// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// Copyright (C) LibreHardwareMonitor and Contributors.
// Partial Copyright (C) Michael Möller <mmoeller@openhardwaremonitor.org> and Contributors.
// All Rights Reserved.

using System;
using System.Runtime.InteropServices;
using System.Text;

namespace LibreHardwareMonitor.Hardware
{
    internal static class FirmwareTable
    {
        public static byte[] GetTable(Interop.Kernel32.Provider provider, string table)
        {
            int id = table[3] << 24 | table[2] << 16 | table[1] << 8 | table[0];
            return GetTable(provider, id);
        }

        public static byte[] GetTable(Interop.Kernel32.Provider provider, int table)
        {
            int size;
            try
            {
                size = Interop.Kernel32.GetSystemFirmwareTable(provider, table, IntPtr.Zero, 0);
            }
            catch (DllNotFoundException)
            {
                return null;
            }
            catch (EntryPointNotFoundException)
            {
                return null;
            }

            if (size <= 0)
                return null;


            IntPtr nativeBuffer = Marshal.AllocHGlobal(size);
            Interop.Kernel32.GetSystemFirmwareTable(provider, table, nativeBuffer, size);

            if (Marshal.GetLastWin32Error() != 0)
                return null;


            byte[] buffer = new byte[size];
            Marshal.Copy(nativeBuffer, buffer, 0, size);
            Marshal.FreeHGlobal(nativeBuffer);
            return buffer;
        }

        public static string[] EnumerateTables(Interop.Kernel32.Provider provider)
        {
            int size;
            try
            {
                size = Interop.Kernel32.EnumSystemFirmwareTables(provider, IntPtr.Zero, 0);
            }
            catch (DllNotFoundException)
            {
                return null;
            }
            catch (EntryPointNotFoundException)
            {
                return null;
            }

            IntPtr nativeBuffer = Marshal.AllocHGlobal(size);
            Interop.Kernel32.EnumSystemFirmwareTables(provider, nativeBuffer, size);
            byte[] buffer = new byte[size];
            Marshal.Copy(nativeBuffer, buffer, 0, size);
            Marshal.FreeHGlobal(nativeBuffer);

            string[] result = new string[size / 4];
            for (int i = 0; i < result.Length; i++)
                result[i] = Encoding.ASCII.GetString(buffer, 4 * i, 4);

            return result;
        }
    }
}