refactor performance counter code

This commit performs some general refactoring, including...
- avoid manually duplicating the event list;
- rework the 'is important' event flag;
- remove the new packages (Cyotek.Collections can be replaced with built-in types, and System.ValueTuple won't work in the Mono version used on Linux/Mac);
- improve performance;
- minor cleanup.

3 files changed, 323 insertions, 372 deletions

diff --git a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/ArgumentParser.cs b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/ArgumentParser.cs
index 40691a3e..9c7082c9 100644
--- a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/ArgumentParser.cs
+++ b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/ArgumentParser.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Globalization;
@@ -32,13 +32,6 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands
         /// <param name="index">The zero-based index of the element to get.</param>
         public string this[int index] => this.Args[index];
 
-        /// <summary>A method which parses a string argument into the given value.</summary>
-        /// <typeparam name="T">The expected argument type.</typeparam>
-        /// <param name="input">The argument to parse.</param>
-        /// <param name="output">The parsed value.</param>
-        /// <returns>Returns whether the argument was successfully parsed.</returns>
-        public delegate bool ParseDelegate<T>(string input, out T output);
-
 
         /*********
         ** Public methods
@@ -114,19 +107,6 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands
             return true;
         }
 
-        public bool IsDecimal(int index)
-        {
-            if (!this.TryGet(index, "", out string raw, false))
-                return false;
-
-            if (!decimal.TryParse(raw, NumberStyles.Number, CultureInfo.InvariantCulture, out decimal value))
-            {
-                return false;
-            }
-
-            return true;
-        }
-
         /// <summary>Try to read a decimal argument.</summary>
         /// <param name="index">The argument index.</param>
         /// <param name="name">The argument name for error messages.</param>
diff --git a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/Other/PerformanceCounterCommand.cs b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/Other/PerformanceCounterCommand.cs
index 2260296b..820f1939 100644
--- a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/Other/PerformanceCounterCommand.cs
+++ b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/Other/PerformanceCounterCommand.cs
@@ -7,24 +7,13 @@ using StardewModdingAPI.Framework.PerformanceCounter;
 
 namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
 {
-    // ReSharper disable once UnusedType.Global
+    /// <summary>A set of commands which displays or configures performance monitoring.</summary>
     internal class PerformanceCounterCommand : TrainerCommand
     {
-        /// <summary>The command names and aliases</summary>
-        private readonly Dictionary<SubCommand, string[]> SubCommandNames = new Dictionary<SubCommand, string[]>()
-        {
-            {SubCommand.Summary, new[] {"summary", "sum", "s"}},
-            {SubCommand.Detail, new[] {"detail", "d"}},
-            {SubCommand.Reset, new[] {"reset", "r"}},
-            {SubCommand.Trigger, new[] {"trigger"}},
-            {SubCommand.Enable, new[] {"enable"}},
-            {SubCommand.Disable, new[] {"disable"}},
-            {SubCommand.Examples, new[] {"examples"}},
-            {SubCommand.Concepts, new[] {"concepts"}},
-            {SubCommand.Help, new[] {"help"}},
-        };
-
-        /// <summary>The available commands enum</summary>
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The available commands.</summary>
         private enum SubCommand
         {
             Summary,
@@ -33,16 +22,16 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
             Trigger,
             Enable,
             Disable,
-            Examples,
-            Help,
-            Concepts,
-            None
+            Help
         }
 
+
+        /*********
+        ** Public methods
+        *********/
         /// <summary>Construct an instance.</summary>
-        public PerformanceCounterCommand() : base("pc", PerformanceCounterCommand.GetDescription())
-        {
-        }
+        public PerformanceCounterCommand()
+            : base("performance", PerformanceCounterCommand.GetDescription()) { }
 
         /// <summary>Handle the command.</summary>
         /// <param name="monitor">Writes messages to the console and log file.</param>
@@ -50,92 +39,94 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         /// <param name="args">The command arguments.</param>
         public override void Handle(IMonitor monitor, string command, ArgumentParser args)
         {
-            if (args.TryGet(0, "command", out string subCommandString, false))
+            // parse args
+            SubCommand subcommand = SubCommand.Summary;
             {
-                SubCommand subSubCommand = this.ParseCommandString(subCommandString);
-
-                switch (subSubCommand)
+                if (args.TryGet(0, "command", out string subcommandStr, false) && !Enum.TryParse(subcommandStr, ignoreCase: true, out subcommand))
                 {
-                    case SubCommand.Summary:
-                        this.HandleSummarySubCommand(monitor, args);
-                        break;
-                    case SubCommand.Detail:
-                        this.HandleDetailSubCommand(monitor, args);
-                        break;
-                    case SubCommand.Reset:
-                        this.HandleResetSubCommand(monitor, args);
-                        break;
-                    case SubCommand.Trigger:
-                        this.HandleTriggerSubCommand(monitor, args);
-                        break;
-                    case SubCommand.Examples:
-                        break;
-                    case SubCommand.Concepts:
-                        this.OutputHelp(monitor, SubCommand.Concepts);
-                        break;
-                    case SubCommand.Enable:
-                        SCore.PerformanceCounterManager.EnableTracking = true;
-                        monitor.Log("Performance counter tracking is now enabled", LogLevel.Info);
-                        break;
-                    case SubCommand.Disable:
-                        SCore.PerformanceCounterManager.EnableTracking = false;
-                        monitor.Log("Performance counter tracking is now disabled", LogLevel.Info);
-                        break;
-                    case SubCommand.Help:
-                        if (args.TryGet(1, "command", out string commandString))
-                            this.OutputHelp(monitor, this.ParseCommandString(commandString));
-                        break;
-                    default:
-                        this.LogUsageError(monitor, $"Unknown command {subCommandString}");
-                        break;
+                    this.LogUsageError(monitor, $"Unknown command {subcommandStr}");
+                    return;
                 }
             }
-            else
-                this.HandleSummarySubCommand(monitor, args);
+
+            // handle
+            switch (subcommand)
+            {
+                case SubCommand.Summary:
+                    this.HandleSummarySubCommand(monitor, args);
+                    break;
+
+                case SubCommand.Detail:
+                    this.HandleDetailSubCommand(monitor, args);
+                    break;
+
+                case SubCommand.Reset:
+                    this.HandleResetSubCommand(monitor, args);
+                    break;
+
+                case SubCommand.Trigger:
+                    this.HandleTriggerSubCommand(monitor, args);
+                    break;
+
+                case SubCommand.Enable:
+                    SCore.PerformanceMonitor.EnableTracking = true;
+                    monitor.Log("Performance counter tracking is now enabled", LogLevel.Info);
+                    break;
+
+                case SubCommand.Disable:
+                    SCore.PerformanceMonitor.EnableTracking = false;
+                    monitor.Log("Performance counter tracking is now disabled", LogLevel.Info);
+                    break;
+
+                case SubCommand.Help:
+                    this.OutputHelp(monitor, args.TryGet(1, "command", out _) ? subcommand : null as SubCommand?);
+                    break;
+
+                default:
+                    this.LogUsageError(monitor, $"Unknown command {subcommand}");
+                    break;
+            }
         }
 
+
+        /*********
+        ** Private methods
+        *********/
         /// <summary>Handles the summary sub command.</summary>
         /// <param name="monitor">Writes messages to the console and log file.</param>
         /// <param name="args">The command arguments.</param>
         private void HandleSummarySubCommand(IMonitor monitor, ArgumentParser args)
         {
-            IEnumerable<PerformanceCounterCollection> data;
-
             if (!args.TryGet(1, "mode", out string mode, false))
-            {
                 mode = "important";
-            }
 
+            IEnumerable<PerformanceCounterCollection> data = SCore.PerformanceMonitor.GetCollections();
             switch (mode)
             {
                 case null:
                 case "important":
-                    data = SCore.PerformanceCounterManager.PerformanceCounterCollections.Where(p => p.IsImportant);
+                    data = data.Where(p => p.IsPerformanceCritical);
                     break;
+
                 case "all":
-                    data = SCore.PerformanceCounterManager.PerformanceCounterCollections;
                     break;
+
                 default:
-                    data = SCore.PerformanceCounterManager.PerformanceCounterCollections.Where(p =>
-                        p.Name.ToLowerInvariant().Contains(mode.ToLowerInvariant()));
+                    data = data.Where(p => p.Name.ToLowerInvariant().Contains(mode.ToLowerInvariant()));
                     break;
             }
 
             double? threshold = null;
-
             if (args.TryGetDecimal(2, "threshold", out decimal t, false))
-            {
-                threshold = (double?) t;
-            }
-
-            StringBuilder sb = new StringBuilder();
+                threshold = (double?)t;
 
             TimeSpan interval = TimeSpan.FromSeconds(60);
 
-            sb.AppendLine($"Summary over the last {interval.TotalSeconds} seconds:");
-            sb.AppendLine(this.GetTableString(
+            StringBuilder report = new StringBuilder();
+            report.AppendLine($"Summary over the last {interval.TotalSeconds} seconds:");
+            report.AppendLine(this.GetTableString(
                 data: data,
-                header: new[] {"Collection", "Avg Calls/s", "Avg Exec Time (Game)", "Avg Exec Time (Mods)", "Avg Exec Time (Game+Mods)", "Peak Exec Time"},
+                header: new[] { "Collection", "Avg Calls/s", "Avg Exec Time (Game)", "Avg Exec Time (Mods)", "Avg Exec Time (Game+Mods)", "Peak Exec Time" },
                 getRow: item => new[]
                 {
                     item.Name,
@@ -148,7 +139,7 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
                 true
             ));
 
-            monitor.Log(sb.ToString(), LogLevel.Info);
+            monitor.Log(report.ToString(), LogLevel.Info);
         }
 
         /// <summary>Handles the detail sub command.</summary>
@@ -163,26 +154,16 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
 
             if (args.TryGet(1, "collection", out string collectionName))
             {
-                collections.AddRange(SCore.PerformanceCounterManager.PerformanceCounterCollections.Where(
-                    collection => collection.Name.ToLowerInvariant().Contains(collectionName.ToLowerInvariant())));
+                collections.AddRange(SCore.PerformanceMonitor.GetCollections().Where(collection => collection.Name.ToLowerInvariant().Contains(collectionName.ToLowerInvariant())));
 
-                if (args.IsDecimal(2) && args.TryGetDecimal(2, "threshold", out decimal value, false))
-                {
-                    thresholdMilliseconds = (double?) value;
-                }
-                else
-                {
-                    if (args.TryGet(2, "source", out string sourceName, false))
-                    {
-                        sourceFilter = sourceName;
-                    }
-                }
+                if (args.Count >= 2 && decimal.TryParse(args[2], out _) && args.TryGetDecimal(2, "threshold", out decimal value, false))
+                    thresholdMilliseconds = (double?)value;
+                else if (args.TryGet(2, "source", out string sourceName, false))
+                    sourceFilter = sourceName;
             }
 
             foreach (PerformanceCounterCollection c in collections)
-            {
                 this.OutputPerformanceCollectionDetail(monitor, c, averageInterval, thresholdMilliseconds, sourceFilter);
-            }
         }
 
         /// <summary>Handles the trigger sub command.</summary>
@@ -197,46 +178,44 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
                     case "list":
                         this.OutputAlertTriggers(monitor);
                         break;
+
                     case "collection":
                         if (args.TryGet(2, "name", out string collectionName))
                         {
                             if (args.TryGetDecimal(3, "threshold", out decimal threshold))
                             {
-                                if (args.TryGet(4, "source", out string source, false))
-                                {
-                                    this.ConfigureAlertTrigger(monitor, collectionName, source, threshold);
-                                }
-                                else
-                                {
-                                    this.ConfigureAlertTrigger(monitor, collectionName, null, threshold);
-                                }
+                                if (!args.TryGet(4, "source", out string source, required: false))
+                                    source = null;
+                                this.ConfigureAlertTrigger(monitor, collectionName, source, threshold);
                             }
                         }
                         break;
+
                     case "pause":
-                        SCore.PerformanceCounterManager.PauseAlerts = true;
-                        monitor.Log($"Alerts are now paused.", LogLevel.Info);
+                        SCore.PerformanceMonitor.PauseAlerts = true;
+                        monitor.Log("Alerts are now paused.", LogLevel.Info);
                         break;
+
                     case "resume":
-                        SCore.PerformanceCounterManager.PauseAlerts = false;
-                        monitor.Log($"Alerts are now resumed.", LogLevel.Info);
+                        SCore.PerformanceMonitor.PauseAlerts = false;
+                        monitor.Log("Alerts are now resumed.", LogLevel.Info);
                         break;
+
                     case "dump":
                         this.OutputAlertTriggers(monitor, true);
                         break;
+
                     case "clear":
                         this.ClearAlertTriggers(monitor);
                         break;
+
                     default:
                         this.LogUsageError(monitor, $"Unknown mode {mode}. See 'pc help trigger' for usage.");
                         break;
                 }
-
             }
             else
-            {
                 this.OutputAlertTriggers(monitor);
-            }
         }
 
         /// <summary>Sets up an an alert trigger.</summary>
@@ -246,7 +225,7 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         /// <param name="threshold">The trigger threshold, or 0 to remove.</param>
         private void ConfigureAlertTrigger(IMonitor monitor, string collectionName, string sourceName, decimal threshold)
         {
-            foreach (PerformanceCounterCollection collection in SCore.PerformanceCounterManager.PerformanceCounterCollections)
+            foreach (PerformanceCounterCollection collection in SCore.PerformanceMonitor.GetCollections())
             {
                 if (collection.Name.ToLowerInvariant().Equals(collectionName.ToLowerInvariant()))
                 {
@@ -255,8 +234,8 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
                         if (threshold != 0)
                         {
                             collection.EnableAlerts = true;
-                            collection.AlertThresholdMilliseconds = (double) threshold;
-                            monitor.Log($"Set up alert triggering for '{collectionName}' with '{this.FormatMilliseconds((double?) threshold)}'", LogLevel.Info);
+                            collection.AlertThresholdMilliseconds = (double)threshold;
+                            monitor.Log($"Set up alert triggering for '{collectionName}' with '{this.FormatMilliseconds((double?)threshold)}'", LogLevel.Info);
                         }
                         else
                         {
@@ -275,14 +254,11 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
                                 if (threshold != 0)
                                 {
                                     performanceCounter.Value.EnableAlerts = true;
-                                    performanceCounter.Value.AlertThresholdMilliseconds = (double) threshold;
-                                    monitor.Log($"Set up alert triggering for '{sourceName}' in collection '{collectionName}' with '{this.FormatMilliseconds((double?) threshold)}", LogLevel.Info);
+                                    performanceCounter.Value.AlertThresholdMilliseconds = (double)threshold;
+                                    monitor.Log($"Set up alert triggering for '{sourceName}' in collection '{collectionName}' with '{this.FormatMilliseconds((double?)threshold)}", LogLevel.Info);
                                 }
                                 else
-                                {
                                     performanceCounter.Value.EnableAlerts = false;
-                                }
-
                                 return;
                             }
                         }
@@ -302,7 +278,7 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         private void ClearAlertTriggers(IMonitor monitor)
         {
             int clearedTriggers = 0;
-            foreach (PerformanceCounterCollection collection in SCore.PerformanceCounterManager.PerformanceCounterCollections)
+            foreach (PerformanceCounterCollection collection in SCore.PerformanceMonitor.GetCollections())
             {
                 if (collection.EnableAlerts)
                 {
@@ -329,92 +305,75 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         /// <param name="asDump">True to dump the triggers as commands.</param>
         private void OutputAlertTriggers(IMonitor monitor, bool asDump = false)
         {
-            StringBuilder sb = new StringBuilder();
-            sb.AppendLine("Configured triggers:");
-            sb.AppendLine();
-            var collectionTriggers = new List<(string collectionName, double threshold)>();
-            var sourceTriggers = new List<(string collectionName, string sourceName, double threshold)>();
+            StringBuilder report = new StringBuilder();
+            report.AppendLine("Configured triggers:");
+            report.AppendLine();
+            var collectionTriggers = new List<CollectionTrigger>();
+            var sourceTriggers = new List<SourceTrigger>();
 
-            foreach (PerformanceCounterCollection collection in SCore.PerformanceCounterManager.PerformanceCounterCollections)
+            foreach (PerformanceCounterCollection collection in SCore.PerformanceMonitor.GetCollections())
             {
                 if (collection.EnableAlerts)
-                {
-                    collectionTriggers.Add((collection.Name, collection.AlertThresholdMilliseconds));
-                }
+                    collectionTriggers.Add(new CollectionTrigger(collection.Name, collection.AlertThresholdMilliseconds));
 
-                sourceTriggers.AddRange(from performanceCounter in
-                    collection.PerformanceCounters where performanceCounter.Value.EnableAlerts
-                    select (collection.Name, performanceCounter.Value.Source, performanceCounter.Value.AlertThresholdMilliseconds));
+                sourceTriggers.AddRange(
+                    from counter in collection.PerformanceCounters
+                    where counter.Value.EnableAlerts
+                    select new SourceTrigger(collection.Name, counter.Value.Source, counter.Value.AlertThresholdMilliseconds)
+                );
             }
 
             if (collectionTriggers.Count > 0)
             {
-                sb.AppendLine("Collection Triggers:");
-                sb.AppendLine();
+                report.AppendLine("Collection Triggers:");
+                report.AppendLine();
 
                 if (asDump)
                 {
                     foreach (var item in collectionTriggers)
-                    {
-                        sb.AppendLine($"pc trigger {item.collectionName} {item.threshold}");
-                    }
+                        report.AppendLine($"pc trigger {item.CollectionName} {item.Threshold}");
                 }
                 else
                 {
-                    sb.AppendLine(this.GetTableString(
+                    report.AppendLine(this.GetTableString(
                         data: collectionTriggers,
-                        header: new[] {"Collection", "Threshold"},
-                        getRow: item => new[]
-                        {
-                            item.collectionName,
-                            this.FormatMilliseconds(item.threshold)
-                        },
+                        header: new[] { "Collection", "Threshold" },
+                        getRow: item => new[] { item.CollectionName, this.FormatMilliseconds(item.Threshold) },
                         true
                     ));
                 }
 
-                sb.AppendLine();
+                report.AppendLine();
             }
             else
-            {
-                sb.AppendLine("No collection triggers.");
-            }
+                report.AppendLine("No collection triggers.");
 
             if (sourceTriggers.Count > 0)
             {
-                sb.AppendLine("Source Triggers:");
-                sb.AppendLine();
+                report.AppendLine("Source Triggers:");
+                report.AppendLine();
 
                 if (asDump)
                 {
-                    foreach (var item in sourceTriggers)
-                    {
-                        sb.AppendLine($"pc trigger {item.collectionName} {item.threshold} {item.sourceName}");
-                    }
+                    foreach (SourceTrigger item in sourceTriggers)
+                        report.AppendLine($"pc trigger {item.CollectionName} {item.Threshold} {item.SourceName}");
                 }
                 else
                 {
-                    sb.AppendLine(this.GetTableString(
+                    report.AppendLine(this.GetTableString(
                         data: sourceTriggers,
-                        header: new[] {"Collection", "Source", "Threshold"},
-                        getRow: item => new[]
-                        {
-                            item.collectionName,
-                            item.sourceName,
-                            this.FormatMilliseconds(item.threshold)
-                        },
+                        header: new[] { "Collection", "Source", "Threshold" },
+                        getRow: item => new[] { item.CollectionName, item.SourceName, this.FormatMilliseconds(item.Threshold) },
                         true
                     ));
                 }
 
-                sb.AppendLine();
+                report.AppendLine();
             }
             else
-            {
-                sb.AppendLine("No source triggers.");
-            }
+                report.AppendLine("No source triggers.");
 
-            monitor.Log(sb.ToString(), LogLevel.Info);
+            monitor.Log(report.ToString(), LogLevel.Info);
         }
 
         /// <summary>Handles the reset sub command.</summary>
@@ -422,25 +381,25 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         /// <param name="args">The command arguments.</param>
         private void HandleResetSubCommand(IMonitor monitor, ArgumentParser args)
         {
-            if (args.TryGet(1, "type", out string type, false, new []{"category", "source"}))
+            if (args.TryGet(1, "type", out string type, false, new[] { "category", "source" }))
             {
                 args.TryGet(2, "name", out string name);
 
                 switch (type)
                 {
                     case "category":
-                        SCore.PerformanceCounterManager.ResetCollection(name);
+                        SCore.PerformanceMonitor.ResetCollection(name);
                         monitor.Log($"All performance counters for category {name} are now cleared.", LogLevel.Info);
                         break;
                     case "source":
-                        SCore.PerformanceCounterManager.ResetSource(name);
+                        SCore.PerformanceMonitor.ResetSource(name);
                         monitor.Log($"All performance counters for source {name} are now cleared.", LogLevel.Info);
                         break;
                 }
             }
             else
             {
-                SCore.PerformanceCounterManager.Reset();
+                SCore.PerformanceMonitor.Reset();
                 monitor.Log("All performance counters are now cleared.", LogLevel.Info);
             }
         }
@@ -455,7 +414,7 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         private void OutputPerformanceCollectionDetail(IMonitor monitor, PerformanceCounterCollection collection,
             TimeSpan averageInterval, double? thresholdMilliseconds, string sourceFilter = null)
         {
-            StringBuilder sb = new StringBuilder($"Performance Counter for {collection.Name}:\n\n");
+            StringBuilder report = new StringBuilder($"Performance Counter for {collection.Name}:\n\n");
 
             List<KeyValuePair<string, PerformanceCounter>> data = collection.PerformanceCounters.ToList();
 
@@ -466,15 +425,13 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
             }
 
             if (thresholdMilliseconds != null)
-            {
                 data = data.Where(p => p.Value.GetAverage(averageInterval) >= thresholdMilliseconds).ToList();
-            }
 
             if (data.Any())
             {
-                sb.AppendLine(this.GetTableString(
+                report.AppendLine(this.GetTableString(
                     data: data,
-                    header: new[] {"Mod", $"Avg Exec Time (last {(int) averageInterval.TotalSeconds}s)", "Last Exec Time", "Peak Exec Time", $"Peak Exec Time (last {(int) averageInterval.TotalSeconds}s)"},
+                    header: new[] { "Mod", $"Avg Exec Time (last {(int)averageInterval.TotalSeconds}s)", "Last Exec Time", "Peak Exec Time", $"Peak Exec Time (last {(int)averageInterval.TotalSeconds}s)" },
                     getRow: item => new[]
                     {
                         item.Key,
@@ -488,28 +445,13 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
             }
             else
             {
-                sb.Clear();
-                sb.AppendLine($"Performance Counter for {collection.Name}: none.");
-            }
-
-            monitor.Log(sb.ToString(), LogLevel.Info);
-        }
-
-        /// <summary>Parses a command string and returns the associated command.</summary>
-        /// <param name="commandString">The command string</param>
-        /// <returns>The parsed command.</returns>
-        private SubCommand ParseCommandString(string commandString)
-        {
-            foreach (var i in this.SubCommandNames.Where(i =>
-                i.Value.Any(str => str.Equals(commandString, StringComparison.InvariantCultureIgnoreCase))))
-            {
-                return i.Key;
+                report.Clear();
+                report.AppendLine($"Performance Counter for {collection.Name}: none.");
             }
 
-            return SubCommand.None;
+            monitor.Log(report.ToString(), LogLevel.Info);
         }
 
-
         /// <summary>Formats the given milliseconds value into a string format. Optionally
         /// allows a threshold to return "-" if the value is less than the threshold.</summary>
         /// <param name="milliseconds">The milliseconds to format. Returns "-" if null</param>
@@ -518,175 +460,212 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands.Other
         private string FormatMilliseconds(double? milliseconds, double? thresholdMilliseconds = null)
         {
             if (milliseconds == null || (thresholdMilliseconds != null && milliseconds < thresholdMilliseconds))
-            {
                 return "-";
-            }
 
-            return ((double) milliseconds).ToString("F2");
+            return ((double)milliseconds).ToString("F2");
         }
 
         /// <summary>Shows detailed help for a specific sub command.</summary>
-        /// <param name="monitor">The output monitor</param>
-        /// <param name="subCommand">The sub command</param>
-        private void OutputHelp(IMonitor monitor, SubCommand subCommand)
+        /// <param name="monitor">The output monitor.</param>
+        /// <param name="subcommand">The subcommand.</param>
+        private void OutputHelp(IMonitor monitor, SubCommand? subcommand)
         {
-            StringBuilder sb = new StringBuilder();
-            sb.AppendLine();
+            StringBuilder report = new StringBuilder();
+            report.AppendLine();
 
-            switch (subCommand)
+            switch (subcommand)
             {
-                case SubCommand.Concepts:
-                    sb.AppendLine("A performance counter is a metric which measures execution time. Each performance");
-                    sb.AppendLine("counter consists of:");
-                    sb.AppendLine();
-                    sb.AppendLine(" - A source, which typically is a mod or the game itself.");
-                    sb.AppendLine(" - A ring buffer which stores the data points (execution time and time when it was executed)");
-                    sb.AppendLine();
-                    sb.AppendLine("A set of performance counters is organized in a collection to group various areas.");
-                    sb.AppendLine("Per default, collections for all game events [1] are created.");
-                    sb.AppendLine();
-                    sb.AppendLine("Example:");
-                    sb.AppendLine();
-                    sb.AppendLine("The performance counter collection named 'Display.Rendered' contains one performance");
-                    sb.AppendLine("counters when the game executes the 'Display.Rendered' event, and one additional");
-                    sb.AppendLine("performance counter for each mod which handles the 'Display.Rendered' event.");
-                    sb.AppendLine();
-                    sb.AppendLine("[1] https://stardewvalleywiki.com/Modding:Modder_Guide/APIs/Events");
-                    break;
                 case SubCommand.Detail:
-                    sb.AppendLine("Usage: pc detail <collection> <source>");
-                    sb.AppendLine("       pc detail <collection> <threshold>");
-                    sb.AppendLine();
-                    sb.AppendLine("Displays details for a specific collection.");
-                    sb.AppendLine();
-                    sb.AppendLine("Arguments:");
-                    sb.AppendLine("  <collection>  Required. The full or partial name of the collection to display.");
-                    sb.AppendLine("  <source>      Optional. The full or partial name of the source.");
-                    sb.AppendLine("  <threshold>   Optional. The threshold in milliseconds. Any average execution time below that");
-                    sb.AppendLine("                threshold is not reported.");
-                    sb.AppendLine();
-                    sb.AppendLine("Examples:");
-                    sb.AppendLine("pc detail Display.Rendering                              Displays all performance counters for the 'Display.Rendering' collection");
-                    sb.AppendLine("pc detail Display.Rendering Pathoschild.ChestsAnywhere   Displays the 'Display.Rendering' performance counter for 'Pathoschild.ChestsAnywhere'");
-                    sb.AppendLine("pc detail Display.Rendering 5                            Displays the 'Display.Rendering' performance counters exceeding an average of 5ms");
+                    report.AppendLine("Usage: pc detail <collection> <source>");
+                    report.AppendLine("       pc detail <collection> <threshold>");
+                    report.AppendLine();
+                    report.AppendLine("Displays details for a specific collection.");
+                    report.AppendLine();
+                    report.AppendLine("Arguments:");
+                    report.AppendLine("  <collection>  Required. The full or partial name of the collection to display.");
+                    report.AppendLine("  <source>      Optional. The full or partial name of the source.");
+                    report.AppendLine("  <threshold>   Optional. The threshold in milliseconds. Any average execution time below that");
+                    report.AppendLine("                threshold is not reported.");
+                    report.AppendLine();
+                    report.AppendLine("Examples:");
+                    report.AppendLine("pc detail Display.Rendering                              Displays all performance counters for the 'Display.Rendering' collection");
+                    report.AppendLine("pc detail Display.Rendering Pathoschild.ChestsAnywhere   Displays the 'Display.Rendering' performance counter for 'Pathoschild.ChestsAnywhere'");
+                    report.AppendLine("pc detail Display.Rendering 5                            Displays the 'Display.Rendering' performance counters exceeding an average of 5ms");
                     break;
+
                 case SubCommand.Summary:
-                    sb.AppendLine("Usage: pc summary <mode|name> <threshold>");
-                    sb.AppendLine();
-                    sb.AppendLine("Displays the performance counter summary.");
-                    sb.AppendLine();
-                    sb.AppendLine("Arguments:");
-                    sb.AppendLine("  <mode>      Optional. Defaults to 'important' if omitted. Specifies one of these modes:");
-                    sb.AppendLine("              - all        Displays performance counters from all collections");
-                    sb.AppendLine("              - important  Displays only important performance counter collections");
-                    sb.AppendLine();
-                    sb.AppendLine("  <name>      Optional. Only shows performance counter collections matching the given name");
-                    sb.AppendLine("  <threshold> Optional. Hides the actual execution time if it is below this threshold");
-                    sb.AppendLine();
-                    sb.AppendLine("Examples:");
-                    sb.AppendLine("pc summary all                Shows all events");
-                    sb.AppendLine("pc summary all 5              Shows all events");
-                    sb.AppendLine("pc summary Display.Rendering  Shows only the 'Display.Rendering' collection");
+                    report.AppendLine("Usage: pc summary <mode|name> <threshold>");
+                    report.AppendLine();
+                    report.AppendLine("Displays the performance counter summary.");
+                    report.AppendLine();
+                    report.AppendLine("Arguments:");
+                    report.AppendLine("  <mode>      Optional. Defaults to 'important' if omitted. Specifies one of these modes:");
+                    report.AppendLine("              - all        Displays performance counters from all collections");
+                    report.AppendLine("              - important  Displays only important performance counter collections");
+                    report.AppendLine();
+                    report.AppendLine("  <name>      Optional. Only shows performance counter collections matching the given name");
+                    report.AppendLine("  <threshold> Optional. Hides the actual execution time if it is below this threshold");
+                    report.AppendLine();
+                    report.AppendLine("Examples:");
+                    report.AppendLine("pc summary all                Shows all events");
+                    report.AppendLine("pc summary all 5              Shows all events");
+                    report.AppendLine("pc summary Display.Rendering  Shows only the 'Display.Rendering' collection");
                     break;
+
                 case SubCommand.Trigger:
-                    sb.AppendLine("Usage: pc trigger <mode>");
-                    sb.AppendLine("Usage: pc trigger collection <collectionName> <threshold>");
-                    sb.AppendLine("Usage: pc trigger collection <collectionName> <threshold> <sourceName>");
-                    sb.AppendLine();
-                    sb.AppendLine("Manages alert triggers.");
-                    sb.AppendLine();
-                    sb.AppendLine("Arguments:");
-                    sb.AppendLine("  <mode>           Optional. Specifies if a specific source or a specific collection should be triggered.");
-                    sb.AppendLine("                   - list        Lists current triggers");
-                    sb.AppendLine("                   - collection  Sets up a trigger for a collection");
-                    sb.AppendLine("                   - clear       Clears all trigger entries");
-                    sb.AppendLine("                   - pause       Pauses triggering of alerts");
-                    sb.AppendLine("                   - resume      Resumes triggering of alerts");
-                    sb.AppendLine("                   - dump        Dumps all triggers as commands for copy and paste");
-                    sb.AppendLine("                   Defaults to 'list' if not specified.");
-                    sb.AppendLine();
-                    sb.AppendLine("  <collectionName> Required if the mode 'collection' is specified.");
-                    sb.AppendLine("                   Specifies the name of the collection to be triggered. Must be an exact match.");
-                    sb.AppendLine();
-                    sb.AppendLine("  <sourceName>     Optional. Specifies the name of a specific source. Must be an exact match.");
-                    sb.AppendLine();
-                    sb.AppendLine("  <threshold>      Required if the mode 'collection' is specified.");
-                    sb.AppendLine("                   Specifies the threshold in milliseconds (fractions allowed).");
-                    sb.AppendLine("                   Specify '0' to remove the threshold.");
-                    sb.AppendLine();
-                    sb.AppendLine("Examples:");
-                    sb.AppendLine();
-                    sb.AppendLine("pc trigger collection Display.Rendering 10");
-                    sb.AppendLine("  Sets up an alert trigger which writes on the console if the execution time of all performance counters in");
-                    sb.AppendLine("  the 'Display.Rendering' collection exceed 10 milliseconds.");
-                    sb.AppendLine();
-                    sb.AppendLine("pc trigger collection Display.Rendering 5 Pathoschild.ChestsAnywhere");
-                    sb.AppendLine("  Sets up an alert trigger to write on the console if the execution time of Pathoschild.ChestsAnywhere in");
-                    sb.AppendLine("  the 'Display.Rendering' collection exceed 5 milliseconds.");
-                    sb.AppendLine();
-                    sb.AppendLine("pc trigger collection Display.Rendering 0");
-                    sb.AppendLine("  Removes the threshold previously defined from the collection. Note that source-specific thresholds are left intact.");
-                    sb.AppendLine();
-                    sb.AppendLine("pc trigger clear");
-                    sb.AppendLine("  Clears all previously setup alert triggers.");
+                    report.AppendLine("Usage: pc trigger <mode>");
+                    report.AppendLine("Usage: pc trigger collection <collectionName> <threshold>");
+                    report.AppendLine("Usage: pc trigger collection <collectionName> <threshold> <sourceName>");
+                    report.AppendLine();
+                    report.AppendLine("Manages alert triggers.");
+                    report.AppendLine();
+                    report.AppendLine("Arguments:");
+                    report.AppendLine("  <mode>           Optional. Specifies if a specific source or a specific collection should be triggered.");
+                    report.AppendLine("                   - list        Lists current triggers");
+                    report.AppendLine("                   - collection  Sets up a trigger for a collection");
+                    report.AppendLine("                   - clear       Clears all trigger entries");
+                    report.AppendLine("                   - pause       Pauses triggering of alerts");
+                    report.AppendLine("                   - resume      Resumes triggering of alerts");
+                    report.AppendLine("                   - dump        Dumps all triggers as commands for copy and paste");
+                    report.AppendLine("                   Defaults to 'list' if not specified.");
+                    report.AppendLine();
+                    report.AppendLine("  <collectionName> Required if the mode 'collection' is specified.");
+                    report.AppendLine("                   Specifies the name of the collection to be triggered. Must be an exact match.");
+                    report.AppendLine();
+                    report.AppendLine("  <sourceName>     Optional. Specifies the name of a specific source. Must be an exact match.");
+                    report.AppendLine();
+                    report.AppendLine("  <threshold>      Required if the mode 'collection' is specified.");
+                    report.AppendLine("                   Specifies the threshold in milliseconds (fractions allowed).");
+                    report.AppendLine("                   Specify '0' to remove the threshold.");
+                    report.AppendLine();
+                    report.AppendLine("Examples:");
+                    report.AppendLine();
+                    report.AppendLine("pc trigger collection Display.Rendering 10");
+                    report.AppendLine("  Sets up an alert trigger which writes on the console if the execution time of all performance counters in");
+                    report.AppendLine("  the 'Display.Rendering' collection exceed 10 milliseconds.");
+                    report.AppendLine();
+                    report.AppendLine("pc trigger collection Display.Rendering 5 Pathoschild.ChestsAnywhere");
+                    report.AppendLine("  Sets up an alert trigger to write on the console if the execution time of Pathoschild.ChestsAnywhere in");
+                    report.AppendLine("  the 'Display.Rendering' collection exceed 5 milliseconds.");
+                    report.AppendLine();
+                    report.AppendLine("pc trigger collection Display.Rendering 0");
+                    report.AppendLine("  Removes the threshold previously defined from the collection. Note that source-specific thresholds are left intact.");
+                    report.AppendLine();
+                    report.AppendLine("pc trigger clear");
+                    report.AppendLine("  Clears all previously setup alert triggers.");
                     break;
+
                 case SubCommand.Reset:
-                    sb.AppendLine("Usage: pc reset <type> <name>");
-                    sb.AppendLine();
-                    sb.AppendLine("Resets performance counters.");
-                    sb.AppendLine();
-                    sb.AppendLine("Arguments:");
-                    sb.AppendLine("  <type>  Optional. Specifies if a collection or source should be reset.");
-                    sb.AppendLine("          If omitted, all performance counters are reset.");
-                    sb.AppendLine();
-                    sb.AppendLine("          - source     Clears performance counters for a specific source");
-                    sb.AppendLine("          - collection Clears performance counters for a specific collection");
-                    sb.AppendLine();
-                    sb.AppendLine("  <name>  Required if a <type> is given. Specifies the name of either the collection");
-                    sb.AppendLine("          or the source. The name must be an exact match.");
-                    sb.AppendLine();
-                    sb.AppendLine("Examples:");
-                    sb.AppendLine("pc reset                                    Resets all performance counters");
-                    sb.AppendLine("pc reset source Pathoschild.ChestsAnywhere  Resets all performance for the source named Pathoschild.ChestsAnywhere");
-                    sb.AppendLine("pc reset collection Display.Rendering       Resets all performance for the collection named Display.Rendering");
+                    report.AppendLine("Usage: pc reset <type> <name>");
+                    report.AppendLine();
+                    report.AppendLine("Resets performance counters.");
+                    report.AppendLine();
+                    report.AppendLine("Arguments:");
+                    report.AppendLine("  <type>  Optional. Specifies if a collection or source should be reset.");
+                    report.AppendLine("          If omitted, all performance counters are reset.");
+                    report.AppendLine();
+                    report.AppendLine("          - source     Clears performance counters for a specific source");
+                    report.AppendLine("          - collection Clears performance counters for a specific collection");
+                    report.AppendLine();
+                    report.AppendLine("  <name>  Required if a <type> is given. Specifies the name of either the collection");
+                    report.AppendLine("          or the source. The name must be an exact match.");
+                    report.AppendLine();
+                    report.AppendLine("Examples:");
+                    report.AppendLine("pc reset                                    Resets all performance counters");
+                    report.AppendLine("pc reset source Pathoschild.ChestsAnywhere  Resets all performance for the source named Pathoschild.ChestsAnywhere");
+                    report.AppendLine("pc reset collection Display.Rendering       Resets all performance for the collection named Display.Rendering");
                     break;
             }
 
-            sb.AppendLine();
-            monitor.Log(sb.ToString(), LogLevel.Info);
+            report.AppendLine();
+            monitor.Log(report.ToString(), LogLevel.Info);
         }
 
         /// <summary>Get the command description.</summary>
         private static string GetDescription()
         {
-            StringBuilder sb = new StringBuilder();
-
-            sb.AppendLine("Displays and configures performance counters.");
-            sb.AppendLine();
-            sb.AppendLine("A performance counter records the invocation time of in-game events being");
-            sb.AppendLine("processed by mods or the game itself. See 'concepts' for a detailed explanation.");
-            sb.AppendLine();
-            sb.AppendLine("Usage: pc <command> <action>");
-            sb.AppendLine();
-            sb.AppendLine("Commands:");
-            sb.AppendLine();
-            sb.AppendLine("  summary|sum|s   Displays a summary of important or all collections");
-            sb.AppendLine("  detail|d        Shows performance counter information for a given collection");
-            sb.AppendLine("  reset|r         Resets the performance counters");
-            sb.AppendLine("  trigger         Configures alert triggers");
-            sb.AppendLine("  enable          Enables performance counter recording");
-            sb.AppendLine("  disable         Disables performance counter recording");
-            sb.AppendLine("  examples        Displays various examples");
-            sb.AppendLine("  concepts        Displays an explanation of the performance counter concepts");
-            sb.AppendLine("  help            Displays verbose help for the available commands");
-            sb.AppendLine();
-            sb.AppendLine("To get help for a specific command, use 'pc help <command>', for example:");
-            sb.AppendLine("pc help summary");
-            sb.AppendLine();
-            sb.AppendLine("Defaults to summary if no command is given.");
-            sb.AppendLine();
-
-            return sb.ToString();
+            StringBuilder report = new StringBuilder();
+
+            report.AppendLine("Displays or configures performance monitoring for diagnose issues.");
+            report.AppendLine();
+            report.AppendLine("A 'performance counter' is a metric which measures execution time across a range of time for a source (e.g. a mod).");
+            report.AppendLine("A set of performance counters is organized in a collection to group various areas.");
+            report.AppendLine("For example, the performance counter collection named 'Display.Rendered' contains one performance");
+            report.AppendLine("counter when the game executes the 'Display.Rendered' event, and another counter for each mod which handles it.");
+            report.AppendLine();
+            report.AppendLine("Usage: pc <command> <action>");
+            report.AppendLine();
+            report.AppendLine("Commands:");
+            report.AppendLine();
+            report.AppendLine("  summary    Show a summary of collections.");
+            report.AppendLine("  detail     Show a summary for a given collection.");
+            report.AppendLine("  reset      Reset all performance counters.");
+            report.AppendLine("  trigger    Configure alert triggers.");
+            report.AppendLine("  enable     Enable performance counter recording.");
+            report.AppendLine("  disable    Disable performance counter recording.");
+            report.AppendLine("  help       Show verbose help for the available commands.");
+            report.AppendLine();
+            report.AppendLine("To get help for a specific command, use 'pc help <command>', for example:");
+            report.AppendLine("pc help summary");
+            report.AppendLine();
+            report.AppendLine("Defaults to summary if no command is given.");
+            report.AppendLine();
+
+            return report.ToString();
+        }
+
+
+        /*********
+        ** Private models
+        *********/
+        /// <summary>An alert trigger for a collection.</summary>
+        private class CollectionTrigger
+        {
+            /*********
+            ** Accessors
+            *********/
+            /// <summary>The collection name.</summary>
+            public string CollectionName { get; }
+
+            /// <summary>The trigger threshold.</summary>
+            public double Threshold { get; }
+
+
+            /*********
+            ** Public methods
+            *********/
+            /// <summary>Construct an instance.</summary>
+            /// <param name="collectionName">The collection name.</param>
+            /// <param name="threshold">The trigger threshold.</param>
+            public CollectionTrigger(string collectionName, double threshold)
+            {
+                this.CollectionName = collectionName;
+                this.Threshold = threshold;
+            }
+        }
+
+        /// <summary>An alert triggered for a source.</summary>
+        private class SourceTrigger : CollectionTrigger
+        {
+            /*********
+            ** Accessors
+            *********/
+            /// <summary>The source name.</summary>
+            public string SourceName { get; }
+
+
+            /*********
+            ** Public methods
+            *********/
+            /// <summary>Construct an instance.</summary>
+            /// <param name="collectionName">The collection name.</param>
+            /// <param name="sourceName">The source name.</param>
+            /// <param name="threshold">The trigger threshold.</param>
+            public SourceTrigger(string collectionName, string sourceName, double threshold)
+                : base(collectionName, threshold)
+            {
+                this.SourceName = sourceName;
+            }
         }
     }
 }
diff --git a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/TrainerCommand.cs b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/TrainerCommand.cs
index 8f0d89ba..2b562a08 100644
--- a/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/TrainerCommand.cs
+++ b/src/SMAPI.Mods.ConsoleCommands/Framework/Commands/TrainerCommand.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -66,7 +66,7 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands
         /// <param name="data">The data to display.</param>
         /// <param name="header">The table header.</param>
         /// <param name="getRow">Returns a set of fields for a data value.</param>
-        /// <param name="rightAlign">True to right-align the data, false for left-align. Default false.</param>
+        /// <param name="rightAlign">Whether to right-align the data.</param>
         protected string GetTableString<T>(IEnumerable<T> data, string[] header, Func<T, string[]> getRow, bool rightAlign = false)
         {
             // get table data
@@ -93,19 +93,11 @@ namespace StardewModdingAPI.Mods.ConsoleCommands.Framework.Commands
             };
             lines.AddRange(rows);
 
-            if (rightAlign)
-            {
-                return string.Join(
-                    Environment.NewLine,
-                    lines.Select(line => string.Join(" | ", line.Select((field, i) => field.PadLeft(widths[i], ' ')).ToArray())
-                    )
-                );
-            }
-
             return string.Join(
                 Environment.NewLine,
-                lines.Select(line => string.Join(" | ", line.Select((field, i) => field.PadRight(widths[i], ' ')).ToArray())
-                )
+                lines.Select(line => string.Join(" | ",
+                    line.Select((field, i) => rightAlign ? field.PadRight(widths[i], ' ') : field.PadLeft(widths[i], ' '))
+                ))
             );
         }
     }