local tex = love.graphics.newImage("atlas.png")
tex:setFilter("nearest", "nearest")

local function water_color(layer)
	local value = layer / 24
	return value / 4, value / 2, value
end

local function sand_color(layer)
	return layer / 32 + 0.2, layer / 32 + 0.15, 0.4
end

local function dirt_color(layer)
	if layer < 32 then
		return layer / 40 / 2.5, layer / 80 / 2.5, 0.1
	else
		return 0.05, (layer - 32) / 36 + 0.3, 0.05
	end
end

local function mountain_color(layer)
	if layer < 58 then
		local value = layer / 64 / 2 - 0.1
		return value, value, value
	else
		local value = (layer - 58) / 20 + 0.7
		return value, value, value
	end
end

local function pick_colorfn(maxlayer)
	if maxlayer < 16 then
		return water_color
	elseif maxlayer < 22 then
		return sand_color
	elseif maxlayer < 46 then
		return dirt_color
	else
		return mountain_color
	end
end

local function ease(n)
	return 5 ^ (3.1 * (n ^ 0.3) - 3) + 1 - 1.1 ^ n
end

local WATER = love.graphics.newQuad(1, 1, 8, 8, tex)
local SAND = love.graphics.newQuad(11, 1, 8, 8, tex)
local DIRT = love.graphics.newQuad(21, 1, 8, 8, tex)
local GRASS = love.graphics.newQuad(31, 1, 8, 8, tex)
local STONE = love.graphics.newQuad(1, 11, 8, 8, tex)
local SNOW = love.graphics.newQuad(11, 11, 8, 8, tex)

local function dirt_sprite(layer)
	if layer < 32 then
		return DIRT
	end
	return GRASS
end

local function mountain_sprite(layer)
	if layer < 58 then
		return STONE
	end
	return SNOW
end

local function pick_sprite(maxlayer)
	if maxlayer < 16 then
		return WATER
	end
	if maxlayer < 22 then
		return SAND
	end
	if maxlayer < 46 then
		return dirt_sprite
	end
	return mountain_sprite
end

local z = require("zprite").zchunk.new(tex, 128, 64)

local function update_map()
	z:clear()
	for i = -160, 160 do
		for j = -160, 160 do
			local noise_value = love.math.simplexNoise(i * 0.008, j * 0.008)
			local layers = ease(noise_value) * 64
			z:put(i * 8, j * 8, pick_sprite(layers), math.floor(layers) + 1, pick_colorfn(layers))
			coroutine.yield()
		end
	end
end
local co = coroutine.create(update_map)

local x = 0
local y = 0
local angle = 0
local scale = 1

function love.update(dt)
	for _ = 1, 64 do
		if coroutine.status(co) == "suspended" then
			coroutine.resume(co)
		end
	end

	if love.keyboard.isDown("d") then
		local dx = 256 * math.cos(-angle)
		local dy = 256 * math.sin(-angle)
		x = x - dx * dt
		y = y - dy * dt
	end
	if love.keyboard.isDown("a") then
		local dx = 256 * math.cos(-angle)
		local dy = 256 * math.sin(-angle)
		x = x + dx * dt
		y = y + dy * dt
	end
	if love.keyboard.isDown("s") then
		local dx = 256 * math.cos(-angle + math.pi / 2)
		local dy = 256 * math.sin(-angle + math.pi / 2)
		x = x - dx * dt
		y = y - dy * dt
	end
	if love.keyboard.isDown("w") then
		local dx = 256 * math.cos(-angle + math.pi / 2)
		local dy = 256 * math.sin(-angle + math.pi / 2)
		x = x + dx * dt
		y = y + dy * dt
	end
	if love.keyboard.isDown("q") then
		angle = angle + dt
	end
	if love.keyboard.isDown("e") then
		angle = angle - dt
	end
	if love.keyboard.isDown("f") then
		scale = scale - dt * 5
		if scale < 0.2 then
			scale = 0.2
		end
	end
	if love.keyboard.isDown("r") then
		scale = scale + dt * 5
		if scale > 5 then
			scale = 5
		end
	end
end

local t = love.math.newTransform()

function love.draw()
	for _, chunk in pairs(z._chunks) do
		chunk.z._height_scale = 12 * scale
	end
	t:reset()
	t:translate(love.graphics.getWidth() / 2, love.graphics.getHeight() / 2)
	t:scale(scale, scale)
	t:rotate(angle)
	t:translate(x, y)
	z:draw(t)
end