--
--  layout-functions.lua
--  speedata publisher
--
--  For a list of authors see `git blame'
--  See file COPYING in the root directory for license info.

file_start("layout_functions_lxpath.lua")

local publisher = require("publisher")

local de = require("dimexpr")
local links_module = require("publisher.links")

local sha = require("shalocal")

-- Return filename, pagenumber, box and unit from the arg. Used in imagewidth et al.
--- @param arg table
--- @return string, number, string, string | nil
local function get_filename_pagenum_box_unit_from_arg(arg)
    local filename, box, unit
    box = "cropbox"
    local pagenumber = 1
    filename = publisher.xpath.string_value(arg[1])
    for i = 2, #arg do
        local ai = arg[i]
        local nv = publisher.xpath.number_value(ai)
        local tv = publisher.xpath.string_value(ai)
        if nv then
            pagenumber = nv or 1
        elseif
            tv == "cm"
            or tv == "mm"
            or tv == "in"
            or tv == "sp"
            or tv == "pc"
            or tv == "pt"
            or tv == "pp"
            or tv == "cc"
        then
            unit = tv
        elseif tv == "artbox" or tv == "cropbox" or tv == "bleedbox" or tv == "trimbox" or tv == "mediabox" then
            box = tv
        end
    end
    return filename, pagenumber, box, unit
end

local function visiblepagenumber(pagenumber)
    pagenumber = tonumber(pagenumber)
    return publisher.visible_pagenumbers[pagenumber] or pagenumber
end

local function fnAllocated(dataxml, arg)
    local areaname, framenumber
    local x = publisher.xpath.number_value(arg[1])
    local y = publisher.xpath.number_value(arg[2])
    if not x or not y then
        return nil, "sd:allocated(): x and y must be numbers"
    end
    if #arg > 2 then
        areaname = publisher.xpath.string_value(arg[3])
    end
    if #arg > 3 then
        framenumber = publisher.xpath.number_value(arg[4])
    end

    publisher.page_helpers.setup_page(nil, "layout_functions#allocated", dataxml)
    local grid = assert(publisher.current_grid)
    return { grid:isallocated(x, y, areaname, framenumber) }, nil
end

local function fnCurrentPage(dataxml, _arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#current_page", dataxml)
    return { publisher.current_pagenumber }, nil
end

local function fnCurrentRow(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#current_row", dataxml)
    local areaname = nil
    if #arg == 1 then
        areaname = publisher.xpath.string_value(arg[1])
    end
    return { publisher.current_grid:current_row(areaname) }, nil
end

--- Get the page number of a marker
local function fnpagenumber(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local m = publisher.markers[firstarg]
    if m then
        return { m.page }, nil
    else
        return {}, nil
    end
end

local function current_column(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#current_column", dataxml)
    local firstarg
    if #arg > 0 then
        firstarg = publisher.xpath.string_value(arg[1])
    end
    return { publisher.current_grid:current_column(firstarg) }, nil
end

local function fnAlternating(_dataxml, arg)
    local alt_type = publisher.xpath.string_value(arg[1])
    if not publisher.alternating[alt_type] then
        publisher.alternating[alt_type] = 1
    else
        publisher.alternating[alt_type] = math.fmod(publisher.alternating[alt_type], #arg - 1) + 1
    end
    local val = publisher.xpath.string_value(arg[publisher.alternating[alt_type] + 1])
    publisher.alternating_value[alt_type] = val
    return { val }
end

local function first_free_row(dataxml, arg)
    local firstarg
    if #arg > 0 then
        firstarg = publisher.xpath.string_value(arg[1])
    else
        firstarg = publisher.default_areaname
    end
    local ret = publisher.current_grid:first_free_row(firstarg, nil, dataxml)
    return { ret }, nil
end

-- Get the first mark of a page (for example used in the head of dictionaries)
local function firstmark(_dataxml, arg)
    local pagenumber = publisher.xpath.number_value(arg[1])
    if not pagenumber then
        main.log("error", "firstmark: cannot get page number")
        return {}, "firstmark: cannot get page number"
    end
    local minid = publisher.marker_min[pagenumber]
    if not minid then
        return { "" }, nil
    end
    return { publisher.marker_id_value[minid].name }, nil
end

-- Get the last mark of a page (for example used in the head of dictionaries)
local function lastmark(_dataxml, arg)
    local pagenumber = publisher.xpath.number_value(arg[1])
    if not pagenumber then
        main.log("error", "lastmark: cannot get page number")
        return {}, "lastmark: cannot get page number"
    end
    local maxid = publisher.marker_max[pagenumber]
    if not maxid then
        return { "" }, nil
    end
    return { publisher.marker_id_value[maxid].name }, nil
end

-- Read the contents given in arg[1] and write it to a temporary file.
-- Return the name of the file. Useful in conjunction with sd:decode-base64()
-- and Image to read an image from the data.
local function filecontents(_dataxml, arg)
    local tmpdir = os.getenv("SP_TEMPDIR")
    if tmpdir == nil then
        main.log("error", "SP_TEMPDIR is nil")
        return {}, "SP_TEMPDIR is nil"
    end

    lfs.mkdir(tmpdir)
    local filename = publisher.utilities.string_random(20)
    local path = tmpdir .. publisher.os_separator .. filename
    local file, e = io.open(path, "wb")
    if file == nil then
        main.log("error", string.format("Could not write filecontents into temp directory: %q", e))
        return {}, "Could not write filecontents into the temp directory"
    end
    local firstarg = publisher.xpath.string_value(arg[1])
    file:write(firstarg)
    file:close()
    return { path }
end

local function mode(_dataxml, arg)
    local entry
    for i = 1, #arg do
        local name = publisher.xpath.string_value(arg[i])
        entry = publisher.modes[name]
        if entry then
            return { true }, nil
        end
    end
    return { false }, nil
end

local function keepalternating(_dataxml, arg)
    local alt_type = publisher.xpath.string_value(arg[1])
    local val = publisher.xpath.string_value(publisher.alternating_value[alt_type])
    return { val }, nil
end

local function reset_alternating(_dataxml, arg)
    local alt_type = publisher.xpath.string_value(arg[1])
    publisher.alternating[alt_type] = 0
    return {}, nil
end

local function fnNumberOfColumns(dataxml, arg)
    local areaname
    if #arg > 0 then
        areaname = publisher.xpath.string_value(arg[1])
    end
    publisher.page_helpers.setup_page(nil, "layout_functions#number_of_columns", dataxml)
    return { publisher.current_grid:number_of_columns(areaname) }
end

--- Merge numbers like '1,2,3,4,5, 8, 9,10' into '1-5, 8-10'
local function fnMergePagenumbers(_dataxml, arg)
    local firstarg, secondarg, thirdarg, fourtharg
    firstarg = publisher.xpath.string_value(arg[1])
    if #arg > 1 then
        secondarg = publisher.xpath.string_value(arg[2])
    end
    if #arg > 2 then
        thirdarg = publisher.xpath.string_value(arg[3])
    end
    if #arg > 3 then
        fourtharg = publisher.xpath.boolean_value(arg[4])
    end

    local pagenumbers_string = string.gsub(firstarg or "", "%s", "")
    local mergechar = secondarg or "–"
    local spacer = thirdarg or ", "
    local interaction = fourtharg or false

    local pagenumbers = string.explode(pagenumbers_string, ",")

    -- let's remove duplicates now
    local dupes = {}
    local withoutdupes = {}
    local cap1, cap2
    for i = 1, #pagenumbers do
        local num = pagenumbers[i]
        cap1, cap2 = string.match(num, "^(.)-(.)$")
        if cap1 then
            for n = tonumber(cap1), tonumber(cap2) do
                num = tostring(n)
                if not dupes[num] then
                    withoutdupes[#withoutdupes + 1] = num
                    dupes[num] = true
                end
            end
        else
            if not dupes[num] then
                withoutdupes[#withoutdupes + 1] = num
                dupes[num] = true
            end
        end
    end
    publisher.utilities.stable_sort(withoutdupes, function(elta, eltb)
        return tonumber(elta) < tonumber(eltb)
    end)
    local gethyperlink
    if interaction then
        gethyperlink = function(pagenum)
            return { hyperlink = links_module.hlpage(publisher.options, pagenum) }
        end
    else
        gethyperlink = function(_pagenum)
            return nil
        end
    end

    local p = publisher.par:new(nil, "merge-pagenumbers")
    if mergechar == "" then
        local pagenumber
        for i = 1, #withoutdupes - 1 do
            pagenumber = withoutdupes[i]
            p:append(visiblepagenumber(pagenumber), gethyperlink(pagenumber))
            p:append(spacer)
        end
        pagenumber = withoutdupes[#withoutdupes]
        p:append(visiblepagenumber(pagenumber), gethyperlink(pagenumber))
    else
        -- Buckets have consecutive pages. For example 1,2,3,4,5
        -- So when merging the numbers, we just have to look for the first and last
        -- entry in a bucket.
        local buckets = {}
        local bucket
        local cur
        local prev = -99 ---@type number
        for i = 1, #withoutdupes do
            cur = tonumber(withoutdupes[i]) or 0
            if cur == prev + 1 then
                -- same bucket
                bucket[#bucket + 1] = cur
            else
                bucket = { cur }
                buckets[#buckets + 1] = bucket
            end
            prev = cur
        end

        for i = 1, #buckets do
            if #buckets[i] > 2 then
                local from, to = buckets[i][1], buckets[i][#buckets[i]]
                p:append(visiblepagenumber(from), gethyperlink(from))
                p:append(mergechar)
                p:append(visiblepagenumber(to), gethyperlink(to))
            elseif #buckets[i] == 2 then
                local from, to = buckets[i][1], buckets[i][#buckets[i]]
                p:append(visiblepagenumber(from), gethyperlink(from))
                p:append(spacer)
                p:append(visiblepagenumber(to), gethyperlink(to))
            else
                local to = buckets[i][1]
                p:append(visiblepagenumber(to), gethyperlink(to))
            end
            if i < #buckets then
                p:append(spacer)
            end
        end
    end
    return p, nil
end

local function fnNumberOfRows(dataxml, arg)
    local areaname
    if #arg > 0 then
        areaname = publisher.xpath.string_value(arg[1])
    end
    publisher.page_helpers.setup_page(nil, "layout_functions#number_of_rows", dataxml)
    return { publisher.current_grid:number_of_rows(areaname) }
end

local function fnNumberOfPages(_dataxml, arg)
    local filename = publisher.xpath.string_value(arg[1])
    local img = publisher.images.imageinfo(filename)
    return { img.img.pages }, nil
end

local function imagewidth(dataxml, arg)
    local filename, pagenumber, box, unit = get_filename_pagenum_box_unit_from_arg(arg)
    local img = publisher.images.imageinfo(filename, pagenumber, box)
    publisher.page_helpers.setup_page(nil, "layout_functions#imagewidth", dataxml)

    local width
    if unit then
        width = img.img.width
        local ret
        if unit == "cm" then
            ret = width / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = width / publisher.onemm_sp
        elseif unit == "in" then
            ret = width / publisher.onein_sp
        elseif unit == "sp" then
            ret = width
        elseif unit == "pc" then
            ret = width / publisher.onepc_sp
        elseif unit == "pt" then
            ret = width / publisher.onept_sp
        elseif unit == "pp" then
            ret = width / publisher.onepp_sp
        elseif unit == "dd" then
            ret = width / publisher.onedd_sp
        elseif unit == "cc" then
            ret = width / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 4) }, nil
    else
        width = publisher.current_grid:width_in_gridcells_sp(img.img.width)
        return { width }, nil
    end
end

local function imageheight(dataxml, arg)
    local filename, pagenumber, box, unit = get_filename_pagenum_box_unit_from_arg(arg)
    local img = publisher.images.imageinfo(filename, pagenumber, box)
    publisher.page_helpers.setup_page(nil, "layout_functions#imageheight", dataxml)
    local height
    if unit then
        height = img.img.height
        local ret
        if unit == "cm" then
            ret = height / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = height / publisher.onemm_sp
        elseif unit == "in" then
            ret = height / publisher.onein_sp
        elseif unit == "sp" then
            ret = height
        elseif unit == "pc" then
            ret = height / publisher.onepc_sp
        elseif unit == "pt" then
            ret = height / publisher.onept_sp
        elseif unit == "pp" then
            ret = height / publisher.onepp_sp
        elseif unit == "dd" then
            ret = height / publisher.onedd_sp
        elseif unit == "cc" then
            ret = height / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 4) }, nil
    else
        height = publisher.current_grid:height_in_gridcells_sp(img.img.height)
        return { height }, nil
    end
end

local function file_exists(_dataxml, arg)
    local filename = publisher.xpath.string_value(arg[1])
    if not filename then
        return { false }, nil
    end
    if filename == "" then
        return { false }, nil
    end
    return { kpse.find_file(filename) ~= nil }, nil
end

--- Insert 1000's separator and comma separator
local function format_number(_dataxml, arg)
    local num, thousandssep, commasep
    local msg
    num, msg = publisher.xpath.string_value(arg[1])
    if msg then
        return nil, msg
    end
    thousandssep, msg = publisher.xpath.string_value(arg[2])
    if msg then
        return nil, msg
    end
    commasep, msg = publisher.xpath.string_value(arg[3])
    if msg then
        return nil, msg
    end

    local sign, digits, commadigits = string.match(tostring(num), "([%-%+]?)(%d*)%.?(%d*)")
    local first_digits = math.fmod(#digits, 3)
    local ret = {}
    if first_digits > 0 then
        ret[1] = string.sub(digits, 0, first_digits)
    end
    for i = 1, (#digits - first_digits) / 3 do
        ret[#ret + 1] = string.sub(digits, first_digits + (i - 1) * 3 + 1, first_digits + i * 3)
    end
    local retstr = table.concat(ret, thousandssep)
    if commadigits and #commadigits > 0 then
        return { sign .. retstr .. commasep .. commadigits }, nil
    else
        return { sign .. retstr }, nil
    end
end

local function format_string(_dataxml, arg)
    local argument = {}
    for i = 1, #arg - 1 do
        argument[#argument + 1] = publisher.xpath.string_value(arg[i])
    end
    local unpacked = table.unpack(argument)
    if unpacked == nil or unpacked == "" then
        main.log("error", "format-string: first arguments are empty")
        return ""
    end
    local ret = string.format(publisher.xpath.string_value(arg[#arg]), unpacked)
    return { ret }
end

local function even(_dataxml, arg)
    local firstarg = tonumber(publisher.xpath.number_value(arg[1]))
    if not firstarg then
        main.log("error", "sd:even() - argument is not a number")
        return {}, "sd:even() - argument is not a number"
    end
    return { math.fmod(firstarg, 2) == 0 }, nil
end

local function current_frame_number(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#current_framenumber", dataxml)
    local framename = publisher.xpath.string_value(arg[1])
    if framename == nil then
        return { 1 }, nil
    end
    local current_framenumber = publisher.current_grid:framenumber(framename)
    return { current_framenumber }, nil
end

local function groupheight(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#groupheight", dataxml)
    local groupname = publisher.xpath.string_value(arg[1])
    if not publisher.groups[groupname] then
        main.log("error", "Can't find group", "groupname", groupname)
        return {}, "Can't find group"
    end

    local groupcontents = publisher.groups[groupname].contents
    if not groupcontents then
        main.log("error", string.format("Can't find group with the name %q", groupname))
        return {}, "Can't find group"
    end
    local height
    local unit = arg[2]
    if unit then
        unit = publisher.xpath.string_value(arg[2])
        height = groupcontents.height
        local ret
        if unit == "cm" then
            ret = height / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = height / publisher.onemm_sp
        elseif unit == "in" then
            ret = height / publisher.onein_sp
        elseif unit == "sp" then
            ret = height
        elseif unit == "pc" then
            ret = height / publisher.onepc_sp
        elseif unit == "pt" then
            ret = height / publisher.onept_sp
        elseif unit == "pp" then
            ret = height / publisher.onepp_sp
        elseif unit == "dd" then
            ret = height / publisher.onedd_sp
        elseif unit == "cc" then
            ret = height / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 4) }, nil
    else
        local grid = assert(publisher.current_grid)
        height = grid:height_in_gridcells_sp(groupcontents.height)
        return { height }, nil
    end
end

local function groupwidth(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#groupwidth", dataxml)
    local groupname = publisher.xpath.string_value(arg[1])
    if not publisher.groups[groupname] then
        main.log("error", string.format("Can't find group with the name %q", groupname))
        return {}, "Can't find group"
    end
    local groupcontents = publisher.groups[groupname].contents

    if not groupcontents then
        main.log("error", string.format("Can't find group with the name %q", groupname))
        return {}, "Can't find group"
    end
    local unit = arg[2]
    local width
    if unit then
        unit = publisher.xpath.string_value(arg[2])
        width = groupcontents.width
        local ret
        if unit == "cm" then
            ret = width / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = width / publisher.onemm_sp
        elseif unit == "in" then
            ret = width / publisher.onein_sp
        elseif unit == "sp" then
            ret = width
        elseif unit == "pc" then
            ret = width / publisher.onepc_sp
        elseif unit == "pt" then
            ret = width / publisher.onept_sp
        elseif unit == "pp" then
            ret = width / publisher.onepp_sp
        elseif unit == "dd" then
            ret = width / publisher.onedd_sp
        elseif unit == "cc" then
            ret = width / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 4) }, nil
    else
        local grid = assert(publisher.current_grid)
        width = grid:width_in_gridcells_sp(groupcontents.width)
        return { width }, nil
    end
end

local function odd(_dataxml, arg)
    local firstarg = arg[1]
    local num, msg = publisher.xpath.number_value(firstarg)
    if msg then
        return nil, msg
    end
    num = tonumber(num)
    if not num then
        main.log("error", "sd:odd() - argument is not a number")
        return {}, "sd:odd() - argument is not a number"
    end
    return { math.fmod(num, 2) ~= 0 }, nil
end

local function variable(dataxml, arg)
    local args = {}
    for i = 1, #arg do
        args[#args + 1] = publisher.xpath.string_value(arg[i])
    end
    local varname = table.concat(args)
    local var = dataxml.vars[varname]
    if type(var) == "table" then
        return var, nil
    end
    return { var }, nil
end

local function attr(dataxml, arg)
    local attname = table.concat(arg)
    local att = dataxml[attname]
    return { att }, nil
end

local function variable_exists(dataxml, arg)
    local varname = publisher.xpath.string_value(arg[1])
    return { dataxml.vars[varname] ~= nil }, nil
end

-- SHA-1
local function shaone(_dataxml, arg)
    local args = {}
    for i = 1, #arg do
        args[#args + 1] = publisher.xpath.string_value(arg[i])
    end

    local message = table.concat(args)
    local ret = sha.sha1(message)
    return { ret }, nil
end

local function sha256(_dataxml, arg)
    local args = {}
    for i = 1, #arg do
        args[#args + 1] = publisher.xpath.string_value(arg[i])
    end
    local message = table.concat(args)
    local ret = sha.sha256(message)
    return { ret }, nil
end

local function sha512(_dataxml, arg)
    local args = {}
    for i = 1, #arg do
        args[#args + 1] = publisher.xpath.string_value(arg[i])
    end
    local message = table.concat(args)
    local ret = sha.sha512(message)
    return { ret }, nil
end

local function symbol(_dataxml, arg)
    local p = publisher.par:new(nil, "symbol")
    for _, v in ipairs(arg) do
        local thisarg = publisher.xpath.number_value(v)
        p:append(utf8.char(publisher.puastart + thisarg))
    end
    return p, nil
end

local function markdown(dataxml, arg)
    if arg == nil then
        arg = dataxml
    end
    local str = table_textvalue(arg[1]) or ""
    local htmltext
    htmltext = splib.markdown(str)
    if htmltext then
        htmltext = publisher.splib.htmltoxml("<html><body>" .. htmltext .. "</body></html>")
        return { htmltext }, nil
    end
    return {}, nil
end

local function md5(_dataxml, arg)
    local args = {}
    for i = 1, #arg do
        args[#args + 1] = publisher.xpath.string_value(arg[i])
    end

    local message = table.concat(args)
    local ret = sha.md5(message)
    return { ret }, nil
end

-- convert a textual dimension (e.g. '2cm') to a scalar in another dimension.
local function tounit(_dataxml, arg)
    local unit = publisher.xpath.string_value(arg[1])
    local decimal = publisher.xpath.number_value(arg[3]) or 0
    local width = tex.sp(publisher.xpath.string_value(arg[2]))

    local ret
    if unit == "cm" then
        ret = width / publisher.onecm_sp
    elseif unit == "mm" then
        ret = width / publisher.onemm_sp
    elseif unit == "in" then
        ret = width / publisher.onein_sp
    elseif unit == "sp" then
        ret = width
    elseif unit == "pc" then
        ret = width / publisher.onepc_sp
    elseif unit == "pt" then
        ret = width / publisher.onept_sp
    elseif unit == "pp" then
        ret = width / publisher.onepp_sp
    elseif unit == "dd" then
        ret = width / publisher.onedd_sp
    elseif unit == "cc" then
        ret = width / publisher.onecc_sp
    else
        main.log(
            "error",
            string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
        )
    end
    return { math.round(ret, decimal) }, nil
end

local function fnDimexpr(dataxml, arg)
    local unit = publisher.xpath.string_value(arg[1])
    local secondarg = publisher.xpath.string_value(arg[2])
    local ret = de.string_to_tokenlist(secondarg, dataxml)
    local fun = load("return " .. ret)
    if not fun then
        return nil, "error in sd:dimexpr"
    end
    local value = fun()
    if unit == "cm" then
        ret = value / publisher.onecm_sp
    elseif unit == "mm" then
        ret = value / publisher.onemm_sp
    elseif unit == "in" then
        ret = value / publisher.onein_sp
    elseif unit == "sp" then
        ret = value
    elseif unit == "pc" then
        ret = value / publisher.onepc_sp
    elseif unit == "pt" then
        ret = value / publisher.onept_sp
    elseif unit == "pp" then
        ret = value / publisher.onepp_sp
    elseif unit == "dd" then
        ret = value / publisher.onedd_sp
    elseif unit == "cc" then
        ret = value / publisher.onecc_sp
    else
        main.log(
            "error",
            string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
        )
    end

    return { math.round(ret, 3) }, nil
end
-- Turn &lt;b&gt;Hello&lt;b /&gt; into an HTML table and then into XML structure.
local function decode_html(dataxml, arg)
    if arg == nil then
        arg = dataxml
    end
    local firstarg = publisher.xpath.string_value(arg[1])
    if type(firstarg) == "string" then
        -- A '<' that is not the start of a valid tag (letter, !, /, ?) is
        -- literal text in HTML, e.g. "amount <5". The underlying XML parser
        -- would reject it, so treat it like the HTML tokenizer does and turn
        -- it into &lt; before handing it over.
        firstarg = firstarg:gsub("<([^%a!/?])", "&lt;%1"):gsub("<$", "&lt;")
        local msg = publisher.splib.htmltoxml(firstarg)
        if msg == nil then
            main.log("error", "decode-html failed")
            return nil
        end
        -- two dummy tags because xpath.parse_raw removes the surrounding table
        local doc = publisher.splib.loadxmlstring("<dummy><dummy>" .. msg .. "</dummy></dummy>")
        if doc == nil then
            main.log("error", "decode-html failed")
            return nil
        end
        -- loadxmlstring returns a document table, the outer dummy element is its first child
        return doc[1]
    end
end

local function decode_base64(_dataxml, arg)
    local b = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
    local data = publisher.xpath.string_value(arg[1])
    data = string.gsub(data, "[^" .. b .. "=]", "")
    local a = (
        data:gsub(".", function(x)
            if x == "=" then
                return ""
            end
            local r, f = "", (b:find(x) - 1)
            for i = 6, 1, -1 do
                r = r .. (f % 2 ^ i - f % 2 ^ (i - 1) > 0 and "1" or "0")
            end
            return r
        end):gsub("%d%d%d?%d?%d?%d?%d?%d?", function(x)
            if #x ~= 8 then
                return ""
            end
            local c = 0
            for i = 1, 8 do
                c = c + (x:sub(i, i) == "1" and 2 ^ (8 - i) or 0)
            end
            return string.char(c)
        end)
    )
    return { a }, nil
end

local function count_saved_pages(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local tmp = publisher.pagestore[firstarg]
    if not tmp then
        return { 0 }, "count-saved-pages(): no saved pages found. Return 0"
    else
        -- in backwards mode, tmp contains one entry for each page (a node list)
        -- in forward mode, tmp contains four elements: the number of pages, the position, #publisher.bookmarks, and the page type
        return { #tmp }, nil
    end
end

local function randomitem(_dataxml, arg)
    local x = math.random(#arg)
    return { arg[x] }, nil
end

local function romannumeral(_dataxml, arg)
    local firstarg = publisher.xpath.number_value(arg[1])
    if not firstarg then
        main.log("error", "romannumeral expects a number as the first argument")
        return {}, "romannumeral expects a number as the first argument"
    end
    return { tex.romannumeral(firstarg) }, nil
end

local function aspectratio(_dataxml, arg)
    local filename, pagenumber, box, _ = get_filename_pagenum_box_unit_from_arg(arg)
    local img = publisher.images.imageinfo(filename, pagenumber, box)
    return { img.img.xsize / img.img.ysize }, nil
end

local function pageheight(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#pageheight", dataxml)
    local unit = publisher.xpath.string_value(arg[1]) or "mm"
    if unit then
        local width = publisher.current_page.height
        local ret
        if unit == "cm" then
            ret = width / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = width / publisher.onemm_sp
        elseif unit == "in" then
            ret = width / publisher.onein_sp
        elseif unit == "sp" then
            ret = width
        elseif unit == "pc" then
            ret = width / publisher.onepc_sp
        elseif unit == "pt" then
            ret = width / publisher.onept_sp
        elseif unit == "pp" then
            ret = width / publisher.onepp_sp
        elseif unit == "dd" then
            ret = width / publisher.onedd_sp
        elseif unit == "cc" then
            ret = width / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 0) }, nil
    end
end

local function pagewidth(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#pagewidth", dataxml)
    local unit = publisher.xpath.string_value(arg[1]) or "mm"
    if unit then
        local width = publisher.current_page.width
        local ret
        if unit == "cm" then
            ret = width / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = width / publisher.onemm_sp
        elseif unit == "in" then
            ret = width / publisher.onein_sp
        elseif unit == "sp" then
            ret = width
        elseif unit == "pc" then
            ret = width / publisher.onepc_sp
        elseif unit == "pt" then
            ret = width / publisher.onept_sp
        elseif unit == "pp" then
            ret = width / publisher.onepp_sp
        elseif unit == "dd" then
            ret = width / publisher.onedd_sp
        elseif unit == "cc" then
            ret = width / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 0) }, nil
    end
end

local function fnLength(dataxml, arg)
    publisher.page_helpers.setup_page(nil, "layout_functions#length", dataxml)
    local value = publisher.xpath.string_value(arg[1])
    local unit = "mm"
    if #arg > 1 then
        unit = publisher.xpath.string_value(arg[2]) or "mm"
    end
    if unit then
        local width = tex.sp(dataxml.vars[value])

        local ret
        if unit == "cm" then
            ret = width / publisher.tenmm_sp
        elseif unit == "mm" then
            ret = width / publisher.onemm_sp
        elseif unit == "in" then
            ret = width / publisher.onein_sp
        elseif unit == "sp" then
            ret = width
        elseif unit == "pc" then
            ret = width / publisher.onepc_sp
        elseif unit == "pt" then
            ret = width / publisher.onept_sp
        elseif unit == "pp" then
            ret = width / publisher.onepp_sp
        elseif unit == "dd" then
            ret = width / publisher.onedd_sp
        elseif unit == "cc" then
            ret = width / publisher.onecc_sp
        else
            main.log(
                "error",
                string.format("unsupported unit: %q, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'", unit)
            )
        end
        return { math.round(ret, 0) }, nil
    end
    return {}, "unsupported unit, please use 'sp', 'pt', 'pc', 'cm', 'mm', 'in', 'dd' or 'cc'"
end

local function fnVisiblePagenumber(dataxml, arg)
    local firstarg
    if #arg > 0 then
        firstarg = publisher.xpath.string_value(arg[1])
    else
        publisher.page_helpers.setup_page(nil, "layout_functions#current_page", dataxml)
        firstarg = tostring(publisher.current_pagenumber)
    end
    local vpn = visiblepagenumber(firstarg)
    return { vpn }, nil
end

local function loremipsum(_dataxml, arg)
    local count = 1
    if #arg == 1 then
        local num, msg = publisher.xpath.number_value(arg[1])
        if msg then
            return nil, msg
        end
        count = tonumber(num) or 1
    end

    local lorem = [[
        Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
        tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
        veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
        commodo consequat. Duis aute irure dolor in reprehenderit in voluptate
        velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
        occaecat cupidatat non proident, sunt in culpa qui officia deserunt
        mollit anim id est laborum.
    ]]
    return { string.rep(lorem:gsub("^%s*(.-)%s*$", "%1"):gsub("[%s\n]+", " "), count, " ") }, nil
end

local sdns = "urn:speedata:2009/publisher/functions/en"

local funcs = {
    { "allocated", sdns, fnAllocated, 1, 4 },
    { "alternating", sdns, fnAlternating, 1, -1 },
    { "aspectratio", sdns, aspectratio, 1, 3 },
    { "attr", sdns, attr, 1, -1 },
    { "count-saved-pages", sdns, count_saved_pages, 1, 1 },
    { "current-column", sdns, current_column, 0, 1 },
    { "current-framenumber", sdns, current_frame_number, 0, 1 },
    { "current-page", sdns, fnCurrentPage, 0, 0 },
    { "current-row", sdns, fnCurrentRow, 0, 1 },
    { "decode-base64", sdns, decode_base64, 1, 1 },
    { "decode-html", sdns, decode_html, 1, 1 },
    { "dimexpr", sdns, fnDimexpr, 2, 2 },
    { "dummytext", sdns, loremipsum, 0, 1 },
    { "even", sdns, even, 1, 1 },
    { "file-exists", sdns, file_exists, 1, 1 },
    { "filecontents", sdns, filecontents, 1, 1 },
    { "first-free-row", sdns, first_free_row, 0, 1 },
    { "firstmark", sdns, firstmark, 1, 1 },
    { "format-number", sdns, format_number, 1, 3 },
    { "format-string", sdns, format_string, 1, -1 },
    { "group-height", sdns, groupheight, 1, 2 },
    { "group-width", sdns, groupwidth, 1, 2 },
    { "groupheight", sdns, groupheight, 1, 2 },
    { "groupwidth", sdns, groupwidth, 1, 2 },
    { "imageheight", sdns, imageheight, 1, 4 },
    { "imagewidth", sdns, imagewidth, 1, 4 },
    { "keep-alternating", sdns, keepalternating, 1, -1 },
    { "lastmark", sdns, lastmark, 1, 1 },
    { "length", sdns, fnLength, 1, 2 },
    { "loremipsum", sdns, loremipsum, 0, 1 },
    { "markdown", sdns, markdown, 1, 1 },
    { "md5", sdns, md5, 1, -1 },
    { "merge-pagenumbers", sdns, fnMergePagenumbers, 1, 4 },
    { "mode", sdns, mode, 1, -1 },
    { "number-of-columns", sdns, fnNumberOfColumns, 0, 1 },
    { "number-of-pages", sdns, fnNumberOfPages, 1, 1 },
    { "number-of-rows", sdns, fnNumberOfRows, 0, 1 },
    { "odd", sdns, odd, 1, 1 },
    { "pageheight", sdns, pageheight, 0, 1 },
    { "pagenumber", sdns, fnpagenumber, 1, 1 },
    { "pagewidth", sdns, pagewidth, 0, 1 },
    { "randomitem", sdns, randomitem, 1, -1 },
    { "reset-alternating", sdns, reset_alternating, 1, 1 },
    { "romannumeral", sdns, romannumeral, 1, 1 },
    { "sha1", sdns, shaone, 1, -1 },
    { "sha256", sdns, sha256, 1, -1 },
    { "sha512", sdns, sha512, 1, -1 },
    { "symbol", sdns, symbol, 1, -1 },
    { "todimen", sdns, tounit, 1, 3 },
    { "tounit", sdns, tounit, 1, 3 },
    { "variable-exists", sdns, variable_exists, 1, 1 },
    { "variable", sdns, variable, 1, -1 },
    { "visible-pagenumber", sdns, fnVisiblePagenumber, 0, 1 },
}

local register = publisher.xpath.registerFunction
for _, func in ipairs(funcs) do
    register(func)
end

local libprefix = publisher.splib

-- Contains
local function fnContains(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local secondarg = publisher.xpath.string_value(arg[2])
    return { libprefix.contains(firstarg, secondarg) }, nil
end

-- Matches
local function fnMatches(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local secondarg = publisher.xpath.string_value(arg[2])
    local flags = arg[3] and publisher.xpath.string_value(arg[3]) or ""
    if string.find(flags, "x") then
        main.log("warn", "matches does not support the x flag")
    end
    if flags ~= "" then
        secondarg = "(?" .. flags .. ")" .. secondarg
    end
    return { libprefix.matches(firstarg, secondarg) }, nil
end

-- Replace
local function fnReplace(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local secondarg = publisher.xpath.string_value(arg[2])
    local thirdarg = publisher.xpath.string_value(arg[3])
    return { libprefix.replace(firstarg, secondarg, thirdarg) }, nil
end

-- UpperCase. The built-in upper-case() in lxpath only handles ASCII,
-- the Go version uses the Unicode full case mappings (Straße -> STRASSE).
local function fnUpperCase(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    return { libprefix.uppercase(firstarg) }, nil
end

-- LowerCase
local function fnLowerCase(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    return { libprefix.lowercase(firstarg) }, nil
end

-- Tokenize is the first function we ask 'splib' for help
local function fnTokenize(_dataxml, arg)
    local firstarg = publisher.xpath.string_value(arg[1])
    local secondarg = publisher.xpath.string_value(arg[2])
    if firstarg == nil or secondarg == nil then
        main.log("error", "tokenize: one of the arguments is empty")
        return { "" }, nil
    end
    local seq = libprefix.tokenize(firstarg, secondarg)
    return seq, nil
end

funcs = {
    { "contains", publisher.xpath.fnNS, fnContains, 2, 2 },
    { "matches", publisher.xpath.fnNS, fnMatches, 2, 3 },
    { "tokenize", publisher.xpath.fnNS, fnTokenize, 1, 2 },
    { "replace", publisher.xpath.fnNS, fnReplace, 1, 3 },
    { "upper-case", publisher.xpath.fnNS, fnUpperCase, 1, 1 },
    { "lower-case", publisher.xpath.fnNS, fnLowerCase, 1, 1 },
}

for _, func in ipairs(funcs) do
    register(func)
end

file_end("layout_functions_lxpath.lua")
