Miscellaneous improvements to commands

- OverloadInfo in Before/AfterExecute
  Now you know *exactly* what command is being executed.
- TypeReaders are given the IServiceProvider
  Now you can write TypeReaders for DB-backed data

src/Discord.Net.Commands/Builders/ModuleClassBuilder.cs

@@ -198,19 +198,20 @@ namespace Discord.Commands
 
             var createInstance = ReflectionUtils.CreateBuilder<IModuleBase>(typeInfo, service);
 
-            builder.Callback = async (ctx, args, map) => 
+            builder.Callback = async (ctx, args, map, overload) => 
             {
                 var instance = createInstance(map);
                 instance.SetContext(ctx);
+
                 try
                 {
-                    instance.BeforeExecute();
+                    instance.BeforeExecute(overload);
                     var task = method.Invoke(instance, args) as Task ?? Task.Delay(0);
                     await task.ConfigureAwait(false);
                 }
                 finally
                 {
-                    instance.AfterExecute();
+                    instance.AfterExecute(overload);
                     (instance as IDisposable)?.Dispose();
                 }
             };

src/Discord.Net.Commands/Builders/OverloadBuilder.cs

@@ -4,7 +4,7 @@ using System.Threading.Tasks;
 using System.Collections.Generic;
 using System.Diagnostics;
 
-using CommandCallback = System.Func<Discord.Commands.ICommandContext, object[], System.IServiceProvider, System.Threading.Tasks.Task>;
+using CommandCallback = System.Func<Discord.Commands.ICommandContext, object[], System.IServiceProvider, Discord.Commands.OverloadInfo, System.Threading.Tasks.Task>;
 
 namespace Discord.Commands.Builders
 {

src/Discord.Net.Commands/CommandParser.cs

@@ -1,4 +1,5 @@
-using System.Collections.Immutable;
+using System;
+using System.Collections.Immutable;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -13,7 +14,7 @@ namespace Discord.Commands
             QuotedParameter
         }
         
-        public static async Task<ParseResult> ParseArgs(OverloadInfo overload, ICommandContext context, string input, int startPos)
+        public static async Task<ParseResult> ParseArgs(OverloadInfo overload, ICommandContext context, IServiceProvider services, string input, int startPos)
         {
             ParameterInfo curParam = null;
             StringBuilder argBuilder = new StringBuilder(input.Length);
@@ -110,7 +111,7 @@ namespace Discord.Commands
                     if (curParam == null)
                         return ParseResult.FromError(CommandError.BadArgCount, "The input text has too many parameters.");
 
-                    var typeReaderResult = await curParam.Parse(context, argString).ConfigureAwait(false);
+                    var typeReaderResult = await curParam.Parse(context, argString, services).ConfigureAwait(false);
                     if (!typeReaderResult.IsSuccess && typeReaderResult.Error != CommandError.MultipleMatches)
                         return ParseResult.FromError(typeReaderResult);
 
@@ -133,7 +134,7 @@ namespace Discord.Commands
 
             if (curParam != null && curParam.IsRemainder)
             {
-                var typeReaderResult = await curParam.Parse(context, argBuilder.ToString()).ConfigureAwait(false);
+                var typeReaderResult = await curParam.Parse(context, argBuilder.ToString(), services).ConfigureAwait(false);
                 if (!typeReaderResult.IsSuccess)
                     return ParseResult.FromError(typeReaderResult);
                 argList.Add(typeReaderResult);

src/Discord.Net.Commands/CommandService.cs

@@ -168,8 +168,7 @@ namespace Discord.Commands
             await _moduleLock.WaitAsync().ConfigureAwait(false);
             try
             {
-                ModuleInfo module;
-                if (!_typedModuleDefs.TryRemove(type, out module))
+                if (!_typedModuleDefs.TryRemove(type, out var module))
                     return false;
 
                 return RemoveModuleInternal(module);
@@ -208,15 +207,13 @@ namespace Discord.Commands
         }
         internal IDictionary<Type, TypeReader> GetTypeReaders(Type type)
         {
-            ConcurrentDictionary<Type, TypeReader> definedTypeReaders;
-            if (_typeReaders.TryGetValue(type, out definedTypeReaders))
+            if (_typeReaders.TryGetValue(type, out var definedTypeReaders))
                 return definedTypeReaders;
             return null;
         }
         internal TypeReader GetDefaultTypeReader(Type type)
         {
-            TypeReader reader;
-            if (_defaultTypeReaders.TryGetValue(type, out reader))
+            if (_defaultTypeReaders.TryGetValue(type, out var reader))
                 return reader;
             var typeInfo = type.GetTypeInfo();
 
@@ -287,7 +284,7 @@ namespace Discord.Commands
                 var rawParseResults = new List<ParseResult>();
                 foreach (var overload in overloads)
                 {
-                    rawParseResults.Add(await overload.ParseAsync(context, searchResult, preconditionResult).ConfigureAwait(false));
+                    rawParseResults.Add(await overload.ParseAsync(context, services, searchResult, preconditionResult).ConfigureAwait(false));
                 }
 
                 //order by average score

src/Discord.Net.Commands/IModuleBase.cs

@@ -4,8 +4,8 @@
     {
         void SetContext(ICommandContext context);
 
-        void BeforeExecute();
+        void BeforeExecute(OverloadInfo overload);
         
-        void AfterExecute();
+        void AfterExecute(OverloadInfo overload);
     }
 }

src/Discord.Net.Commands/Info/OverloadInfo.cs

@@ -18,7 +18,7 @@ namespace Discord.Commands
         private static readonly MethodInfo _convertParamsMethod = typeof(OverloadInfo).GetTypeInfo().GetDeclaredMethod(nameof(ConvertParamsList));
         private static readonly ConcurrentDictionary<Type, Func<IEnumerable<object>, object>> _arrayConverters = new ConcurrentDictionary<Type, Func<IEnumerable<object>, object>>();
 
-        private readonly Func<ICommandContext, object[], IServiceProvider, Task> _action;
+        private readonly Func<ICommandContext, object[], IServiceProvider, OverloadInfo, Task> _action;
 
         public CommandInfo Command { get; }
         public int Priority { get; }
@@ -65,7 +65,7 @@ namespace Discord.Commands
             return PreconditionResult.FromSuccess();
         }
 
-        public async Task<ParseResult> ParseAsync(ICommandContext context, SearchResult searchResult, PreconditionResult? preconditionResult = null)
+        public async Task<ParseResult> ParseAsync(ICommandContext context, IServiceProvider services, SearchResult searchResult, PreconditionResult? preconditionResult = null)
         {
             if (!searchResult.IsSuccess)
                 return ParseResult.FromError(searchResult);
@@ -84,7 +84,7 @@ namespace Discord.Commands
 
             input = input.Substring(matchingAlias.Length);
 
-            return await CommandParser.ParseArgs(this, context, input, 0).ConfigureAwait(false);
+            return await CommandParser.ParseArgs(this, context, services, input, 0).ConfigureAwait(false);
         }
 
         public Task<ExecuteResult> ExecuteAsync(ICommandContext context, ParseResult parseResult, IServiceProvider services)
@@ -140,7 +140,7 @@ namespace Discord.Commands
             await Command.Module.Service._cmdLogger.DebugAsync($"Executing {GetLogText(context)}").ConfigureAwait(false);
             try
             {
-                await _action(context, args, map).ConfigureAwait(false);
+                await _action(context, args, map, this).ConfigureAwait(false);
             }
             catch (Exception ex)
             {

src/Discord.Net.Commands/Info/ParameterInfo.cs

@@ -56,9 +56,11 @@ namespace Discord.Commands
             return PreconditionResult.FromSuccess();
         }
 
-        public async Task<TypeReaderResult> Parse(ICommandContext context, string input)
+        public async Task<TypeReaderResult> Parse(ICommandContext context, string input, IServiceProvider services)
         {
-            return await _reader.Read(context, input).ConfigureAwait(false);
+            services = services ?? EmptyServiceProvider.Instance;
+
+            return await _reader.Read(context, input, services).ConfigureAwait(false);
         }
 
         public override string ToString() => Name;

src/Discord.Net.Commands/ModuleBase.cs

@@ -15,11 +15,11 @@ namespace Discord.Commands
             return await Context.Channel.SendMessageAsync(message, isTTS, embed, options).ConfigureAwait(false);
         }
 
-        protected virtual void BeforeExecute()
+        protected virtual void BeforeExecute(OverloadInfo overload)
         {
         }
 
-        protected virtual void AfterExecute()
+        protected virtual void AfterExecute(OverloadInfo overload)
         {
         }
 
@@ -32,8 +32,8 @@ namespace Discord.Commands
             Context = newValue;
         }
 
-        void IModuleBase.BeforeExecute() => BeforeExecute();
+        void IModuleBase.BeforeExecute(OverloadInfo overload) => BeforeExecute(overload);
 
-        void IModuleBase.AfterExecute() => AfterExecute();
+        void IModuleBase.AfterExecute(OverloadInfo overload) => AfterExecute(overload);
     }
 }

src/Discord.Net.Commands/Readers/ChannelTypeReader.cs

@@ -9,7 +9,7 @@ namespace Discord.Commands
     internal class ChannelTypeReader<T> : TypeReader
         where T : class, IChannel
     {
-        public override async Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override async Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             if (context.Guild != null)
             {

src/Discord.Net.Commands/Readers/EnumTypeReader.cs

@@ -44,7 +44,7 @@ namespace Discord.Commands
             _enumsByValue = byValueBuilder.ToImmutable();
         }
 
-        public override Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             T baseValue;
             object enumValue;

src/Discord.Net.Commands/Readers/MessageTypeReader.cs

@@ -1,4 +1,5 @@
-using System.Globalization;
+using System;
+using System.Globalization;
 using System.Threading.Tasks;
 
 namespace Discord.Commands
@@ -6,7 +7,7 @@ namespace Discord.Commands
     internal class MessageTypeReader<T> : TypeReader
         where T : class, IMessage
     {
-        public override async Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override async Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             ulong id;
 

src/Discord.Net.Commands/Readers/PrimitiveTypeReader.cs

@@ -27,7 +27,7 @@ namespace Discord.Commands
             _score = score;
         }
 
-        public override Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             T value;
             if (_tryParse(input, out value))

src/Discord.Net.Commands/Readers/RoleTypeReader.cs

@@ -9,7 +9,7 @@ namespace Discord.Commands
     internal class RoleTypeReader<T> : TypeReader
         where T : class, IRole
     {
-        public override Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             ulong id;
 

src/Discord.Net.Commands/Readers/TypeReader.cs

@@ -1,9 +1,10 @@
-using System.Threading.Tasks;
+using System;
+using System.Threading.Tasks;
 
 namespace Discord.Commands
 {
     public abstract class TypeReader
     {
-        public abstract Task<TypeReaderResult> Read(ICommandContext context, string input);
+        public abstract Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services);
     }
 }

src/Discord.Net.Commands/Readers/UserTypeReader.cs

@@ -10,7 +10,7 @@ namespace Discord.Commands
     internal class UserTypeReader<T> : TypeReader
         where T : class, IUser
     {
-        public override async Task<TypeReaderResult> Read(ICommandContext context, string input)
+        public override async Task<TypeReaderResult> Read(ICommandContext context, string input, IServiceProvider services)
         {
             var results = new Dictionary<ulong, TypeReaderValue>();
             IReadOnlyCollection<IUser> channelUsers = (await context.Channel.GetUsersAsync(CacheMode.CacheOnly).Flatten().ConfigureAwait(false)).ToArray(); //TODO: must be a better way?