--  TODO: test multiplayer functionality
--
-- Note: The x-coordinate is reversed in sign between minetest and minecraft,
-- and the API compensates for this.

if minetest.request_insecure_environment then
   ie = minetest.request_insecure_environment()
else
   ie = _G
end

local source = ie.debug.getinfo(1).source:sub(2)
-- Detect windows via backslashes in paths
local mypath = minetest.get_modpath(minetest.get_current_modname())
local is_windows = (nil ~= string.find(ie.package.path..ie.package.cpath..source..mypath, "%\\%?"))
local path_separator
if is_windows then
   path_separator = "\\"
else
   path_separator = "/"
end
mypath = mypath .. path_separator

local script_window_id = "minetest-rjm-python-script"

ie.package.path = ie.package.path .. ";" .. mypath .. "?.lua"
if is_windows then
   ie.package.cpath = ie.package.cpath .. ";" .. mypath .. "?.dll"
else
   ie.package.cpath = ie.package.cpath .. ";" .. mypath .. "?.so"
end

local block = ie.require("block")
local socket = ie.require("socket")

local block_hits = {}
local chat_record = {}
local player_table = {}
local socket_client_list = {}

script_running = false
restrict_to_sword = true
max_player_id = 0
default_player_id = -1
world_immutable = false

local settings = Settings(mypath .. "settings.conf")
local update_settings = false
python_interpreter = settings:get("python")
if python_interpreter == nil then
    python_interpreter = "python"
    update_settings = true
    settings:set("python", python_interpreter)
end
local local_only = settings:get_bool("restrict_to_local_connections")
if local_only == nil then
    local_only = false
    update_settings = true
    settings:set("restrict_to_local_connections", tostring(local_only))
end
local ws = settings:get_bool("support_websockets")
if ws == nil then
    ws = true
    update_settings = true
    settings:set("support_websockets", tostring(ws))
end
if update_settings then settings:write() end

local settings = Settings(mypath .. "override.conf")
local x = settings:get("python")
if x ~= nil then
   python_interpreter = x
end
x = settings:get_bool("restrict_to_local_connections")
if x ~= nil then
   local_only = x
end
x = settings:get_bool("support_websockets")
if x ~= nil then
   ws = x 
end

local remote_address
if local_only then
    remote_address = "127.0.0.1"
else
    remote_address = "*"
end

local server,err = socket.bind(remote_address, 4711)
assert(server, err)

server:setoption('tcp-nodelay',true)
server:settimeout(0)

local ws_server = nil

if ws then
	if not bit or not bit.bxor then bit = ie.require("slowbit32") end
    tools = ie.require("tools")
    base64 = ie.require("base64")
    ws_server = socket.bind(remote_address, 14711)
    ws_server:setoption('tcp-nodelay',true)
    ws_server:settimeout(0)
end


minetest.register_globalstep(function(dtime)
    local newclient,err

    if server then
        newclient,err = server:accept()
        if not err then
           newclient:settimeout(0)
           table.insert(socket_client_list,
               {client=newclient,handler=safe_handle_command,read_mode="*l"})
           minetest.log("action", "RJM socket client connected")
        end
    end
    if ws_server then
        newclient,err = ws_server:accept()
        if not err then
           newclient:settimeout(0)
           table.insert(socket_client_list,
               {client=newclient,handler=handle_websocket_header,ws={},read_mode="*l"})
           minetest.log("action", "RJM websocket client attempting handshake")
        end
    end

    local command_count = 1000

    for i = 1, #socket_client_list do
       err = false
       local line
       local finished = false

       while not err and not finished do
         local source = socket_client_list[i]
         line,err = source.client:receive(source.read_mode)
         if err == "closed" then
            table.remove(socket_client_list,i)
            minetest.log("action", "RJM socket client disconnected")
            finished = true
         elseif not err then
            err = source:handler(line)
            if err then
              source.client:close()
              table.remove(socket_client_list,i)
              if err ~= "closed" then
                  minetest.log("error", "Error "..err.." in command: RJM socket client disconnected")
              end
              finished = true
              err = "handling"
            else
              command_count = command_count - 1
              if command_count < 0 then
                 finished = true
              end
            end
         end
		end

		if finished then break end
    end

	flush_block_buffer()
end)

local old_is_protected = minetest.is_protected
function minetest.is_protected(pos, name)
    return world_immutable or old_is_protected(pos, name)
end

minetest.register_on_shutdown(function()
    if (script_running) then
       minetest.log("action", "Stopping scripts")
       kill(script_window_id)
       script_running = false
    end
    minetest.log("action", "RJM socket clients disconnected")
    for i = 1, #socket_client_list do
        socket_client_list[i].client:close()
    end
    socket_client_list = {}
    player_table = {}
    max_player_id = 0
    default_player_id = -1
end)

minetest.register_on_joinplayer(function(player)
    minetest.log("action", "Hello, player "..player:get_player_name())
    max_player_id = max_player_id + 1
    player_table[max_player_id] = player
    if default_player_id < 0 then default_player_id = max_player_id end
end)

minetest.register_on_leaveplayer(function(player)
    minetest.log("action", "Goodbye, player "..player:get_player_name())
    local id = get_player_id(player)
    if id then player_table[id] = nil end
    if id == default_player_id then
        default_player_id = max_player_id
        for i,p in pairs(player_table) do
          if p ~= nil and i < default_player_id then default_player_id = i end
        end
    end
end)

minetest.register_on_punchnode(function(pos, oldnode, puncher, pointed_thing)
    -- TODO: find a way to get right clicks
    -- TODO: find a way to get clicked side
    if (puncher:is_player()) then
       local item = puncher:get_wielded_item()
       if not restrict_to_sword or (item and item:get_name():find("%:sword")) then
          table.insert(block_hits, pos.x..","..pos.y..","..(-pos.z)..",7,"..get_entity_id(puncher))
       end
    end
end)

minetest.register_chatcommand("top",
	{params="" ,
	description="Move player on top of everything.",
	func = function(name, args)
		local player = minetest.get_player_by_name(name)
		local pos = player:getpos()
		pos.y = get_height(pos.x, pos.z)+1.5
		player:setpos(pos)
	end})

if minetest.emerge_area then
    minetest.register_chatcommand("emerge",
    	{params="[<size>]" ,
    	description="Emerge cubical area at and above player (default size=200).",
    	func = function(name, args)
    		local player = minetest.get_player_by_name(name)
    		local pos = player:getpos()
    		local size
    		if args ~= "" then
    		    size = tonumber(args)
                    else
                        size = 200
                    end
                    local p1 = {x = math.floor(pos.x - size/2), y = pos.y, z = math.floor(pos.z - size/2) }
                    local p2 = {x = math.ceil(pos.x + size/2), y = pos.y + size, z = math.ceil(pos.z + size/2) }
                    minetest.emerge_area(p1,p2)
    	end})
end

minetest.register_chatcommand("py",
	{params="[<script> [<args>]]" ,
	description="Run python script in raspberryjammod/mcpipy directory, killing any previous script",
	func = function(name, args) python(name, args, true) end })
minetest.register_chatcommand("python",
	{params="[<script> [<args>]]" ,
	description="Run python script in raspberryjammod/mcpipy directory, killing any previous script",
	func = function(name, args) python(name, args, true) end })
minetest.register_chatcommand("apy",
	{params="[<script> [<args>]]" ,
	description="Run python script in raspberryjammod/mcpipy directory, without killing any previous script",
	func = function(name, args) python(name, args, false) end })
minetest.register_chatcommand("addpython",
	{params="[<script> [<args>]]" ,
	description="Run python script in raspberryjammod/mcpipy directory, without killing any previous script",
	func = function(name, args) python(name, args, false) end })

function python(name, args, kill_script)
	if (kill_script and script_running) then
	   kill(script_window_id)
	   minetest.chat_send_all("Killed running scripts")
	   script_running = false
	end

	if args == "" then return end

	local script, argtext = args:match("^([^ ]+) *(.*)")
	if argtext:sub(#argtext) == " " then argtext = argtext:sub(1,#argtext - 1) end

	if not script then return true end

	if script:find("%.%.") then
	   minetest.chat_send_all("Sandbox violation in script name")
	   return true
	end

	script_running = true
	local mcpipy_path = mypath .. path_separator .. "mcpipy" .. path_separator
	background_launch(script_window_id, mcpipy_path, '"' .. python_interpreter .. '" "' .. mcpipy_path .. script .. '.py" ' .. argtext)
    return true
 end

local function sanitize_pipe(s)
	return s:gsub("%&", "&amp;"):gsub("%|", "&#124;")
end

minetest.register_on_chat_message(function(name, message)
    local id = get_player_id_by_name(name)
    table.insert(chat_record, id .. "," .. sanitize_pipe(message))
    return false
end)

function get_player_id(player)
    local name = player:get_player_name()
    for id,p in pairs(player_table) do
       if p:get_player_name() == name then
           return id
       end
    end
    return nil
end

function get_player_id_by_name(name)
    for id,p in pairs(player_table) do
       if p:get_player_name() == name then
           return id
       end
    end
    return nil
end

function get_entity_id(entity)
    if not entity:is_player() then
       return 0x7FFFFFFF
    else
       return get_player_id(entity)
    end
end

function handle_entity(cmd, id, args)
    local entity
    if id == nil then
        entity = player_table[default_player_id]
    else
        entity = player_table[id]
    end
    if entity == nil then
        return "fail"
    end
    if cmd == "getPos" then
        local pos = entity:getpos()
        return (pos.x+0.5)..","..(pos.y+0.5)..","..(0.5-pos.z)
    elseif cmd == "getTile" then
        local pos = entity:getpos()
        return math.floor(pos.x+0.5)..","..math.floor(pos.y+0.5)..","..math.floor(0.5-pos.z)
    elseif cmd == "setPos" then
        entity:setpos({x=tonumber(args[1])-0.5, y=tonumber(args[2])-0.5, z=0.5-tonumber(args[3])})
    elseif cmd == "setTile" then
        entity:setpos({x=tonumber(args[1]), y=tonumber(args[2])-0.5, z=-tonumber(args[3])})
    elseif cmd == "getPitch" then
        return tonumber(entity:get_look_pitch() * -180 / math.pi)
    elseif cmd == "getRotation" then
        return tonumber((270 - entity:get_look_yaw() * 180 / math.pi) % 360)
    elseif cmd == "getDirection" then
        local dir = entity:get_look_dir()
        return (dir.x)..","..(dir.y)..","..(-dir.z)
    elseif cmd == "setPitch" then
        -- TODO: For mysterious reasons, set_look_pitch() and get_look_pitch()
        -- values are opposite sign, so we don't negate here. Ideally, the mod
        -- would detect this to make sure that if it's fixed in the next version
        -- this wouldn't be an issue.
        entity:set_look_pitch(tonumber(args[1]) * math.pi / 180)
    elseif cmd == "setRotation" then
        -- TODO: For mysterious reasons, set_look_yaw() and get_look_yaw()
        -- values differ by pi/2. Ideally, the mod
        -- would detect this to make sure that if it's fixed in the next version
        -- this wouldn't be an issue.
        entity:set_look_yaw((180-tonumber(args[1])) * math.pi / 180)
    elseif cmd == "setDirection" then
        -- TODO: Fix set_look_yaw() and get_look_yaw() compensation.
        local x = tonumber(args[1])
        local y = tonumber(args[2])
        local z = tonumber(args[3])
        local xz = math.sqrt(x*x+z*z)
        if xz >= 1e-9 then
           entity:set_look_yaw(- math.atan2(-x,z))
        end
        if x*x + y*y + z*z >= 1e-18 then
           entity:set_look_pitch(math.atan2(-y, xz))
        end
    end
    return nil
end

function parse_node(args, start)
    local id, meta
    if #args < start then
        return {name="air"}
    elseif #args == start then
        return block.id_meta_to_node(tonumber(args[start]),0)
    else
	    return block.id_meta_to_node(tonumber(args[start]),tonumber(args[start+1]))
    end
    return node
end

function get_height(x, z)
	-- TODO: Handle larger heights than 1024
	-- TODO: Wait for emergence?
	for ycoord = 1024,-1024,-1 do
		local node = minetest.get_node_or_nil({x=x,y=ycoord,z=z})
		if node and node.name ~= "air" then
			return ycoord
		end
	end
	return -1025
end

local block_buffer = {}
local block_buffer_p1 = {}
local block_buffer_p2 = {}

function flush_block_buffer()
	if #block_buffer >= 1 then
		local vm = minetest.get_voxel_manip()
		local emin,emax = vm:read_from_map(block_buffer_p1,block_buffer_p2)
		local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
		local data = vm:get_data()
		local param2 = vm:get_param2_data()
		for i=1,#block_buffer do
			local v = block_buffer[i]
			local index = area:indexp(v.pos)
			data[index] = minetest.get_content_id(v.node.name)
			param2[index] = v.node.param2
		end
		vm:set_data(data)
		vm:set_param2_data(param2)
		vm:update_liquids()
		vm:write_to_map()
		vm:update_map()
	else
		for i=1,#block_buffer do
			minetest.set_node(block_buffer[i].pos, block_buffer[i].node)
		end
	end
	block_buffer = {}
	block_buffer_p1 = {}
	block_buffer_p2 = {}
end

local function buffered_set_node(pos, node)
	-- ensure buffer cuboid is no more than about 10000 in size

	local new_block_buffer_p1 = {x=block_buffer_p1.x,y=block_buffer_p1.y,z=block_buffer_p1.z}
	local new_block_buffer_p2 = {x=block_buffer_p2.x,y=block_buffer_p2.y,z=block_buffer_p2.z}
	if not block_buffer_p1.x or pos.x < block_buffer_p1.x then new_block_buffer_p1.x = pos.x end
	if not block_buffer_p1.y or pos.y < block_buffer_p1.y then new_block_buffer_p1.y = pos.y end
	if not block_buffer_p1.z or pos.z < block_buffer_p1.z then new_block_buffer_p1.z = pos.z end
	if not block_buffer_p2.x or pos.x > block_buffer_p2.x then new_block_buffer_p2.x = pos.x end
	if not block_buffer_p2.y or pos.y > block_buffer_p2.y then new_block_buffer_p2.y = pos.y end
	if not block_buffer_p2.z or pos.z > block_buffer_p2.z then new_block_buffer_p2.z = pos.z end

	if #block_buffer > 0 and (new_block_buffer_p2.x - new_block_buffer_p2.x + 1) *
		 (new_block_buffer_p2.y - new_block_buffer_p2.y + 1) *
		 (new_block_buffer_p2.z - new_block_buffer_p2.z + 1) > 10000 then

		 flush_block_buffer()
		 block_buffer_p1.x = pos.x
		 block_buffer_p1.y = pos.y
		 block_buffer_p1.z = pos.z
		 block_buffer_p2.x = pos.x
		 block_buffer_p2.y = pos.y
		 block_buffer_p2.z = pos.z
	else
		block_buffer_p1 = new_block_buffer_p1
		block_buffer_p2 = new_block_buffer_p2
	end

	table.insert(block_buffer, {pos=pos, node=node})
end

local function set_nodes_with_voxelmanip(x1,y1,z1,x2,y2,z2,node)
	local p1 = {x=x1,y=y1,z=z1}
	local p2 = {x=x2,y=y2,z=z2}
	local vm = minetest.get_voxel_manip()
	local emin,emax = vm:read_from_map(p1,p2)
	local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
	local data = vm:get_data()
	local param2 = vm:get_param2_data()
	local content = minetest.get_content_id(node.name)
	for index in area:iterp(p1,p2) do
		data[index] = content
		param2[index] = node.param2
	end
	vm:set_data(data)
	vm:set_param2_data(param2)
	vm:update_liquids()
	vm:write_to_map()
	vm:update_map()
end

local function setNodes(args, node)
	local x1 = math.min(tonumber(args[1]),tonumber(args[4]))
	local x2 = math.max(tonumber(args[1]),tonumber(args[4]))
	local y1 = math.min(tonumber(args[2]),tonumber(args[5]))
	local y2 = math.max(tonumber(args[2]),tonumber(args[5]))
	local z1 = math.min(-tonumber(args[3]),-tonumber(args[6]))
	local z2 = math.max(-tonumber(args[3]),-tonumber(args[6]))

	local volume = (x2+1-x1)*(y2+1-y1)*(z2+1-z1)

	if 50 <= volume and volume <= 20000000 then
		set_nodes_with_voxelmanip(x1,y1,z1,x2,y2,z2,node)
	else
		for ycoord = y1,y2 do
			for xcoord = x1,x2 do
				for zcoord = z1,z2 do
				   minetest.set_node({x=xcoord,y=ycoord,z=zcoord},node)
				end
			end
		end
	end
end

function handle_world(cmd, args)
    if cmd == "setBlock" then
        local node = parse_node(args, 4)
        buffered_set_node({x=tonumber(args[1]),y=tonumber(args[2]),z=-tonumber(args[3])},node)
    elseif cmd == "setNode" then
        local node = {name=args[4]}
        if args[5] then node.param2 = tonumber(args[5]) end
        buffered_set_node({x=tonumber(args[1]),y=tonumber(args[2]),z=-tonumber(args[3])},node)
    elseif cmd == "setBlocks" then
        local node = parse_node(args, 7)
		setNodes(args, node)
    elseif cmd == "setNodes" then
        local node = {name=args[7]}
        if args[8] then node.param2 = tonumber(args[8]) end
		setNodes(args, node)
    elseif cmd == "getNode" then
        local node = minetest.get_node({x=tonumber(args[1]),y=tonumber(args[2]),z=-tonumber(args[3])})
        return node.name .. "," .. node.param2
    elseif cmd == "getAllNodes" then
        local nodes = {}
        for name,_ in pairs(minetest.registered_nodes) do
            table.insert(nodes,sanitize_pipe(name))
        end
        return table.concat(nodes,'|')
    elseif cmd == "getBlockWithData" or cmd == "getBlock" then
        local node = minetest.get_node({x=tonumber(args[1]),y=tonumber(args[2]),z=-tonumber(args[3])})
        local id, meta = block.node_to_id_meta(node)
        if cmd == "getBlock" then
            return tostring(id)
        else
            return id..","..meta
        end
    elseif cmd == "getBlocksWithData" or cmd == "getBlocks" or cmd == "getNodes" then
		local x1 = math.min(tonumber(args[1]),tonumber(args[4]))
		local x2 = math.max(tonumber(args[1]),tonumber(args[4]))
		local y1 = math.min(tonumber(args[2]),tonumber(args[5]))
		local y2 = math.max(tonumber(args[2]),tonumber(args[5]))
		local z1 = math.min(tonumber(args[3]),tonumber(args[6]))
		local z2 = math.max(tonumber(args[3]),tonumber(args[6]))
		
		local data = {}
		
		if cmd == "getBlocksWithData" then 
			for y = y1,y2 do
				for x = x1,x2 do
					for z = z1,z2 do
						local node = minetest.get_node({x=x,y=y,z=-z})
						local id, meta = block.node_to_id_meta(node)
						table.insert(data, id .. "," .. meta)
					end
				end
			end
		elseif cmd == "getNodes" then
			for y = y1,y2 do
				for x = x1,x2 do
					for z = z1,z2 do
						local node = minetest.get_node({x=x,y=y,z=-z})
						table.insert(data, sanitize_pipe(node.name) .. "," .. node.param2)
					end
				end
			end
		else
			for y = y1,y2 do
				for x = x1,x2 do
					for z = z1,z2 do
						local node = minetest.get_node({x=x,y=y,z=-z})
						local id, _ = block.node_to_id_meta(node)
						table.insert(data, tostring(id))
					end
				end
			end
		end
		
		if cmd == "getBlocks" then
			return table.concat(data, ",")
		else
			return table.concat(data, "|")
		end
    elseif cmd == "getHeight" then
	    return tonumber(get_height(tonumber(args[1]),-tonumber(args[2])))
    elseif cmd == "getPlayerId" then
        if #args > 0 then
            local id = get_player_id_by_name(args[1])
            if id == nil then
               return "fail"
            else
               return ""..id
            end
        else
            return ""..default_player_id
        end
    elseif cmd == "getPlayerIds" then
        local ids = {}
        for id,_ in pairs(player_table) do
            table.insert(ids, id)
        end
        table.sort(ids)
        return table.concat(ids, "|")
    elseif cmd == "setting" then
        if args[1] == "world_immutable" then
            world_immutable = (0 ~= tonumber(args[2]))
        end
    end
    return nil

end

function handle_events(cmd, args)
    if (cmd == "setting") then
       if (args[1] == "restrict_to_sword") then
           restrict_to_sword = (0 ~= tonumber(args[2]))
       end
    elseif (cmd == "block.hits") then
       local h = block_hits
       block_hits = {}
       return table.concat(h, "|")
    elseif (cmd == "chat.posts") then
       local c = chat_record
       chat_record = {}
       return table.concat(c, "|")
    elseif (cmd == "clear") then
       block_hits = {}
       chat_record = {}
    end
    return nil
end

function background_launch(window_identifier, working_dir, cmd)
    -- TODO: non-Windows
    if not is_windows then return false end
    local cmdline = 'start "' .. window_identifier .. '" /D "' .. working_dir .. '" /MIN ' .. cmd
    minetest.log("action", "launching ["..cmdline.."]")
    ie.os.execute(cmdline)
end

function kill(window_identifier)
    -- TODO: non-Windows
    minetest.log('taskkill /F /FI "WINDOWTITLE eq  ' .. window_identifier .. '"')
    ie.os.execute('taskkill /F /FI "WINDOWTITLE eq  ' .. window_identifier .. '"')
end

function safe_handle_command(source,line)
    local status, err = pcall(function()
             local response = handle_command(line)
             if response then source.client:send(response.."\n") end
          end)
    return err
end

function handle_command(line)
    local cmd, argtext = line:match("^([^(]+)%((.*)%)")
    if not cmd then return end

    if #block_buffer > 0 and cmd ~= "world.setBlock" and cmd ~= "world.setNode" then
        flush_block_buffer()
    end

    local args = {}
    for argument in argtext:gmatch("([^,]+)") do
        table.insert(args, argument)
    end
    if cmd:sub(1,6) == "world." then
        return handle_world(cmd:sub(7),args)
    elseif cmd:sub(1,7) == "player." then
        if args[1] == "None" then
            -- Compatibility with mcpi library included with RaspberryJuice --
            table.remove(args,1) 
        end
        return handle_entity(cmd:sub(8),nil,args)
    elseif cmd:sub(1,7) == "entity." then
        local player = tonumber(args[1])
        table.remove(args,1)
        return handle_entity(cmd:sub(8),player,args)
    elseif cmd:sub(1,7) == "events." then
        return handle_events(cmd:sub(8),args)
    elseif cmd == "chat.post" then
        minetest.chat_send_all(argtext)
    end
    return nil
end

function complete_data(source,data)
    local needed = tonumber(source.read_mode)
    local have = data:len()

    if source.ws.saved_data then
        source.ws.saved_data = source.ws.saved_data .. data
    else
        source.ws.saved_data = data
    end

    if have >= needed then
        local out = source.ws.saved_data
        source.ws.saved_data = nil
        return out
    else
        source.read_mode = ""..(needed-have)
        return nil
    end
end

function send_message(remote,opcode,data)
    local out = string.char(0x80 + opcode)
    local len = data:len()
    if len > 65535 then
        out = out .. string.char(127)
        for i = 56,0,-8 do
           out = out .. string.char(bit.band(bit.rshift(len, i),0xFF))
        end
    elseif len > 125 then
        out = out .. string.char(126)
        out = out .. string.char(bit.rshift(len, 8)) .. string.char(bit.band(len,0xFF))
    else
        out = out .. string.char(len)
    end
    out = out .. data
    remote.client:send(out)
    return nil
end

function handle_websocket_complete_payload(source,data)
    if source.ws.opcode == 0x09 then
       -- ping -> pong
        send_message(source,0x0A,data)
    elseif source.ws.opcode == 0x02 or source.ws.opcode == 0x01 then
        local status, err = pcall(function()
                 local response = handle_command(data)
                 if response then send_message(source,0x01,response.."\n") end
              end)
        return err
    end

    return nil
end

function handle_websocket_payload(source,data)
    data = complete_data(source,data)
    if data == nil then return nil end
    local mask = data:sub(1,4)
    local decoded = ""
    for i = 1,source.ws.payload_len do
        decoded = decoded .. string.char(bit.bxor( mask:byte( ((i-1)%4) + 1 ), data:byte(4+i) ))
    end

    if source.ws.payload then
        decoded = source.ws.payload .. decoded
    end

    source.read_mode = "2"
    source.handler = handle_websocket_frame

    if source.ws.frame_end then
        source.ws.payload = nil
        return handle_websocket_complete_payload(source,decoded)
    else
        source.ws.payload = decoded
    end

    return nil
end

function handle_websocket_payload_len(source,data)
    data = complete_data(source,data)
    if data == nil then return nil end
    if source.read_mode == "1" then
        source.ws.payload_len = data:byte(1)
    elseif source.read_mode == "2" then
        source.ws.payload_len = bit.lshift(data:byte(1),8)+data:byte(2)
    elseif source.read_mode == "8" then
        source.ws.payload_len =
            bit.lshift(data:byte(1),56)+
            bit.lshift(data:byte(2),48)+
            bit.lshift(data:byte(3),40)+
            bit.lshift(data:byte(4),32)+
            bit.lshift(data:byte(5),24)+
            bit.lshift(data:byte(6),16)+
            bit.lshift(data:byte(7),8)+
            data:byte(8)
    end
    source.read_mode = ""..(4+source.ws.payload_len)
    source.handler = handle_websocket_payload
    return nil
end

function handle_websocket_frame(source,data)
    data = complete_data(source,data)
    if data == nil then return nil end
    local x = data:byte(1)
    --print(string.format("frame %02x %02x",data:byte(1),data:byte(2)))
    source.ws.frame_end = (0 ~= bit.band(0x80, x))
    local opcode = bit.band(0xF, x)
    if opcode == 0x08 then
        --print("closing")
        source.client:close()
        return "closed"
    end
    if opcode ~= 0 then
        source.ws.opcode = opcode
    end
    local y = data:byte(2)
    source.ws.mask = (0 ~= bit.band(0x80, y))
    if not source.ws.mask and opcode <= 0x02 then
        return "unmasked data ("..opcode..")"
    end
    local payload_len = bit.band(y, 0x7F)
    if payload_len == 126 then
        source.handler = handle_websocket_payload_len
        source.read_mode = "2"
    elseif payload_len == 127 then
        source.handler = handle_websocket_payload_len
        source.read_mode = "8"
    else
        source.read_mode = "1"
        return handle_websocket_payload_len(source,string.char(payload_len))
    end
    return nil
end

function handle_websocket_header(source,line)
    if line:find("^Upgrade%: +websocket") then
        source.ws.isWebsocket = true
        return nil
    end

    if not source.ws.key then
        source.ws.key = line:match("^Sec%-WebSocket%-Key%: +([=+/0-9A-Za-z]+)")
    end

    if line == "" then
        if source.ws.isWebsocket and source.ws.key then
            local new_key = base64.encode(tools.sha1(source.ws.key .. '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'))
            source.ws = {}
            local response = "HTTP/1.1 101 Switching Protocols\r\n"..
                             "Upgrade: websocket\r\n"..
                             "Connection: Upgrade\r\n"..
                             "Sec-WebSocket-Accept: "..new_key.."\r\n\r\n";
            source.client:send(response)
            source.read_mode = "2"
            source.handler = handle_websocket_frame
            minetest.log("action","Websocket handshake")
            return nil
        else
            return "invalid websocket request"
        end
    end

    return nil
end



-- os.execute("python scratch_pycraft.py")