gregExtractor/Services/DiffService.cs

using gregExtractor.Models;

namespace gregExtractor.Services;

public sealed class DiffService
{
    public HookDiff Diff(List<HookDefinition> oldHooks, List<HookDefinition> newHooks)
    {
        oldHooks ??= new List<HookDefinition>();
        newHooks ??= new List<HookDefinition>();

        Dictionary<string, HookDefinition> oldMap = oldHooks
            .GroupBy(GetKey)
            .ToDictionary(group => group.Key, group => group.Last(), StringComparer.Ordinal);

        Dictionary<string, HookDefinition> newMap = newHooks
            .GroupBy(GetKey)
            .ToDictionary(group => group.Key, group => group.Last(), StringComparer.Ordinal);

        HookDefinition[] added = newMap
            .Where(pair => !oldMap.ContainsKey(pair.Key))
            .Select(pair => pair.Value)
            .OrderBy(x => x.Group, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.ClassName, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.MethodName, StringComparer.OrdinalIgnoreCase)
            .ToArray();

        HookDefinition[] removed = oldMap
            .Where(pair => !newMap.ContainsKey(pair.Key))
            .Select(pair => pair.Value)
            .OrderBy(x => x.Group, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.ClassName, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.MethodName, StringComparer.OrdinalIgnoreCase)
            .ToArray();

        HookDefinition[] changed = newMap
            .Where(pair => oldMap.TryGetValue(pair.Key, out HookDefinition? oldHook) && HasSignatureChange(oldHook, pair.Value))
            .Select(pair => pair.Value)
            .OrderBy(x => x.Group, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.ClassName, StringComparer.OrdinalIgnoreCase)
            .ThenBy(x => x.MethodName, StringComparer.OrdinalIgnoreCase)
            .ToArray();

        return new HookDiff(added, removed, changed);
    }

    public static string GetKey(HookDefinition hook)
    {
        return Normalize($"{hook.Namespace}.{hook.ClassName}::{hook.MethodName}");
    }

    private static bool HasSignatureChange(HookDefinition oldHook, HookDefinition newHook)
    {
        if (!string.Equals(Normalize(oldHook.ReturnType), Normalize(newHook.ReturnType), StringComparison.Ordinal))
            return true;

        if (oldHook.Parameters.Count != newHook.Parameters.Count)
            return true;

        for (int i = 0; i < oldHook.Parameters.Count; i++)
        {
            HookParameter oldParameter = oldHook.Parameters[i];
            HookParameter newParameter = newHook.Parameters[i];

            if (!string.Equals(Normalize(oldParameter.Type), Normalize(newParameter.Type), StringComparison.Ordinal))
                return true;

            if (!string.Equals(Normalize(oldParameter.Name), Normalize(newParameter.Name), StringComparison.Ordinal))
                return true;
        }

        return false;
    }

    private static string Normalize(string value)
    {
        return (value ?? string.Empty)
            .Replace("global::", string.Empty)
            .Replace(" ", string.Empty)
            .Trim();
    }
}