モジュール:Utility/Scale

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local libraryUtil = require('libraryUtil')
local table       = require('Module:TableExtensions')

function math.isNaN(v)
	--return tostring(v) == '-nan'
	return v ~= v
end
local log10e = 1 / math.log(10)
function math.log10(x)
	return math.log(x) * log10e 
end

-- ============
-- Define utils
-- ============
local unit = { 0, 1 }
local function identity(num)
	return num
end

-- function: asNumber - as number if possible
local function asNumber(value)
	local typename = type(value)
	if typename == 'number' then
		return value
	elseif typename == 'string' then
		return tonumber(value)
	else
		error('The "value" type must be "number" or "string".')
	end
end

-- function: constant
local function constant(num)
	return function()
		return num
	end
end

-- function: normalize
local function normalize(a, b)
	b = b - a
	if math.isNaN(b) then
		return constant(b)
	elseif b == 0 then
		return constant(0.5)
	else
		return function(x)
			return (x - a) / b
		end
	end
end

-- function: interpolateValue
local function interpolateValue(a, b)
	return function(t)
		return a + (b - a) * t
	end
end

-- function: clamper - generate clamp function
local function clamper(a, b)
	if a > b then
		a, b = b, a
	end
	return function(x)
		return math.max(a, math.min(b, x))
	end
end

-- function: bimap
local function bimap(domain, range, interpolate)
	local d1 = domain[1]
	local d2 = domain[2]
	local r1 = range[1]
	local r2 = range[2]
	if d2 < d1 then
		d1 = normalize(d2, d1)
		r1 = interpolate(r2, r1)
	else
		d1 = normalize(d1, d2)
		r1 = interpolate(r1, r2)
	end
	return function(x)
		return r1(d1(x))
	end
end

-- function: tickIncrement
local e10 = math.sqrt(50)
local e5  = math.sqrt(10)
local e2h = math.sqrt(5)
local e2  = math.sqrt(2)
local function tickIncrement(start, stop, count)
	local step  = (stop - start) / math.max(0, count)
	local power = math.floor(math.log10(step))
	local error = step / (10 ^ power)
	local nice
	if power >= 0 then
		if error >= e10 then
			nice = 10
		elseif error >= e5 then
			nice = 5
		elseif error >= e2h then
			nice = 2.5
		elseif error >= e2 then
			nice = 2
		else
			nice = 1
		end
		return nice * (10 ^ power)
	else
		if error >= e10 then
			nice = 10
		elseif error >= e5 then
			nice = 5
		elseif error >= e2h then
			nice = 2.5
		elseif error >= e2 then
			nice = 2
		else
			nice = 1
		end
		return -(10 ^ -power) / nice
	end
end

-- ================
-- namespace: scale
-- ================
local scale = {}

-- ================
-- type: Continuous
-- ================
local __Scale__ContinuousType = 'continuous'
local __Scale__Continuous = {
	__typename = __Scale__ContinuousType,
}

-- [Constructor]
function __Scale__Continuous.__new(transform, untransform)
	local obj = {
		typename     = __Scale__ContinuousType,
		domain       = unit,
		range        = { 0, 100 },
		_clamp       = identity,
		_piecewise   = bimap,
		_interpolate = interpolateValue,
		_transform   = transform,
		_untransform = untransform,
		_input       = nil,
		_output      = nil,
	}
	return setmetatable(obj, { __index = __Scale__Continuous })
end

-- [Property] Set domain
function __Scale__Continuous:setDomain(newDomain)
	libraryUtil.checkType('setDomain', 1, newDomain, 'table')
	if #newDomain < 2 then
		error('The "domain" table size must be at least 2.')
	end

	self.domain = table.mapValue(newDomain, asNumber)
	self:_rescale()
	return self
end

-- [Property] Set range
function __Scale__Continuous:setRange(newRange)
	libraryUtil.checkType('setRange', 1, newRange, 'table')
	if #newRange < 2 then
		error('The "range" table size must be at least 2.')
	end

	self.range = table.map(newRange, asNumber)
	self:_rescale()
	return self
end

-- [Function] Rescale
function __Scale__Continuous:_rescale()
	local n = math.min(#self.domain, #self.range)
	if self._clamp ~= identity then
		self._clamp = clamper(self.domain[0], self.domain[n - 1])
	end
	if n > 2 then
		error('The multiple values of the domain aren\'t currently supported.')
	else
		self._piecewise = bimap
	end
	self._input = nil
	self._output = nil
end

-- [Function] Scale
function __Scale__Continuous:scale(x)
	libraryUtil.checkType('scale', 1, x, 'number')

	if math.isNaN(x) then
		return nil
	else
		if not self._output then
			self._output = self._piecewise(
				table.mapValue(self.domain, self._transform),
				self.range,
				self._interpolate)
		end
		return self._output(self._transform(self._clamp(x)))
	end
end

-- [Function] Invert
function __Scale__Continuous:invert(y)
	libraryUtil.checkType('invert', 1, y, 'number')
	
	if not self._input then
		self._input = self._piecewise(
			self.range,
			table.mapValue(self.domain, self._transform),
			interpolateValue)
	end
	return self._clamp(self._untransform(self._input(y)))
end

-- =============================
-- type: LinearScale: Continuous
-- =============================
local __Scale__LinearType = 'linear'
local __Scale__Linear = {
	__typename = __Scale__LinearType,
}
setmetatable(__Scale__Linear, { __index = __Scale__Continuous })

-- [Constructor]
function __Scale__Linear.new()
	local obj = __Scale__Continuous.__new(identity, identity)
	return setmetatable(obj, { __index = __Scale__Linear })
end

-- [Function] Nice
function __Scale__Linear:nice(count)
	libraryUtil.checkType('nice', 1, count, 'number', true)
	count = count or 10
	
	local i0 = 1
	local i1 = #self.domain
	local start = self.domain[i0]
	local stop  = self.domain[i1]
	if start > stop then
		start, stop = stop, start
		i0, i1 = i1, i0
	end
	
	local prestep, step
	local maxIter = 5
	while maxIter > 0 do
		step = tickIncrement(start, stop, count)
		if step == prestep then
			self.domain[i0] = start
			self.domain[i1] = stop
			break
		elseif step > 0 then
			start = math.floor(start / step) * step
			stop  = math.ceil (stop  / step) * step
		elseif step < 0 then
			start = math.ceil (start * step) / step
			stop  = math.floor(stop  * step) / step
		else
			break
		end
		
		prestep = step
		maxIter = maxIter - 1
	end
	return self
end

-- [Export]
scale.LinearScale = __Scale__Linear

return scale