using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using DotnetStandardStreams;

namespace DotnetStandardStreamsTests;

public class FileTextSourceTests
{
	private string _tempFilename = string.Empty;

	private void CleanupTempFile()
	{
		if (File.Exists(_tempFilename))
			File.Delete(_tempFilename);
	}

	private void CreateInputFile()
	{
		_tempFilename = Path.GetTempFileName();
		const string content = "1\r\n2\r\n\r\n4\r\n5\r\n6\r\n7\r\n8\r\n9\r\n10\r\n";
		CleanupTempFile();
		File.WriteAllText(_tempFilename, content);
	}

	private void CreateEmptyInputFile()
	{
		_tempFilename = Path.GetTempFileName();
		CleanupTempFile();
		File.WriteAllText(_tempFilename, string.Empty);
	}

	private void WrapFileTest(Action<ITextSource> testCode, Action? explicitSourceCreation = null)
	{
		explicitSourceCreation ??= CreateInputFile;
		explicitSourceCreation();
		try
		{
			ITextSource source = new FileTextSource(_tempFilename);
			source.Open();
			try
			{
				testCode(source);
			}
			finally
			{
				source.Close();
			}
		}
		finally
		{
			CleanupTempFile();
		}
	}

	[Fact]
	public void CanReadAllFromFile()
	{
		WrapFileTest(static textSource =>
		{
			List<string> actual = textSource.ReadAll().ToList();
			actual.Count.ShouldBe(10);
			actual.ShouldBe(["1", "2", "", "4", "5", "6", "7", "8", "9", "10"]);
		});
	}

	[Fact]
	public void CanReadIndividualLinesFromFile()
	{
		WrapFileTest(static textSource =>
		{
			string s;
			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("1");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("2");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("4");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("5");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("6");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("7");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("8");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("9");

			s = textSource.Read();
			textSource.Eof().ShouldBe(false);
			s.ShouldBe("10");

			_ = textSource.Read();
			textSource.Eof().ShouldBe(true);
		});
	}

	[Fact]
	public void CanWhileLoopThroughFileNormally()
	{
		WrapFileTest(static textSource =>
		{
			int lineCount = 0;
			_ = textSource.Read();

			while (!textSource.Eof())
			{
				lineCount++;
				_ = textSource.Read();
			}

			lineCount.ShouldBe(10);
		});
	}

	[Fact]
	public void CanReadAllThroughFileNormally()
	{
		WrapFileTest(static textSource =>
		{
			List<string> lines = textSource.ReadAll().ToList();
			int lineCount = lines.Count;
			lineCount.ShouldBe(10);
			lines.ShouldBe(["1", "2", "", "4", "5", "6", "7", "8", "9", "10"]);
		});
	}

	[Fact]
	public void CanWhileLoopThroughEmptyFile()
	{
		WrapFileTest(
			static textSource =>
			{
				int lineCount = 0;
				_ = textSource.Read();

				while (!textSource.Eof())
				{
					lineCount++;
					_ = textSource.Read();
				}

				lineCount.ShouldBe(0);
			},
			CreateEmptyInputFile);
	}

	[Fact]
	public void CanReadAllThroughEmptyFile()
	{
		WrapFileTest(static textSource =>
			{
				List<string> lines = textSource.ReadAll().ToList();
				int lineCount = lines.Count;
				lineCount.ShouldBe(0);
			},
			CreateEmptyInputFile);
	}
}