using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace HidLibrary.Honeywell1902Series
{
  public class Scanner1902 : IDisposable
  {
    private const int HidReportId = 0x4;
    private const int ErrorBeepMessage = 0x20;
    private const int SuccessBeepMessage = 0x40;
    private const int StartScanMessage = 0x4;
    private const int EndScanMessage = 0x1;

    public event InsertedEventHandler Inserted;
    public event RemovedEventHandler Removed;
    public event DataRecievedEventHandler DataRecieved;

    public delegate void InsertedEventHandler();
    public delegate void RemovedEventHandler();
    public delegate void DataRecievedEventHandler(byte[] data);

    private readonly HidDevice _scanner;
    private int _isReading;

    public Scanner1902(string devicePath) : this(HidDevices.GetDevice(devicePath)) { }

    public Scanner1902(HidDevice hidDevice)
    {
      _scanner = hidDevice;

      _scanner.Inserted += ScannerInserted;
      _scanner.Removed += ScannerRemoved;

      if (!_scanner.IsOpen) _scanner.OpenDevice();
      _scanner.MonitorDeviceEvents = true;

      BeginReadReport();
    }

    public string DevicePath { get { return _scanner.DevicePath; } }
    public bool IsListening { get; private set; }
    public bool IsConnected { get { return _scanner.IsConnected; } }

    public static IEnumerable<Scanner1902> Enumerate(int vid, int pid)
    {

      return HidDevices.Enumerate(vid, pid).Select(x => new Scanner1902(x));
    }

    public void ErrorBeep()
    {
      var report = _scanner.CreateReport();

      report.ReportId = HidReportId;
      report.Data[0] = ErrorBeepMessage;

      _scanner.WriteReport(report);
    }

    public void SuccessBeep()
    {
      var report = _scanner.CreateReport();

      report.ReportId = HidReportId;
      report.Data[0] = SuccessBeepMessage;

      _scanner.WriteReport(report);
    }

    public void StartScan()
    {
      var report = _scanner.CreateReport();

      report.ReportId = HidReportId;
      report.Data[0] = StartScanMessage;

      _scanner.WriteReport(report);
    }

    public void EndScan()
    {
      var report = _scanner.CreateReport();

      report.ReportId = HidReportId;
      report.Data[0] = EndScanMessage;

      _scanner.WriteReport(report);
    }

    public void StartListen() { IsListening = true; }
    public void StopListen() { IsListening = false; }

    private void BeginReadReport()
    {
      if (Interlocked.CompareExchange(ref _isReading, 1, 0) == 1) return;
      _scanner.ReadReport(ReadReport);
    }

    private void ReadReport(HidReport report)
    {
      var scannerReport = new Report1902(report);
      var data = new byte[] { };
      var currentPosition = 0;
      var readRequired = false;

      if (scannerReport.Length > 0 & scannerReport.ReadStatus == HidDeviceData.ReadStatus.Success)
      {
        do
        {
          if (scannerReport.MoreData && readRequired) scannerReport = new Report1902(_scanner.ReadReport());
          else readRequired = true;

          if (!scannerReport.Exists) continue;

          Array.Resize(ref data, data.GetUpperBound(0) + scannerReport.Data.Length + 1);
          Array.Copy(scannerReport.Data, 0, data, currentPosition, scannerReport.Data.Length);
          currentPosition += scannerReport.Data.Length;

        } while (scannerReport.MoreData && scannerReport.Exists);

        if (IsListening && data.Length > 0 && DataRecieved != null) DataRecieved(data);
      }

      if (scannerReport.ReadStatus != HidDeviceData.ReadStatus.NotConnected) _scanner.ReadReport(ReadReport);
      else _isReading = 0;
    }

    private void ScannerInserted()
    {
      BeginReadReport();
      if (Inserted != null) Inserted();
    }

    private void ScannerRemoved()
    {
      if (Removed != null) Removed();
    }

    public void Dispose()
    {
      _scanner.CloseDevice();
      GC.SuppressFinalize(this);
    }

    ~Scanner1902()
    {
      Dispose();
    }
  }
}