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

namespace HikvisionAttendanceService.Interop;

internal static class HikvisionTemplateInterop
{
    // These wrappers allow template query/delete/sync with direct HCNetSDK.dll calls.
    [DllImport("HCNetSDK.dll", CallingConvention = CallingConvention.StdCall)]
    private static extern bool NET_DVR_SetDeviceConfig(
        int lUserID,
        uint dwCommand,
        int lChannel,
        IntPtr lpInBuffer,
        uint dwInBufferSize,
        IntPtr lpStatusList,
        IntPtr lpInParamBuffer,
        uint dwInParamBufferSize);

    [DllImport("HCNetSDK.dll", CallingConvention = CallingConvention.StdCall)]
    private static extern bool NET_DVR_GetDeviceConfig(
        int lUserID,
        uint dwCommand,
        int lChannel,
        IntPtr lpOutBuffer,
        uint dwOutBufferSize,
        ref uint lpBytesReturned,
        IntPtr lpStatusList,
        IntPtr lpInParamBuffer,
        uint dwInParamBufferSize);

    // Command IDs are the official ACS face/fingerprint config commands.
    private const uint NET_DVR_SET_FACE_PARAM_CFG = 2568;
    private const uint NET_DVR_GET_FACE_PARAM_CFG = 2569;
    private const uint NET_DVR_DEL_FACE_PARAM_CFG = 2570;
    private const uint NET_DVR_SET_FINGERPRINT_PARAM = 2573;
    private const uint NET_DVR_GET_FINGERPRINT_PARAM = 2574;
    private const uint NET_DVR_DEL_FINGERPRINT_PARAM = 2575;

    [StructLayout(LayoutKind.Sequential)]
    internal struct NET_DVR_FACE_PARAM_CFG
    {
        public uint dwSize;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
        public byte[] byCardNo;
        public uint dwFaceLen;
        public IntPtr pFaceBuffer;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 128)]
        public byte[] byRes;
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct NET_DVR_FINGERPRINT_PARAM
    {
        public uint dwSize;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
        public byte[] byCardNo;
        public byte byFingerPrintID;
        public byte byEnableCardReader;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
        public byte[] byRes1;
        public uint dwFingerPrintLen;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2048)]
        public byte[] byFingerData;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]
        public byte[] byRes2;
    }

    internal static bool SetFaceParam(int userId, int channel, string cardNo, byte[] faceData, out string error)
    {
        error = "";
        var cfg = new NET_DVR_FACE_PARAM_CFG
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FACE_PARAM_CFG)),
            byCardNo = new byte[32],
            byRes = new byte[128],
            dwFaceLen = (uint)(faceData?.Length ?? 0),
            pFaceBuffer = IntPtr.Zero
        };
        CopyAscii(cardNo, cfg.byCardNo);

        IntPtr cfgPtr = IntPtr.Zero;
        IntPtr facePtr = IntPtr.Zero;
        try
        {
            if (faceData == null || faceData.Length == 0)
            {
                error = "faceData is empty";
                return false;
            }

            facePtr = Marshal.AllocHGlobal(faceData.Length);
            Marshal.Copy(faceData, 0, facePtr, faceData.Length);
            cfg.pFaceBuffer = facePtr;

            cfgPtr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, cfgPtr, false);

            return NET_DVR_SetDeviceConfig(userId, NET_DVR_SET_FACE_PARAM_CFG, channel, cfgPtr, cfg.dwSize, IntPtr.Zero, IntPtr.Zero, 0);
        }
        finally
        {
            if (cfgPtr != IntPtr.Zero) Marshal.FreeHGlobal(cfgPtr);
            if (facePtr != IntPtr.Zero) Marshal.FreeHGlobal(facePtr);
        }
    }

    internal static bool GetFaceParam(int userId, int channel, string cardNo, out byte[] faceData)
    {
        faceData = Array.Empty<byte>();
        var cfg = new NET_DVR_FACE_PARAM_CFG
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FACE_PARAM_CFG)),
            byCardNo = new byte[32],
            byRes = new byte[128]
        };
        CopyAscii(cardNo, cfg.byCardNo);

        uint returned = 0;
        IntPtr cfgPtr = IntPtr.Zero;
        try
        {
            cfgPtr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, cfgPtr, false);

            if (!NET_DVR_GetDeviceConfig(userId, NET_DVR_GET_FACE_PARAM_CFG, channel, cfgPtr, cfg.dwSize, ref returned, IntPtr.Zero, IntPtr.Zero, 0))
                return false;

            var outCfg = Marshal.PtrToStructure<NET_DVR_FACE_PARAM_CFG>(cfgPtr);
            if (outCfg.dwFaceLen == 0 || outCfg.pFaceBuffer == IntPtr.Zero)
                return true;

            faceData = new byte[outCfg.dwFaceLen];
            Marshal.Copy(outCfg.pFaceBuffer, faceData, 0, (int)outCfg.dwFaceLen);
            return true;
        }
        finally
        {
            if (cfgPtr != IntPtr.Zero) Marshal.FreeHGlobal(cfgPtr);
        }
    }

    internal static bool DeleteFaceParam(int userId, int channel, string cardNo)
    {
        var cfg = new NET_DVR_FACE_PARAM_CFG
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FACE_PARAM_CFG)),
            byCardNo = new byte[32],
            byRes = new byte[128]
        };
        CopyAscii(cardNo, cfg.byCardNo);

        IntPtr cfgPtr = IntPtr.Zero;
        try
        {
            cfgPtr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, cfgPtr, false);
            return NET_DVR_SetDeviceConfig(userId, NET_DVR_DEL_FACE_PARAM_CFG, channel, cfgPtr, cfg.dwSize, IntPtr.Zero, IntPtr.Zero, 0);
        }
        finally
        {
            if (cfgPtr != IntPtr.Zero) Marshal.FreeHGlobal(cfgPtr);
        }
    }

    internal static bool SetFingerprintParam(int userId, int channel, string cardNo, byte fingerId, byte[] fpData)
    {
        var cfg = new NET_DVR_FINGERPRINT_PARAM
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FINGERPRINT_PARAM)),
            byCardNo = new byte[32],
            byRes1 = new byte[2],
            byFingerData = new byte[2048],
            byRes2 = new byte[64],
            byFingerPrintID = fingerId,
            byEnableCardReader = 1,
            dwFingerPrintLen = (uint)Math.Min(fpData?.Length ?? 0, 2048)
        };
        CopyAscii(cardNo, cfg.byCardNo);
        if (fpData != null && fpData.Length > 0)
            Buffer.BlockCopy(fpData, 0, cfg.byFingerData, 0, (int)cfg.dwFingerPrintLen);

        IntPtr ptr = IntPtr.Zero;
        try
        {
            ptr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, ptr, false);
            return NET_DVR_SetDeviceConfig(userId, NET_DVR_SET_FINGERPRINT_PARAM, channel, ptr, cfg.dwSize, IntPtr.Zero, IntPtr.Zero, 0);
        }
        finally
        {
            if (ptr != IntPtr.Zero) Marshal.FreeHGlobal(ptr);
        }
    }

    internal static bool GetFingerprintParam(int userId, int channel, string cardNo, byte fingerId, out byte[] fpData)
    {
        fpData = Array.Empty<byte>();
        var cfg = new NET_DVR_FINGERPRINT_PARAM
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FINGERPRINT_PARAM)),
            byCardNo = new byte[32],
            byRes1 = new byte[2],
            byFingerData = new byte[2048],
            byRes2 = new byte[64],
            byFingerPrintID = fingerId,
            byEnableCardReader = 1
        };
        CopyAscii(cardNo, cfg.byCardNo);

        uint returned = 0;
        IntPtr ptr = IntPtr.Zero;
        try
        {
            ptr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, ptr, false);
            if (!NET_DVR_GetDeviceConfig(userId, NET_DVR_GET_FINGERPRINT_PARAM, channel, ptr, cfg.dwSize, ref returned, IntPtr.Zero, IntPtr.Zero, 0))
                return false;

            var outCfg = Marshal.PtrToStructure<NET_DVR_FINGERPRINT_PARAM>(ptr);
            if (outCfg.dwFingerPrintLen == 0)
                return true;

            fpData = new byte[outCfg.dwFingerPrintLen];
            Buffer.BlockCopy(outCfg.byFingerData, 0, fpData, 0, (int)outCfg.dwFingerPrintLen);
            return true;
        }
        finally
        {
            if (ptr != IntPtr.Zero) Marshal.FreeHGlobal(ptr);
        }
    }

    internal static bool DeleteFingerprintParam(int userId, int channel, string cardNo, byte fingerId)
    {
        var cfg = new NET_DVR_FINGERPRINT_PARAM
        {
            dwSize = (uint)Marshal.SizeOf(typeof(NET_DVR_FINGERPRINT_PARAM)),
            byCardNo = new byte[32],
            byRes1 = new byte[2],
            byFingerData = new byte[2048],
            byRes2 = new byte[64],
            byFingerPrintID = fingerId,
            byEnableCardReader = 1
        };
        CopyAscii(cardNo, cfg.byCardNo);

        IntPtr ptr = IntPtr.Zero;
        try
        {
            ptr = Marshal.AllocHGlobal((int)cfg.dwSize);
            Marshal.StructureToPtr(cfg, ptr, false);
            return NET_DVR_SetDeviceConfig(userId, NET_DVR_DEL_FINGERPRINT_PARAM, channel, ptr, cfg.dwSize, IntPtr.Zero, IntPtr.Zero, 0);
        }
        finally
        {
            if (ptr != IntPtr.Zero) Marshal.FreeHGlobal(ptr);
        }
    }

    private static void CopyAscii(string text, byte[] target)
    {
        if (target == null || target.Length == 0)
            return;

        if (string.IsNullOrWhiteSpace(text))
            return;

        var bytes = Encoding.ASCII.GetBytes(text.Trim());
        var len = Math.Min(bytes.Length, target.Length);
        Buffer.BlockCopy(bytes, 0, target, 0, len);
    }
}