// Copyright (c) Microsoft Corporation. All rights reserved.

// Licensed under the MIT License.

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.IO;

using System.Linq;

using System.Net;

using System.Net.Sockets;

using System.Reflection;

using System.Text;

using System.Threading.Tasks;

using Schemy;

namespace Examples.command_server

{

class Program

{

delegate object Function(object input);

static void Main(string[] args)

{

Interpreter.CreateSymbolTableDelegate extension = _ => new Dictionary<Symbol, object>()

{

{ Symbol.FromString("get-current-os"), NativeProcedure.Create(() => GetCurrentSystem()) },

{ Symbol.FromString("chain"), new NativeProcedure(funcs => new Function(input => funcs.Cast<Function>().Select(b => input = b(input)).Last())) },

{ Symbol.FromString("say-hi"), NativeProcedure.Create<Function>(() => name => $"Hello {name}!") },

{ Symbol.FromString("man-freebsd"), NativeProcedure.Create<Function>(() => cmd => Geturl(/sitelet?url=https%3A%2F%2Fgithub.com%2Fmicrosoft%2Fschemy%2Fblob%2Fmaster%2Fsrc%2Fexamples%2Fcommand_server%2F%24%26quot%3Bhttps%3A%2F%2Fwww.freebsd.org%2Fcgi%2Fman.cgi%3Fquery%3D%7Bcmd%7D%26amp%3Bformat%3Dascii%26quot%3B)) },

{ Symbol.FromString("man-linux"), NativeProcedure.Create<Function>(() => cmd => Geturl(/sitelet?url=https%3A%2F%2Fgithub.com%2Fmicrosoft%2Fschemy%2Fblob%2Fmaster%2Fsrc%2Fexamples%2Fcommand_server%2F%24%26quot%3Bhttp%3A%2F%2Fman7.org%2Flinux%2Fman-pages%2Fman1%2F%257Bcmd%257D.1.html%26quot%3B)) },

{ Symbol.FromString("truncate-string"), NativeProcedure.Create<int, Function>(len => input => ((string)input).Substring(0, len)) },

};

var interpreter = new Interpreter(new[] { extension }, new ReadOnlyFileSystemAccessor());

if (args.Contains("--repl")) // start the REPL with all implemented functions

{

interpreter.REPL(Console.In, Console.Out);

return;

}

else

{

// starts a TCP server that receives request (cmd <data>) and sends response back.

var engines = new Dictionary<string, Function>();

foreach (var fn in Directory.GetFiles(Path.GetDirectoryName(Assembly.GetEntryAssembly().Location), "*.ss"))

{

Console.WriteLine($"Loading file {fn}");

LoadScript(interpreter, fn);

engines[Path.GetFileNameWithoutExtension(fn)] = (Function)interpreter.Environment[Symbol.FromString("EXECUTE")];

}

string ip = "127.0.0.1"; int port = 8080;

var server = new TcpListener(IPAddress.Parse(ip), port);

server.Start();

Console.WriteLine($"Server started at {ip}:{port}");

try

{

using (var c = server.AcceptTcpClient())

using (var cs = c.GetStream())

using (var sr = new StreamReader(cs))

using (var sw = new StreamWriter(cs))

{

Console.WriteLine($"Client accepted at {c.Client.RemoteEndPoint}");

while (!sr.EndOfStream)

{

string line = sr.ReadLine();

string[] parsed = line.Split(new[] { ' ' }, 2);

if (parsed.Length != 2)

{

sw.WriteLine($"cannot parse {line}");

sw.Flush();

}

else

{

string engine = parsed[0], request = parsed[1];

if (!engines.ContainsKey(engine))

{

sw.WriteLine($"engine not found: {engine}");

sw.Flush();

}

else

{

string output = (string)(engines[engine](request));

sw.WriteLine(output);

sw.Flush();

}

}

}

}

}

catch (IOException) { }

}

}

static void LoadScript(Interpreter interpreter, string file)

{

using (Stream script = File.OpenRead(file))

using (TextReader reader = new StreamReader(script))

{

var res = interpreter.Evaluate(reader);

if (res.Error != null) throw res.Error;

}

}

// support: windows, freebsd, linux, unknown

static string GetCurrentSystem()

{

var os = System.Environment.OSVersion.Platform;

if (os.ToString().Contains("Win")) return "windows";

if (os == PlatformID.Unix)

{

Process proc = new Process() { StartInfo = new ProcessStartInfo("uname") { RedirectStandardOutput = true } };

proc.Start();

var output = proc.StandardOutput.ReadToEnd().Trim();

proc.WaitForExit();

foreach (var w in new[] { "freebsd", "linux" })

{

if (output.IndexOf(w, StringComparison.OrdinalIgnoreCase) >= 0) return w;

}

}

return "unknown";

}

static string Geturl(/sitelet?url=https%3A%2F%2Fgithub.com%2Fmicrosoft%2Fschemy%2Fblob%2Fmaster%2Fsrc%2Fexamples%2Fcommand_server%2Fstring%2520url)

{

using (var wc = new System.Net.WebClient())

{

return wc.DownloadString(url);

}

}

}

}