function lerp(x0, x1, t)
	return x0*(1-t) + x1*t
end

function blendExp(x0, x1, t)
	return x0^(1-t)*x1^t
end

local sw = 640
local sh = 480

local font
local fs = 12

local coordsA = {}
local coordsB = {}
local coordsAL = {}
local coordsBL = {}

local input = {
	  [0]=0.9013,
	 [60]=1.3685,
	[120]=1.1046,
	[180]=1.1633,
	[240]=0.7332,
	[300]=0.8603,
	[360]=0.9013,
}
local xPrecision = 60/20

local win = {
	T = 1.5,
	B = -0.5,
	L = 0,
	R = 360,
	stepX = 30,
	stepY = 0.25,
}
win.scaleX = 1/(win.L - win.R)
win.scaleY = 1/(win.T - win.B)

function screenX(x)
	return sw*(win.L-x)*win.scaleX
end

function screenY(y)
	return sh*(win.T-y)*win.scaleY
end

function addPoint(coords, x, y)
	coords[#coords+1] = screenX(x)
	coords[#coords+1] = screenY(y)
end

function index(t, x)
	if type(x) ~= type(0) then
		return nil
	end

	local x0
	local x1
	for tx, ty in pairs(t) do
		-- we can't guarantee the order the key/values come in
		if tx ~= "interpolator" then
			-- x0 = largest tx that doesn't go over x
			if tx <= x and (x0 == nil or tx > x0) then
				x0 = tx
			end
			-- x1 = smallest tx that doesn't go under x
			if tx > x and (x1 == nil or tx < x1) then
				x1 = tx
			end
		end
	end
	x1 = x1 or x0

	local y0 = rawget(t, x0)
	local y1 = rawget(t, x1)
	local f = rawget(t, "interpolator")
	local y = f(y0, y1, (x - x0)/(x1 - x0))
	return y
end

function love.load()
	if not love.graphics.setMode(sw, sh) then
		error("couldn't setMode ("..sw.." by "..sh..")")
	end

	love.graphics.setCaption("hey it's a graph")

	--font = love.graphics.newFont("DejaVuSansMono.ttf", fs)
	--love.graphics.setFont(font)
	setmetatable(input, {__index = index})

	input.interpolator = lerp
	for x=win.L, win.R, xPrecision do
		local y = input[x]
		addPoint(coordsA, x, y)
		addPoint(coordsAL, x, math.log(y))
	end

	input.interpolator = blendExp
	for x=win.L, win.R, xPrecision do
		local y = input[x]
		addPoint(coordsB, x, y)
		addPoint(coordsBL, x, math.log(y))
	end
end

function love.keypressed(key)
	if key == "escape" then
		love.event.push("quit")
	end
end

local drawCoords = love.graphics.line
local drawText = love.graphics.print

function color(hex)
	local r = tonumber(string.sub(hex, 1,2), 16)
	local g = tonumber(string.sub(hex, 3,4), 16)
	local b = tonumber(string.sub(hex, 5,6), 16)
	love.graphics.setColor(r,g,b)
end

function drawVert(x)
	drawCoords(x, 0, x, sh)
end

function drawHoriz(y)
	drawCoords(0, y, sw, y)
end

function love.draw()
	love.graphics.setBackgroundColor(255,255,255)
	love.graphics.clear()

	for x=win.L, win.R, win.stepX do
		color("d3e2e7")
		local rx = screenX(x)
		drawVert(rx)
		color("808080")
		drawText(tostring(x), rx, sh - fs)
	end

	for y=win.B, win.T, win.stepY do
		color("c6cce3")
		local ry = screenY(y)
		drawHoriz(ry)
		color("808080")
		drawText(tostring(y), 0, ry)
	end

	color("404040")
	drawVert(screenX(0))
	drawHoriz(screenY(0))

	color("57C1BB")
	drawCoords(coordsA)
	drawCoords(coordsAL)

	color("9F65C5")
	drawCoords(coordsB)
	drawCoords(coordsBL)
end