local p = {}

-- if the template has censuses=HRV it will show all known censuses from 1857 to 2021
-- regardless of whether the article contains data
-- without this parameter in the template, it will only show the years entered in the article
local godine_hr = {1857, 1869, 1880, 1890, 1900, 1910, 1921, 1931, 1948, 1953,
	1961, 1971, 1981, 1991, 2001, 2011, 2021, }

-- translations begin
local view_template_link = "[[Template:Croatian population data graph|v]]"
local izvori_hr = "[[Template:Croatian population data graph/Sources|Croatian Bureau of Statistics publications]]"
	      
local max_height = 8 -- that's for 8em; also set the cell height in the template's css

-- all valid param names: for historical reasons, on enwiki some are in Croatian and some in English
param_names = {
	title    = {"title", "naslov"},
	entity   = {"entity", "područje"},
	note     = {"note", "napomena"},
	sources  = {"sources", "izvori"},
	censuses = {"censuses", "popisi"}
}

labels = {
	trend    = "Population trends ", -- EN:"Population trends " HR:"Kretanje broja stanovnika od "
	trendsep = "–",                  -- EN:"–"              HR:" do "
	ord      = "population",         -- EN:"population"     HR:"broj stanovnika"
	nb       = "'''Note:'''",        -- EN:"'''Note:'''"    HR:"'''Napomena:"
	ref      = "'''Sources:'''",     -- EN:"'''Sources:'''" HR:"'''Izvori:"
	YYYYsuf  = "",                   -- EN:""               HR:"."
}
-- translations end

function p.dijagram(frame)
	local data = {}

	local targs = frame:getParent().args --template arguments in template call
	local margs = frame.args --module arguments in #invoke

	param_values = {}
	local tmp
	for param, names in pairs(param_names) do
		tmp = nil
		for _, name in ipairs(names) do
			tmp = tmp or targs[name] or margs[name]
		end
		param_values[param] = tmp
	end
	for label, tx in pairs(labels) do
		labels[label] = margs[label] or labels[label] --add possibility to change labels from module invocation
	end
    mw.logObject(param_values)
    
	--loop through all parameters; most of them are parameters of the form pYYYY or aN/pN pairs
	for k, v in pairs(targs) do
			local Y = tonumber(string.match(k, "^p(%d%d%d%d)$")) -- parameters like p2021, for population in 2021
			if Y then
				local p = tonumber(v)
				--mw.log(g,p)
				if p then data[Y] = p end
			end
			
			local n = string.match(k, "^a(%d%d?)$") -- up to 99 pairs of year/population parameters: a1/p1 … a99/p99 (old param syntax)
			if n then
				local Y = tonumber(v)
				local p = tonumber(targs["p"..n])
				--mw.log(g,p)
				if Y and p then
					data[Y] = p
					end
				end
	end
	
	--years present in the template; we need them in the table for sorting
	local years = {}
	local data_max = 0
	for k, v in pairs(data) do
		table.insert(years, k)
		if data[k]>data_max then data_max=data[k] end
	end
	
	table.sort(years)
	
--html table where each cell will contain one column (div) of the bar chart
--here, we create cells in two rows
	local tr1 = mw.html.create( "tr" )
	tr1 : tag("td") : addClass("kbs-ordinate") 
	      : tag("span") : addClass("kbs-ordinate-text") : wikitext(labels["ord"]) : done()
    local tr2 = mw.html.create( "tr" )
    tr2 : tag("td") : done()
	
	if (param_values["censuses"]=="HRV") then
		yrs_to_show = godine_hr
	else
		yrs_to_show = years
		end

	local first, last = Nil, Nil
    for _, Y in ipairs(yrs_to_show) do
    	if years[1]<=Y and Y<=years[#years] then --don't show left and right of the only known ones, but yrs_to_show all between
    		first = first or Y
    		last = Y
	    	local value = data[Y] or 0
	    	local data_class = value<10000 and "kbs-data" or "kbs-data-smaller"
	    	local mark = (value>0 and value) or "" -- do not show 0 or Nil
	        tr1 : tag("td") : addClass("kbs-for-columns") 
	              : tag("div") : addClass(data_class)  : wikitext(mark) : done()
	              : tag("div") : addClass("kbs-columns") 
	              : cssText("height:"..0.01*math.floor(100*value*max_height/data_max).."em;") : done()
	        tr2 : tag("td") : addClass("kbs-years") : wikitext(Y .. labels["YYYYsuf"]) : done()
    		end
    end

-- title above table with diagram
-- in template, enter: Settlement X or Municipality Y or City Z

    local data_for = param_values["entity"] and (param_values["entity"] ~= "") and ("'''" .. param_values["entity"] .. "''': ") 
                       or ""
                      
    local kbs = labels["trend"] .. first..labels["YYYYsuf"] .. labels["trendsep"] .. last..labels["YYYYsuf"]
    local title = data_for .. (param_values["title"] and (param_values["title"] ~= "") and param_values["title"] or kbs)

-- table for bar chart   
    local tbl = mw.html.create( "table" )
    tbl : addClass("kbs-table")
        : node(tr1)
        : node(tr2)
        : attr('role', 'presentation')
    
    local ttl = mw.html.create( "div" )
    ttl : addClass("kbs-title") 
    local ttl_left = mw.html.create( "div" )
    ttl_left : addClass("kbs-title-left") : wikitext(title)
    local ttl_right = mw.html.create( "div" )
    ttl_right : addClass("kbs-title-right") : wikitext(view_template_link)
    ttl : node(ttl_left) : node(ttl_right)
    
    local tbl_ttl = mw.html.create( "div" )
    tbl_ttl : addClass("kbs-title-table-scrollable")
    		: tag("div") : addClass("kbs-title-table")
    		   : node(ttl)
    		   : node(tbl)
    		   : done()

-- Note:… and Sources:… below the diagram
    local note = param_values["note"] or ""
    local sources = ""
    
    if param_values["censuses"] == "HRV" then
    	sources = izvori_hr
    	end

    sources = param_values["sources"] or sources
    
    local nte = mw.html.create( "div" ) : addClass("kbs-note")
    if note ~="" then
    	nte : wikitext(labels["nb"] .. note .. " ")
    	end
	if sources ~="" then
		nte : wikitext(labels["ref"] .. sources)
	end

	local nte_src = mw.html.create( "div" )
	nte_src : addClass("kbs-note-nonscrollable") 
			: node(nte)

	local everything = mw.html.create() : node(tbl_ttl) : node(nte_src)
	return everything
end
 
return p