local vec3 = require "vec3"
local streetutil = require "streetutil"

local laneutil = { }

local function subtract(a, b)
	return { a[1] - b[1], a[2] - b[2], a[3] - b[3] }
end 

local function scale(a, b)
	return { a[1] * b, a[2] * b, a[3] * b }
end 

function laneutil.makeLanes(input)
	local result = { }
 
	for i = 1, #input do
	local entry = input[i]
 
	local p0 = entry[1]
	local p1 = entry[2]
	local t0 = entry[3]
	local t1 = entry[4]
	local width = entry[5]
	p0 = vec3.new(p0[1], p0[2], p0[3])
	p1 = vec3.new(p1[1], p1[2], p1[3])
 
	t0 = vec3.normalize(vec3.new(t0[1], t0[2], t0[3]))
	t1 = vec3.normalize(vec3.new(t1[1], t1[2], t1[3]))
 
	local length = vec3.distance(p0, p1)
	local angle = vec3.angleUnit(t0, t1)
 
	local scale = streetutil.calcScale(length, angle)
 
	t0 = vec3.mul(scale, t0)
	t1 = vec3.mul(scale, t1)
 
	table.insert(result, { { p0.x, p0.y, p0.z }, { t0.x, t0.y, t0.z }, width } )
	table.insert(result, { { p1.x, p1.y, p1.z }, { t1.x, t1.y, t1.z }, width } )
	end 
 
	return result
end

function laneutil.createLanes(data, transportModes, speed, width, linkable)
	assert(data.curves ~= nil)

	local result = { nodes = {} }
	if speed then result.speedLimit = speed end
	if linkable then result.linkable = linkable end
	result.transportModes = transportModes
	
	local w = 0
	if width then w = width end
	
	for k, v in pairs(data.curves) do
		local nodes = result.nodes
		for i=1, #v do
			local points = v[i]
			if #points == 2 then
				local tangent = subtract(points[2], points[1])
				nodes[#nodes + 1] = { points[1], tangent, w }
				nodes[#nodes + 1] = { points[2], tangent, w }
			elseif #points == 3 then
				local tangent1 = scale(subtract(points[2], points[1]), 2.0)
				local tangent2 = scale(subtract(points[3], points[2]), 2.0)
				nodes[#nodes + 1] = { points[1], tangent1, w }
				nodes[#nodes + 1] = { points[3], tangent2, w }
			elseif #points == 4 then
				local tangent1 = scale(subtract(points[2], points[1]), 3.0)
				local tangent2 = scale(subtract(points[4], points[3]), 3.0)
				nodes[#nodes + 1] = { points[1], tangent1, w }
				nodes[#nodes + 1] = { points[4], tangent2, w }
			else
				assert(false)
			end
		end
	end	
	
	return result
end

return laneutil