using System;
using System.Globalization;
using System.IO;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;
using Renci.SshNet.Sftp;
using Renci.SshNet.Tests.Common;
using System.Threading;
using Renci.SshNet.Sftp.Responses;
using Renci.SshNet.Common;

namespace Renci.SshNet.Tests.Classes.Sftp
{
    /// <summary>
    /// - In read mode
    /// - Bytes in (read) buffer, but not read from
    /// - New length less than client position and less than server position
    /// </summary>
    [TestClass]
    public class SftpFileStreamTest_SetLength_DataInReadBuffer_NewLengthLessThanPosition : SftpFileStreamTestBase
    {
        private string _path;
        private SftpFileStream _sftpFileStream;
        private byte[] _handle;
        private uint _bufferSize;
        private uint _readBufferSize;
        private uint _writeBufferSize;
        private MockSequence _sequence;
        private long _length;

        private SftpFileAttributes _fileAttributes;
        private SftpFileAttributes _originalFileAttributes;
        private SftpFileAttributes _newFileAttributes;
        private byte[] _readBytes;
        private byte[] _actualReadBytes;

        protected override void SetupData()
        {
            var random = new Random();

            _path = random.Next().ToString(CultureInfo.InvariantCulture);
            _handle = GenerateRandom(random.Next(2, 6), random);
            _bufferSize = (uint)random.Next(1, 1000);
            _readBufferSize = (uint)random.Next(1, 1000);
            _writeBufferSize = (uint)random.Next(100, 1000);
            _readBytes = new byte[5];
            _actualReadBytes = GenerateRandom(_readBytes.Length + 2, random); // add 2 bytes in read buffer
            _length = _readBytes.Length - 2;

            _fileAttributes = new SftpFileAttributesBuilder().WithExtension("X", "ABC")
                                                             .WithExtension("V", "VValue")
                                                             .WithGroupId(random.Next())
                                                             .WithLastAccessTime(DateTime.UtcNow.AddSeconds(random.Next()))
                                                             .WithLastWriteTime(DateTime.UtcNow.AddSeconds(random.Next()))
                                                             .WithPermissions((uint)random.Next())
                                                             .WithSize(_length + 100)
                                                             .WithUserId(random.Next())
                                                             .Build();
            _originalFileAttributes = _fileAttributes.Clone();
            _newFileAttributes = null;
        }

        protected override void SetupMocks()
        {
            _sequence = new MockSequence();
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestOpen(_path, Flags.Read | Flags.Write, false))
                           .Returns(_handle);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.CalculateOptimalReadLength(_bufferSize))
                           .Returns(_readBufferSize);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.CalculateOptimalWriteLength(_bufferSize, _handle))
                           .Returns(_writeBufferSize);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.IsOpen)
                           .Returns(true);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestRead(_handle, 0, _readBufferSize))
                           .Returns(_actualReadBytes);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.IsOpen)
                           .Returns(true);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestFStat(_handle, false))
                           .Returns(_fileAttributes);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestFSetStat(_handle, _fileAttributes))
                           .Callback<byte[], SftpFileAttributes>((bytes, attributes) => _newFileAttributes = attributes.Clone());
        }

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

            _sftpFileStream = new SftpFileStream(SftpSessionMock.Object, _path, FileMode.Open, FileAccess.ReadWrite, (int)_bufferSize);
            _sftpFileStream.Read(_readBytes, 0, _readBytes.Length);
        }

        protected override void Act()
        {
            _sftpFileStream.SetLength(_length);
        }

        [TestMethod]
        public void PositionShouldReturnLengthOfStream()
        {
            SftpSessionMock.InSequence(_sequence).Setup(p => p.IsOpen).Returns(true);

            Assert.AreEqual(_length, _sftpFileStream.Position);

            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(3));
        }

        [TestMethod]
        public void RequestFSetStatOnSftpSessionShouldBeInvokedOnce()
        {
            SftpSessionMock.Verify(p => p.RequestFSetStat(_handle, _fileAttributes), Times.Once);
        }

        [TestMethod]
        public void SizeOfSftpFileAttributesShouldBeModifiedToNewLengthBeforePassedToRequestFSetStat()
        {
            DictionaryAssert.AreEqual(_originalFileAttributes.Extensions, _newFileAttributes.Extensions);
            Assert.AreEqual(_originalFileAttributes.GroupId, _newFileAttributes.GroupId);
            Assert.AreEqual(_originalFileAttributes.LastAccessTime, _newFileAttributes.LastAccessTime);
            Assert.AreEqual(_originalFileAttributes.LastWriteTime, _newFileAttributes.LastWriteTime);
            Assert.AreEqual(_originalFileAttributes.Permissions, _newFileAttributes.Permissions);
            Assert.AreEqual(_originalFileAttributes.UserId, _newFileAttributes.UserId);

            Assert.AreEqual(_length, _newFileAttributes.Size);
        }

        [TestMethod]
        public void ReadShouldStartFromEndOfStream()
        {
            SftpSessionMock.InSequence(_sequence).Setup(p => p.IsOpen).Returns(true);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestRead(_handle, (uint) _length, _readBufferSize))
                           .Returns(Array.Empty<byte>());

            var byteRead = _sftpFileStream.ReadByte();

            Assert.AreEqual(-1, byteRead);

            SftpSessionMock.Verify(p => p.RequestRead(_handle, (uint) _length, _readBufferSize), Times.Once);
            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(3));
        }

        [TestMethod]
        public void WriteShouldStartFromEndOfStream()
        {
            var bytesToWrite = GenerateRandom(_writeBufferSize);
            byte[] bytesWritten = null;

            SftpSessionMock.InSequence(_sequence).Setup(p => p.IsOpen).Returns(true);
            SftpSessionMock.InSequence(_sequence)
                           .Setup(p => p.RequestWrite(_handle, (uint) _length, It.IsAny<byte[]>(), 0, bytesToWrite.Length, It.IsAny<AutoResetEvent>(), null))
                           .Callback<byte[], ulong, byte[], int, int, AutoResetEvent, Action<SftpStatusResponse>>((handle, serverOffset, data, offset, length, wait, writeCompleted) =>
                           {
                               bytesWritten = data.Take(offset, length);
                               wait.Set();
                           });

            _sftpFileStream.Write(bytesToWrite, 0, bytesToWrite.Length);

            Assert.IsNotNull(bytesWritten);
            CollectionAssert.AreEqual(bytesToWrite, bytesWritten);

            SftpSessionMock.Verify(p => p.RequestWrite(_handle, (uint)_length, It.IsAny<byte[]>(), 0, bytesToWrite.Length, It.IsAny<AutoResetEvent>(), null), Times.Once);
            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(3));
        }
    }
}