BepInEx/BepInEx.Preloader.Core/Patching/PatcherContext.cs

using System.Collections.Generic;
using System.Reflection;
using Mono.Cecil;

namespace BepInEx.Preloader.Core.Patching
{
    /// <summary>
    ///     A definition of an individual patch for use by <see cref="AssemblyPatcher"/>.
    /// </summary>
    public class PatchDefinition
    {
        public PatchDefinition(TargetAssemblyAttribute targetAssembly, BasePatcher instance, MethodInfo methodInfo)
        {
            TargetAssembly = targetAssembly;
            Instance = instance;
            MethodInfo = methodInfo;

            FullName = $"{MethodInfo.DeclaringType.FullName}/{MethodInfo.Name} -> {TargetAssembly.TargetAssembly}";
        }

        public PatchDefinition(TargetTypeAttribute targetType, BasePatcher instance, MethodInfo methodInfo)
        {
            TargetType = targetType;
            Instance = instance;
            MethodInfo = methodInfo;

            FullName =
                $"{MethodInfo.DeclaringType.FullName}/{MethodInfo.Name} -> {TargetType.TargetAssembly}/{TargetType.TargetType}";
        }

        /// <summary>
        ///     The assembly / assemblies this patch will target, if there any.
        /// </summary>
        public TargetAssemblyAttribute TargetAssembly { get; } = null;

        /// <summary>
        ///     The type / types this patch will target, if there are any.
        /// </summary>
        public TargetTypeAttribute TargetType { get; } = null;

        /// <summary>
        ///     The instance of the <see cref="BasePatcher"/> this <see cref="PatchDefinition"/> originates from.
        /// </summary>
        public BasePatcher Instance { get; }

        /// <summary>
        ///     The method that will perform the patching logic defined by this <see cref="PatchDefinition"/> instance.
        /// </summary>
        public MethodInfo MethodInfo { get; }

        /// <summary>
        ///     A friendly name for this patch definition, for use in logging and error tracking.
        /// </summary>
        public string FullName { get; }
    }

    /// <summary>
    /// Context provided to patcher plugins from the associated patcher engine.
    /// </summary>
    public class PatcherContext
    {
        /// <summary>
        ///     <para>Contains a list of assemblies that will be patched and loaded into the runtime.</para>
        ///     <para>
        ///         The dictionary has the name of the file, without any directories. These are used by the dumping
        ///         functionality, and as such, these are also required to be unique. They do not have to be exactly the same as
        ///         the real filename, however they have to be mapped deterministically.
        ///     </para>
        ///     <para>Order is not respected, as it will be sorted by dependencies.</para>
        /// </summary>
        public Dictionary<string, AssemblyDefinition> AvailableAssemblies { get; } = new();

        /// <summary>
        ///     <para>Contains a dictionary of assemblies that have been loaded as part of executing this assembly patcher.</para>
        ///     <para>
        ///         The key is the same key as used in <see cref="LoadedAssemblies" />, while the value is the actual assembly
        ///         itself.
        ///     </para>
        /// </summary>
        public Dictionary<string, Assembly> LoadedAssemblies { get; } = new();

        /// <summary>
        ///     A list of plugins that will be initialized and executed, in the order of the list.
        /// </summary>
        public List<BasePatcher> PatcherPlugins { get; } = new();

        /// <summary>
        ///     A list of individual patches that <see cref="AssemblyPatcher"/> will execute, generated by parsing <see cref="PatcherPlugins"/>.
        /// </summary>
        public List<PatchDefinition> PatchDefinitions { get; } = new();

        /// <summary>
        ///     The directory location as to where patched assemblies will be saved to and loaded from disk, for debugging
        ///     purposes. Defaults to BepInEx/DumpedAssemblies/<ProcessName>
        /// </summary>
        public string DumpedAssembliesPath { get; internal set; }
    }
}