local p = {}
--=========
local getArgs   = require('Module:Arguments').getArgs

local unit_names =	{
						["millimetre"]  = "mm",	
						["centimetre"] = "cm",
						["metre"]      = "m" ,
						["kilometre"]  = "km",
						["inch"]       = "in",
						["foot"]       = "fr",
						["yard"]       = "yd",
						["mile"]       = "mi",
						["gram"]       = "g" ,
						["kilogram"]   = "kg",
					};
----
local length_dimensions_pid = {  -- Clustering dimensions of same physical property makes it easier to iterate over them.
								["length"]   = "P2043",
								["height"]   = "P2048",
								["width"]    = "P2049",
								["depth"]    = "P2610",
								["diameter"] = "P2386"
							}
local other_dimensions_pid = {
								["mass"]     = "P2067",
								["scale"]    = "P1752"
							}
----
function p._get_unit_qid( qid, pid )
	local entity = mw.wikibase.getEntityObject( qid )
	if entity['claims'][pid]    == nil then return nil end
	if entity['claims'][pid][1] == nil then return nil end
	if entity['claims'][pid][1]['mainsnak']['datavalue']['value']['unit']   == nil then return nil end
	local work = entity['claims'][pid][1]['mainsnak']['datavalue']['value']['unit']
	work = string.sub(work, 32)
	return work
end
----
function p._get_amount( qid, pid )
	local entity = mw.wikibase.getEntityObject(qid)
	if entity['claims'][pid]    == nil then return nil end
	if entity['claims'][pid][1] == nil then return nil end
	if entity['claims'][pid][1]['mainsnak']['datavalue']['value']['amount']   == nil then return nil end	
	local work = entity['claims'][pid][1]['mainsnak']['datavalue']['value']['amount']
	-- For some weird reason Wikidata returns "+2" instead of "2"; removing leading +
	if string.sub(work, 1, 1) == "+" then work = string.sub(work, 2) end
	return  work
end
----
function p.get_unit_qid( frame )
	local qid = getArgs(frame)["qid"]
	local pid = getArgs(frame)["pid"]
	local unit_qid = p._get_unit_qid( qid, pid )
	return unit_qid
end
----
function p.get_unit_label( frame )
	local qid = getArgs(frame)["qid"]
	local pid = getArgs(frame)["pid"]
	local unit_qid = p._get_unit_qid( qid, pid )
	return mw.wikibase.label( unit_qid )
	-- return mw.wikibase.getLabelByLang( unit_qid, 'ru' )
end
----
function p._get_unit_label_en( qid, pid )
	local unit_qid = p._get_unit_qid( qid, pid )
	if not unit_qid then return nil end
	return mw.wikibase.getLabelByLang( unit_qid, 'en' )
end
function p.get_unit_label_en( frame )
	local qid = getArgs(frame)["qid"]
	local pid = getArgs(frame)["pid"]
	--local unit_qid = p._get_unit_qid( qid, pid )
	--return mw.wikibase.getLabelByLang( unit_qid, 'en' )
	return p._get_unit_label_en( qid, pid )
end
----
function p._get_unit_abbreviation( qid, pid )
	-- return "plouf " .. qid .. "--" .. pid
	local unit_name = p._get_unit_label_en( qid, pid )
	return unit_names[unit_name]
end
function p.get_unit_abbreviation( frame )
	local qid = getArgs(frame)["qid"]
	local pid = getArgs(frame)["pid"]
	return p._get_unit_abbreviation( qid, pid )
end
----
function p._get_length_unit_in_use( qid )
	-- Detects the unit used to express lengths. 
	-- This assumes that the same unit is used for length, width etc. (seriously why would you do otherwise?)
	for dim_name, dim_pid in next, length_dimensions_pid do
		local this_unit_abbr = p._get_unit_abbreviation( qid, dim_pid )
		if this_unit_abbr then return this_unit_abbr end
	end
	return "No length unit was found"
end
function p.get_length_unit_in_use( frame )
	local qid = getArgs(frame)["qid"]
	return p._get_length_unit_in_use( qid )
end
----
function p.display_size_template( frame )
	local qid = getArgs(frame)["qid"]
	local reference_unit = p._get_length_unit_in_use( qid )
	local length_value   = p._get_amount( qid, length_dimensions_pid["length"]   )
	local height_value   = p._get_amount( qid, length_dimensions_pid["height"]   )
	local width_value    = p._get_amount( qid, length_dimensions_pid["width"]    )
	local depth_value    = p._get_amount( qid, length_dimensions_pid["depth"]    )
	local diameter_value = p._get_amount( qid, length_dimensions_pid["diameter"] )
	return frame:expandTemplate{ title = 'Size', args = { unit = reference_unit , length = length_value , height = height_value, width = width_value, thickness = depth_value, diameter = diameter_value } }
end

---- This will start by trying to display a Size template,
--   then a Weight template for the mass if given, 
--   and finally the scale if given
function p.display_all_sizes( frame )
	local qid = getArgs(frame)["qid"]
	local reference_unit = p._get_length_unit_in_use( qid )
	local length_value   = p._get_amount( qid, length_dimensions_pid["length"]   )
	local height_value   = p._get_amount( qid, length_dimensions_pid["height"]   )
	local width_value    = p._get_amount( qid, length_dimensions_pid["width"]    )
	local depth_value    = p._get_amount( qid, length_dimensions_pid["depth"]    )
	local diameter_value = p._get_amount( qid, length_dimensions_pid["diameter"] )
	work = frame:expandTemplate{ title = 'Size', args = { unit = reference_unit , length = length_value , height = height_value, width = width_value, thickness = depth_value, diameter = diameter_value } }
	
	-- Mass
	local mass_value = p._get_amount( qid, other_dimensions_pid["mass"]   )
	local mass_unit  = p._get_unit_abbreviation( qid, other_dimensions_pid["mass"] )
	if mass_value then 
		if work ~= "" then work = work .. "<br />" end
		work = work .. frame:expandTemplate{ title = 'Weight', args = { mass_unit, mass_value } }
	end
	-- Scale
	local scale_value = p._get_amount( qid, other_dimensions_pid["scale"]   )
	if scale_value then
		scale_string = ""
		if     (tonumber(scale_value) == 1) then scale_string = "1:1"
		elseif (tonumber(scale_value) >  1) then scale_string = "1:" .. scale_value
			-- Convention in Wikidata is that larger-than-lifesize scales have a negative number
		elseif (tonumber(scale_value) <  1) then scale_string = abs(scale_value) .. ":1" 
		else return "Error in determing scale"	end
		
		if work ~= "" then work = work .. "<br />" end
		work = work .. mw.wikibase.label( "Q193642" ) .. ": " .. scale_string
	end
	return work
end


----
function p.get_unit_label_by_lang( frame )
	local qid  = getArgs(frame)["qid"]
	local pid  = getArgs(frame)["pid"]
	local lang = getArgs(frame)["lang"]
	if not lang then lang = "en" end
	local unit_qid = p._get_unit_qid( qid, pid )
	return mw.wikibase.getLabelByLang( unit_qid, lang )
end
----
function p.get_amount( frame )
	local qid = getArgs(frame)["qid"]
	local pid = getArgs(frame)["pid"]
	local amount = p._get_amount( qid, pid )
	return amount
end

--=========
return p