-- Implement [[Template:Time ago]]



local numberSpell, yesno  -- lazy load



function numberSpell(arg)

	numberSpell = require('Module:NumberSpell')._main

	return numberSpell(arg)

end



function yesno(arg)

	yesno = require('Module:Yesno')

	return yesno(arg)

end



local p = {}



-- Table to convert entered text values to numeric values.

local timeText = {

	'seconds' = 1,

	'minutes' = 60,

	'hours' = 3600,

	'days' = 86400,

	'weeks' = 604800,

	'months' = 2629800,  -- 365.25 * 24 * 60 * 60 / 12

	'years' = 31557600

}



-- Table containing tables of possible units to use in output.

local timeUnits = {

	1 = { 'second', 'seconds', "second's", "seconds'" },

	60 = { 'minute', 'minutes', "minutes'", "minutes'" },

	3600 = { 'hour', 'hours', "hour's", "hours'" },

	86400 = { 'day', 'days', "day's", "days'" },

	604800 = { 'week', 'weeks', "week's", "weeks'", unit = 'w' },

	2629800 = { 'month', 'months', "month's", "months'", unit = 'm'  },

	31557600 = { 'year', 'years', "year's", "years'", unit = 'y'  }

}



function p._main( args )

	-- Initialize variables

	local lang = mw.language.getContentLanguage()

	local auto_magnitude_num

	local min_magnitude_num

	local magnitude = args.magnitude

	local min_magnitude = args.min_magnitude

	local purge = args.purge



	-- Add a purge link if something (usually "yes") is entered into the purge parameter

	if purge then

		purge = ' <span class="plainlinks">([' .. mw.title.getCurrentTitle():fullUrl('action=purge') .. ' purge])</span>'

	else

		purge = ''

	end



	-- Check that the entered timestamp is valid. If it isn't, then give an error message.

	local success, inputTime = pcall( lang.formatDate, lang, 'xnU', args1 )

	if not success then

		return '<strong class="error">Error: first parameter cannot be parsed as a date or time.</strong>'

	end



	-- Store the difference between the current time and the inputted time, as well as its absolute value.

	local timeDiff = lang:formatDate( 'xnU' ) - inputTime

	local absTimeDiff = math.abs( timeDiff )



	if magnitude then

		auto_magnitude_num = 0

		min_magnitude_num = timeTextmagnitude

	else

		-- Calculate the appropriate unit of time if it was not specified as an argument.

		local autoMagnitudeData = {

			{ factor = 2, amn = 31557600 },

			{ factor = 2, amn = 2629800 },

			{ factor = 2, amn = 86400 },

			{ factor = 2, amn = 3600 },

			{ factor = 2, amn = 60 }

		}

		for _, t in ipairs( autoMagnitudeData ) do

			if absTimeDiff / t.amn >= t.factor then

				auto_magnitude_num = t.amn

				break

			end

		end

		auto_magnitude_num = auto_magnitude_num or 1

		if min_magnitude then

			min_magnitude_num = timeTextmin_magnitude

		else

			min_magnitude_num = -1

		end

	end



	if not min_magnitude_num then

		-- Default to seconds if an invalid magnitude is entered.

		min_magnitude_num = 1

	end



	local result_num

	local magnitude_num = math.max( min_magnitude_num, auto_magnitude_num )

	local unit = timeUnitsmagnitude_num].unit

	if unit and absTimeDiff >= 864000 then

		local Date = require('Module:Date')._Date

		local input = lang:formatDate('Y-m-d H:i:s', args1])  -- Date needs a clean date

		input = Date(input)

		if input then

			local id

			if input.hour == 0 and input.minute == 0 then

				id = 'currentdate'

			else

				id = 'currentdatetime'

			end

			result_num = (Date(id) - input):age(unit)

		end

	end

	result_num = result_num or math.floor ( absTimeDiff / magnitude_num )



	local punctuation_key, suffix

	if timeDiff >= 0 then -- Past

		if result_num == 1 then

			punctuation_key = 1

		else

			punctuation_key = 2

		end

		if args.ago == '' then

			suffix = ''

		else

			suffix = ' ' .. (args.ago or 'ago')

		end

	else -- Future

		if args.ago == '' then

			suffix = ''

			if result_num == 1 then

				punctuation_key = 1

			else

				punctuation_key = 2

			end

		else

			suffix = ' time'

			if result_num == 1 then

				punctuation_key = 3

			else

				punctuation_key = 4

			end

		end

	end

	local result_unit = timeUnits magnitude_num ][ punctuation_key 



	-- Convert numerals to words if appropriate.

	local spell_out = args.spellout

	local spell_out_max = tonumber(args.spelloutmax)

	local result_num_text

	if spell_out and (

		( spell_out == 'auto' and 1 <= result_num and result_num <= 9 and result_num <= ( spell_out_max or 9 ) ) or

		( yesno( spell_out ) and 1 <= result_num and result_num <= 100 and result_num <= ( spell_out_max or 100 ) )

		)

	then

		result_num_text = numberSpell( result_num )

	else

		result_num_text = tostring( result_num )

	end

	

	-- numeric or string

	local numeric_out = args.numeric

	local result = ""

	if numeric_out then

		result = tostring( result_num )

	else

		result = result_num_text .. ' ' .. result_unit .. suffix -- Spaces for suffix have been added in earlier.

	end



	return result .. purge

end



function p.main( frame )

	local args = require( 'Module:Arguments' ).getArgs( frame, {

		valueFunc = function( k, v )

			if v then

				v = v:match( '^%s*(.-)%s*$' ) -- Trim whitespace.

				if k == 'ago' or v ~= '' then

					return v

				end

			end

			return nil

		end,

		wrappers = 'Template:Time ago'

	})

	return p._main( args )

end



return p