract class ValueProviderDecorator : IValueProvider
        {
            readonly IValueProvider baseProvider;
 
            public ValueProviderDecorator(IValueProvider baseProvider) {
                if (baseProvider == null)
                    throw new ArgumentNullException();
                this.baseProvider = baseProvider;
            }
 
            public virtual object GetValue(object target) { return baseProvider.GetValue(target); }
 
            public virtual void SetValue(object target, object value) { baseProvider.SetValue(target, value); }
        }
        class NullToDefaultValueProvider : ValueProviderDecorator
        {
            //readonly object defaultValue;
            readonly Func<object> defaultValueGenerator;
 
            //public NullToDefaultValueProvider(IValueProvider baseProvider, object defaultValue) : base(baseProvider) {
            //  this.defaultValue = defaultValue;
            //}
 
            public NullToDefaultValueProvider(IValueProvider baseProvider, Func<object> defaultValueGenerator) : base(baseProvider) {
                this.defaultValueGenerator = defaultValueGenerator;
            }
 
            public override void SetValue(object target, object value) {
                base.SetValue(target, value ?? defaultValueGenerator.Invoke());
                //base.SetValue(target, value ?? defaultValue);
            }
        }
 
        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization) {
            IList<JsonProperty> props = base.CreateProperties(type, memberSerialization);
            if (type.IsClass) {
                ConstructorInfo ctor = type.GetConstructor(Type.EmptyTypes);
                if (ctor != null) {
                    object referenceInstance = ctor.Invoke(null);
                    foreach (JsonProperty prop in props.Where(p => p.Readable)) {
                        if (!prop.PropertyType.IsValueType) {
                            var a = type.GetMember(prop.PropertyName); 
                            if (prop.Writable) {
                                if (prop.PropertyType.GetConstructor(Type.EmptyTypes) != null) {
                                    // defaultValueCreator will create new instance, then get the value from a field in that object. Prevents deserialized nulls from sharing with other instances.
                                    Func<object> defaultValueCreator = () => prop.ValueProvider.GetValue(ctor.Invoke(null));
                                    prop.ValueProvider = new NullToDefaultValueProvider(prop.ValueProvider, defaultValueCreator);
                                }
                                else if (prop.PropertyType.IsArray) {
                                    Func<object> defaultValueCreator = () => (prop.ValueProvider.GetValue(referenceInstance) as Array).Clone();
                                    prop.ValueProvider = new NullToDefaultValueProvider(prop.ValueProvider, defaultValueCreator);
                                }
                            }
                            if (prop.ShouldSerialize == null)
                                prop.ShouldSerialize = instance =>
                                {
                                    object val = prop.ValueProvider.GetValue(instance);
                                    object refVal = prop.ValueProvider.GetValue(referenceInstance);
                                    return !ConfigManager.ObjectEquals(val, refVal);
                                };
                        }
                    }
                }
            }
            return props;
        }
    }
}