local def
local F = minetest.formspec_escape
local ch_core = advtrains.lines.ch_core
local S = advtrains.lines.translate
--[[
Jednoduchá funkce, která vyhodnotí condition jako podmínku
a podle výsledku vrátí buď true_result, nebo false_result.
]]
local function ifthenelse(condition, true_result, false_result)
	if condition then
		return true_result
	else
		return false_result
	end
end
-- Singularis-Merge: Emulate certain ch functionality
local function prihlasovaci_na_zobrazovaci(prihlasovaci)
	return prihlasovaci -- no-op. On CH used to colorize the name to reflect the rank of the player
end

local max_stations = 60

local MODE_NORMAL = 0 -- normální zastávka (výchozí nebo mezilehlá)
local MODE_REQUEST_STOP = 1 -- zastávka na znamení (mezilehlá)
local MODE_HIDDEN = 2 -- skrytá zastávka (výchozí nebo mezilehlá)
local MODE_DISABLED = 3 -- vypnutá zastávka (mezilehlá nebo koncová)
local MODE_FINAL = 4 -- koncová zastávka (linka zde jízdu končí)
local MODE_FINAL_HIDDEN = 5 -- koncová zastávka skrytá
local MODE_FINAL_CONTINUE = 6 -- koncová zastávka (vlak pokračuje jako jiná linka)

local color_red = core.get_color_escape_sequence("#ff0000")
local color_green = core.get_color_escape_sequence("#00ff00")

local cancel_linevar = assert(advtrains.lines.cancel_linevar)
local get_last_passages = assert(advtrains.lines.get_last_passages)
local get_line_description = assert(advtrains.lines.get_line_description)
local linevar_decompose = assert(advtrains.lines.linevar_decompose)
local try_get_linevar_def = assert(advtrains.lines.try_get_linevar_def)

local show_last_passages_formspec -- forward declaration

local function check_rights(pinfo, owner)
    if pinfo.role == "new" or pinfo.role == "none" then
        return false
    end
    if owner == nil or pinfo.role == "admin" or pinfo.player_name == owner then
        return true
    end
    return false
end

local function get_stn_from_linevar(linevar)
    local line, stn = linevar_decompose(linevar)
    return ifthenelse(line ~= nil, stn, nil)
end

local function add_linevar(stn, linevar_def)
    local station = advtrains.lines.stations[stn]
    if station == nil then
        return false, "Chybná stanice!"
    end
    local linevars = station.linevars
    if linevars == nil then
        linevars = {}
        station.linevars = linevars
    end
    if linevars[linevar_def.name] ~= nil then
        return false, "Nemohu přidat, varianta linky '"..linevar_def.name.."' již existuje."
    end
    linevars[linevar_def.name] = linevar_def
    return true, nil
end

local function same_stops(stops1, stops2)
    assert(stops1)
    assert(stops2)
    if #stops1 ~= #stops2 then
        return false
    end
    for i, stop in ipairs(stops1) do
        if stop.stn ~= stops2[i].stn then
            return false
        end
    end
    return true
end

local function replace_linevar(stn, linevar_def)
    local station = advtrains.lines.stations[stn]
    if station == nil or station.linevars == nil then
        return false, S("No such station")
    end
    local linevar = assert(linevar_def.name)
    local linevars = station.linevars
    local old_linevar_def = linevars[linevar]
    if old_linevar_def == nil then
        return false, S("Cannot replace, because lineval @1 does not yet exist", linevar)
    end
    linevars[linevar] = linevar_def
    local restart_count = 0
    if not same_stops(old_linevar_def.stops, linevar_def.stops) then
        -- změnily se zastávky, musíme restartovat vlaky:
        for train_id, train in pairs(advtrains.trains) do
            local ls = train.line_status
            if ls ~= nil and ls.linevar == linevar then
                core.log("action", "Train "..train_id.." restarted from index "..ls.linevar_index.." due to replacement of linevar '"..linevar.."'.")
                ls.linevar_index = 1
                restart_count = restart_count + 1
            end
        end
    end
    if restart_count > 0 then
        return true, S("@1 trains restarted due to changes", restart_count)
    else
        return true, nil
    end
end

local function delete_linevar(stn, linevar)
    local station = advtrains.lines.stations[stn]
    if station == nil or station.linevars == nil then
        return false, S("No such station")
    end
    local linevars = station.linevars
    if linevars[assert(linevar)] == nil then
        return false, S("Cannot delete, because lineval @1 does not yet exist", linevar)
    end
    linevars[linevar] = nil
    for train_id, train in pairs(advtrains.trains) do
        local ls = train.line_status
        if ls ~= nil and ls.linevar == linevar then
            core.log("action", "Train "..train_id.." removed from deleted linevar '"..linevar.."'.")
            cancel_linevar(train)
        end
    end
    return true, nil
end

local function get_formspec(custom_state)
	local pinfo = ch_core.normalize_player(assert(custom_state.player_name))
	if pinfo.player == nil then
		minetest.log("error", "Expected player not in game!")
		return ""
	end

    local selection_index_raw = custom_state.selection_index
	local selection_index = selection_index_raw or 1
    local formspec = {
        ch_core.formspec_header({formspec_version = 6, size = {20, 16}, auto_background = true}),
        "label[0.5,0.6;"..S("Line Editor").."]"..
        "style[s01_pos",
    }
    for i = 2, max_stations do
        table.insert(formspec, string.format(",s%02d_pos", i))
    end
    table.insert(formspec, ";font=mono;font_size=-4]"..
        "style[rc;font=mono]"..
        "tablecolumns[color;text,align=right;text;text,align=center;color;text,width=7;color;text]"..
        "table[0.5,1.25;19,5;linevar;#ffffff,"..S("LINE,ROUTE,VAR.")..",#ffffff,"..S("OWNER")..",#ffffff,STATUS")

    for _, linevar_def in ipairs(custom_state.linevars) do
        local lv_line, lv_stn, lv_rc = linevar_decompose(linevar_def.name)
        local color = ifthenelse(linevar_def.disabled, "#cccccc", "#ffffff")
        table.insert(formspec,
            ","..color..","..F(lv_line)..","..F(get_line_description(linevar_def, {first_stop = true, last_stop = true}))..
            ","..F(lv_rc)..","..ifthenelse(linevar_def.owner == pinfo.player_name, "#00ff00", color)..",")
        table.insert(formspec, F(prihlasovaci_na_zobrazovaci(linevar_def.owner)))
        table.insert(formspec, ","..color..",")
        if linevar_def.disabled then
            table.insert(formspec, "vypnutá")
        end
    end
    if selection_index_raw ~= nil then
        table.insert(formspec, ";"..selection_index.."]")
    else
        table.insert(formspec, ";]")
    end
    if pinfo.role ~= "new" then
        table.insert(formspec, "button[14.5,0.3;3.5,0.75;create;"..S("New Line...").."]")
    end
    local has_rights_to_open_variant =
        pinfo.role == "admin" or selection_index == 1 or
        pinfo.player_name == custom_state.linevars[selection_index - 1].owner

    if selection_index > 1 and has_rights_to_open_variant then
        table.insert(formspec, "button[10.5,0.3;3.5,0.75;delete;"..S("Delete Line").."]")
    end
    table.insert(formspec, "button_exit[18.75,0.3;0.75,0.75;close;X]"..
        "field[0.5,7;1.25,0.75;line;"..S("Line:")..";"..F(custom_state.line).."]"..
        "field[2,7;1.5,0.75;rc;"..S("Variant:")..";"..F(custom_state.rc).."]"..
        "field[3.75,7;3,0.75;train_name;"..S("Dest. Display:")..";"..F(custom_state.train_name).."]")
    if pinfo.role ~= "admin" then
        table.insert(formspec, "label[7,6.75;"..S("Owner:").."\n")
    else
        table.insert(formspec, "field[7,7;4,0.75;owner;"..S("Owner:")..";")
    end
    table.insert(formspec, F(custom_state.owner).."]"..
        "checkbox[11.25,7.25;disable_linevar;"..S("Disable")..";"..custom_state.disable_linevar.."]"..
        "field[13.5,7;3,0.75;continues;"..S("Continues:")..";"..F(custom_state.continues).."]")

    if custom_state.message ~= "" then
        table.insert(formspec, "label[0.5,8.25;"..F(custom_state.message).."]")
    end
    if selection_index > 1 then
        table.insert(formspec, "button[5,15;4.5,0.75;last_passages;"..S("Last passages").."]"..
        "tooltip[last_passages;Zobrazí přehled časů několika posledních jízd na dané variantě linky.]")
    end
    if has_rights_to_open_variant then
        table.insert(formspec, "button[10,15;4.5,0.75;save;"..
            ifthenelse(custom_state.compiled_linevar == nil, S("Verify/Save").."]", S("Save changes").."]"))
    end
    table.insert(formspec, "button[15,15.25;4,0.5;reset;"..S("Reset changes").."]")
    table.insert(formspec, "tooltip[line;"..
        S("Line designation. Must not be empty. This identifies a certain line.").."]"..
        "tooltip[rc;"..S("Line variant code. Optional, can be used to identify different variants of a line (e.g. branches).").."]"..
        "tooltip[train_name;"..S("Optional field, name of the line as used in departure displays and on timetables.").."]"..
        "tooltip[disable_linevar;"..S("Check to disable the timetable.\nA disabled timetable will not be used for new trains, trains already on the line will finish it.").."]")

    table.insert(formspec, "container[0,8.75]"..
        "label[0.5,0.25;"..S("Dep.").."]"..
        "label[2,0.25;"..S("St.Time").."]"..
        "label[3.5,0.25;"..S("Station Code").."]"..
        "label[6.25,0.25;"..S("Mode").."]"..
        "label[11,0.25;"..S("Track").."]"..
        "label[12.5,0.25;"..S("Position").."]"..
        "scrollbaroptions[min=0;max=550;arrows=show]"..
        "scrollbar[19,0.5;0.5,5.5;vertical;evl_scroll;"..custom_state.evl_scroll.."]"..
        "scroll_container[0.5,0.5;18.5,5.5;evl_scroll;vertical]"..
        "box[0,0;20,70;#00808040]") -- box[] = pozadí

    -- výchozí zastávka:
    table.insert(formspec,
        "label[0.1,0.4;0]"..
        "field[1.5,0;1.25,0.75;s01_wait;;"..F(custom_state.stops[1].wait).."]"..
        "field[3,0;2.5,0.75;s01_stn;;"..F(custom_state.stops[1].stn).."]"..
        "dropdown[5.75,0;4.5,0.75;s01_mode;"..S("Normal")..","..S("Hidden (normal)")..";"..custom_state.stops[1].mode..";true]"..
        "field[10.5,0;1.25,0.75;s01_track;;"..F(custom_state.stops[1].track).."]"..
        "field[12,0;3,0.75;s01_pos;;"..F(custom_state.stops[1].pos).."]"..
        "label[15.25,0.4;"..F(custom_state.stops[1].label).."]")

    -- ostatní zastávky:
    local y_base, y_scale = 0, 1
    for i = 2, max_stations do
        local stop = custom_state.stops[i]
        local n
        if i < 10 then
            n = "0"..i
        else
            n = tostring(i)
        end
        local y = string.format("%f", y_base + (i - 1) * y_scale)
        local y2 = string.format("%f", y_base + (i - 1) * y_scale + 0.4) -- for a label
        table.insert(formspec,
            "field[0,"..y..";1.25,0.75;s"..n.."_dep;;"..F(stop.dep).."]"..
            "field[1.5,"..y..";1.25,0.75;s"..n.."_wait;;"..F(stop.wait).."]"..
            "field[3,"..y..";2.5,0.75;s"..n.."_stn;;"..F(stop.stn).."]"..
            "dropdown[5.75,"..y..";4.5,0.75;s"..n..
                "_mode;"..S("Normal")..","..S("Request Stop (experimental)")..","..S("Hidden")..","..S("Inactive")..","..S("Terminus")..","..S("Terminus (hidden)")..","..
            S("Terminus (continuing)")..";"..stop.mode..";true]"..
            "field[10.5,"..y..";1.25,0.75;s"..n.."_track;;"..F(stop.track).."]"..
            "field[12,"..y..";3,0.75;s"..n.."_pos;;"..F(stop.pos).."]"..
            "label[15.25,"..y2..";"..F(stop.label).."]")
    end

    table.insert(formspec,
        "scroll_container_end[]"..
        "tooltip[0,0;1.5,1;"..S("Departure: Time (in seconds) after the start of the timetable at which the train departs from this station.\nIt is used to calculate delays. Stations on the line are sorted by their departure time.\nSet this field empty to delete a station from the timetable.").."]"..
        "tooltip[1.5,0;1.5,1;"..S("Stop time: Minimum time (in seconds) for which the train stops at the station before departing.").."]"..
        "tooltip[3.5,0;2.75,1;"..S("Station code: The code of the station to stop/pass.").."]"..
        "tooltip[6.25,0;4.75,1;"..S("Stop mode:\nNormal - Train stops and departs after the stop time\nRequest stop - Train stops when the 'stop request' button is pressed\nHidden - like Normal, but is not shown in passenger timetable\nInactive - passes without stopping\nTerminus - Train stops and ends the timetable operation\nTerminus (hidden) - like Terminus, but will not appear in the passenger timetable\nTerminus (continuing) - Train will continue as timetable configured in the stop rail at the terminus location").."]"..
        "container_end[]")

	-- if pinfo.role ~= "new" then
	return table.concat(formspec)
end

local mode_from_formspec_map = {MODE_NORMAL, MODE_REQUEST_STOP, MODE_HIDDEN, MODE_DISABLED, MODE_FINAL, MODE_FINAL_HIDDEN, MODE_FINAL_CONTINUE}
local mode_to_formspec_map = table.key_value_swap(mode_from_formspec_map)

local function mode_to_formspec(i, raw_mode)
    if i == 1 then
        return ifthenelse(raw_mode ~= nil and raw_mode == MODE_HIDDEN, 2, 1)
    elseif raw_mode == nil then
        return 1
    else
        return mode_to_formspec_map[raw_mode] or 1
    end
end

local function mode_from_formspec(i, fs_mode)
    if i == 1 then
        return ifthenelse(fs_mode == 2, MODE_HIDDEN, nil)
    else
        local result = mode_from_formspec_map[fs_mode]
        return ifthenelse(result ~= nil and result ~= MODE_NORMAL, result, nil)
    end
end

local function custom_state_set_selection_index(custom_state, new_selection_index)
    -- this will also refresh stops and resets the changes
    assert(custom_state.player_name)
    assert(custom_state.linevars)
    assert(new_selection_index)
    local current_linevar = custom_state.linevars[new_selection_index - 1]
    custom_state.selection_index = new_selection_index or 1
    local stops = custom_state.stops
    if stops == nil then
        stops = {}
        custom_state.stops = stops
    end
    local linevar_stops
    if current_linevar ~= nil then
        linevar_stops = current_linevar.stops
    else
        linevar_stops = {}
    end

    for i = 1, max_stations do
        local stop = linevar_stops[i]
        if stop ~= nil then
            stops[i] = {
                dep = tostring(assert(stop.dep)),
                wait = tostring(stop.wait or 10),
                stn = assert(stop.stn),
                mode = mode_to_formspec(i, stop.mode),
                track = stop.track or "",
                pos = stop.pos or "",
                label = "",
            }
        else
            stops[i] = {
                dep = ifthenelse(i == 1, "0", ""),
                wait = "10",
                stn = "",
                mode = 1,
                track = "",
                pos = "",
                label = "",
            }
        end
    end
    if current_linevar ~= nil then
        local lv_line, lv_stn, lv_rc = linevar_decompose(current_linevar.name)
        custom_state.line = lv_line or ""
        custom_state.rc = lv_rc or ""
        custom_state.train_name = current_linevar.train_name or ""
        custom_state.owner = assert(current_linevar.owner)
        custom_state.disable_linevar = ifthenelse(current_linevar.disabled, "true", "false")
        custom_state.continues = current_linevar.continue_line or ""
        if custom_state.continues ~= "" then
            custom_state.continues = custom_state.continues.."/"..(current_linevar.continue_rc or "")
        end
    else
        custom_state.line = ""
        custom_state.rc = ""
        custom_state.train_name = ""
        custom_state.owner = custom_state.player_name
        custom_state.disable_linevar = "false"
        custom_state.continues = ""
    end
    custom_state.owner = prihlasovaci_na_zobrazovaci(custom_state.owner)
    custom_state.compiled_linevar = nil
    custom_state.evl_scroll = 0
    custom_state.message = ""
end

local function num_transform(s)
    local prefix = s:match("^([0-9]+)/")
    if prefix == nil then
        return s
    end
    return string.format(" %020d%s", tonumber(prefix) or 0, s:sub(#prefix, -1))
end

local function linevars_sorter(a, b)
    return num_transform(a.name) < num_transform(b.name)
end

local function custom_state_refresh_linevars(custom_state, linevar_to_select)
    assert(custom_state.player_name)
    local linevars = {}
    for _, stdata in pairs(advtrains.lines.stations) do
        if stdata.linevars ~= nil then
            for _, linevar_def in pairs(stdata.linevars) do
                table.insert(linevars, linevar_def)
            end
        end
    end
    table.sort(linevars, linevars_sorter)
    custom_state.selection_index = nil
    custom_state.linevars = linevars
    custom_state.compiled_linevar = nil
    if linevar_to_select ~= nil then
        for i, linevar_def in ipairs(linevars) do
            if linevar_def.name == linevar_to_select then
                custom_state_set_selection_index(custom_state, i + 1)
                return true
            end
        end
        return false
    end
end

local function custom_state_compile_linevar(custom_state)
    local stations = advtrains.lines.stations
    local line = assert(custom_state.line)
    local stn = assert(custom_state.stops[1].stn)
    local rc = assert(custom_state.rc)
    local train_name = assert(custom_state.train_name)
    local owner = assert(custom_state.owner)
    local stops = {}
    if line == "" then
        return false, S("Line name must not be empty!")
    elseif line:find("[/|\\]") then
        return false, S("Line name must not contain characters '/', '|' or '\\'!")
    elseif line:len() > 256 then
        return false, S("Line name must not exceed 256 characters!")
    elseif stn == "" then
        return false, S("Starting station code must not be empty!")
    elseif rc:find("[/|\\]") then
        return false, S("Routing code must not contain '/', '|' or '\\'!")
    elseif owner == "" then
        return false, S("Line owner must not be empty!")
    elseif train_name:len() > 256 then
        return false, S("Train name must not exceed 256 characters!")
    elseif custom_state.continues:len() - custom_state.continues:gsub("/", ""):len() > 1 then
        return false, S("Field 'Continuation' must contain maximum 1 '/'!")
    end
    -- Zkontrolovat zastávky:
    local errcount = 0
    local finalcount = 0
    local dep_to_index = {}
    for i, stop in ipairs(assert(custom_state.stops)) do
        local good_label
        stop.label = ""
        if stop.dep == "" then
            -- přeskočit
        elseif not stop.dep:match("^[0-9][0-9]*$") then
            errcount = errcount + 1
            stop.label = color_red..S("Incorrect departure time format!")
        elseif tonumber(stop.dep) < 0 or tonumber(stop.dep) > 3600 then
            errcount = errcount + 1
            stop.label = color_red..S("Departure time must lie within 0-3600 seconds!")
        elseif dep_to_index[tonumber(stop.dep)] ~= nil then
            errcount = errcount + 1
            stop.label = color_red..S("Duplicate departure time!")
        else
            dep_to_index[tonumber(stop.dep)] = i
            if stop.stn == "" or stations[stop.stn] == nil or stations[stop.stn].name == nil then
                errcount = errcount + 1
                stop.label = color_red..S("Unknown station code!")
            elseif stop.stn:find("[/|\\]") then
                errcount = errcount + 1
                stop.label = color_red..S("Station code must not contain '/', '|' or '\\'!")
            elseif stop.track:len() > 16 then
                errcount = errcount + 1
                stop.label = color_red..S("Line name must not exceed 16 characters!")
            elseif stop.pos ~= "" and not stop.pos:match("^[-0-9][0-9]*,[-0-9][0-9]*,[-0-9][0-9]*$") then
                errcount = errcount + 1
                stop.label = color_red..S("Incorrect format for stop position!")
            elseif stop.pos:len() > 22 then
                errcount = errcount + 1
                stop.label = color_red..S("Stop position must not exceed 22 characters!")
            else
                -- v pořádku:
                local new_stop = {
                    stn = stop.stn,
                    dep = tonumber(stop.dep),
                }
                local new_mode = mode_from_formspec(i, stop.mode)
                if new_mode ~= nil then
                    new_stop.mode = new_mode
                    if i > 1 and (new_mode == MODE_FINAL or new_mode == MODE_FINAL_CONTINUE or new_mode == MODE_FINAL_HIDDEN) then
                        finalcount = finalcount + 1
                    end
                end
                if stop.pos ~= "" then
                    new_stop.pos = stop.pos
                end
                if stop.track ~= "" then
                    new_stop.track = stop.track
                end
                local new_wait = tonumber(stop.wait)
                if new_wait ~= nil and new_wait == math.floor(new_wait) and new_wait >= 0 and new_wait <= 3600 then
                    new_stop.wait = new_wait
                end
                table.insert(stops, new_stop)
                if stop.stn ~= "" then
                    stop.label = color_green.."= "..assert(stations[stop.stn].name)
                end
            end
        end
    end
    if errcount > 0 then
        return false, S("@1 errors while checking line setup!", errcount)
    end
    if finalcount == 0 then
        return false, S("Line setup must contain at least 1 terminus stop!")
    end
    table.sort(stops, function(a, b) return a.dep < b.dep end)

    local index_vychozi, index_cil
    for i, stop in ipairs(stops) do
        local mode = stop.mode or MODE_NORMAL
        if mode ~= MODE_DISABLED and mode ~= MODE_HIDDEN and mode ~= MODE_FINAL_HIDDEN then
            if index_vychozi == nil then
                index_vychozi = i
            end
            index_cil = i
        end
        if mode == MODE_FINAL or mode == MODE_FINAL_CONTINUE or mode == MODE_FINAL_HIDDEN then
            break
        end
    end

    custom_state.compiled_linevar = {
        name = line.."/"..stops[1].stn.."/"..rc,
        owner = owner, -- ch_core.jmeno_na_prihlasovaci(owner),
        stops = stops,
        continue_line = "",
        continue_rc = "",
        index_vychozi = index_vychozi,
        index_cil = index_cil,
    }
    if train_name ~= "" then
        custom_state.compiled_linevar.train_name = train_name
    end
    if custom_state.disable_linevar == "true" then
        custom_state.compiled_linevar.disabled = true
    end
    local continues_split = custom_state.continues:find("/")
    if continues_split == nil then
        custom_state.compiled_linevar.continue_line = custom_state.continues
    else
        custom_state.compiled_linevar.continue_line = custom_state.continues:sub(1, continues_split - 1)
        custom_state.compiled_linevar.continue_rc = custom_state.continues:sub(continues_split + 1, -1)
    end
    return true, nil
end

local function formspec_callback(custom_state, player, formname, fields)
    local reload_stations, update_formspec = false, false
    -- print("DEBUG: "..dump2({custom_state = custom_state, formname = formname, fields = fields}))

	if fields.quit then
		return
	end
    -- scrollbar:
    if fields.evl_scroll then
        local event = core.explode_scrollbar_event(fields.evl_scroll)
        if event.type == "CHG" then
            custom_state.evl_scroll = event.value
        end
    end
    -- checkbox:
    if fields.disable_linevar then
        custom_state.disable_linevar = fields.disable_linevar
    end
    -- dropdowns:
    for i = 1, max_stations do
        local id = string.format("s%02d_mode", i)
        local n = tonumber(fields[id])
        if n ~= nil then
            custom_state.stops[i].mode = n
        end
    end
    -- fields:
    for _, key in ipairs({"line", "rc", "train_name", "owner", "continues"}) do
        if fields[key] then
            custom_state[key] = fields[key]
        end
    end
    for i, stop in ipairs(custom_state.stops) do
        local prefix = string.format("s%02d_", i)
        for _, key in ipairs({"dep", "wait", "stn", "track", "pos"}) do
            local value = fields[prefix..key]
            if value then
                stop[key] = value
            end
        end
    end
    -- selection:
    if fields.linevar then
        local event = core.explode_table_event(fields.linevar)
        if event.type == "CHG" or event.type == "DCL" then
            custom_state_set_selection_index(custom_state, assert(tonumber(event.row)))
            update_formspec = true
        end
    end

    -- buttons:
    if fields.create then
        custom_state_set_selection_index(custom_state, 1)
        update_formspec = true
    elseif fields.reset then
        custom_state_set_selection_index(custom_state, custom_state.selection_index or 1)
        update_formspec = true
    elseif fields.save then
        local pinfo = ch_core.normalize_player(player)
        if pinfo.role == "new" or pinfo.role == "none" then
            core.log("error", "Access violation in line editor caused by '"..pinfo.player_name.."'!")
            return -- access violation!
        end
        if custom_state.compiled_linevar == nil then
            -- zkontrolovat a skompilovat
            local success, errmsg = custom_state_compile_linevar(custom_state)
            if success then
                -- TODO: zkontrolovat práva a možnost přepsání i zde!
                custom_state.message = color_green..S("No issues found, the line can now be saved!")
            else
                custom_state.message = color_red..S("Error in line setup: ")..(errmsg or S("Unknown reason"))
            end
            update_formspec = true
        else
            -- pokusit se uložit...
            custom_state.message = ""

            local selection_index = custom_state.selection_index or 1
            local selected_linevar, selected_linevar_def, selected_linevar_station
            local to_linevar, to_linevar_def, to_linevar_station
            local new_linevar, new_linevar_def, new_linevar_station

            -- NEW:
            new_linevar_def = custom_state.compiled_linevar
            new_linevar = new_linevar_def.name
            new_linevar_station = get_stn_from_linevar(new_linevar)

            -- SELECTED:
            if custom_state.selection_index > 1 and custom_state.linevars[selection_index - 1] ~= nil then
                selected_linevar_def, selected_linevar_station = try_get_linevar_def(custom_state.linevars[selection_index - 1].name)
                if selected_linevar_def ~= nil then
                    selected_linevar = selected_linevar_def.name
                end
            end

            -- TO OVERWRITE:
            to_linevar_def, to_linevar_station = try_get_linevar_def(new_linevar)
            if to_linevar_def ~= nil then
                to_linevar = to_linevar_def.name
            end

            local success, errmsg
            if selected_linevar == nil then
                if to_linevar == nil then
                    -- zcela nová varianta
                    core.log("action", "Will add a new linevar '"..new_linevar.."'")
                    success, errmsg = add_linevar(new_linevar_station, new_linevar_def)
                else
                    -- replace
                    core.log("action", "Will replace an existing linevar '"..new_linevar.."'")
                    success = check_rights(pinfo, to_linevar_def.owner)
                    if success then
                        success, errmsg = replace_linevar(new_linevar_station, new_linevar_def)
                    else
                        errmsg = S("Insufficient permissions to edit '@1'.", to_linevar)
                    end
                end
            elseif to_linevar == nil then
                -- delete and add
                core.log("action", "Will delete selected linevar '"..selected_linevar.."' and add new linevar '"..new_linevar.."'")
                success = check_rights(pinfo, selected_linevar_def.owner)
                if success then
                    success, errmsg = delete_linevar(selected_linevar_station, selected_linevar)
                    if success then
                        success, errmsg = add_linevar(new_linevar_station, new_linevar_def)
                    end
                else
                    errmsg = S("Insufficient permissions to edit '@1'.", selected_linevar)
                end
            elseif selected_linevar ~= to_linevar then
                -- delete and replace
                core.log("action", "Will add delete selected linevar '"..selected_linevar.."' and replace existing linevar '"..new_linevar.."'")
                success = check_rights(pinfo, to_linevar_def.owner)
                if success then
                    success = check_rights(pinfo, selected_linevar_def.owner)
                    if success then
                        success, errmsg = delete_linevar(selected_linevar_station, selected_linevar)
                        if success then
                            success, errmsg = replace_linevar(new_linevar_station, new_linevar_def)
                        end
                    else
                        errmsg = S("Insufficient permissions to edit '@1'.", selected_linevar)
                    end
                else
                    errmsg = S("Insufficient permissions to edit '@1'.", to_linevar)
                end
            else
                -- replace
                core.log("action", "Will replace existing linevar '"..new_linevar.."'")
                success = check_rights(pinfo, to_linevar_def.owner)
                if success then
                    success, errmsg = replace_linevar(new_linevar_station, new_linevar_def)
                else
                    errmsg = S("Insufficient permissions to edit '@1'.", to_linevar)
                end
            end

            if success then
                custom_state.message = color_green..S("Line '@1' successfully saved!", new_linevar)
                custom_state_refresh_linevars(custom_state, new_linevar)
            else
                custom_state.message = color_red..S("Error in line setup: ")..(errmsg or S("Unknown reason"))
            end
            update_formspec = true
        end

    elseif fields.delete then
        local pinfo = ch_core.normalize_player(player)
        if pinfo.role == "new" or pinfo.role == "none" then
            core.log("error", "Access violation in line editor caused by '"..pinfo.player_name.."'!")
            return -- access violation!
        end
        local selection_index = custom_state.selection_index or 1
        local selected_linevar, selected_linevar_def, selected_linevar_station
        if selection_index > 1 and custom_state.linevars[selection_index - 1] ~= nil then
            selected_linevar_def, selected_linevar_station = try_get_linevar_def(custom_state.linevars[selection_index - 1].name)
            if selected_linevar_def ~= nil then
                selected_linevar = selected_linevar_def.name
            end
            local success, errmsg
            success = check_rights(pinfo, selected_linevar_def.owner)
            if success then
                success, errmsg = delete_linevar(selected_linevar_station, selected_linevar)
            else
                errmsg = S("Insufficient permissions to edit '@1'.", selected_linevar)
            end
            if success then
                custom_state.message = S("Line '@1' successfully deleted!", selected_linevar)
                custom_state_refresh_linevars(custom_state)
                custom_state_set_selection_index(custom_state, 1)
            else
                custom_state.message = S("Deletion failed: ")..(errmsg or S("Unknown reason"))
            end
            update_formspec = true
        end
    elseif fields.last_passages then
        local selected_linevar_def = try_get_linevar_def(custom_state.linevars[(custom_state.selection_index or 1) - 1].name)
        if selected_linevar_def ~= nil then
            assert(selected_linevar_def.name)
            show_last_passages_formspec(player, selected_linevar_def, assert(selected_linevar_def.name))
            return
        end
    end

	if update_formspec then
		return get_formspec(custom_state)
	end
end

local function show_editor_formspec(player, linevar_to_select)
    if player == nil then return false end
	local custom_state = {
		player_name = assert(player:get_player_name()),
        evl_scroll = 0,
        message = "",
        continues = "",
	}
    if not custom_state_refresh_linevars(custom_state, linevar_to_select) then
        custom_state_set_selection_index(custom_state, 1)
    end
	ch_core.show_formspec(player, "advtrains_line_automation:editor_linek", get_formspec(custom_state), formspec_callback, custom_state, {})
end

-- make line editor globally available
advtrains.lines.open_line_editor = show_editor_formspec

local function lp_formspec_callback(custom_state, player, formname, fields)
    if fields.back then
        show_editor_formspec(player, custom_state.selected_linevar)
    elseif fields.update then
		local selected_linevar_def = try_get_linevar_def(custom_state.selected_linevar)
        if selected_linevar_def ~= nil then
            show_last_passages_formspec(player, selected_linevar_def, custom_state.selected_linevar)
        end
    end
end

show_last_passages_formspec = function(player, linevar_def, selected_linevar)
	local rwt = advtrains.lines.rwt
    local formspec = {
        "formspec_version[6]"..
        "size[20,10]"..
        "label[0.5,0.6;",
        S("Last passages of line @1", F(assert(linevar_def.name))),
        "]"..
        "tablecolumns[text;text;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5;text,width=5]",
        "table[0.5,1.25;19,8;jizdy;",S("Code"),",",S("Station"),",1.j.,2.j.,3.j.,4.j.,5.j.,6.j.,7.j.,8.j.,9.j.,10.j."
    }
    local passages, stops = get_last_passages(linevar_def)
    local max_time = {}
    if passages ~= nil then
        for j = 1, 10 do
            max_time[j] = 0
            if passages[j] == nil then
                passages[j] = {}
            end
        end
        -- stání na výchozí zastávce:
        table.insert(formspec, ",,"..S("At start station:"))
        for j = 1, 10 do
            local wait = passages[j].wait
            if wait ~= nil then
                table.insert(formspec, ","..wait.." s")
            else
                table.insert(formspec, ",-")
            end
        end
        -- odjezd z výchozí zastávky:
        table.insert(formspec, ","..F(stops[1][1])..","..F(stops[1][2]).." "..S("(departed)"))
        for j = 1, 10 do
            local time = passages[j][1]
            if time ~= nil then
                table.insert(formspec, ",("..core.formspec_escape(rwt.t_str(time, 1))..")")
                if rwt.is_before(max_time[j], time) then
                    max_time[j] = time
                end
            else
                table.insert(formspec, ",-")
            end
        end
        -- odjezdy z ostatních zasŧávek:
        for i = 2, #stops do -- i = index zastávky
            table.insert(formspec, ","..F(stops[i][1])..","..F(stops[i][2]))
            for j = 1, 10 do -- j = index jízdy
                local dep_vych = passages[j][1]
                local time = passages[j][i]
                if time ~= nil and dep_vych ~= nil then
                    table.insert(formspec, ","..(rwt.diff(dep_vych, time)))
                    if rwt.is_before(max_time[j], time) then
                        max_time[j] = time
                    end
                else
                    table.insert(formspec, ",-")
                end
            end
        end
        table.insert(formspec, ",,"..S("Travelling:"))
        for i = 1, 10 do
            if max_time[i] ~= 0 then
                table.insert(formspec, ",_"..(rwt.diff(passages[i][1], max_time[i])).."_")
            else
                table.insert(formspec, ",-")
            end
        end
    end
    table.insert(formspec, ";]"..
		"button[13.75,0.3;1.75,0.75;update;"..S("Update").."]"..
        "button[17.75,0.3;1.75,0.75;back;"..S("Back").."]"..
        "tooltip[jizdy;"..S("Time data in seconds of railway time").."]")
    formspec = table.concat(formspec)
    local custom_state = {
        player_name = player:get_player_name(),
        selected_linevar = selected_linevar,
    }
    ch_core.show_formspec(player, "advtrains_line_automation:posledni_jizdy", formspec, lp_formspec_callback, custom_state, {})
end

def = {
    -- params = "",
    description = S("Open line editor"),
    privs = {railway_operator = true},
    func = function(player_name, param) show_editor_formspec(minetest.get_player_by_name(player_name)) end,
}
core.register_chatcommand("line_editor", def)