using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
using System.IO;

namespace SMFTP
{
    /// <remarks>
    /// Wrapper Managed Class around putty sftp.
    /// <example> 
    /// <code>
    /// SFTPClient client = new SFTPClient();
    /// if(client.Connect("sftp.somedomain.com","user","password","22"))    
    ///    bool bFetchedFile = client.CmdExec_Any("get somefile.txt");
    /// </code>
    /// </example>
    /// </remarks>
    public class SFTPClient : IDisposable
    {
        #region Private Statics

        /// <summary>
        /// Used in the all to LoadLibrary * Names here
        /// * if you change it here * also change DllImports (below)
        /// </summary>
        private const string PSFTP_FILENAME = "psftp.dll";

        /// <summary>
        /// We only want to load the Psftp dll once per process        
        /// </summary>
        private static bool s_PSFTPDLL_IsLoaded = false;

        /// <summary>
        /// Responsible for creating an active connection
        /// </summary>
        [DllImport("psftp.dll")]
        private static extern int dllmain(int argc, [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPStr)] String[] argv);

        /// <summary>
        /// Responsible for running a command on an active connection
        /// </summary>
        [DllImport("psftp.dll")]
        private static extern int do_sftp2([MarshalAs(UnmanagedType.LPStr)] string cmdLine);

        /// <summary>
        /// Responsible for Putty Cleanup
        /// </summary>
        [DllImport("psftp.dll")]
        private static extern void dllmain_cleanup();

        /// <summary>
        /// Loads the Putty Dll
        /// </summary>
        [DllImport("kernel32.dll")]
        private static extern IntPtr LoadLibrary(String dllname);

        #endregion

        #region Construction / Destruction

        /// <summary>
        /// Create a SFTClient Object
        /// </summary>
        public SFTPClient()
        {
            // Extract the Native Dll to the Temp Directory,
            // if it is not already there...
            if (!File.Exists(_pstfpTempFileNameNPath))
            {
                using (BinaryReader br = new BinaryReader(Assembly.GetExecutingAssembly().GetManifestResourceStream(("SMFTP.Components." + PSFTP_FILENAME))))
                using (BinaryWriter bw = new BinaryWriter(new FileStream(_pstfpTempFileNameNPath, FileMode.Create)))
                {
                    byte[] buffer = new byte[64 * 1024];
                    int numread = br.Read(buffer, 0, buffer.Length);
                    while (numread > 0)
                    {
                        bw.Write(buffer, 0, numread);
                        numread = br.Read(buffer, 0, buffer.Length);
                    }
                    bw.Flush();
                }
            }

            // Load the dll, if it isn't already
            if (!s_PSFTPDLL_IsLoaded)
            {
                IntPtr hDll = LoadLibrary(_pstfpTempFileNameNPath);
                s_PSFTPDLL_IsLoaded = (hDll != IntPtr.Zero);
            }
            if (!s_PSFTPDLL_IsLoaded)
                throw new Exception(("Failed to load " + _pstfpTempFileNameNPath + ". Something terrible is wrong"));
        }

        /// <summary>
        /// Finalizer
        /// </summary>
        ~SFTPClient()
        {
            Dispose(false);
        }

        #endregion

        #region Private Members

        private bool _IsConnected = false;
        private bool _disposed = false;
        private readonly string _pstfpTempFileNameNPath = Path.GetTempPath() + PSFTP_FILENAME;

        #endregion

        #region Main Putty Functions

        /// <summary>
        /// Start a Connection to the specified Host with the specified credentials
        /// </summary>
        /// <param name="hostname">url to sftp host</param>
        /// <param name="username">user credential</param>
        /// <param name="password">password credential</param>
        /// <param name="port">port to connect to (default 22)</param>
        /// <returns>true if connection occured successfully, false otherwise</returns>
        public bool Connect(string hostname, string username, string password, string port = "22")
        {
            if (String.IsNullOrEmpty(hostname) || String.IsNullOrEmpty(username) || String.IsNullOrEmpty(password) || String.IsNullOrEmpty(port))
                throw new ArgumentException("Empty String not valid for any of the arguments");

            Disconnect();
            int nResult = dllmain(10, new String[] { Assembly.GetExecutingAssembly().Location, "-l", username, "-pw", password, "-P", port, "-batch", "-y", hostname });
            if (nResult != 0) // Error occured connecting to host with specified prms
                return false;

            _IsConnected = true;
            return true;            
        }        

        /// <summary>
        /// End the active Connection
        /// </summary>
        public bool Disconnect()
        {
            if (_IsConnected)
            {
                dllmain_cleanup();
                _IsConnected = false;
            }
            return !_IsConnected;
        }

        /// <summary>
        /// Performs the specified Command on the Active Connection
        /// </summary>
        /// <param name="Command">a Command including optional parameters like "dir *.*" that can be understood by psftp</param>
        /// <returns>true, if command run successfully, falser otherwise</returns>
        public bool CmdExec_Any(string Command)
        {            
            // Perform the Action
            if (_IsConnected)
            {
                bool bPerformedAction = (do_sftp2(Command) == 1);
                return bPerformedAction;
            }
            return false;
        }

        #endregion

        #region Command Helpers (Assumes Active Connection)

        /// <summary>
        /// Set the Working Directory Locally
        /// </summary>
        /// <param name="path">path to a local directory</param>
        /// <param name="bCreateIfNotExists">true to create the local directory, if it doesn't exist, false otherwise</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExec_LocalDirSet(string path, bool bCreateIfNotExists = false)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if(String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            bool bSuccess = CmdExec_Any("lcd " + path);
            if (!bSuccess && bCreateIfNotExists)
            {
                Directory.CreateDirectory(path);
                if(Directory.Exists(path))
                   bSuccess = CmdExec_Any("lcd " + path);
            }
            return bSuccess;
        }

        /// <summary>
        /// Set the Working Directory on the Remote sftp connection
        /// </summary>
        /// <param name="path">path to a remote directory</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExec_RemoteDirSet(string path)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            // Always make paths absolute * safer *
            if (path[0] != '/' && path[0] != '\\')
                path = '/' + path;

            bool bSuccess = CmdExec_Any("cd " + path);
            return bSuccess;
        }

        /// <summary>
        /// Checks for existence of the Directory on the Server
        /// </summary>
        /// <param name="path">path to a remote directory</param>
        /// <returns>true, if remote directory exists, false otherwise</returns>
        public bool CmdExec_RemoteDirExists(string path)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            // Always make paths absolute * safer *
            if (path[0] != '/' && path[0] != '\\')
                path = '/' + path;

            bool bSuccess = CmdExec_Any("cd /"); // make sure we are at the root dir
            if (bSuccess)
                bSuccess = CmdExec_Any("cd " + path);
            if (bSuccess)
                bSuccess = CmdExec_Any("cd /"); // back to root dir
            return bSuccess;
        }

        /// <summary>
        /// Download a Directory at once including all it's files. if bRecursive is set,
        /// Download all child directories and files
        /// </summary>
        /// <param name="bRecursive">If bRecursive is true, recursively fetch files and directories</param>
        /// <param name="path">path to a remote directory</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MGetDir(bool bRecursive, string path)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            // Always make paths absolute * safer *
            if (path[0] != '/' && path[0] != '\\')
                path = '/' + path;

            string mgetCmd = bRecursive ? "mget -r " : "mget ";
            bool bSuccess = CmdExec_Any(mgetCmd + path);
            return bSuccess;
        }
        
        /// <summary>
        /// Download multiple files at once
        /// <example>
        /// "*.c" "filename1.txt" "*.sln"
        /// </example>
        /// </summary>
        /// <param name="filenames_or_wildcards">space seperated list of multiple filenames or wildcards</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MGetFiles(string filenames_or_wildcards)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(filenames_or_wildcards))
                throw new ArgumentException("filenames_or_wildcards can not be empty");

            bool bSuccess = CmdExec_Any("mget " + filenames_or_wildcards);
            return bSuccess;
        }

        /// <summary>
        /// Upload a Directory at once including all it's files. if bRecursive is set,
        /// Upload all child directories and files
        /// </summary>
        /// <param name="bRecursive">If bRecursive is true, recursively put files and directories</param>
        /// <param name="path">path to a local directory</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MPutDir(bool bRecursive, string path)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            string mgetCmd = bRecursive ? "mput -r " : "mget ";
            bool bSuccess = CmdExec_Any(mgetCmd + path);
            return bSuccess;
        }

        /// <summary>
        /// Upload multiple files at once
        /// <example>
        /// "*.c" "filename1.txt" "*.sln"
        /// </example>
        /// </summary>
        /// <param name="filenames_or_wildcards">space seperated list of multiple filenames or wildcards</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MPutFiles(string filenames_or_wildcards)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(filenames_or_wildcards))
                throw new ArgumentException("filenames_or_wildcards can not be empty");

            bool bSuccess = CmdExec_Any("mput " + filenames_or_wildcards);
            return bSuccess;
        }

        /// <summary>
        /// Delete multiple files at once from the server
        /// <example>
        /// "*.c" "filename1.txt" "*.sln"
        /// </example>
        /// </summary>
        /// <param name="filenames_or_wildcards">space seperated list of multiple filenames or wildcards</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MDelFiles(string filenames_or_wildcards)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(filenames_or_wildcards))
                throw new ArgumentException("filenames_or_wildcards can not be empty");

            bool bSuccess = CmdExec_Any("del " + filenames_or_wildcards);
            return bSuccess;
        }

        /// <summary>
        /// Removes a Directory from the server. Directory must be empty in order 
        /// to be removed.
        /// </summary>
        /// <param name="path">path to a remote directory</param>
        /// <returns>true, if successful, false otherwise</returns>
        public bool CmdExe_MDelDir(string path)
        {
            if (!_IsConnected)
                throw new Exception("Not Connected");
            if (String.IsNullOrEmpty(path))
                throw new ArgumentException("path can not be empty");

            // Always make paths absolute * safer *
            if (path[0] != '/' && path[0] != '\\')
                path = '/' + path;

            bool bSuccess = CmdExec_Any("" + path);
            return bSuccess;
        }

        #endregion

        #region IDisposable Members

        public void Dispose()
        {
            Dispose(true);

            // Use SupressFinalize in case a subclass
            // of this type implements a finalizer
            GC.SuppressFinalize(this);            
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!_disposed)
            {
                if (disposing)
                {
                    // Free Managed Resources
                }
                
                // Free Unmanaged Resources
                Disconnect();
                _disposed = true;
            }
        }

        #endregion
    }
}