local Wire = {
	NORTH = 1,
	EAST = 2,
	SOUTH = 4,
	WEST = 8,
}

Wire.directions = {
	{bit = Wire.NORTH, opposite = Wire.SOUTH, x = 0, y = -1},
	{bit = Wire.EAST, opposite = Wire.WEST, x = 1, y = 0},
	{bit = Wire.SOUTH, opposite = Wire.NORTH, x = 0, y = 1},
	{bit = Wire.WEST, opposite = Wire.EAST, x = -1, y = 0},
}

function Wire.has(mask, bit)
	return math.floor((mask or 0) / bit) % 2 == 1
end

function Wire.add(mask, bit)
	mask = mask or 0
	return Wire.has(mask, bit) and mask or mask + bit
end

function Wire.remove(mask, bit)
	mask = mask or 0
	return Wire.has(mask, bit) and mask - bit or mask
end

function Wire.directionBetween(a, b)
	local dx, dy = b.x - a.x, b.y - a.y
	for _, direction in ipairs(Wire.directions) do
		if direction.x == dx and direction.y == dy then return direction end
	end
end

-- Circuit colours are deliberately independent from the RGB gameplay layers.
-- A stable hash makes a route keep the same editor colour after save/load.
local palette = {
	{1.00, 0.78, 0.20},
	{0.20, 0.92, 0.92},
	{1.00, 0.42, 0.72},
	{0.62, 1.00, 0.32},
	{0.72, 0.55, 1.00},
	{1.00, 0.55, 0.22},
}

function Wire.color(circuitId)
	local hash = 0
	for index = 1, #(circuitId or "") do
		hash = (hash * 33 + circuitId:byte(index)) % 65521
	end
	return palette[hash % #palette + 1]
end

return Wire