using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using Vanara.Extensions;
using Vanara.InteropServices;
using Vanara.PInvoke;

namespace Vanara.PInvoke
{
	public static partial class Kernel32
	{
		/// <summary>A <see cref="SafeHandle"/> for memory allocated as moveable HGLOBAL.</summary>
		/// <seealso cref="System.Runtime.InteropServices.SafeHandle"/>
		public class SafeMoveableHGlobalHandle : SafeMemoryHandleExt<Kernel32.MoveableHGlobalMemoryMethods>
		{
			/// <summary>Initializes a new instance of the <see cref="SafeMoveableHGlobalHandle"/> class.</summary>
			/// <param name="handle">The handle.</param>
			/// <param name="ownsHandle">if set to <c>true</c> if this class is responsible for freeing the memory on disposal.</param>
			public SafeMoveableHGlobalHandle(IntPtr handle, bool ownsHandle = true) : base(handle, handle == default ? 0 : GlobalSize(handle), ownsHandle) { }

			/// <summary>Initializes a new instance of the <see cref="SafeMoveableHGlobalHandle"/> class.</summary>
			/// <param name="size">The size of memory to allocate, in bytes.</param>
			/// <exception cref="System.ArgumentOutOfRangeException">size - The value of this argument must be non-negative</exception>
			public SafeMoveableHGlobalHandle(SizeT size) : base(size) { }

			/// <summary>
			/// Allocates from unmanaged memory to represent an array of pointers and marshals the unmanaged pointers (IntPtr) to the native
			/// array equivalent.
			/// </summary>
			/// <param name="bytes">Array of unmanaged pointers</param>
			/// <returns>SafeMoveableHGlobalHandle object to an native (unmanaged) array of pointers</returns>
			public SafeMoveableHGlobalHandle(byte[] bytes) : base(bytes?.Length ?? 0)
			{
				if (Size == 0) return;
				CallLocked(p => Marshal.Copy(bytes, 0, p, sz));
			}

			/// <summary>
			/// Initializes a new instance of the <see cref="SafeMoveableHGlobalHandle"/> class from a <see cref="SafeAllocatedMemoryHandle"/>
			/// instance, copying all the memory.
			/// </summary>
			/// <param name="source">The source memory block.</param>
			public SafeMoveableHGlobalHandle(SafeAllocatedMemoryHandle source) : base(source) { }

			/// <summary>Initializes a new instance of the <see cref="SafeMoveableHGlobalHandle"/> class.</summary>
			[ExcludeFromCodeCoverage]
			internal SafeMoveableHGlobalHandle() : base(0) { }

			/// <summary>Represents a NULL memory pointer.</summary>
			public static SafeMoveableHGlobalHandle Null { get; } = new SafeMoveableHGlobalHandle(IntPtr.Zero, false);

			/// <summary>
			/// Allocates from unmanaged memory to represent a structure with a variable length array at the end and marshal these structure
			/// elements. It is the callers responsibility to marshal what precedes the trailing array into the unmanaged memory. ONLY
			/// structures with attribute StructLayout of LayoutKind.Sequential are supported.
			/// </summary>
			/// <typeparam name="T">Type of the trailing array of structures</typeparam>
			/// <param name="values">Collection of structure objects</param>
			/// <param name="prefixBytes">Number of bytes preceding the trailing array of structures</param>
			/// <returns><see cref="SafeMoveableHGlobalHandle"/> object to an native (unmanaged) structure with a trail array of structures</returns>
			public static SafeMoveableHGlobalHandle CreateFromList<T>(IEnumerable<T> values, int prefixBytes = 0) =>
				new(InteropExtensions.MarshalToPtr(values, mm.AllocMem, out _, prefixBytes, mm.LockMem, mm.UnlockMem), true);

			/// <summary>Allocates from unmanaged memory sufficient memory to hold an array of strings.</summary>
			/// <param name="values">The list of strings.</param>
			/// <param name="packing">The packing type for the strings.</param>
			/// <param name="charSet">The character set to use for the strings.</param>
			/// <param name="prefixBytes">Number of bytes preceding the trailing strings.</param>
			/// <returns>
			/// <see cref="SafeMoveableHGlobalHandle"/> object to an native (unmanaged) array of strings stored using the <paramref
			/// name="packing"/> model and the character set defined by <paramref name="charSet"/>.
			/// </returns>
			public static SafeMoveableHGlobalHandle CreateFromStringList(IEnumerable<string> values, StringListPackMethod packing = StringListPackMethod.Concatenated,
				CharSet charSet = CharSet.Auto, int prefixBytes = 0) => new(InteropExtensions.MarshalToPtr(values, packing, mm.AllocMem, out _, charSet, prefixBytes, mm.LockMem, mm.UnlockMem), true);

			/// <summary>Allocates from unmanaged memory sufficient memory to hold an object of type T.</summary>
			/// <typeparam name="T">Native type</typeparam>
			/// <param name="value">The value.</param>
			/// <returns><see cref="SafeMoveableHGlobalHandle"/> object to an native (unmanaged) memory block the size of T.</returns>
			public static SafeMoveableHGlobalHandle CreateFromStructure<T>(in T value = default) =>
				new(InteropExtensions.MarshalToPtr(value, mm.AllocMem, out _, 0, mm.LockMem, mm.UnlockMem), true);

			/// <summary>Converts an <see cref="IntPtr"/> to a <see cref="SafeMoveableHGlobalHandle"/> where it owns the reference.</summary>
			/// <param name="ptr">The <see cref="IntPtr"/>.</param>
			/// <returns>The result of the conversion.</returns>
			public static implicit operator SafeMoveableHGlobalHandle(IntPtr ptr) => new(ptr, true);
		}
	}
}