using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

using Microsoft.VisualStudio.TestTools.UnitTesting;

using Moq;

using Renci.SshNet.Common;
using Renci.SshNet.Sftp;

namespace Renci.SshNet.Tests.Classes.Sftp
{
    [TestClass]
    public class SftpFileStreamTest_OpenAsync_FileModeCreate_FileAccessReadWrite_FileDoesNotExist : SftpFileStreamAsyncTestBase
    {
        private Random _random;
        private string _path;
        private FileMode _fileMode;
        private FileAccess _fileAccess;
        private int _bufferSize;
        private uint _readBufferSize;
        private uint _writeBufferSize;
        private byte[] _handle;
        private SftpFileStream _target;
        private CancellationToken _cancellationToken;

        protected override void SetupData()
        {
            base.SetupData();

            _random = new Random();
            _path = _random.Next().ToString();
            _fileMode = FileMode.Create;
            _fileAccess = FileAccess.ReadWrite;
            _bufferSize = _random.Next(5, 1000);
            _readBufferSize = (uint)_random.Next(5, 1000);
            _writeBufferSize = (uint)_random.Next(5, 1000);
            _handle = GenerateRandom(_random.Next(1, 10), _random);
            _cancellationToken = new CancellationToken();
        }

        protected override void SetupMocks()
        {
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestOpenAsync(_path, Flags.Read | Flags.Write | Flags.CreateNewOrOpen | Flags.Truncate, _cancellationToken))
                               .ReturnsAsync(_handle);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.CalculateOptimalReadLength((uint)_bufferSize))
                               .Returns(_readBufferSize);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.CalculateOptimalWriteLength((uint)_bufferSize, _handle))
                               .Returns(_writeBufferSize);
        }

        protected override async Task ActAsync()
        {
            _target = await SftpFileStream.OpenAsync(SftpSessionMock.Object, _path, _fileMode, _fileAccess, _bufferSize, _cancellationToken);
        }

        [TestMethod]
        public void CanReadShouldReturnTrue()
        {
            Assert.IsTrue(_target.CanRead);
        }

        [TestMethod]
        public void CanSeekShouldReturnTrue()
        {
            Assert.IsTrue(_target.CanSeek);
        }

        [TestMethod]
        public void CanWriteShouldReturnTrue()
        {
            Assert.IsTrue(_target.CanWrite);
        }

        [TestMethod]
        public void CanTimeoutShouldReturnTrue()
        {
            Assert.IsTrue(_target.CanTimeout);
        }

        [TestMethod]
        public void PositionShouldReturnZero()
        {
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.IsOpen)
                               .Returns(true);

            var actual = _target.Position;

            Assert.AreEqual(0L, actual);

            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(1));
        }

        [TestMethod]
        public async Task ReadShouldStartReadingAtBeginningOfFile()
        {
            var buffer = new byte[8];
            var data = new byte[] { 5, 4, 3, 2, 1 };
            var expected = new byte[] { 0, 5, 4, 3, 2, 1, 0, 0 };

            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.IsOpen)
                               .Returns(true);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestReadAsync(_handle, 0UL, _readBufferSize, _cancellationToken))
                               .ReturnsAsync(data);

            var actual = await _target.ReadAsync(buffer, 1, data.Length);

            Assert.AreEqual(data.Length, actual);
            Assert.IsTrue(buffer.IsEqualTo(expected));

            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(1));
            SftpSessionMock.Verify(p => p.RequestReadAsync(_handle, 0UL, _readBufferSize, _cancellationToken), Times.Once);
        }

        [TestMethod]
        public async Task WriteShouldStartWritingAtBeginningOfFile()
        {
            var buffer = new byte[_writeBufferSize];

            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.IsOpen)
                               .Returns(true);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestWriteAsync(_handle, 0UL, buffer, 0, buffer.Length, _cancellationToken))
                               .Returns(Task.CompletedTask);

            await _target.WriteAsync(buffer, 0, buffer.Length);

            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(1));
            SftpSessionMock.Verify(p => p.RequestWriteAsync(_handle, 0UL, buffer, 0, buffer.Length, _cancellationToken), Times.Once);
        }

        [TestMethod]
        public void RequestOpenOnSftpSessionShouldBeInvokedOnce()
        {
            SftpSessionMock.Verify(p => p.RequestOpenAsync(_path, Flags.Read | Flags.Write | Flags.CreateNewOrOpen | Flags.Truncate, _cancellationToken), Times.Once);
        }
    }
}