using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using AMWD.Common.Packing.Ar;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTests.Common.Packing.Ar
{
	[TestClass]
	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
	public class ArWriterTests
	{
		private readonly DateTime fixedDateTime = new(2023, 03, 01, 10, 20, 30, 0, DateTimeKind.Utc);

		private readonly Dictionary<string, string> files = new();

		private Stream outStream;

		[TestInitialize]
		public void Initialize()
		{
			files.Clear();
			for (int i = 0; i < 3; i++)
			{
				var (filePath, content) = GenerateTestFile();
				files.Add(filePath, content);
			}

			outStream = new MemoryStream();
		}

		[TestCleanup]
		public void Cleanup()
		{
			foreach (var kvp in files)
				File.Delete(kvp.Key);

			files.Clear();

			outStream.Dispose();
			outStream = null;
		}

		[TestMethod]
		public void ShouldInitializeArchive()
		{
			// Arrange
			byte[] initBytes = new byte[8];

			// Act
			_ = new ArWriter(outStream);

			outStream.Seek(0, SeekOrigin.Begin);

			// Assert
			Assert.AreEqual(initBytes.Length, outStream.Length);

			outStream.Read(initBytes, 0, initBytes.Length);
			CollectionAssert.AreEqual(Encoding.ASCII.GetBytes("!<arch>\n"), initBytes);
		}

		[TestMethod]
		public void ShouldWriteOneFile()
		{
			// Arrange
			var firstFileKvp = files.First();
			byte[] headerBytes = new byte[60];
			byte[] contentBytes = new byte[14];

			var writer = new ArWriter(outStream);

			// Act
			writer.WriteFile(firstFileKvp.Key, 123, 456);

			outStream.Seek(8, SeekOrigin.Begin); // set behind init bytes

			// Assert
			Assert.AreEqual(8 + headerBytes.Length + contentBytes.Length, outStream.Length);

			outStream.Read(headerBytes, 0, headerBytes.Length);
			outStream.Read(contentBytes, 0, contentBytes.Length);

			string header = Encoding.ASCII.GetString(headerBytes);
			string content = Encoding.UTF8.GetString(contentBytes);

			Assert.AreEqual($"{Path.GetFileName(firstFileKvp.Key),-16}1677666030  123   456   100644  14        `\n", header);
			Assert.AreEqual(firstFileKvp.Value, content);
		}

		[TestMethod]
		public void ShouldWriteMultipleFiles()
		{
			// Arrange
			var writer = new ArWriter(outStream);

			// Act
			foreach (var kvp in files)
				writer.WriteFile(kvp.Key, 123, 456);

			outStream.Seek(8, SeekOrigin.Begin);

			// Assert
			Assert.AreEqual((8 + 3 * 60 + 3 * 14), outStream.Length);

			foreach (var kvp in files)
			{
				byte[] headerBytes = new byte[60];
				byte[] contentBytes = new byte[14];

				outStream.Read(headerBytes, 0, headerBytes.Length);
				outStream.Read(contentBytes, 0, contentBytes.Length);

				string header = Encoding.ASCII.GetString(headerBytes);
				string content = Encoding.UTF8.GetString(contentBytes);

				Assert.AreEqual($"{Path.GetFileName(kvp.Key),-16}1677666030  123   456   100644  14        `\n", header);
				Assert.AreEqual(kvp.Value, content);
			}
		}

		[TestMethod]
		public void ShouldPadToEven()
		{
			// Arrange
			var (filePath, fileContent) = GenerateTestFile(13);

			try
			{
				byte[] headerBytes = new byte[60];
				byte[] contentBytes = new byte[14];

				var writer = new ArWriter(outStream);

				// Act
				writer.WriteFile(filePath, 123, 456);

				outStream.Seek(8, SeekOrigin.Begin);

				// Assert
				Assert.AreEqual(8 + headerBytes.Length + contentBytes.Length, outStream.Length);

				outStream.Read(headerBytes, 0, headerBytes.Length);
				outStream.Read(contentBytes, 0, contentBytes.Length);

				string header = Encoding.ASCII.GetString(headerBytes);
				string content = Encoding.UTF8.GetString(contentBytes);

				Assert.AreEqual($"{Path.GetFileName(filePath),-16}1677666030  123   456   100644  13        `\n", header);
				Assert.AreEqual(fileContent + "\n", content);
			}
			finally
			{
				File.Delete(filePath);
			}
		}

		[TestMethod]
		[ExpectedException(typeof(ArgumentException))]
		public void ShouldFailOnFileNameTooLong()
		{
			// Arrange
			var (filePath, _) = GenerateTestFile();
			try
			{
				string path = Path.GetDirectoryName(filePath);
				string fileName = Path.GetFileName(filePath);
				fileName = fileName.PadLeft(20, 'a');

				File.Move(filePath, Path.Combine(path, fileName));
				filePath = Path.Combine(path, fileName);

				var writer = new ArWriter(outStream);

				// Act
				writer.WriteFile(filePath, 123, 456);

				// Assert - Exception
				Assert.Fail();
			}
			finally
			{
				File.Delete(filePath);
			}
		}

		[TestMethod]
		public void ShouldWriteEmptyOnNegativeUserId()
		{
			// Arrange
			var firstFileKvp = files.First();
			byte[] headerBytes = new byte[60];
			byte[] contentBytes = new byte[14];

			var writer = new ArWriter(outStream);

			// Act
			writer.WriteFile(firstFileKvp.Key, -123, 456);

			outStream.Seek(8, SeekOrigin.Begin);

			// Assert
			Assert.AreEqual(8 + headerBytes.Length + contentBytes.Length, outStream.Length);

			outStream.Read(headerBytes, 0, headerBytes.Length);
			outStream.Read(contentBytes, 0, contentBytes.Length);

			string header = Encoding.ASCII.GetString(headerBytes);
			string content = Encoding.UTF8.GetString(contentBytes);

			Assert.AreEqual($"{Path.GetFileName(firstFileKvp.Key),-16}1677666030        456   100644  14        `\n", header);
			Assert.AreEqual(firstFileKvp.Value, content);
		}

		[TestMethod]
		public void ShouldWriteEmptyOnNegativeGroupId()
		{
			// Arrange
			var firstFileKvp = files.First();
			byte[] headerBytes = new byte[60];
			byte[] contentBytes = new byte[14];

			var writer = new ArWriter(outStream);

			// Act
			writer.WriteFile(firstFileKvp.Key, 123, -456);

			outStream.Seek(8, SeekOrigin.Begin);

			// Assert
			Assert.AreEqual(8 + headerBytes.Length + contentBytes.Length, outStream.Length);

			outStream.Read(headerBytes, 0, headerBytes.Length);
			outStream.Read(contentBytes, 0, contentBytes.Length);

			string header = Encoding.ASCII.GetString(headerBytes);
			string content = Encoding.UTF8.GetString(contentBytes);

			Assert.AreEqual($"{Path.GetFileName(firstFileKvp.Key),-16}1677666030  123         100644  14        `\n", header);
			Assert.AreEqual(firstFileKvp.Value, content);
		}

		[TestMethod]
		public void ShouldWriteEmptyOnNegativeMode()
		{
			// Arrange
			var firstFileKvp = files.First();
			byte[] headerBytes = new byte[60];
			byte[] contentBytes = new byte[14];

			var writer = new ArWriter(outStream);

			// Act
			writer.WriteFile(firstFileKvp.Key, 123, 456, -1);

			outStream.Seek(8, SeekOrigin.Begin);

			// Assert
			Assert.AreEqual(8 + headerBytes.Length + contentBytes.Length, outStream.Length);

			outStream.Read(headerBytes, 0, headerBytes.Length);
			outStream.Read(contentBytes, 0, contentBytes.Length);

			string header = Encoding.ASCII.GetString(headerBytes);
			string content = Encoding.UTF8.GetString(contentBytes);

			Assert.AreEqual($"{Path.GetFileName(firstFileKvp.Key),-16}1677666030  123   456           14        `\n", header);
			Assert.AreEqual(firstFileKvp.Value, content);
		}

		[TestMethod]
		[ExpectedException(typeof(ArgumentException))]
		public void ShouldFailOnNonWritableStream()
		{
			// Arrange
			using var testStream = new NonWriteStream();

			// Act
			_ = new ArWriter(testStream);

			// Assert - ArgumentException
			Assert.Fail();
		}

		private (string filePath, string content) GenerateTestFile(int length = 14)
		{
			string filePath = Path.GetTempFileName();
			string text = CryptographyHelper.GetRandomString(length);

			File.WriteAllText(filePath, text);
			File.SetLastWriteTimeUtc(filePath, fixedDateTime);
			return (filePath, text);
		}

		private class NonWriteStream : MemoryStream
		{
			public NonWriteStream()
				: base()
			{ }

			public override bool CanWrite => false;
		}
	}
}