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using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using IPA.Config;
using IPA.Logging;
using IPA.Utilities;
#if NET3
using Net3_Proxy;
#endif
namespace IPA.Loader
{
/// <summary>
/// The type that handles value injecting into a plugin's Init.
/// </summary>
public static class PluginInitInjector
{
/// <summary>
/// A typed injector for a plugin's Init method. When registered, called for all associated types. If it returns null, the default for the type will be used.
/// </summary>
/// <param name="previous">the previous return value of the function, or <see langword="null"/> if never called for plugin.</param>
/// <param name="param">the <see cref="ParameterInfo"/> of the parameter being injected.</param>
/// <param name="meta">the <see cref="PluginLoader.PluginMetadata"/> for the plugin being loaded.</param>
/// <returns>the value to inject into that parameter.</returns>
public delegate object InjectParameter(object previous, ParameterInfo param, PluginLoader.PluginMetadata meta);
/// <summary>
/// Adds an injector to be used when calling future plugins' Init methods.
/// </summary>
/// <param name="type">the type of the parameter.</param>
/// <param name="injector">the function to call for injection.</param>
public static void AddInjector(Type type, InjectParameter injector)
{
injectors.Add(new TypedInjector(type, injector));
}
private struct TypedInjector : IEquatable<TypedInjector>
{
public Type Type;
public InjectParameter Injector;
public TypedInjector(Type t, InjectParameter i)
{ Type = t; Injector = i; }
public object Inject(object prev, ParameterInfo info, PluginLoader.PluginMetadata meta)
=> Injector(prev, info, meta);
public bool Equals(TypedInjector other)
=> Type == other.Type && Injector == other.Injector;
public override bool Equals(object obj)
=> obj is TypedInjector i && Equals(i);
public override int GetHashCode()
=> Type.GetHashCode() ^ Injector.GetHashCode();
public static bool operator ==(TypedInjector a, TypedInjector b) => a.Equals(b);
public static bool operator !=(TypedInjector a, TypedInjector b) => !a.Equals(b);
}
private static readonly List<TypedInjector> injectors = new List<TypedInjector>
{
new TypedInjector(typeof(Logger), (prev, param, meta) => prev ?? new StandardLogger(meta.Name)),
#pragma warning disable CS0618 // Type or member is obsolete
new TypedInjector(typeof(IModPrefs), (prev, param, meta) => prev ?? new ModPrefs(meta)),
#pragma warning restore CS0618 // Type or member is obsolete
new TypedInjector(typeof(PluginLoader.PluginMetadata), (prev, param, meta) => prev ?? meta),
new TypedInjector(typeof(IConfigProvider), (prev, param, meta) =>
{
if (prev != null) return prev;
var cfgProvider = Config.Config.GetProviderFor(meta.Name, param);
cfgProvider.Load();
return cfgProvider;
})
};
private static int? MatchPriority(Type target, Type source)
{
if (target == source) return int.MaxValue;
if (!target.IsAssignableFrom(source)) return null;
if (!target.IsInterface && !source.IsSubclassOf(target)) return int.MinValue;
int value = 0;
while (true)
{
if (source == null) return value;
if (target.IsInterface && source.GetInterfaces().Contains(target))
return value;
else if (target == source)
return value;
else
{
value--; // lower priority
source = source.BaseType;
}
}
}
internal static void Inject(MethodInfo init, PluginLoader.PluginInfo info)
{
var instance = info.Plugin;
var meta = info.Metadata;
var initArgs = new List<object>();
var initParams = init.GetParameters();
var previousValues = new Dictionary<TypedInjector, object>(injectors.Count);
foreach (var param in initParams)
{
var paramType = param.ParameterType;
var value = paramType.GetDefault();
var toUse = injectors.Select(i => (inject: i, priority: MatchPriority(paramType, i.Type))) // check match priority, combine it
.Where(t => t.priority != null) // filter null priorities
.Select(t => (t.inject, priority: t.priority.Value)) // remove nullable
.OrderByDescending(t => t.priority) // sort by value
.Select(t => t.inject); // remove priority value
// this tries injectors in order of closest match by type provided
foreach (var pair in toUse)
{
object prev = null;
if (previousValues.ContainsKey(pair))
prev = previousValues[pair];
var val = pair.Inject(prev, param, meta);
if (previousValues.ContainsKey(pair))
previousValues[pair] = val;
else
previousValues.Add(pair, val);
if (val == null) continue;
value = val;
break;
}
initArgs.Add(value);
}
init.Invoke(instance, initArgs.ToArray());
}
}
}