/+
Author:
    Colin Grogan
    github.com/grogancolin

Description:
        Implementation of the expect tool (http://expect.sourceforge.net/) in D.

License:
        Boost Software License - Version 1.0 - August 17th, 2003

        Permission is hereby granted, free of charge, to any person or organization
        obtaining a copy of the software and accompanying documentation covered by
        this license (the "Software") to use, reproduce, display, distribute,
        execute, and transmit the Software, and to prepare derivative works of the
        Software, and to permit third-parties to whom the Software is furnished to
        do so, all subject to the following:

        The copyright notices in the Software and this entire statement, including
        the above license grant, this restriction and the following disclaimer,
        must be included in all copies of the Software, in whole or in part, and
        all derivative works of the Software, unless such copies or derivative
        works are solely in the form of machine-executable object code generated by
        a source language processor.

        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
        SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
        FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
        ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
        DEALINGS IN THE SOFTWARE.
+/
module dexpect;

import std.conv : to;
import std..string;
import core.thread : Thread, Duration, msecs;
import std.datetime : Clock;
import std.algorithm : canFind;
import std.path : isAbsolute;
import std.stdio : File, stdout;
import std.range : isOutputRange;

//alias Expect = ExpectImpl!ExpectSink;

/// ExpectImpl spawns a process in a Spawn object.
/// You then call expect("desired output"); sendLine("desired Input");
/// to interact with said process
public class ExpectImpl(OutputRange) if(isOutputRange!(OutputRange, string)){
	/// Amount of time to wait before ending expect call.
	private Duration _timeout=5000.msecs;

	/// The index in allData where the last succesful expect was found
	private size_t indexLastExpect;

	/// The spawn object. Platform dependant. See $Spawn
	private Spawn spawn;

	/// String containing the last string expect function was called on
	private string lastExpect;

	OutputRange _sink;
	/// Constructs an Expect that runs cmd with no args
	this(string cmd, OutputRange sink){
		this(cmd, [], sink);
	}
	/// Constructs an Expect that runs cmd with args
	/// On linux, this passes the args with cmd on front if required
	/// On windows, it passes the args as a single string seperated by spaces
	this(string cmd, string[] args, OutputRange sink){
		this.sink = sink;
		this._sink.put("Spawn  : %s %(%s %)", cmd, args);
		this.spawn.spawn(cmd, args);
	}

	/// Calls the spawns cleanup routine.
	~this(){
		this.spawn.cleanup();
	}

	/// Expects toExpect in output of spawn within Spawns timeout
	public int expect(string toExpect){
		return expect(toExpect, this.timeout);
	}

	/// Expects toExpect in output of spawn within custom timeout
	public int expect(string toExpect, Duration timeout){
		return expect([toExpect], timeout);

		/+this._sink.put("Expect : %s", toExpect);
		Thread.sleep(50.msecs);
		auto startTime = Clock.currTime;
		auto timeLastPrintedMessage = Clock.currTime;
		while(Clock.currTime < startTime + timeout){
			this.spawn.readNextChunk;
			// gives a status update to the user. Takes longer than the default timeout,
			// so usually you wont see it
			if(Clock.currTime >= timeLastPrintedMessage + 5100.msecs){
				string update = this.data.length > 50 ? this.data[$-50..$] : this.data;
				this._sink.put("Last %s chars of data: %s", update.length, update.strip);
				timeLastPrintedMessage = Clock.currTime;
			}
			// check if we finally have what we want in the output, if so, return
			if(this.spawn.allData[indexLastExpect..$].canFind(toExpect)){
				indexLastExpect = this.spawn.allData.lastIndexOf(toExpect);
				this.lastExpect = toExpect;
				return 1;
			}
		}
		throw new ExpectException(format("Duration: %s. Timed out expecting %s in {\n%s\n}",timeout, toExpect, this.data));
		+/
	}

	public int expect(string[] arr, Duration timeout){
		this._sink.put("Expect : %s", arr);
		Thread.sleep(50.msecs);
		auto startTime = Clock.currTime;
		auto timeLastPrintedMessage = Clock.currTime;
		while(Clock.currTime < startTime + timeout){
			// gives a status update to the user. Takes longer than the default timeout,
			// so usually you wont see it
			if(Clock.currTime >= timeLastPrintedMessage + 5100.msecs){
				string update = this.data.length > 50 ? this.data[$-50..$] : this.data;
				this._sink.put("Last %s chars of data: %s", update.length, update.strip);
				timeLastPrintedMessage = Clock.currTime;
			}
			foreach(int idx, string toExpect; arr){
				this.spawn.readNextChunk;
				// check if we finally have what we want in the output, if so, return
				if(this.spawn.allData[indexLastExpect..$].canFind(toExpect)){
					indexLastExpect = this.spawn.allData.lastIndexOf(toExpect);
					this.lastExpect = toExpect;
					return idx;
				}
			}
		}
		throw new ExpectException(format("Duration: %s. Timed out expecting %s in {\n%s\n}", timeout, arr, this.data));
	}
	/// Sends a line to the pty. Ensures it ends with newline
	public void sendLine(string command){
		if(command.length == 0 || command[$-1] != '\n')
			this.send(command ~ '\n');
		else
			this.send(command);
	}
	/// Sends command to the pty
	public void send(string command){
		this._sink.put("Sending: %s", command.replace("\n", "\\n"));
		this.spawn.sendData(command);
	}
	/// Reads data from the spawn
	/// This function will sleep for timeToWait' Duration if nothing was read first time
	/// timeToWait is 50.msecs by default
	public void read(Duration timeToWait=150.msecs){
		auto len = this.data.length;
		this.spawn.readNextChunk;
		if(len == this.data.length){
			Thread.sleep(timeToWait);
			this.spawn.readNextChunk;
		}
	}
	/// Reads all available data. Ends when subsequent reads dont increase length of allData
	public void readAllAvailable(){
		auto len = this.spawn.allData.length;
		while(true){
			this.read;
			if(len == this.spawn.allData.length) break;
			len = this.spawn.allData.length;
		}
	}

	public:
	/// Sets the default timeout
	@property timeout(Duration t) { this._timeout = t; }
	/// Sets the timeout to t milliseconds
	@property timeout(long t) { this._timeout = t.msecs; }
	/// Returns the timeout
	@property auto timeout(){ return this._timeout; }
	/// Returns all data before the last succesfull expect
	@property string before(){ return this.spawn.allData[0..indexLastExpect]; }
	/// Reads and then returns all data after the last succesfull expect. WARNING: May block if spawn is constantly writing data
	@property string after(){ readAllAvailable; return this.spawn.allData[indexLastExpect..$]; }
	@property string data(){ return this.spawn.allData; }

	@property auto sink(){ return this._sink; }
	@property void sink(OutputRange f){ this._sink = f; }
}

public class Expect : ExpectImpl!ExpectSink{

	this(string cmd, File[] oFiles ...){
		ExpectSink newSink = ExpectSink(oFiles);
		this(cmd, newSink);
	}
	this(string cmd, string[] args, File[] oFiles ...){
		ExpectSink newSink = ExpectSink(oFiles);
		this(cmd, args, newSink);
	}
	this(string cmd, ExpectSink sink){
		this(cmd, [], sink);
	}
	this(string cmd, string[] args, ExpectSink sink){
		super(cmd, args, sink);
	}

}

public struct ExpectSink{
	File[] files;
	@property void addFile(File f){ files ~= f; }
	@property File[] file(){ return files; }

	void put(Args...)(string fmt, Args args){
		foreach(file; files){
			file.lockingTextWriter.put(format(fmt, args) ~ "\n");
		}
	}
}

/// Holds information on how to spawn off subprocesses
/// On Linux systems, it uses forkpty
/// On Windows systems, it uses OVERLAPPED io on named pipes
struct Spawn{
	string allData;
	version(Posix){
		private Pty pty;
	}
	version(Windows){
		HANDLE inWritePipe;
		HANDLE outReadPipe;
		OVERLAPPED overlapped;
		ubyte[4096] overlappedBuffer;
	}

	void spawn(string cmd){
		this.spawn(cmd, []);
	}
	void spawn(string cmd, string[] args){
		version(Posix){
			import std.path;
			string firstArg = constructPathToExe(cmd);
			if(args.length == 0 || args[0] != firstArg)
				args = [firstArg] ~ args;
			this.pty = spawnProcessInPty(cmd, args);
		}
		version(Windows){ // FIXME the constructing path to exe here is broken
			              // what happens when you send a relative path to this function? it breaks.
			string fqp = cmd;
			if(!cmd.isAbsolute)
				fqp = cmd.constructPathToExe;
			auto pipes = startChild(fqp, ([fqp] ~ args).join(" "));
			this.inWritePipe = pipes.inwritepipe;
			this.outReadPipe = pipes.outreadpipe;
			overlapped.hEvent = overlappedBuffer.ptr;
			Thread.sleep(100.msecs); // need to give the pipes a moment to connect
		}
	}
	/// On windows, calls CloseHandle on the io handles Spawn uses
	/// Does nothing on linux as linux automatically closes resources when parent dies
	void cleanup(){
		version(Windows){
			CloseHandle(this.inWritePipe);
			CloseHandle(this.outReadPipe);
		}
	}
	/// Sends command to the pty
	public void sendData(string command){
		version(Posix){
			this.pty.sendToPty(command);
		}
		version(Windows){
			this.inWritePipe.writeData(command);
		}
	}
	/// Returns the next toRead of data as a string
	public void readNextChunk(){
		version(Posix){
			auto data = this.pty.readFromPty();
			import std.stdio;
			if(data.length > 0)
				allData ~= data.idup;
		}
		version(Windows){
			OVERLAPPED ov;
			ov.Offset = allData.length;
			if(ReadFileEx(this.outReadPipe, overlappedBuffer.ptr, overlappedBuffer.length, &ov, cast(void*)&readData) == 0){
				if(GetLastError == 997)
					throw new ExpectException("readNextChunk - pending io");
				else {
				// may need to handle other errors here
				// TODO: Investigate
				}
			}
			allData ~= (cast(char*)overlappedBuffer).fromStringz;
			overlappedBuffer.destroy;
			Thread.sleep(100.msecs);
		}
	}
}

version(Posix){
	extern(C) static int forkpty(int* master, char* name, void* termp, void* winp);
	extern(C) static char* ttyname(int fd);

	const toRead = 4096;
  /**
  * A data structure to hold information on a Pty session
  * Holds its fd and a utility property to get its name
  */
	public struct Pty{
		int fd;
		@property string name(){ return ttyname(fd).fromStringz.idup; };
	}

	/**
  * Sets the Pty session to non-blocking mode
  */
	void setNonBlocking(Pty pty){
		import core.sys.posix.unistd;
		import core.sys.posix.fcntl;
		int currFlags = fcntl(pty.fd, F_GETFL, 0) | O_NONBLOCK;
		fcntl(pty.fd, F_SETFL, currFlags);
	}

	/**
  * Spawns a process in a pty session
  * By convention the first arg in args should be == program
  */
	public Pty spawnProcessInPty(string program, string[] args)
	{
		import core.sys.posix.unistd;
		import core.sys.posix.fcntl;
		import core.thread;
		Pty master;
		int pid = forkpty(&(master).fd, null, null, null);
		assert(pid != -1, "Error forking pty");
		if(pid==0){ //child
			execl(program.toStringz,
				args.length > 0 ? args.join(" ").toStringz : null , null);
		}
		else{ // master
			int currFlags = fcntl(master.fd, F_GETFL, 0);
			currFlags |= O_NONBLOCK;
			fcntl(master.fd, F_SETFL, currFlags);
			Thread.sleep(100.msecs); // slow down the main thread to give the child a chance to write something
			return master;
		}
		return Pty(-1);
	}

	/**
  * Sends a string to a pty.
  */
	void sendToPty(Pty pty, string data){
		import core.sys.posix.unistd;
		const(void)[] rawData = cast(const(void)[]) data;
		while(rawData.length){
			long sent = write(pty.fd, rawData.ptr, rawData.length);
			if(sent < 0)
				throw new Exception(format("Error writing to %s", pty.name));
			rawData = rawData[sent..$];
		}
	}

	/**
	  * Reads from a pty session
	  * Returns the string that was read
	  */
	string readFromPty(Pty pty){
		import core.sys.posix.unistd;
		import std.conv : to;
		ubyte[toRead] buf;
		immutable long len = read(pty.fd, buf.ptr, toRead);
		if(len >= 0){
			return cast(string)(buf[0..len]);
		}
		return "";
	}

}

version(Windows){

	import core.sys.windows.windows;

	/+  The below was stolen (and slightly modified) from Adam Ruppe's terminal emulator.
		https://github.com/adamdruppe/terminal-emulator/blob/master/terminalemulator.d
		Thanks Adam!
	+/
	extern(Windows){
		/// Reads from an IO device (https://msdn.microsoft.com/en-us/library/windows/desktop/aa365468%28v=vs.85%29.aspx)
		BOOL ReadFileEx(HANDLE, LPVOID, DWORD, OVERLAPPED*, void*);

		BOOL PostThreadMessageA(DWORD, UINT, WPARAM, LPARAM);

		BOOL RegisterWaitForSingleObject( PHANDLE phNewWaitObject, HANDLE hObject, void* Callback,
			PVOID Context, ULONG dwMilliseconds, ULONG dwFlags);

		BOOL SetHandleInformation(HANDLE, DWORD, DWORD);

		HANDLE CreateNamedPipeA( LPCTSTR lpName, DWORD dwOpenMode, DWORD dwPipeMode, DWORD nMaxInstances,
			DWORD nOutBufferSize, DWORD nInBufferSize, DWORD nDefaultTimeOut, LPSECURITY_ATTRIBUTES lpSecurityAttributes);

		BOOL UnregisterWait(HANDLE);
		void SetLastError(DWORD);
		private void readData(DWORD errorCode, DWORD numberOfBytes, OVERLAPPED* overlapped){
			auto data = (cast(ubyte*) overlapped.hEvent)[0 .. numberOfBytes];
		}
		private void writeData(HANDLE h, string data){
			uint written;
			// convert data into a c string
			auto cstr = cast(void*)data.toStringz;
			if(WriteFile(h, cstr, data.length, &written, null) == 0)
				throw new ExpectException("WriteFile " ~ to!string(GetLastError()));
		}
	}

	__gshared HANDLE waitHandle;
	__gshared bool childDead;

	void childCallback(void* tidp, bool) {
		auto tid = cast(DWORD) tidp;
		UnregisterWait(waitHandle);

		PostThreadMessageA(tid, WM_QUIT, 0, 0);
		childDead = true;
	}

	/// this is good. best to call it with plink.exe so it can talk to unix
	/// note that plink asks for the password out of band, so it won't actually work like that.
	/// thus specify the password on the command line or better yet, use a private key file
	/// e.g.
	/// startChild!something("plink.exe", "plink.exe user@server -i key.ppk \"/home/user/terminal-emulator/serverside\"");
	auto startChild(string program, string commandLine) {
		// thanks for a random person on stack overflow for this function
		static BOOL MyCreatePipeEx(PHANDLE lpReadPipe, PHANDLE lpWritePipe, LPSECURITY_ATTRIBUTES lpPipeAttributes,
			DWORD nSize, DWORD dwReadMode, DWORD dwWriteMode)
		{
			HANDLE ReadPipeHandle, WritePipeHandle;
			DWORD dwError;
			CHAR[MAX_PATH] PipeNameBuffer;

			if (nSize == 0) {
				nSize = 4096;
			}

			static int PipeSerialNumber = 0;

			import core.stdc..string;
			import core.stdc.stdio;

			// could use format here, but C function will add \0 like windows wants
			// so may as well use it
			sprintf(PipeNameBuffer.ptr,
				"\\\\.\\Pipe\\DExpectPipe.%08x.%08x".ptr,
				GetCurrentProcessId(),
				PipeSerialNumber++
				);

			ReadPipeHandle = CreateNamedPipeA(
				PipeNameBuffer.ptr,
				1/*PIPE_ACCESS_INBOUND*/ | dwReadMode,
				0/*PIPE_TYPE_BYTE*/ | 0/*PIPE_WAIT*/,
				1,             // Number of pipes
				nSize,         // Out buffer size
				nSize,         // In buffer size
				120 * 1000,    // Timeout in ms
				lpPipeAttributes
				);

			if (! ReadPipeHandle) {
				return FALSE;
			}

			WritePipeHandle = CreateFileA(
				PipeNameBuffer.ptr,
				GENERIC_WRITE,
				0,                         // No sharing
				lpPipeAttributes,
				OPEN_EXISTING,
				FILE_ATTRIBUTE_NORMAL | dwWriteMode,
				null                       // Template file
				);

			if (INVALID_HANDLE_VALUE == WritePipeHandle) {
				dwError = GetLastError();
				CloseHandle( ReadPipeHandle );
				SetLastError(dwError);
				return FALSE;
			}

			*lpReadPipe = ReadPipeHandle;
			*lpWritePipe = WritePipeHandle;

			return( TRUE );
		}

		SECURITY_ATTRIBUTES saAttr;
		saAttr.nLength = SECURITY_ATTRIBUTES.sizeof;
		saAttr.bInheritHandle = true;
		saAttr.lpSecurityDescriptor = null;

		HANDLE inreadPipe;
		HANDLE inwritePipe;
		if(CreatePipe(&inreadPipe, &inwritePipe, &saAttr, 0) == 0)
			throw new Exception("CreatePipe");
		if(!SetHandleInformation(inwritePipe, 1/*HANDLE_FLAG_INHERIT*/, 0))
			throw new Exception("SetHandleInformation");
		HANDLE outreadPipe;
		HANDLE outwritePipe;
		if(MyCreatePipeEx(&outreadPipe, &outwritePipe, &saAttr, 0, FILE_FLAG_OVERLAPPED, 0) == 0)
			throw new Exception("CreatePipe");
		if(!SetHandleInformation(outreadPipe, 1/*HANDLE_FLAG_INHERIT*/, 0))
			throw new Exception("SetHandleInformation");

		STARTUPINFO startupInfo;
		startupInfo.cb = startupInfo.sizeof;

		startupInfo.dwFlags = STARTF_USESTDHANDLES;
		startupInfo.hStdInput = inreadPipe;
		startupInfo.hStdOutput = outwritePipe;
		startupInfo.hStdError = GetStdHandle(STD_ERROR_HANDLE);//outwritePipe;

		PROCESS_INFORMATION pi;

		if(commandLine.length > 255)
			throw new Exception("command line too long");
		char[256] cmdLine;
		cmdLine[0 .. commandLine.length] = commandLine[];
		cmdLine[commandLine.length] = 0;

		if(CreateProcessA(program is null ? null : toStringz(program), cmdLine.ptr, null, null, true, 0/*0x08000000 /* CREATE_NO_WINDOW */, null /* environment */, null, &startupInfo, &pi) == 0)
			throw new Exception("CreateProcess " ~ to!string(GetLastError()));

		if(RegisterWaitForSingleObject(&waitHandle, pi.hProcess, &childCallback, cast(void*) GetCurrentThreadId(), INFINITE, 4 /* WT_EXECUTEINWAITTHREAD */ | 8 /* WT_EXECUTEONLYONCE */) == 0)
			throw new Exception("RegisterWaitForSingleObject");

		struct Pipes { HANDLE inwritepipe, outreadpipe; }
		return Pipes(inwritePipe, outreadPipe);

	}
}

/+ --------------- Utils --------------- +/
/**
  * Exceptions thrown during expecting data.
  */
class ExpectException : Exception {
	this(string message, string file = __FILE__, size_t line = __LINE__, Throwable next = null){
		super(message, file, line, next);
	}
}

/**
  * Searches all dirs on path for exe if required,
  * or simply calls it if it's a relative or absolute path
  */
string constructPathToExe(string exe){
	import std.path;
	import std.algorithm;
	import std.file : exists;
	import std.process : environment;

	// if it already has a / or . at the start, assume the exe is correct
	if(exe[0..1]==dirSeparator || exe[0..1]==".") return exe;
	auto matches = environment["PATH"].split(pathSeparator)
		.map!(path => path~dirSeparator~exe)
		.filter!(path => path.exists);
	return matches.empty ? exe : matches.front;
}
version(Posix){
	unittest{
		assert("sh".constructPathToExe == "/bin/sh");
		assert("./myexe".constructPathToExe == "./myexe");
		assert("/myexe".constructPathToExe == "/myexe");
	}
}