1 files changed, 187 insertions, 0 deletions
diff --git a/src/SMAPI/Framework/Deprecations/DeprecationManager.cs b/src/SMAPI/Framework/Deprecations/DeprecationManager.cs
new file mode 100644
index 00000000..288abde2
--- /dev/null
+++ b/src/SMAPI/Framework/Deprecations/DeprecationManager.cs
@@ -0,0 +1,187 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+
+namespace StardewModdingAPI.Framework.Deprecations
+{
+    /// <summary>Manages deprecation warnings.</summary>
+    internal class DeprecationManager
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The deprecations which have already been logged (as 'mod name::noun phrase::version').</summary>
+        private readonly HashSet<string> LoggedDeprecations = new(StringComparer.OrdinalIgnoreCase);
+
+        /// <summary>Encapsulates monitoring and logging for a given module.</summary>
+        private readonly IMonitor Monitor;
+
+        /// <summary>Tracks the installed mods.</summary>
+        private readonly ModRegistry ModRegistry;
+
+        /// <summary>The queued deprecation warnings to display.</summary>
+        private readonly IList<DeprecationWarning> QueuedWarnings = new List<DeprecationWarning>();
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="monitor">Encapsulates monitoring and logging for a given module.</param>
+        /// <param name="modRegistry">Tracks the installed mods.</param>
+        public DeprecationManager(IMonitor monitor, ModRegistry modRegistry)
+        {
+            this.Monitor = monitor;
+            this.ModRegistry = modRegistry;
+        }
+
+        /// <summary>Get a mod for the closest assembly registered as a source of deprecation warnings.</summary>
+        /// <returns>Returns the source name, or <c>null</c> if no registered assemblies were found.</returns>
+        public IModMetadata? GetModFromStack()
+        {
+            return this.ModRegistry.GetFromStack();
+        }
+
+        /// <summary>Get a mod from its unique ID.</summary>
+        /// <param name="modId">The mod's unique ID.</param>
+        public IModMetadata? GetMod(string modId)
+        {
+            return this.ModRegistry.Get(modId);
+        }
+
+        /// <summary>Log a deprecation warning.</summary>
+        /// <param name="source">The mod which used the deprecated code, if known.</param>
+        /// <param name="nounPhrase">A noun phrase describing what is deprecated.</param>
+        /// <param name="version">The SMAPI version which deprecated it.</param>
+        /// <param name="severity">How deprecated the code is.</param>
+        /// <param name="unlessStackIncludes">A list of stack trace substrings which should suppress deprecation warnings if they appear in the stack trace.</param>
+        /// <param name="logStackTrace">Whether to log a stack trace showing where the deprecated code is in the mod.</param>
+        public void Warn(IModMetadata? source, string nounPhrase, string version, DeprecationLevel severity, string[]? unlessStackIncludes = null, bool logStackTrace = true)
+        {
+            // skip if already warned
+            string cacheKey = $"{source?.DisplayName ?? "<unknown>"}::{nounPhrase}::{version}";
+            if (this.LoggedDeprecations.Contains(cacheKey))
+                return;
+
+            // warn if valid
+            ImmutableStackTrace stack = ImmutableStackTrace.Get(skipFrames: 1);
+            if (!this.ShouldSuppress(stack, unlessStackIncludes))
+            {
+                this.LoggedDeprecations.Add(cacheKey);
+                this.QueuedWarnings.Add(new DeprecationWarning(source, nounPhrase, version, severity, stack, logStackTrace));
+            }
+        }
+
+        /// <summary>A placeholder method used to track deprecated code for which a separate warning will be shown.</summary>
+        /// <param name="version">The SMAPI version which deprecated it.</param>
+        /// <param name="severity">How deprecated the code is.</param>
+        public void PlaceholderWarn(string version, DeprecationLevel severity) { }
+
+        /// <summary>Print any queued messages.</summary>
+        public void PrintQueued()
+        {
+            foreach (DeprecationWarning warning in this.QueuedWarnings.OrderBy(p => p.ModName).ThenBy(p => p.NounPhrase))
+            {
+                // build message
+                string message = $"{warning.ModName} uses deprecated code ({warning.NounPhrase} is deprecated since SMAPI {warning.Version}).";
+
+                // get log level
+                LogLevel level;
+                switch (warning.Level)
+                {
+                    case DeprecationLevel.Notice:
+                        level = LogLevel.Trace;
+                        break;
+
+                    case DeprecationLevel.Info:
+                        level = LogLevel.Debug;
+                        break;
+
+                    case DeprecationLevel.PendingRemoval:
+                        level = LogLevel.Warn;
+                        break;
+
+                    default:
+                        throw new NotSupportedException($"Unknown deprecation level '{warning.Level}'.");
+                }
+
+                // log message
+                if (level == LogLevel.Trace)
+                {
+                    if (warning.LogStackTrace)
+                        message += $"\n{this.GetSimplifiedStackTrace(warning.StackTrace, warning.Mod)}";
+                    this.Monitor.Log(message, level);
+                }
+                else
+                {
+                    this.Monitor.Log(message, level);
+                    if (warning.LogStackTrace)
+                        this.Monitor.Log(this.GetSimplifiedStackTrace(warning.StackTrace, warning.Mod), LogLevel.Debug);
+                }
+            }
+
+            this.QueuedWarnings.Clear();
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get whether a deprecation warning should be suppressed.</summary>
+        /// <param name="stack">The stack trace for which it was raised.</param>
+        /// <param name="unlessStackIncludes">A list of stack trace substrings which should suppress deprecation warnings if they appear in the stack trace.</param>
+        private bool ShouldSuppress(ImmutableStackTrace stack, string[]? unlessStackIncludes)
+        {
+            if (unlessStackIncludes?.Any() == true)
+            {
+                string stackTrace = stack.ToString();
+                foreach (string method in unlessStackIncludes)
+                {
+                    if (stackTrace.Contains(method))
+                        return true;
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>Get the simplest stack trace which shows where in the mod the deprecated code was called from.</summary>
+        /// <param name="stack">The stack trace.</param>
+        /// <param name="mod">The mod for which to show a stack trace.</param>
+        private string GetSimplifiedStackTrace(ImmutableStackTrace stack, IModMetadata? mod)
+        {
+            // unknown mod, show entire stack trace
+            if (mod == null)
+                return stack.ToString();
+
+            // get frame info
+            var frames = stack
+                .GetFrames()
+                .Select(frame => (Frame: frame, Mod: this.ModRegistry.GetFrom(frame)))
+                .ToArray();
+            var modIds = new HashSet<string>(
+                from frame in frames
+                let id = frame.Mod?.Manifest.UniqueID
+                where id != null
+                select id
+            );
+
+            // can't filter to the target mod
+            if (modIds.Count != 1 || !modIds.Contains(mod.Manifest.UniqueID))
+                return stack.ToString();
+
+            // get stack frames for the target mod, plus one for context
+            var framesStartingAtMod = frames.SkipWhile(p => p.Mod == null).ToArray();
+            var displayFrames = framesStartingAtMod.TakeWhile(p => p.Mod != null).ToArray();
+            displayFrames = displayFrames.Concat(framesStartingAtMod.Skip(displayFrames.Length).Take(1)).ToArray();
+
+            // build stack trace
+            StringBuilder str = new();
+            foreach (var frame in displayFrames)
+                str.Append(new StackTrace(frame.Frame));
+            return str.ToString().TrimEnd();
+        }
+    }
+}