using System;
using System.Runtime.InteropServices;
using Dalamud.Game.Text.SeStringHandling;
using Dalamud.Hooking;

namespace NominaOcculta {
    internal class GameFunctions : IDisposable {
        private static class Signatures {
            internal const string GenerateName = "E8 ?? ?? ?? ?? 48 8D 8B ?? ?? ?? ?? E8 ?? ?? ?? ?? 48 85 C0 74 1B 48 8D 8B ?? ?? ?? ?? E8 ?? ?? ?? ?? 48 8B 8B ?? ?? ?? ?? 48 8B D0 E8 ?? ?? ?? ?? 48 8B CB 48 8B 7C 24";
            internal const string Utf8StringCtor = "E8 ?? ?? ?? ?? 44 2B F7";
            internal const string Utf8StringDtor = "80 79 21 00 75 12";
            internal const string AtkTextNodeSetText = "E8 ?? ?? ?? ?? 49 8B FC";
            internal const string LoadExd = "40 53 56 57 48 81 EC ?? ?? ?? ?? 48 8B 05 ?? ?? ?? ?? 48 33 C4 48 89 84 24 ?? ?? ?? ?? 41 0F B6 D9";
        }

        private delegate IntPtr GenerateNameDelegate(int race, int clan, int gender, IntPtr first, IntPtr last);

        private delegate IntPtr Utf8StringCtorDelegate(IntPtr memory);

        private delegate void Utf8StringDtorDelegate(IntPtr memory);

        private delegate void AtkTextNodeSetTextDelegate(IntPtr node, IntPtr text);

        private delegate byte LoadExdDelegate(IntPtr a1, string sheetName, byte a3, byte a4);

        private delegate IntPtr GetExcelModuleDelegate(IntPtr uiModule);

        private Utf8StringCtorDelegate Utf8StringCtor { get; }
        private Utf8StringDtorDelegate Utf8StringDtor { get; }
        private GenerateNameDelegate InternalGenerateName { get; }
        private LoadExdDelegate LoadExd { get; }

        private Hook<AtkTextNodeSetTextDelegate> AtkTextNodeSetTextHook { get; }

        internal delegate void AtkTextNodeSetTextEventDelegate(IntPtr node, IntPtr text, ref SeString? overwrite);
        internal event AtkTextNodeSetTextEventDelegate? AtkTextNodeSetText;

        private Plugin Plugin { get; }

        private IntPtr First { get; }
        private IntPtr Last { get; }

        internal GameFunctions(Plugin plugin) {
            this.Plugin = plugin;

            this.Utf8StringCtor = Marshal.GetDelegateForFunctionPointer<Utf8StringCtorDelegate>(this.Plugin.SigScanner.ScanText(Signatures.Utf8StringCtor));
            this.Utf8StringDtor = Marshal.GetDelegateForFunctionPointer<Utf8StringDtorDelegate>(this.Plugin.SigScanner.ScanText(Signatures.Utf8StringDtor));
            this.InternalGenerateName = Marshal.GetDelegateForFunctionPointer<GenerateNameDelegate>(this.Plugin.SigScanner.ScanText(Signatures.GenerateName));
            this.LoadExd = Marshal.GetDelegateForFunctionPointer<LoadExdDelegate>(this.Plugin.SigScanner.ScanText(Signatures.LoadExd));

            this.AtkTextNodeSetTextHook = new Hook<AtkTextNodeSetTextDelegate>(
                this.Plugin.SigScanner.ScanText(Signatures.AtkTextNodeSetText),
                this.OnAtkTextNodeSetText
            );
            this.AtkTextNodeSetTextHook.Enable();

            this.First = Marshal.AllocHGlobal(128);
            this.Last = Marshal.AllocHGlobal(128);

            this.Utf8StringCtor(this.First);
            this.Utf8StringCtor(this.Last);
        }

        public void Dispose() {
            this.Utf8StringDtor(this.Last);
            this.Utf8StringDtor(this.First);
            Marshal.FreeHGlobal(this.Last);
            Marshal.FreeHGlobal(this.First);
            this.AtkTextNodeSetTextHook.Dispose();
        }

        private unsafe void OnAtkTextNodeSetText(IntPtr node, IntPtr text) {
            SeString? overwrite = null;
            this.AtkTextNodeSetText?.Invoke(node, text, ref overwrite);

            if (overwrite != null) {
                fixed (byte* newText = overwrite.Encode().Terminate()) {
                    this.AtkTextNodeSetTextHook.Original(node, (IntPtr) newText);
                }

                return;
            }

            this.AtkTextNodeSetTextHook.Original(node, text);
        }

        public string? GenerateName(int race, int clan, int gender) {
            this.InternalGenerateName(race, clan, gender, this.First, this.Last);

            var first = Marshal.PtrToStringUTF8(Marshal.ReadIntPtr(this.First));
            var last = Marshal.PtrToStringUTF8(Marshal.ReadIntPtr(this.Last));

            if (string.IsNullOrEmpty(first) || string.IsNullOrEmpty(last)) {
                return null;
            }

            return $"{first} {last}";
        }

        public unsafe void LoadSheet(string name) {
            var ui = this.Plugin.Common.Functions.GetUiModule();
            var getExcelModulePtr = *(*(IntPtr**) ui + 5);
            var getExcelModule = Marshal.GetDelegateForFunctionPointer<GetExcelModuleDelegate>(getExcelModulePtr);
            var excelModule = getExcelModule(ui);
            var exdModule = *(IntPtr*) (excelModule + 8);
            var excel = *(IntPtr*) (exdModule + 0x20);

            this.LoadExd(excel, name, 0, 1);
        }
    }
}