// File: Services/WinApi.cs

using System.Runtime.InteropServices;

namespace WebmrAPI.Services
{
    public static class WinApi
    {
        public const uint PROCESS_QUERY_INFORMATION = 0x00000400;
        public const uint PROCESS_VM_READ           = 0x00000010;
        public const uint PROCESS_VM_OPERATION      = 0x00000008;

        public const uint MEM_COMMIT                = 0x00001000;
        public const uint MEM_FREE                  = 0x00010000;
        public const uint MEM_RESERVE               = 0x00002000;

        public const uint MEM_IMAGE                 = 0x01000000;
        public const uint MEM_MAPPED                = 0x00040000;
        public const uint MEM_PRIVATE               = 0x00020000;

        public static int  LastError { get => Marshal.GetLastWin32Error(); }
        public static uint MBISize   { get => (uint)Marshal.SizeOf(typeof(MEMORY_BASIC_INFORMATION)); }

        private static string GetHexValue(uint data)
        {
            return $"0x{data:X8}";
        }

        public static string GetStateString(uint state)
        {
            switch (state)
            {
                case MEM_COMMIT:  return "MEM_COMMIT";
                case MEM_FREE:    return "MEM_FREE";
                case MEM_RESERVE: return "MEM_RESERVE";
                default: return GetHexValue(state);
            }
        }

        public static string GetProtectString(uint protect)
        {
            switch (protect)
            {
                default: return GetHexValue(protect);
            }
        }

        public static string GetTypeString(uint type)
        {
            switch (type)
            {
                case MEM_IMAGE:   return "MEM_IMAGE";
                case MEM_MAPPED:  return "MEM_MAPPED";
                case MEM_PRIVATE: return "MEM_PRIVATE";
                default: return GetHexValue(type);
            }
        }

        // https://learn.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-memory_basic_information
        [StructLayout(LayoutKind.Sequential)]
        public struct MEMORY_BASIC_INFORMATION
        {
            public IntPtr BaseAddress;
            public IntPtr AllocationBase;
            public uint AllocationProtect;
            public ushort PartitionId;
            public UIntPtr RegionSize;
            public uint State;
            public uint Protect;
            public uint Type;
        }


        // https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-openprocess
        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern IntPtr OpenProcess(
            uint dwDesiredAccess,
            [MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
            uint dwProcessId
        );

        // https://learn.microsoft.com/en-us/windows/win32/api/handleapi/nf-handleapi-closehandle
        [DllImport("kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool CloseHandle(IntPtr hObject);

        // https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-virtualqueryex
        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern int VirtualQueryEx(
            IntPtr hProcess,
            IntPtr lpAddress,
            out MEMORY_BASIC_INFORMATION lpBuffer,
            uint dwLength
        );
    }
}