using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace PlebSkylinesLauncher.Helpers
{
    public class DllInjector
    {
        private static readonly IntPtr IntptrZero = (IntPtr)0;

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr OpenProcess(uint dwDesiredAccess, int bInheritHandle, uint dwProcessId);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern int CloseHandle(IntPtr hObject);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string lpModuleName);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, uint flAllocationType, uint flProtect);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern int WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] buffer, uint size, int lpNumberOfBytesWritten);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttribute, IntPtr dwStackSize, IntPtr lpStartAddress,
            IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);

        public static DllInjectionResult Inject(Process process, string dllPath)
        {
            if (!File.Exists(dllPath))
            {
                return DllInjectionResult.DllNotFound;
            }

            if (!PerformInjection((uint)process.Id, dllPath))
            {
                return DllInjectionResult.InjectionFailed;
            }

            return DllInjectionResult.Success;
        }

        private static bool PerformInjection(uint targetProcess, string dllPath)
        {
            var hndProc = OpenProcess(0x2 | 0x8 | 0x10 | 0x20 | 0x400, 1, targetProcess);

            if (hndProc == IntptrZero)
            {
                return false;
            }

            var lpLlAddress = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");

            if (lpLlAddress == IntptrZero)
            {
                return false;
            }

            var lpAddress = VirtualAllocEx(hndProc, (IntPtr)null, (IntPtr)dllPath.Length, (0x1000 | 0x2000), 0X40);

            if (lpAddress == IntptrZero)
            {
                return false;
            }

            var bytes = Encoding.ASCII.GetBytes(dllPath);

            if (WriteProcessMemory(hndProc, lpAddress, bytes, (uint)bytes.Length, 0) == 0)
            {
                return false;
            }

            if (CreateRemoteThread(hndProc, (IntPtr)null, IntptrZero, lpLlAddress, lpAddress, 0, (IntPtr)null) == IntptrZero)
            {
                return false;
            }

            CloseHandle(hndProc);

            return true;
        }
    }
}