//   SparkleShare, a collaboration and sharing tool.
//   Copyright (C) 2010  Hylke Bons <hylkebons@gmail.com>
//
//   This program is free software: you can redistribute it and/or modify
//   it under the terms of the GNU Lesser General Public License as 
//   published by the Free Software Foundation, either version 3 of the 
//   License, or (at your option) any later version.
//
//   This program is distributed in the hope that it will be useful,
//   but WITHOUT ANY WARRANTY; without even the implied warranty of
//   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//   GNU General Public License for more details.
//
//   You should have received a copy of the GNU General Public License
//   along with this program. If not, see <http://www.gnu.org/licenses/>.


using System;
using System.Diagnostics;
using System.Text.RegularExpressions;
using System.Net;

using IO = System.IO;

namespace SparkleLib {

    public class SSHAuthenticationInfo : AuthenticationInfo {

        public string PrivateKeyFilePath;
        public string PrivateKey;

        public string PublicKeyFilePath;
        public string PublicKey;

        public string KnownHostsFilePath;

        string Path;


        public SSHAuthenticationInfo ()
        {
            string config_path = IO.Path.GetDirectoryName (SparkleConfig.DefaultConfig.FullPath);
            Path = IO.Path.Combine (config_path, "ssh");

            KnownHostsFilePath = IO.Path.Combine (Path, "known_hosts");

            if (!IO.Directory.Exists (Path)) {
                IO.Directory.CreateDirectory (Path);
                CreateKeyPair ();
            
            } else {
                foreach (string file_path in IO.Directory.GetFiles (Path)) {
                    if (file_path.EndsWith (".key")) {
                        PrivateKeyFilePath = file_path;
                        PrivateKey         = IO.File.ReadAllText (file_path);
                    }

                    if (file_path.EndsWith (".key.pub")) {
                        PublicKeyFilePath = file_path;
                        PublicKey         = IO.File.ReadAllText (file_path);
                    }
                }
            }
        }


        bool CreateKeyPair ()
        {
            string key_file_name = DateTime.Now.ToString ("yyyy-MM-dd_HH\\hmm") + ".key";
            string key_file_path = IO.Path.Combine (Path, key_file_name);
            string computer_name = Dns.GetHostName ();

            if (computer_name.EndsWith (".local"))
                computer_name = computer_name.Substring (0, computer_name.Length - ".local".Length);

            string arguments =
                "-t rsa "  + // Crypto type
                "-b 4096 " + // Key size
                "-P \"\" " + // No password
                "-C \"" + computer_name + " (SparkleShare)\" " + // Key comment
                "-f \"" + key_file_name + "\"";

            var process = new SparkleProcess ("ssh-keygen", arguments);
            process.StartInfo.WorkingDirectory = Path;

            process.Start ();
            process.WaitForExit ();

            if (process.ExitCode == 0) {
                PrivateKeyFilePath = key_file_path;
                PrivateKey = IO.File.ReadAllText (key_file_path);

                PublicKeyFilePath = key_file_path + ".pub";
                PublicKey = IO.File.ReadAllText (key_file_path + ".pub");

                SparkleLogger.LogInfo ("Auth", "Created key pair: " + key_file_name);
                return true;

            } else {
                SparkleLogger.LogInfo ("Auth", "Could not create key pair");
                return false;
            }
        }


        void StartKeyAgent ()
        {
            Process [] processes = Process.GetProcessesByName ("ssh-agent");

            if (processes.Length > 1)
                return;
            
            SparkleLogger.LogInfo ("Auth", "No key agent running, starting one...");

            var process = new SparkleProcess ("ssh-agent", null);
            string output = process.StartAndReadStandardOutput ();

            Match auth_sock_match = new Regex (@"SSH_AUTH_SOCK=([^;\n\r]*)").Match (output);

            if (auth_sock_match.Success)
                Environment.SetEnvironmentVariable ("SSH_AUTH_SOCK", auth_sock_match.Groups [1].Value);
        }
    }
}