//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
//
// Use of this sample source code is subject to the terms of the Microsoft
// license agreement under which you licensed this sample source code. If
// you did not accept the terms of the license agreement, you are not
// authorized to use this sample source code. For the terms of the license,
// please see the license agreement between you and Microsoft or, if applicable,
// see the LICENSE.RTF on your install media or the root of your tools installation.
// THE SAMPLE SOURCE CODE IS PROVIDED "AS IS", WITH NO WARRANTIES OR INDEMNITIES.
//
#region Using directives

using System;
using System.Runtime.InteropServices;

#endregion

public enum GpsServiceState : int
{
    Off = 0,
    On = 1,
    StartingUp = 2, 
    ShuttingDown = 3,
    Unloading = 4,
    Uninitialized = 5,
    Unknown = -1
}

namespace Microsoft.WindowsMobile.Samples.Location
{

    [StructLayout(LayoutKind.Sequential)]
    internal struct FileTime
    {
        int dwLowDateTime;
        int dwHighDateTime;
    }

    /// <summary>
    /// GpsDeviceState holds the state of the gps device and the friendly name if the 
    /// gps supports them.
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    public class GpsDeviceState
    {
        public static int GpsMaxFriendlyName = 64;
        public static int GpsDeviceStructureSize = 216;

        int serviceState = 0;
        /// <summary>
        /// State of the GPS Intermediate Driver service
        /// </summary>
        public GpsServiceState ServiceState
        {
            get {return (GpsServiceState)serviceState;}
        }

        int deviceState = 0;
        /// <summary>
        /// Status of the actual GPS device driver.
        /// </summary>
        public GpsServiceState DeviceState
        {
            get {return (GpsServiceState)deviceState;}
        }

        string friendlyName = "";
        /// <summary>
        /// Friendly name of the real GPS device we are currently using.
        /// </summary>
        public string FriendlyName
        {
            get {return friendlyName;}
        }

        /// <summary>
        /// Constructor of GpsDeviceState.  It copies values from the native pointer 
        /// passed in. 
        /// </summary>
        /// <param name="pGpsDevice">Native pointer to memory that contains
        /// the GPS_DEVICE data</param>
        public GpsDeviceState(IntPtr pGpsDevice)
        {
            // make sure our pointer is valid
            if (pGpsDevice == IntPtr.Zero)
            {
                throw new ArgumentException();
            }

            // read in the service state which starts at offset 8
            serviceState = Marshal.ReadInt32(pGpsDevice, 8);
            // read in the device state which starts at offset 12
            deviceState = Marshal.ReadInt32(pGpsDevice, 12);

            // the friendly name starts at offset 88
            IntPtr pFriendlyName = (IntPtr)(pGpsDevice.ToInt32() + 88);
            // marshal the native string into our gpsFriendlyName
            friendlyName = Marshal.PtrToStringUni(pFriendlyName);
        }
    }
}