// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using Peek.Common.Models;

namespace Peek.Common.Extensions
{
    public static class IPropertyStoreExtensions
    {
        /// <summary>
        /// Helper method that retrieves a uint value from the given property store.
        /// Returns 0 if the value is not a VT_UI4 (4-byte unsigned integer in little-endian order).
        /// </summary>
        /// <param name="propertyStore">The property store</param>
        /// <param name="key">The pkey</param>
        /// <returns>The uint value</returns>
        public static uint? TryGetUInt(this IPropertyStore propertyStore, PropertyKey key)
        {
            if (propertyStore == null)
            {
                return null;
            }

            try
            {
                PropVariant propVar;

                propertyStore.GetValue(ref key, out propVar);

                // VT_UI4 Indicates a 4-byte unsigned integer formatted in little-endian byte order.
                if ((VarEnum)propVar.Vt == VarEnum.VT_UI4)
                {
                    return propVar.UlVal;
                }
                else
                {
                    return null;
                }
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>
        /// Helper method that retrieves a ulong value from the given property store.
        /// Returns 0 if the value is not a VT_UI8 (8-byte unsigned integer in little-endian order).
        /// </summary>
        /// <param name="propertyStore">The property store</param>
        /// <param name="key">the pkey</param>
        /// <returns>the ulong value</returns>
        public static ulong? TryGetULong(this IPropertyStore propertyStore, PropertyKey key)
        {
            if (propertyStore == null)
            {
                return null;
            }

            try
            {
                PropVariant propVar;

                propertyStore.GetValue(ref key, out propVar);

                // VT_UI8 Indicates an 8-byte unsigned integer formatted in little-endian byte order.
                if ((VarEnum)propVar.Vt == VarEnum.VT_UI8)
                {
                    return propVar.UhVal;
                }
                else
                {
                    return null;
                }
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>
        /// Helper method that retrieves a string value from the given property store.
        /// </summary>
        /// <param name="propertyStore">The property store</param>
        /// <param name="key">The pkey</param>
        /// <returns>The string value</returns>
        public static string? TryGetString(this IPropertyStore propertyStore, PropertyKey key)
        {
            if (propertyStore == null)
            {
                return null;
            }

            try
            {
                PropVariant propVar;

                propertyStore.GetValue(ref key, out propVar);

                if ((VarEnum)propVar.Vt == VarEnum.VT_LPWSTR)
                {
                    return Marshal.PtrToStringUni(propVar.P) ?? string.Empty;
                }
                else
                {
                    return null;
                }
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>
        /// Helper method that retrieves an array of string values from the given property store.
        /// </summary>
        /// <param name="propertyStore">The property store</param>
        /// <param name="key">The pkey</param>
        /// <returns>The array of string values</returns>
        public static string[]? TryGetStringArray(this IPropertyStore propertyStore, PropertyKey key)
        {
            if (propertyStore == null)
            {
                return null;
            }

            try
            {
                PropVariant propVar;
                propertyStore.GetValue(ref key, out propVar);

                List<string>? values = null;

                if ((VarEnum)propVar.Vt == (VarEnum.VT_LPWSTR | VarEnum.VT_VECTOR))
                {
                    values = new List<string>();
                    for (int elementIndex = 0; elementIndex < propVar.Calpwstr.CElems; elementIndex++)
                    {
                        var stringVal = Marshal.PtrToStringUni(Marshal.ReadIntPtr(propVar.Calpwstr.PElems, elementIndex));
                        if (stringVal != null)
                        {
                            values.Add(stringVal);
                        }
                    }
                }

                return values?.ToArray();
            }
            catch (Exception)
            {
                return null;
            }
        }
    }
}