using System.Runtime.InteropServices;

namespace ChangeT50.Adapter;

/// <summary>
/// Dynamic .NET wrapper for all 16 documented Change.dll exports.
/// The supplied binary requires a Windows x86 process.
/// </summary>
public sealed class ChangeNativeLibrary : IDisposable
{
    private IntPtr _module;
    private readonly OpenComDelegate _openCom;
    private readonly CloseComDelegate _closeCom;
    private readonly QueryCardDelegate _queryCard;
    private readonly GetCardInfoDelegate _getCardInfo;
    private readonly SetCardInfoDelegate _setCardInfo;
    private readonly UploadDelegate _upload;
    private readonly DbConnectDelegate _dbConnect;
    private readonly DbDisconnectDelegate _dbDisconnect;
    private readonly GetCustomerListDelegate _getCustomerList;
    private readonly GetCountDelegate _getCustomerCount;
    private readonly GetDepartmentListDelegate _getDepartmentList;
    private readonly GetCountDelegate _getDepartmentCount;
    private readonly DownBlacklistDelegate _downBlacklist;
    private readonly GetCountDelegate _downBlacklistCount;
    private readonly DownCustomerInfoDelegate _downCustomerInfo;
    private readonly GetCustomerByNumberDelegate _getCustomerByNumber;

    public ChangeNativeLibrary(string dllPath)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(dllPath);
        ChangeAbi.EnsureNativeLoadEnvironment();

        var fullPath = Path.GetFullPath(dllPath);
        if (!File.Exists(fullPath))
        {
            throw new FileNotFoundException("Change.dll was not found.", fullPath);
        }

        _module = NativeLibrary.Load(fullPath);
        try
        {
            _openCom = Bind<OpenComDelegate>("OpenCom");
            _closeCom = Bind<CloseComDelegate>("CloseCom");
            _queryCard = Bind<QueryCardDelegate>("CapNBQueryCard");
            _getCardInfo = Bind<GetCardInfoDelegate>("CapGetNBCardInfo");
            _setCardInfo = Bind<SetCardInfoDelegate>("CapSetNBCardInfo");
            _upload = Bind<UploadDelegate>("CapUpload");
            _dbConnect = Bind<DbConnectDelegate>("CapDBConnect");
            _dbDisconnect = Bind<DbDisconnectDelegate>("CapDBDiscon");
            _getCustomerList = Bind<GetCustomerListDelegate>("CapGetCustomerList");
            _getCustomerCount = Bind<GetCountDelegate>("CapGetCustomerCount");
            _getDepartmentList = Bind<GetDepartmentListDelegate>("CapGetDepList");
            _getDepartmentCount = Bind<GetCountDelegate>("CapGetDepCount");
            _downBlacklist = Bind<DownBlacklistDelegate>("CapDownBlacklist");
            _downBlacklistCount = Bind<GetCountDelegate>("CapDownBlacklistCount");
            _downCustomerInfo = Bind<DownCustomerInfoDelegate>("CapDownCustomerInfo");
            _getCustomerByNumber = Bind<GetCustomerByNumberDelegate>("CapGetCustomerByNum");
        }
        catch
        {
            NativeLibrary.Free(_module);
            _module = IntPtr.Zero;
            throw;
        }
    }

    public int OpenReader() => _openCom();

    public void CloseReader() => _closeCom();

    public int QueryCard(out int uid) => _queryCard(out uid);

    public int ReadCard(out CustomerInfoNative customer)
    {
        customer = default;
        return _getCardInfo(ref customer);
    }

    /// <summary>
    /// Writes a debit result to the physical card. Do not call without an approved test card and amount.
    /// </summary>
    public int DebitCard(
        int customerId,
        int amountCents,
        int walletNumber,
        DateTime tradeTime,
        out long psamId,
        out int psamTradeNumber,
        out int tac)
    {
        var nativeTradeTime = Marshal.StringToHGlobalAnsi(tradeTime.ToString("yyyy-MM-dd HH:mm:ss"));
        try
        {
            return _setCardInfo(
                customerId,
                amountCents,
                walletNumber,
                nativeTradeTime,
                out psamId,
                out psamTradeNumber,
                out tac);
        }
        finally
        {
            Marshal.FreeHGlobal(nativeTradeTime);
        }
    }

    /// <summary>
    /// Uploads a completed trade. The vendor API does not document the output message length,
    /// so the caller owns and sizes the unmanaged message buffer.
    /// </summary>
    public int UploadTrade(ref UploadInfoNative upload, IntPtr messageBuffer) =>
        _upload(ref upload, messageBuffer);

    public int ConnectWebService(string serviceUrl)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(serviceUrl);
        var nativeUrl = Marshal.StringToHGlobalAnsi(serviceUrl);
        try
        {
            return _dbConnect(nativeUrl);
        }
        finally
        {
            Marshal.FreeHGlobal(nativeUrl);
        }
    }

    public void DisconnectWebService() => _dbDisconnect();

    public int GetCustomerCount() => _getCustomerCount();

    public int GetCustomerList(IntPtr customerBuffer) => _getCustomerList(customerBuffer);

    public int GetDepartmentCount() => _getDepartmentCount();

    public int GetDepartmentList(IntPtr departmentBuffer) => _getDepartmentList(departmentBuffer);

    public int GetBlacklistCount() => _downBlacklistCount();

    public int GetBlacklist(IntPtr cardNumberBuffer) => _downBlacklist(cardNumberBuffer);

    public int GetCustomer(int customerId, out DownInfoNative customer)
    {
        customer = default;
        return _downCustomerInfo(customerId, ref customer);
    }

    public int GetCustomers(int firstCustomerId, int count, IntPtr customerBuffer) =>
        _getCustomerByNumber(firstCustomerId, count, customerBuffer);

    public void Dispose()
    {
        if (_module == IntPtr.Zero)
        {
            return;
        }

        NativeLibrary.Free(_module);
        _module = IntPtr.Zero;
        GC.SuppressFinalize(this);
    }

    private T Bind<T>(string exportName) where T : Delegate
    {
        if (!NativeLibrary.TryGetExport(_module, exportName, out var address))
        {
            throw new EntryPointNotFoundException($"Change.dll export '{exportName}' was not found.");
        }

        return Marshal.GetDelegateForFunctionPointer<T>(address);
    }

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int OpenComDelegate();

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void CloseComDelegate();

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int QueryCardDelegate(out int uid);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int GetCardInfoDelegate(ref CustomerInfoNative customer);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int SetCardInfoDelegate(
        int customerId,
        int amountCents,
        int walletNumber,
        IntPtr tradeTime,
        out long psamId,
        out int psamTradeNumber,
        out int tac);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int UploadDelegate(ref UploadInfoNative upload, IntPtr messageBuffer);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int DbConnectDelegate(IntPtr serviceUrl);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void DbDisconnectDelegate();

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int GetCustomerListDelegate(IntPtr customers);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int GetCountDelegate();

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int GetDepartmentListDelegate(IntPtr departments);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int DownBlacklistDelegate(IntPtr cardNumbers);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int DownCustomerInfoDelegate(int customerId, ref DownInfoNative customer);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int GetCustomerByNumberDelegate(int firstCustomerId, int count, IntPtr customers);
}