2-- lzb.lua
-- Enforced and/or automatic train override control, providing the on_train_approach callback

--[[
Documentation of train.lzb table
train.lzb = {
	trav_index = Current index that the traverser has advanced so far
	checkpoints = table containing oncoming signals, in order of index
		{
			pos = position of the point
			index = where this is on the path
			speed = speed allowed to pass. nil = no effect
			callback = function(pos, id, train, index, speed, lzbdata)
			-- Function that determines what to do on the train in the moment it drives over that point.
			-- When spd==0, called instead when train has stopped in front
			-- nil = no effect
			lzbdata = {}
			-- Table of custom data filled in by approach callbacks
			-- Whenever an approach callback inserts an LZB checkpoint with changed lzbdata,
			-- all consecutive approach callbacks will see these passed as lzbdata table.
			
			udata = arbitrary user data, no official way to retrieve (do not use)
		}
	trav_lzbdata = currently active lzbdata table at traverser index
}
The LZB subsystem keeps track of "checkpoints" the train will pass in the future, and has two main tasks:
1. run approach callbacks, and run callbacks when passing LZB checkpoints
2. keep track of the permitted speed at checkpoints, and make sure that the train brakes accordingly
To perform 2, it populates the train.path_speed table which is handled along with the path subsystem.
This table is used in trainlogic.lua/train_step_b() and applied to the velocity calculations.

Note: in contrast to node enter callbacks, which are called when the train passes the .5 index mark, LZB callbacks are executed on passing the .0 index mark!
If an LZB checkpoint has speed 0, the train will still enter the node (the enter callback will be called), but will stop at the 0.9 index mark (for details, see SLOW_APPROACH in trainlogic.lua)

The start point for the LZB traverser (and thus the first node that will receive an approach callback) is floor(train.index) + 1. This means, once the LZB checkpoint callback has fired,
this path node will not receive any further approach callbacks for the same approach situation
]]


local params = {
	BRAKE_SPACE = 10,
	AWARE_ZONE  = 50,

	ADD_STAND  =  2.5,
	ADD_SLOW   =  1.5,
	ADD_FAST   =  7,
	ZONE_ROLL  =  2,
	ZONE_HOLD  =  5, -- added on top of ZONE_ROLL
	ZONE_VSLOW =  3, -- When speed is <2, still allow accelerating

	DST_FACTOR =  1.5,

	SHUNT_SPEED_MAX = advtrains.SHUNT_SPEED_MAX,
}

function advtrains.set_lzb_param(par, val)
	if params[par] and tonumber(val) then
		params[par] = tonumber(val)
	else
		error("Inexistant param or not a number")
	end
end

local function resolve_latest_lzbdata(ckp, index)
	local i = #ckp
	local ckpi
	while i>0 do
		ckpi = ckp[i]
		if ckpi.index <= index and ckpi.lzbdata then
			return ckpi.lzbdata
		end
		i=i-1
	end
	return {}
end

local function look_ahead(id, train)
	local lzb = train.lzb
	if lzb.zero_checkpoint then
		-- if the checkpoints list contains a zero checkpoint, don't look ahead
		-- in order to not trigger approach callbacks on the wrong path
		return
	end
	
	local acc = advtrains.get_acceleration(train, 1)
	-- worst-case: the starting point is maximum speed
	local vel = train.max_speed or train.velocity
	local brakedst = ( -(vel*vel) / (2*acc) ) * params.DST_FACTOR
	
	--local brake_i = advtrains.path_get_index_by_offset(train, train.index, brakedst + params.BRAKE_SPACE)
	-- worst case (don't use index_by_offset)
	local brake_i = atfloor(train.index + brakedst + params.BRAKE_SPACE)
	atprint("LZB: looking ahead up to ", brake_i)
	
	--local aware_i = advtrains.path_get_index_by_offset(train, brake_i, AWARE_ZONE)
	
	local trav = lzb.trav_index
	-- retrieve latest lzbdata
	if not lzb.trav_lzbdata then
		lzb.trav_lzbdata = resolve_latest_lzbdata(lzb.checkpoints, trav)
	end
	
	if lzb.trav_lzbdata.off_track then
		--previous position was off track, do not scan any further
	end
	
	while trav <= brake_i and not lzb.zero_checkpoint do
		local pos = advtrains.path_get(train, trav)
		-- check offtrack
		if trav - 1 == train.path_trk_f then
			lzb.trav_lzbdata.off_track = true
			advtrains.lzb_add_checkpoint(train, trav - 1, 0, nil, lzb.trav_lzbdata)
		else
			-- run callbacks
			-- Note: those callbacks are defined in trainlogic.lua for consistency with the other node callbacks
			advtrains.tnc_call_approach_callback(pos, id, train, trav, lzb.trav_lzbdata)
			
		end
		trav = trav + 1
		
	end
	
	lzb.trav_index = trav
	
end
advtrains.lzb_look_ahead = look_ahead


local function call_runover_callbacks(id, train)
	if not train.lzb then return end
	
	local i = 1
	local idx = atfloor(train.index)
	local ckp = train.lzb.checkpoints
	while ckp[i] do
		if ckp[i].index <= idx then
			atprint("LZB: checkpoint run over: i=",ckp[i].index,"s=",ckp[i].speed)
			-- call callback
			local it = ckp[i]
			if it.callback then
				it.callback(it.pos, id, train, it.index, it.speed, train.lzb.lzbdata)
			end
			-- note: lzbdata is always defined as look_ahead was called before
			table.remove(ckp, i)
		else
			i = i + 1
		end
	end
end

-- Flood-fills train.path_speed, based on this checkpoint 
local function apply_checkpoint_to_path(train, checkpoint)
	if not checkpoint.speed then
		return
	ende media fetching via http
ENABLE_CURSES       - Build with (n)curses; Enables a server side terminal (command line option: --terminal)
ENABLE_FREETYPE     - Build with FreeType2; Allows using TTF fonts
ENABLE_GETTEXT      - Build with Gettext; Allows using translations
ENABLE_GLES         - Search for Open GLES headers & libraries and use them
ENABLE_LEVELDB      - Build with LevelDB; Enables use of LevelDB map backend
ENABLE_POSTGRESQL   - Build with libpq; Enables use of PostgreSQL map backend (PostgreSQL 9.5 or greater recommended)
ENABLE_REDIS        - Build with libhiredis; Enables use of Redis map backend
ENABLE_SPATIAL      - Build with LibSpatial; Speeds up AreaStores
ENABLE_SOUND        - Build with OpenAL, libogg & libvorbis; in-game Sounds
ENABLE_LUAJIT       - Build with LuaJIT (much faster than non-JIT Lua)
ENABLE_SYSTEM_GMP   - Use GMP from system (much faster than bundled mini-gmp)
RUN_IN_PLACE        - Create a portable install (worlds, settings etc. in current directory)
USE_GPROF           - Enable profiling using GProf
VERSION_EXTRA       - Text to append to version (e.g. VERSION_EXTRA=foobar -> Minetest 0.4.9-foobar)

Library specific options:

BZIP2_INCLUDE_DIR               - Linux only; directory where bzlib.h is located
BZIP2_LIBRARY                   - Linux only; path to libbz2.a/libbz2.so
CURL_DLL                        - Only if building with cURL on Windows; path to libcurl.dll
CURL_INCLUDE_DIR                - Only if building with cURL; directory where curl.h is located
CURL_LIBRARY                    - Only if building with cURL; path to libcurl.a/libcurl.so/libcurl.lib
EGL_INCLUDE_DIR                 - Only if building with GLES; directory that contains egl.h
EGL_LIBRARY                     - Only if building with GLES; path to libEGL.a/libEGL.so
FREETYPE_INCLUDE_DIR_freetype2  - Only if building with Freetype2; directory that contains an freetype directory with files such as ftimage.h in it
FREETYPE_INCLUDE_DIR_ft2build   - Only if building with Freetype2; directory that contains ft2build.h
FREETYPE_LIBRARY                - Only if building with Freetype2; path to libfreetype.a/libfreetype.so/freetype.lib
FREETYPE_DLL                    - Only if building with Freetype2 on Windows; path to libfreetype.dll
GETTEXT_DLL                     - Only when building with Gettext on Windows; path to libintl3.dll
GETTEXT_ICONV_DLL               - Only when building with Gettext on Windows; path to libiconv2.dll
GETTEXT_INCLUDE_DIR             - Only when building with Gettext; directory that contains iconv.h
GETTEXT_LIBRARY                 - Only when building with Gettext on Windows; path to libintl.dll.a
GETTEXT_MSGFMT                  - Only when building with Gettext; path to msgfmt/msgfmt.exe
IRRLICHT_DLL                    - Only on Windows; path to Irrlicht.dll
IRRLICHT_INCLUDE_DIR            - Directory that contains IrrCompileConfig.h
IRRLICHT_LIBRARY                - Path to libIrrlicht.a/libIrrlicht.so/libIrrlicht.dll.a/Irrlicht.lib
LEVELDB_INCLUDE_DIR             - Only when building with LevelDB; directory that contains db.h
LEVELDB_LIBRARY                 - Only when building with LevelDB; path to libleveldb.a/libleveldb.so/libleveldb.dll.a
LEVELDB_DLL                     - Only when building with LevelDB on Windows; path to libleveldb.dll
POSTGRESQL_INCLUDE_DIR          - Only when building with PostgreSQL; directory that contains libpq-fe.h
POSTGRESQL_LIBRARY              - Only when building with PostgreSQL; path to libpq.a/libpq.so
REDIS_INCLUDE_DIR               - Only when building with Redis; directory that contains hiredis.h
REDIS_LIBRARY                   - Only when building with Redis; path to libhiredis.a/libhiredis.so
SPATIAL_INCLUDE_DIR             - Only when building with LibSpatial; directory that contains spatialindex/SpatialIndex.h
SPATIAL_LIBRARY                 - Only when building with LibSpatial; path to libspatialindex_c.so/spatialindex-32.lib
LUA_INCLUDE_DIR                 - Only if you want to use LuaJIT; directory where luajit.h is located
LUA_LIBRARY                     - Only if you want to use LuaJIT; path to libluajit.a/libluajit.so
MINGWM10_DLL                    - Only if compiling with MinGW; path to mingwm10.dll
OGG_DLL                         - Only if building with sound on Windows; path to libogg.dll
OGG_INCLUDE_DIR                 - Only if building with sound; directory that contains an ogg directory which contains ogg.h
OGG_LIBRARY                     - Only if building with sound; path to libogg.a/libogg.so/libogg.dll.a
OPENAL_DLL                      - Only if building with sound on Windows; path to OpenAL32.dll
OPENAL_INCLUDE_DIR              - Only if building with sound; directory where al.h is located
OPENAL_LIBRARY                  - Only if building with sound; path to libopenal.a/libopenal.so/OpenAL32.lib
OPENGLES2_INCLUDE_DIR           - Only if building with GLES; directory that contains gl2.h
OPENGLES2_LIBRARY               - Only if building with GLES; path to libGLESv2.a/libGLESv2.so
SQLITE3_INCLUDE_DIR             - Directory that contains sqlite3.h
SQLITE3_LIBRARY                 - Path to libsqlite3.a/libsqlite3.so/sqlite3.lib
VORBISFILE_DLL                  - Only if building with sound on Windows; path to libvorbisfile-3.dll
VORBISFILE_LIBRARY              - Only if building with sound; path to libvorbisfile.a/libvorbisfile.so/libvorbisfile.dll.a
VORBIS_DLL                      - Only if building with sound on Windows; path to libvorbis-0.dll
VORBIS_INCLUDE_DIR              - Only if building with sound; directory that contains a directory vorbis with vorbisenc.h inside
VORBIS_LIBRARY                  - Only if building with sound; path to libvorbis.a/libvorbis.so/libvorbis.dll.a
XXF86VM_LIBRARY                 - Only on Linux; path to libXXf86vm.a/libXXf86vm.so
ZLIB_DLL                        - Only on Windows; path to zlib1.dll
ZLIBWAPI_DLL                    - Only on Windows; path to zlibwapi.dll
ZLIB_INCLUDE_DIR                - Directory that contains zlib.h
ZLIB_LIBRARY                    - Path to libz.a/libz.so/zlibwapi.lib

Compiling on Windows:
---------------------
- This section is outdated. In addition to what is described here:
  - In addition to minetest, you need to download minetest_game.
  - If you wish to have sound support, you need libogg, libvorbis and libopenal

- You need:
	* CMake:
		http://www.cmake.org/cmake/resources/software.html
	* MinGW or Visual Studio
		http://www.mingw.org/
		http://msdn.microsoft.com/en-us/vstudio/default
	* Irrlicht SDK 1.7:
		http://irrlicht.sourceforge.net/downloads.html
	* Zlib headers (zlib125.zip)
		http://www.winimage.com/zLibDll/index.html
	* Zlib library (zlibwapi.lib and zlibwapi.dll from zlib125dll.zip):
		http://www.winimage.com/zLibDll/index.html
	* SQLite3 headers and library
		https://www.sqlite.org/download.html
	* Optional: gettext library and tools:
		http://gnuwin32.sourceforge.net/downlinks/gettext.php
		- This is used for other UI languages. Feel free to leave it out.
	* And, of course, Minetest:
		http://minetest.net/download
- Steps:
	- Select a directory called DIR hereafter in which you will operate.
	- Make sure you have CMake and a compiler installed.
	- Download all the other stuff to DIR and extract them into there.
	  ("extract here", not "extract to packagename/")
	  NOTE: zlib125dll.zip needs to be extracted into zlib125dll
	  NOTE: You need to extract sqlite3.h & sqlite3ext.h from sqlite3 source
	      and sqlite3.dll & sqlite3.def from sqlite3 precompiled binaries
	      into "sqlite3" directory, and generate sqlite3.lib using command
	      "LIB /DEF:sqlite3.def /OUT:sqlite3.lib"
	- All those packages contain a nice base directory in them, which
	  should end up being the direct subdirectories of DIR.
	- You will end up with a directory structure like this (+=dir, -=file):
	-----------------
	+ DIR
		- zlib-1.2.5.tar.gz
		- zlib125dll.zip
		- irrlicht-1.8.3.zip
		- sqlite-amalgamation-3130000.zip (SQLite3 headers)
		- sqlite-dll-win32-x86-3130000.zip (SQLite3 library for 32bit system)
		- 110214175330.zip (or whatever, this is the minetest source)
		+ zlib-1.2.5
			- zlib.h
			+ win32
			...
		+ zlib125dll
			- readme.txt
			+ dll32
			...
		+ irrlicht-1.8.3
			+ lib
			+ include
			...
		+ sqlite3
			sqlite3.h
			sqlite3ext.h
			sqlite3.lib
			sqlite3.dll
		+ gettext (optional)
			+bin
			+include
			+lib
		+ minetest
			+ src
			+ doc
			- CMakeLists.txt
			...
	-----------------
	- Start up the CMake GUI
	- Select "Browse Source..." and select DIR/minetest
	- Now, if using MSVC:
		- Select "Browse Build..." and select DIR/minetest-build
	- Else if using MinGW:
		- Select "Browse Build..." and select DIR/minetest
	- Select "Configure"
	- Select your compiler
	- It will warn about missing stuff, ignore that at this point. (later don't)
	- Make sure the configuration is as follows
	  (note that the versions may differ for you):
	-----------------
	BUILD_CLIENT             [X]
	BUILD_SERVER             [ ]
	CMAKE_BUILD_TYPE         Release
	CMAKE_INSTALL_PREFIX     DIR/minetest-install
	IRRLICHT_SOURCE_DIR      DIR/irrlicht-1.8.3
	RUN_IN_PLACE             [X]
	WARN_ALL                 [ ]
	ZLIB_DLL                 DIR/zlib125dll/dll32/zlibwapi.dll
	ZLIB_INCLUDE_DIR         DIR/zlib-1.2.5
	ZLIB_LIBRARIES           DIR/zlib125dll/dll32/zlibwapi.lib
	GETTEXT_BIN_DIR          DIR/gettext/bin
	GETTEXT_INCLUDE_DIR      DIR/gettext/include
	GETTEXT_LIBRARIES        DIR/gettext/lib/intl.lib
	GETTEXT_MSGFMT           DIR/gettext/bin/msgfmt
	-----------------
	- If CMake complains it couldn't find SQLITE3, choose "Advanced" box on the
	  right top corner, then specify the location of SQLITE3_INCLUDE_DIR and
	  SQLITE3_LIBRARY manually.
	- If you want to build 64-bit minetest, you will need to build 64-bit version
	  of irrlicht engine manually, as only 32-bit pre-built library is provided.
	- Hit "Configure"
	- Hit "Configure" once again 8)
	- If something is still coloured red, you have a problem.
	- Hit "Generate"
	If using MSVC:
		- Open the generated minetest.sln
		- The project defaults to the "Debug" configuration. Make very sure to
		  select "Release", unless you want to debug some stuff (it's slower
		  and might not even work at all)
		- Build the ALL_BUILD project
		- Build the INSTALL project
		- You should now have a working game with the executable in
			DIR/minetest-install/bin/minetest.exe
		- Additionally you may create a zip package by building the PACKAGE
		  project.
	If using MinGW:
		- Using the command line, browse to the build directory and run 'make'
		  (or mingw32-make or whatever it happens to be)
		- You may need to copy some of the downloaded DLLs into bin/, see what
		  running the produced executable tells you it doesn't have.
		- You should now have a working game with the executable in
			DIR/minetest/bin/minetest.exe

Windows releases of minetest are built using a bat script like this:
--------------------------------------------------------------------

set sourcedir=%CD%
set installpath="C:\tmp\minetest_install"
set irrlichtpath="C:\tmp\irrlicht-1.7.2"

set builddir=%sourcedir%\bvc10
mkdir %builddir%
pushd %builddir%
cmake %sourcedir% -G "Visual Studio 10" -DIRRLICHT_SOURCE_DIR=%irrlichtpath% -DRUN_IN_PLACE=TRUE -DCMAKE_INSTALL_PREFIX=%installpath%
if %errorlevel% neq 0 goto fail
"C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe" ALL_BUILD.vcxproj /p:Configuration=Release
if %errorlevel% neq 0 goto fail
"C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe" INSTALL.vcxproj /p:Configuration=Release
if %errorlevel% neq 0 goto fail
"C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe" PACKAGE.vcxproj /p:Configuration=Release
if %errorlevel% neq 0 goto fail
popd
echo Finished.
exit /b 0

:fail
popd
echo Failed.
exit /b 1

License of Minetest textures and sounds
---------------------------------------

This applies to textures and sounds contained in the main Minetest
distribution.

Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
http://creativecommons.org/licenses/by-sa/3.0/

Authors of media files
-----------------------
Everything not listed in here:
Copyright (C) 2010-2012 celeron55, Perttu Ahola <celeron55@gmail.com>

ShadowNinja:
  textures/base/pack/smoke_puff.png

Paramat:
  textures/base/pack/menu_header.png

erlehmann:
  misc/minetest-icon-24x24.png
  misc/minetest-icon.ico
  misc/minetest.svg
  textures/base/pack/logo.png

License of Minetest source code
-------------------------------

Minetest
Copyright (C) 2010-2017 celeron55, Perttu Ahola <celeron55@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 2.1 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

Irrlicht
---------------

This program uses the Irrlicht Engine. http://irrlicht.sourceforge.net/

 The Irrlicht Engine License

Copyright © 2002-2005 Nikolaus Gebhardt

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute
it freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you
      must not claim that you wrote the original software. If you use
	  this software in a product, an acknowledgment in the product
	  documentation would be appreciated but is not required.
   2. Altered source versions must be plainly marked as such, and must
      not be misrepresented as being the original software.
   3. This notice may not be removed or altered from any source
      distribution.


JThread
---------------

This program uses the JThread library. License for JThread follows:

Copyright (c) 2000-2006  Jori Liesenborgs (jori.liesenborgs@gmail.com)

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

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 AND NONINFRINGEMENT.  IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.

Lua
---------------

Lua is licensed under the terms of the MIT license reproduced below.
This means that Lua is free software and can be used for both academic
and commercial purposes at absolutely no cost.

For details and rationale, see https://www.lua.org/license.html .

Copyright (C) 1994-2008 Lua.org, PUC-Rio.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

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 AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Fonts
---------------

Bitstream Vera Fonts Copyright:

  Copyright (c) 2003 by Bitstream, Inc. All Rights Reserved. Bitstream Vera is
  a trademark of Bitstream, Inc.

Arimo - Apache License, version 2.0
  Digitized data copyright (c) 2010-2012 Google Corporation.

Cousine - Apache License, version 2.0
  Digitized data copyright (c) 2010-2012 Google Corporation.

DroidSansFallBackFull:

  Copyright (C) 2008 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.