using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using HarmonyLib;
using Sandbox.Definitions;
using Sandbox.Engine.Networking;
using Sandbox.Game.World;
using VRage.Game;

namespace Plugin.ClientModLoader;

[HarmonyPatch]
internal static class ModInjector
{
    public static HashSet<ulong> Mods = [];
    private static readonly List<MyObjectBuilder_Checkpoint.ModItem> AdditionalFilledModItems = [];

    [HarmonyPatch(typeof(MyWorkshop), nameof(MyWorkshop.DownloadWorldModsBlockingInternal))]
    [HarmonyPrefix]
    private static void DownloadModsBlockingPrefix(ref List<MyObjectBuilder_Checkpoint.ModItem> mods, ref List<MyObjectBuilder_Checkpoint.ModItem> __state)
    {
        AdditionalFilledModItems.Clear();
        __state = mods;
        AppendToList(ref mods);
    }

    [HarmonyPatch(typeof(MyWorkshop), nameof(MyWorkshop.DownloadWorldModsBlockingInternal))]
    [HarmonyPostfix]
    private static void DownloadModsBlockingPostfix(List<MyObjectBuilder_Checkpoint.ModItem> mods, List<MyObjectBuilder_Checkpoint.ModItem> __state)
    {
        foreach (var mod in mods)
        {
            var index = __state.FindIndex(b =>
                b.PublishedFileId == mod.PublishedFileId && b.PublishedServiceName == mod.PublishedServiceName);
            
            if (index != -1)
            {
                var stateMod = __state[index];
                stateMod.SetModData(mod.GetModData());
                __state[index] = stateMod;
            }
            else if (Mods.Contains(mod.PublishedFileId))
                AdditionalFilledModItems.Add(mod);
            else
                __state.Add(mod);
        }
    }

    [HarmonyPatch(typeof(MyWorkshop), nameof(MyWorkshop.DownloadModsAsync))]
    [HarmonyTranspiler]
    private static IEnumerable<CodeInstruction> DownloadModsAsyncTranspiler(IEnumerable<CodeInstruction> instructions)
    {
        var getCount = AccessTools.PropertyGetter(typeof(List<MyObjectBuilder_Checkpoint.ModItem>), nameof(List<MyObjectBuilder_Checkpoint.ModItem>.Count));
        return new CodeMatcher(instructions)
            .SearchForward(b => b.Calls(getCount))
            .Advance(1)
            .Insert(
                CodeInstruction.LoadField(typeof(ModInjector), nameof(Mods)),
                new(OpCodes.Callvirt, AccessTools.PropertyGetter(typeof(HashSet<ulong>), nameof(HashSet<ulong>.Count))),
                new(OpCodes.Add)
            )
            .Instructions();
    }
    
    [HarmonyPatch(typeof(MyDefinitionManager), nameof(MyDefinitionManager.LoadData))]
    [HarmonyPrefix]
    private static void LoadDefinitionsPrefix(ref List<MyObjectBuilder_Checkpoint.ModItem> mods) => AppendToList(ref mods);

    [HarmonyPatch(typeof(MyScriptManager), nameof(MyScriptManager.LoadData))]
    [HarmonyTranspiler]
    private static IEnumerable<CodeInstruction> LoadScriptsTranspiler(IEnumerable<CodeInstruction> instructions, ILGenerator generator)
    {
        var staticGetter = AccessTools.PropertyGetter(typeof(MySession), nameof(MySession.Static));
        var modsGetter = AccessTools.PropertyGetter(typeof(MySession), nameof(MySession.Mods));
        return new CodeMatcher(instructions, generator)
            .Start()
            .DeclareLocal(typeof(List<MyObjectBuilder_Checkpoint.ModItem>), out var modsLocal)
            .CreateLabel(out var start)
            .InsertAndAdvance(
                new(OpCodes.Call, staticGetter),
                new(OpCodes.Call, modsGetter),
                new(OpCodes.Stloc, modsLocal),
                new(OpCodes.Ldloc, modsLocal),
                new(OpCodes.Brfalse, start),
                new(OpCodes.Ldloca, modsLocal),
                CodeInstruction.Call(typeof(ModInjector), nameof(AppendToList))
            )
            .MatchStartForward(CodeMatch.Calls(staticGetter), CodeMatch.Calls(modsGetter))
            .Repeat(a => a
                .SetAndAdvance(OpCodes.Ldloc, modsLocal)
                .SetAndAdvance(OpCodes.Nop, null))
            .Instructions();
    }

    private static void AppendToList(ref List<MyObjectBuilder_Checkpoint.ModItem> mods)
    {
        // copy
        mods = mods.ToList();

        mods.AddRange(AdditionalFilledModItems.Count > 0
            ? AdditionalFilledModItems
            : Mods.Select(mod => new MyObjectBuilder_Checkpoint.ModItem(mod, "Steam")));
    }
}