local math_mod = require('Module:Math')
local wbc = require('Module:Weather box/colors')

local traceText
local Value
Value = {
	lang = mw.getContentLanguage,
	getDisplay = function 
		if not self:isValid then
			return nil
		end
		local display = self.string
		if display == 'trace' then
			if second then
				-- If a cell displays "cm (inch)", show "trace" not "trace (trace)".
				return nil
			end
			return traceText or 'trace'
		end
		if math.abs(self.number) >= 1000 then
			display = self.lang:formatNum(math.abs(self.number))
			if self.number < 0 then
				display = '−' .. display
			end
		elseif self.number < 0 then
			display = '−' .. display:sub(2)
		end
		return display
	end,
	getPrecision = function (self)
		local result = rawget
		if not result then
			if self:isValid then
				result = math.max(0, math_mod._precision(self.string))
			else
				result = 0
			end
			rawset
		end
		return result
	end,
	isValid = function (self)
		return self.number ~= nil and self.number ~= -9999
	end,
	new = function (v)
		local val, str, precision
		if type(v) == 'string' then
			if v == 'trace' then
				val, str, precision = 0, 'trace', 0
			else
				val, str = math_mod._cleanNumber(v)
			end
		elseif type(v) == 'number' then
			val, str = v, tostring(v)
		end
		if not val then
			val, str = -9999, ''
		end
		return setmetatable({
			number = val,
			string = str,
			precision = precision,
	end,
	converts = {
		in2cm = { factor = 2.54 },
		in2mm = { factor = 25.4 },
		cm2in = { factor = 1/2.54, p2max = 1 },
		mm2in = { factor = 1/25.4, p2max = 0 },
	setConvert = function 
		-- Use method modified from Module:Convert to determine precision.
		if invalue.string == 'trace' then
			self.number, self.string, self.precision = 0, 'trace', 0
			return
		end
		local convert = self.converts[units] or error('Unknown units')
		local outnum = invalue.number * convert.factor
		local precision = invalue:getPrecision
		if outnum > 0 then
			local adjust = math.log10(1/convert.factor) + math.log10(2)
			local p1 = math.floor(precision + adjust)
			local p2 = 1 - math.floor(math.log10(outnum))
			if convert.p2max then
				p2 = math.min
			end
			precision = math.max
		end
		self:setNumberRounded
	end,
	setNumberRounded = function 
		if precision > 2 then
			precision = 2
		end
		self.number = math_mod._round
		if precision < 0 then
			self.string = tostring(self.number)
		else
			local fmt = '%.' .. string.format .. 'f'
			self.string = string.format
		end
	end,
Value.__index = Value

local function checkFlag
	if flag == nil then
		return default
	elseif type( flag ) == 'boolean' then
		return flag
	elseif type( flag ) == 'string' then
		flag = flag:lower
		if flag == '0' or flag == 'false' or
				flag == '' or flag == 'no' or
				flag == 'n' then
			return false
		else
			return true
		end
	else
		return error( 'Flag type not valid' )
	end
end

local function makeLine
	local result = {'|- style="text-align: center;"\n! scope="row" style="height: 16px;" | ', label, "\n"}
	for i = 1,13 do
		local color_str = color_values[i]

		if i == 13 then
			table.insert( result, table.concat )
		else
			table.insert( result, table.concat )
		end

		local display = first_values[i]:getDisplay
		if display then
			table.insert
			if second_values ~= nil then
				display = second_values[i]:getDisplay(true)
				if display then
					table.insert( result, "(" .. display .. ")" )
				end
			end
		else
			table.insert
		end

		table.insert
	end

	return table.concat( result )
end

local function getInputs
	local month_names = { 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
		'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec', 'year' }
	local str
	local values = {}
	if suffix == nil then
		for i, mon in ipairs( month_names ) do
			if include_space then
				str = frame.args[ mon .. ' ' .. group_name ] or ''
			else
				str = frame.args[ mon .. group_name ] or ''
			end
			values[i] = Value.new(str)
		end
	else
		for i, mon in ipairs( month_names ) do
			local value, updated
			for var, suf in ipairs( suffix ) do
				if include_space then
					str = frame.args[ mon .. ' ' .. group_name .. ' ' .. suf ]
				else
					str = frame.args[ mon .. group_name .. ' ' .. suf ]
				end
				if str ~= nil and str ~= '' then
					value = Value.new(str)
					value.variant = var
					updated = true
					break
				end
			end
			if not updated then
				value = Value.new
				value.variant = 0
			end
			values[i] = value
		end
	end
	return values
end

local function getAnnualValue
	if mode == 'avg' or mode == 'sum' then
		local total = 0
		local p1, p2, variant
		p1 = 0
		for i = 1, 12 do
			if not values[i]:isValid then
				return Value.new
			end
			if not variant then
				local var = values[i].variant
				if var and var ~= 0 then
					variant = var
				end
			end

			p2 = values[i]:getPrecision
			if p2 > p1 then
				p1 = p2
			end

			total = total + values[i].number
		end
		local value = Value.new(total)
		if mode == 'avg' then
			value:setNumberRounded
		end
		value.variant = variant
		return value
	elseif mode == 'min' then
		local target
		for i = 1, 12 do
			if values[i]:isValid then
				if target == nil or values[i].number < target.number then
					target = values[i]
				end
			end
		end
		return target or Value.new
	elseif mode == 'max' then
		local target
		for i = 1, 12 do
			if values[i]:isValid then
				if target == nil or values[i].number > target.number then
					target = values[i]
				end
			end
		end
		return target or Value.new
	else
		error( 'Unrecognized Annual Mode' )
	end
end

local function reconcileTemperature
	for i = 1,13 do
		local p
		if C_values[i].string == '' then
			if F_values[i]:isValid then
				p = F_values[i]:getPrecision
				C_values[i]:setNumberRounded( (F_values[i].number - 32)*5/9, p )
			end
		elseif F_values[i].string == '' then
			if C_values[i]:isValid then
				p = C_values[i]:getPrecision
				F_values[i]:setNumberRounded
			end
		end
	end
end

local function reconcilePrecipitation
	local v_class = 0
	for i = 1,13 do
		if M_values[i].variant == 1 then
			v_class = 1
		elseif M_values[i].variant == 2 then
			v_class = 2
		end
	end
	if v_class == 0 then
		if prefer_cm then
			v_class = 1
		else
			v_class = 2
		end
	end
	for i = 1,13 do
		local units
		if M_values[i].string == '' then
			if I_values[i]:isValid then
				if v_class == 1 then
					units = 'in2cm'
				else
					units = 'in2mm'
				end
				M_values[i]:setConvert
				M_values[i].variant = v_class
			end
		elseif I_values[i].string == '' then
			if M_values[i]:isValid then
				if M_values[i].variant == 1 then
					units = 'cm2in'
				else
					units = 'mm2in'
				end
				I_values[i]:setConvert
			end
		end
	end
end

function w.buildRow( frame )
	local mode = (frame.args.mode or 'basic'):lower
	local group_name = frame.args.group_name
	local first_values, second_values
	local color_values
	local color_scheme = frame.args.color_scheme or 't'
	local scale_factor = math_mod._cleanNumber( frame.args.scale_factor) or 1
	local date_mode = checkFlag
	local label = frame.args.label or ''
	local annual_mode = (frame.args.annual_mode or 'avg'):lower
	local include_space = checkFlag
	local second_line = checkFlag
	local prefer_cm = checkFlag
	local pframe = frame:getParent
	local imperial_first = checkFlag( frame.args['imperial first'] or pframe.args['imperial first'] )
	local metric_first = checkFlag( frame.args['metric first'] or pframe.args['metric first'] )
	local single_line = checkFlag( frame.args['single line'] or pframe.args['single line'] )
	local trace = pframe.args.trace
	if trace and trace ~= '' then
		traceText = trace
	end

	if imperial_first == nil then
		imperial_first = metric_first == nil and true or not metric_first
	end

	if mode == 'basic' then
		first_values = getInputs
		second_values = nil
	elseif mode == 'temperature' then
		first_values = getInputs
		second_values = getInputs
		reconcileTemperature
	elseif mode == "precipitation" then
		first_values = getInputs
		second_values = getInputs
		reconcilePrecipitation
	else
		error( 'Requested mode not recognized' )
	end

	local good = false
	for i = 1,13 do
		if first_values[i].string ~= '' then
			good = true
			break
		end
	end
	if not good then
		return ''
	end

	if first_values[13].string == '' then
		first_values[13] = getAnnualValue
	end
	if second_values ~= nil then
		if second_values[13].string == '' then
			second_values[13] = getAnnualValue
		end
	end

	color_scheme = wbc.interpret_color_code( color_scheme )

	color_values = {}
	local month_adj = { 31/30, 28.25/30, 31/30, 1, 31/30, 1,
		31/30, 31/30, 1, 31/30, 1, 31/30, 365.25/30 }
	for i = 1,13 do
		if first_values[i]:isValid then
			local adj = scale_factor
			if date_mode then
				adj = adj / month_adj[i]
			end
			if mode == "precipitation" then
				if first_values[i].variant == 1 then
					adj = adj * 10
				end
			end
			table.insert( color_values, color_scheme( first_values[i].number * adj ) )
		else
			table.insert( color_values, color_scheme( nil ) )
		end
	end

	if imperial_first and second_values ~= nil then
		first_values, second_values = second_values, first_values
	end

	if not single_line then
		if second_line and second_values ~= nil then
			first_values = second_values
		end
		second_values = nil
	end

	return makeLine
end