FileInfoExtensions.cs

using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Text;

namespace BytecodeApi.Extensions;

/// <summary>
/// Provides a set of <see langword="static" /> methods for interaction with <see cref="FileInfo" /> objects.
/// </summary>
public static class FileInfoExtensions
{
	extension(FileInfo file)
	{
		/// <summary>
		/// Opens the file, reads the contents of the file into a <see cref="byte" />[], and then closes the file.
		/// </summary>
		/// <returns>
		/// A new <see cref="byte" />[] containing the contents of the file.
		/// </returns>
		public byte[] ReadAllBytes()
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadAllBytes(file.FullName);
		}
		/// <summary>
		/// Opens the file, reads all lines of the file into a <see cref="string" />[], and then closes the file.
		/// </summary>
		/// <returns>
		/// A new <see cref="string" />[] containing all lines of the file.
		/// </returns>
		public string[] ReadAllLines()
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadAllLines(file.FullName);
		}
		/// <summary>
		/// Opens the file, reads all lines of the file with the specified encoding into a <see cref="string" />[], and then closes the file.
		/// </summary>
		/// <param name="encoding">The encoding applied to the contents of the file.</param>
		/// <returns>
		/// A new <see cref="string" />[] containing all lines of the file.
		/// </returns>
		public string[] ReadAllLines(Encoding encoding)
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadAllLines(file.FullName, encoding);
		}
		/// <summary>
		/// Opens a text file, reads all lines of the file into a <see cref="string" />, and then closes the file.
		/// </summary>
		/// <returns>
		/// A <see cref="string" /> containing all lines of the file.
		/// </returns>
		public string ReadAllText()
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadAllText(file.FullName);
		}
		/// <summary>
		/// Opens a text file, reads all lines of the file with the specified encoding into a <see cref="string" />, and then closes the file.
		/// </summary>
		/// <param name="encoding">The encoding applied to the contents of the file.</param>
		/// <returns>
		/// A <see cref="string" /> containing all lines of the file.
		/// </returns>
		public string ReadAllText(Encoding encoding)
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadAllText(file.FullName, encoding);
		}
		/// <summary>
		/// Reads the lines of a file.
		/// </summary>
		/// <returns>
		/// All the lines of the file, or the lines that are the result of a query.
		/// </returns>
		public IEnumerable<string> ReadLines()
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadLines(file.FullName);
		}
		/// <summary>
		/// Reads the lines of a file that has a specified encoding.
		/// </summary>
		/// <param name="encoding">The encoding applied to the contents of the file.</param>
		/// <returns>
		/// All the lines of the file, or the lines that are the result of a query.
		/// </returns>
		public IEnumerable<string> ReadLines(Encoding encoding)
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return File.ReadLines(file.FullName, encoding);
		}
		/// <summary>
		/// Deletes the :Zone.Identifier alternate data stream for this file.
		/// </summary>
		/// <returns>
		/// <see langword="true" />, if the :Zone.Identifier alternate data stream was present and could be deleted;
		/// otherwise, <see langword="false" />.
		/// </returns>
		[SupportedOSPlatform("windows")]
		public bool Unblock()
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);

			return Native.DeleteFile($"{file.FullName}:Zone.Identifier");
		}
		/// <summary>
		/// Compares the contents of two files. Returns <see langword="true" />, if both files are of equal size and equal binary content.
		/// </summary>
		/// <param name="other">The other <see cref="FileInfo" /> to compare to this <see cref="FileInfo" />.</param>
		/// <returns>
		/// <see langword="true" />, if both files are of equal size and equal binary content;
		/// otherwise, <see langword="false" />.
		/// </returns>
		public bool CompareContents(FileInfo other)
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);
			Check.ArgumentNull(other);
			Check.FileNotFound(other.FullName);

			FileInfo a = new(file.FullName);
			FileInfo b = new(other.FullName);

			if (a.Length == b.Length)
			{
				using FileStream streamA = a.OpenRead();
				using FileStream streamB = b.OpenRead();

				byte[] bufferA = new byte[4096];
				byte[] bufferB = new byte[4096];
				int bytesReadA;
				int bytesReadB;

				do
				{
					bytesReadA = streamA.Read(bufferA);
					bytesReadB = streamB.Read(bufferB);
					if (bytesReadA != bytesReadB || !bufferA.Compare(bufferB)) return false;
				}
				while (bytesReadA > 0 || bytesReadB > 0);

				return true;
			}
			else
			{
				return false;
			}
		}
		/// <summary>
		/// Searches the file for the first occurrence of <paramref name="sequence" />. If not found, returns -1.
		/// </summary>
		/// <param name="sequence">The <see cref="byte" />[] to search for.</param>
		/// <returns>
		/// The index of the first occurrence of <paramref name="sequence" /> and -1, if not found.
		/// </returns>
		public long FindSequence(byte[] sequence)
		{
			return file.FindSequence(sequence, 0);
		}
		/// <summary>
		/// Searches the file for the first occurrence of <paramref name="sequence" /> starting from <paramref name="startIndex" />. If not found, returns -1.
		/// </summary>
		/// <param name="sequence">The <see cref="byte" />[] to search for.</param>
		/// <param name="startIndex">The zero-based starting position to start searching from.</param>
		/// <returns>
		/// The index of the first occurrence of <paramref name="sequence" /> and -1, if not found.
		/// </returns>
		public long FindSequence(byte[] sequence, int startIndex)
		{
			Check.ArgumentNull(file);
			Check.FileNotFound(file.FullName);
			Check.ArgumentNull(sequence);
			Check.ArgumentEx.ArrayElementsRequired(sequence);
			Check.ArgumentOutOfRangeEx.GreaterEqual0(startIndex);

			using FileStream stream = file.OpenRead();
			stream.Seek(startIndex, SeekOrigin.Begin);
			long index = stream.FindSequence(sequence);
			return index == -1 ? -1 : index + startIndex;
		}
	}
}

[SupportedOSPlatform("windows")]
file static class Native
{
	[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
	[return: MarshalAs(UnmanagedType.Bool)]
	public static extern bool DeleteFile(string name);
}