local data = mw.loadData ('Module:USN fleet totals/data');						-- get the detailed list of ship types and their counts, the grand total of active and reserve ships, and the total planned ships
local get_args = require ('Module:Arguments').getArgs;


--[[--------------------------< R O U N D >--------------------------------------------------------------------

rounds <count> to nearest multiple of 5.

]]

local function round (count)
	if 0 == count % 5 then
		return count;															-- <count> is xx0, xx5 so return unmolested
	elseif 2.5 > (count % 5) then
		return count - (count % 5);												-- <count> is xx1, xx2 so return xx0
	else
		return count + (5 - (count % 5));										-- <count> is xx3, xx4 so return xx5
	end
end


--[[--------------------------< U S N _ F L E E T _ T O T A L S >----------------------------------------------

implements {{USN fleet totals}}

This function returns one of three values according to the text sting in {{{1}}} (frame.args[1]):
	active – the 'grand total' (active and reserved fleets) rounded to the nearest multiple of 5					-- {{USN fleet totals|active}}
	planned – the 'planned total' (ships under construction or on order) rounded to the nearest multiple of 5		-- {{USN fleet totals|planned}}
	retire – number of ships to be decommissioned or taken out of service											-- {{USN fleet totals|retire}}
	retire-year – planned retirement year farthest in the future													-- {{USN fleet totals|retire-year}}
	<anything or nothing> – the long string of fleet totals created by Module:USN fleet totals						-- {{USN fleet totals}}

]]

local function USN_fleet_totals (frame)
	if 'active' == frame.args[1] then											-- number of active and reseved fleet ships
		return round (data.grand_total);										-- round to nearest multiple of 5
	elseif 'planned' == frame.args[1] then										-- under construction and on-order ships
		return round (data.planned_total);										-- round to nearest multiple of 5
	elseif 'retire' == frame.args[1] then										-- ships to be decommissioned or taken out of service
		return round (data.retirements_total);									-- round to nearest multiple of 5
	elseif 'retire-year' == frame.args[1] then
		return data.retirements_year_max;
	else																		-- {{{1}}} is anything else
		return data.fleet_totals_str;											-- return the detailed fleet totals
	end
end


--[[--------------------------< _ D E C O M _ E O S _ C O M M O N >--------------------------------------------

common function to implement {{decommission}} and {{end of service}} templates
	
]]

local function _decom_eos_common (args_t, phrases_t, template_name)
	local out_t = {};

	if phrases_t[args_t[1]] then												-- is keyword valid?
		table.insert (out_t, phrases_t[args_t[1]]);								-- yes, get the associated string
	elseif args_t[1] then														-- no, but not nil so emit appropriate error message
		return '<span style="color:#d33"><kbd>{{[[Template:' .. template_name .. '|' .. template_name ..']]}}</kbd>: error: unknown keyword: ' .. args_t[1] .. '</span>';
	else																		-- missing keyword so emit error message
		return '<span style="color:#d33"><kbd>{{[[Template:' .. template_name .. '|' .. template_name ..']]}}</kbd>: error: missing keyword</span>'
	end

	if args_t[2] then															-- did we get this optional parameter?
		local year = mw.text.trim (args_t[2]):match ('^%d%d%d%d$');				-- attempt to get a four digit year

		if year then															-- did we find a 'year'?  TODO: validate? must be this or a future year? never in the past?
			table.insert (out_t, year);											-- add the year to the output
		else																	-- here when a four-digit 'year' not found
			return '<span style="color:#d33"><kbd>{{[[Template:' .. template_name .. '|' .. template_name ..']]}}</kbd>: error: invalid year</span>';
		end
	end

	return table.concat (out_t, ' ');											-- assemble into a big string and done
end


--[[--------------------------< D E C O M M I S S I O N >------------------------------------------------------

implements {{decommission}}

Takes two positional parameters:
	{{{1}}} – (required) one of two keywords that cause the template to return an appropriate phrase; phrases are
				defined in ~/data.  The keywords are 'scheduled' and 'proposed'
	{{{2}}} – (optional) year when decommissioning is expected to occur
	
]]

local function decommission (frame)
	local args_t = get_args (frame);											-- get parameters from the template into a local table
	return _decom_eos_common (args_t, data.decommission_t, 'decommission');		-- call common function to error check the inputs and return the rendered string
end


--[[--------------------------< E N D _ O F _ S E R V I C E >--------------------------------------------------

implements {{end of service}}

Takes two positional parameters:
	{{{1}}} – (required) one of two keywords that cause the template to return an appropriate phrase; phrases are
				defined in ~/data.  The keywords are 'scheduled' and 'proposed'
	{{{2}}} – (optional) year when end of service is expected to occur
	
]]

local function end_of_service (frame)
	local args_t = get_args (frame);											-- get parameters from the template into a local table
	return _decom_eos_common (args_t, data.end_of_service_t, 'end of service');	-- call common function to error check the inputs and return the rendered string
end	


--[[--------------------------< E X P O R T S >----------------------------------------------------------------
]]

return 
	{
	USN_fleet_totals = USN_fleet_totals,
	
	decommission = decommission,
	end_of_service = end_of_service,
	}