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

using Microsoft.VisualStudio.TestTools.UnitTesting;

using Moq;

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

namespace Renci.SshNet.Tests.Classes.Sftp
{
    [TestClass]
    public class SftpFileStreamTest_Ctor_FileModeAppend_FileAccessWrite : SftpFileStreamTestBase
    {
        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 SftpFileAttributes _fileAttributes;

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

            _random = new Random();
            _path = _random.Next().ToString();
            _fileMode = FileMode.Append;
            _fileAccess = FileAccess.Write;
            _bufferSize = _random.Next(5, 1000);
            _readBufferSize = (uint)_random.Next(5, 1000);
            _writeBufferSize = (uint)_random.Next(5, 1000);
            _handle = GenerateRandom(_random.Next(1, 10), _random);
            _fileAttributes = new SftpFileAttributesBuilder().WithLastAccessTime(DateTime.UtcNow.AddSeconds(_random.Next()))
                                                             .WithLastWriteTime(DateTime.UtcNow.AddSeconds(_random.Next()))
                                                             .WithSize(_random.Next())
                                                             .WithUserId(_random.Next())
                                                             .WithGroupId(_random.Next())
                                                             .WithPermissions((uint)_random.Next())
                                                             .Build();
        }

        protected override void SetupMocks()
        {
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestOpen(_path, Flags.Write | Flags.Append | Flags.CreateNewOrOpen, false))
                               .Returns(_handle);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.CalculateOptimalReadLength((uint)_bufferSize))
                               .Returns(_readBufferSize);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.CalculateOptimalWriteLength((uint)_bufferSize, _handle))
                               .Returns(_writeBufferSize);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestFStat(_handle, false))
                               .Returns(_fileAttributes);
        }

        protected override void Act()
        {
            _target = new SftpFileStream(SftpSessionMock.Object,
                                         _path,
                                         _fileMode,
                                         _fileAccess,
                                         _bufferSize);
        }

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

            var actual = _target.Position;

            Assert.AreEqual(_fileAttributes.Size, actual);

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

        [TestMethod]
        public void ReadShouldThrowNotSupportedException()
        {
            var buffer = new byte[_readBufferSize];

            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.IsOpen)
                               .Returns(true);

            try
            {
                _ = _target.Read(buffer, 0, buffer.Length);
                Assert.Fail();
            }
            catch (NotSupportedException ex)
            {
                Assert.IsNull(ex.InnerException);
                Assert.AreEqual("Read not supported.", ex.Message);
            }

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

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

            try
            {
                _ = _target.ReadByte();
                Assert.Fail();
            }
            catch (NotSupportedException ex)
            {
                Assert.IsNull(ex.InnerException);
                Assert.AreEqual("Read not supported.", ex.Message);
            }

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

        [TestMethod]
        public void WriteShouldStartWritingAtEndOfFile()
        {
            var buffer = new byte[_writeBufferSize];

            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.IsOpen)
                               .Returns(true);
            _ = SftpSessionMock.InSequence(MockSequence)
                               .Setup(p => p.RequestWrite(_handle, (ulong)_fileAttributes.Size, buffer, 0, buffer.Length, It.IsNotNull<AutoResetEvent>(), null));

            _target.Write(buffer, 0, buffer.Length);

            SftpSessionMock.Verify(p => p.IsOpen, Times.Exactly(1));
            SftpSessionMock.Verify(p => p.RequestWrite(_handle, (ulong)_fileAttributes.Size, buffer, 0, buffer.Length, It.IsNotNull<AutoResetEvent>(), null), Times.Once);
        }

        [TestMethod]
        public void RequestOpenOnSftpSessionShouldBeInvokedOnce()
        {
            SftpSessionMock.Verify(p => p.RequestOpen(_path, Flags.Write | Flags.Append | Flags.CreateNewOrOpen, false), Times.Once);
        }

        [TestMethod]
        public void RequestFStatOnSftpSessionShouldBeInvokedOnce()
        {
            SftpSessionMock.Verify(p => p.RequestFStat(_handle, false), Times.Once);
        }
    }
}