local gc=love.graphics
local int,ceil,rnd=math.floor,math.ceil,math.random
local max,min,sin=math.max,math.min,math.sin
local ins,rem=table.insert,table.remove

local function NULL(...)end
local SCR=SCR
local BGvars={_G=_G,SHADER=SHADER}
local BG
local back={}
back.none={
	draw=function()
		gc.clear(.15,.15,.15)
	end,
}
back.grey={
	draw=function()
		gc.clear(.3,.3,.3)
	end,
}
back.glow={
	init=function()
		t=0
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		local t=(sin(t*.5)+sin(t*.7)+sin(t*.9+1)+sin(t*1.5)+sin(t*2+10))*.08
		gc.clear(t,t,t)
	end,
}--Light-dark
back.rgb={
	init=function()
		t=0
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		gc.clear(
			sin(t*1.2)*.15+.2,
			sin(t*1.5)*.15+.2,
			sin(t*1.9)*.15+.2
		)
	end,
}--Changing pure color
back.flink={
	init=function()
		t=0
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		local t=.13-t%3%1.9
		if t<.2 then gc.clear(t,t,t)
		else gc.clear(0,0,0)
		end
	end,
}--Flash after random time

local wingColor={
	{0., .9, .9,.626},
	{.3, 1., .3,.626},
	{.9, .9, 0.,.626},
	{1., .5, 0.,.626},
	{1., .3, .3,.626},
	{.5, 0., 1.,.626},
	{.3, .3, 1.,.626},
	{0., .9, .9,.626},
}
back.wing={
	init=function()
		gc.setDefaultFilter("linear","linear")
		bar=gc.newCanvas(41,1)
		gc.push("transform")
			gc.origin()
			gc.setCanvas(bar)
			for x=0,20 do
				gc.setColor(1,1,1,x/11)
				gc.rectangle("fill",x,0,1,1)
				gc.rectangle("fill",41-x,0,1,1)
			end
			gc.setCanvas()
		gc.pop()
		BG.resize()
	end,
	resize=function()
		crystal={}
		W,H=SCR.w,SCR.h
		for i=1,16 do
			crystal[i]={
				x=i<9 and W*.05*i or W*.05*(28-i),
				y=H*.1,
				a=0,
				va=0,
				f=i<9 and .012-i*.0005 or .012-(17-i)*.0005
			}
		end
	end,
	update=function()
		for i=1,16 do
			local B=crystal[i]
			B.a=B.a+B.va
			B.va=B.va*.986-B.a*B.f
		end
	end,
	draw=function()
		gc.clear(.06,.06,.06)
		local sy=H*.8
		for i=1,8 do
			gc.setColor(wingColor[i])
			local B=crystal[i]
			gc.draw(bar,B.x,B.y,B.a,1,sy,20,0)
			B=crystal[17-i]
			gc.draw(bar,B.x,B.y,B.a,1,sy,20,0)
		end
	end,
	event=function(level)
		for i=1,8 do
			local B=crystal[i]
			B.va=B.va+.001*level*(1+rnd())
			B=crystal[17-i]
			B.va=B.va-.001*level*(1+rnd())
		end
	end,
	discard=function()
		bar,crystal=nil
	end,
}--Flandre's wing

back.fan={
	init=function()
		fan=_G.title_fan
		t=0
		petal={}
		BG.resize()
	end,
	resize=function()
		CX,CY=SCR.w/2,SCR.h/2
		W,H=SCR.w,SCR.h
	end,
	update=function()
		t=t+1
		if t%10==0 then
			ins(petal,{
				x=SCR.w*rnd(),
				y=0,
				vy=2+rnd()*2,
				vx=rnd()*2-.5,
				rx=4+rnd()*4,
				ry=4+rnd()*4,
			})
		end
		for i=#petal,1,-1 do
			local P=petal[i]
			P.y=P.y+P.vy
			if P.y>H then
				rem(petal,i)
			else
				P.x=P.x+P.vx
				P.vx=P.vx+rnd()*.01
				P.rx=max(min(P.rx+rnd()-.5,10),2)
				P.ry=max(min(P.ry+rnd()-.5,10),2)
			end
		end
	end,
	draw=function()
		gc.push("transform")
		gc.translate(CX,CY+20*sin(t*.02))
		gc.scale(SCR.k)
		gc.clear(.1,.1,.1)
		gc.setLineWidth(320)
		gc.setColor(.3,.2,.3)
		gc.arc("line","open",0,420,500,-.8*3.1416,-.2*3.1416)

		gc.setLineWidth(4)
		gc.setColor(.7,.5,.65)
		gc.arc("line","open",0,420,660,-.799*3.1416,-.201*3.1416)
		gc.arc("line","open",0,420,340,-.808*3.1416,-.192*3.1416)
		gc.line(-281,224,-530,30.5)
		gc.line(281,224,530,30.5)

		gc.setLineWidth(6)
		gc.setColor(.55,.5,.6)
		local F=fan
		for i=1,8 do
			gc.polygon("line",F[i])
		end

		gc.setLineWidth(2)
		gc.setColor(.6,.3,.5)
		gc.origin()
		for i=1,#petal do
			local P=petal[i]
			gc.ellipse("fill",P.x,P.y,P.rx,P.ry)
		end
		gc.pop()
	end,
	discard=function()
		petal=nil
	end,
}

back.aura={
	init=function()
		t=rnd()*3600
		BG.resize(SCR.w,SCR.h)
	end,
	resize=function(_,h)
		SHADER.aura:send("w",SCR.W)
		SHADER.aura:send("h",h*SCR.dpi)
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		SHADER.aura:send("t",t)
		gc.setShader(SHADER.aura)
		gc.rectangle("fill",0,0,SCR.w,SCR.h)
		gc.setShader()
	end,
}--Cool liquid background
back.bg1={
	init=function()
		t=0
		BG.resize()
	end,
	resize=function()
		SHADER.gradient1:send("w",SCR.W)
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		SHADER.gradient1:send("t",t)
		gc.setShader(SHADER.gradient1)
		gc.rectangle("fill",0,0,SCR.w,SCR.h)
		gc.setShader()
	end,
}--Horizonal red-blue gradient
back.bg2={
	init=function()
		t=0
		BG.resize(nil,SCR.h)
	end,
	resize=function(_,h)
		SHADER.gradient2:send("h",h*SCR.dpi)
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		SHADER.gradient2:send("t",t)
		gc.setShader(SHADER.gradient2)
		gc.rectangle("fill",0,0,SCR.w,SCR.h)
		gc.setShader()
	end,
}--Vertical red-green gradient
back.rainbow={
	init=function()
		t=0
		BG.resize(SCR.w,SCR.h)
	end,
	resize=function(_,h)
		SHADER.rgb1:send("w",SCR.W)
		SHADER.rgb1:send("h",h*SCR.dpi)
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		SHADER.rgb1:send("t",t)
		gc.setShader(SHADER.rgb1)
		gc.rectangle("fill",0,0,SCR.w,SCR.h)
		gc.setShader()
	end,
}--Colorful RGB
back.rainbow2={
	init=function()
		t=0
		BG.resize(SCR.w,SCR.h)
	end,
	resize=function(_,h)
		SHADER.rgb2:send("w",SCR.W)
		SHADER.rgb2:send("h",h*SCR.dpi)
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		SHADER.rgb2:send("t",t)
		gc.setShader(SHADER.rgb2)
		gc.rectangle("fill",0,0,SCR.w,SCR.h)
		gc.setShader()
	end,
}--Blue RGB
back.lightning={
	init=function()
		t=0
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		local t=2.5-t%20%6%2.5
		if t<.3 then gc.clear(t,t,t)
		else gc.clear(0,0,0)
		end
	end,
}--Lightning

local blocks=require("parts/mino")
local scs={.5,1.5,.5,1.5,.5,1.5,.5,1.5,.5,1.5,1,1,0,2}
back.lightning2={
	init=function()
		t=0
		colorLib=_G.SKIN.libColor
		colorSet=_G.SETTING.skin
		blockImg=_G.TEXTURE.miniBlock
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		local R=7-int(t*.5%7)
		local T=1.2-t%10%3%1.2
		if T<.3 then gc.clear(T,T,T)
		else gc.clear(0,0,0)
		end
		local _=colorLib[colorSet[R]]
		gc.setColor(_[1],_[2],_[3],.12)
		gc.draw(blockImg[R],640,360,t%3.1416*6,400,400,scs[2*R],#blocks[R][0]-scs[2*R-1])
	end,
}--Fast lightning + spining tetromino

local matrixT={}for i=1,50 do matrixT[i]={}for j=1,50 do matrixT[i][j]=love.math.noise(i,j)+2 end end
back.matrix={
	init=function()
		t=rnd()*3600
	end,
	update=function(dt)
		t=t+dt
	end,
	draw=function()
		gc.clear(.15,.15,.15)
		gc.push("transform")
			local k=SCR.k
			gc.scale(k)
			local Y=ceil(SCR.h/80/k)
			for x=1,ceil(SCR.w/80/k)do
				for y=1,Y do
					gc.setColor(1,1,1,sin(x+matrixT[x][y]*t)*.1+.1)
					gc.rectangle("fill",80*x,80*y,-80,-80)
				end
			end
		gc.pop()
	end,
}

back.space={
	init=function()
		stars={}
		W,H=SCR.w+20,SCR.h+20
		BG.resize(SCR.w,SCR.h)
	end,
	resize=function()
		local S=stars
		for i=1,1260,5 do
			local s=rnd(26,40)*.1
			S[i]=s*SCR.k			--Size
			S[i+1]=rnd(W)-10		--X
			S[i+2]=rnd(H)-10		--Y
			S[i+3]=(rnd()-.5)*.01*s	--Vx
			S[i+4]=(rnd()-.5)*.01*s	--Vy
		end
	end,
	update=function()
		local S=stars
		--Star moving
		for i=1,1260,5 do
			S[i+1]=(S[i+1]+S[i+3])%W
			S[i+2]=(S[i+2]+S[i+4])%H
		end
	end,
	draw=function()
		gc.clear(.2,.2,.2)
		if not stars[1]then return end
		gc.translate(-10,-10)
		gc.setColor(.8,.8,.8)
		for i=1,1260,5 do
			local s=stars
			local x,y=s[i+1],s[i+2]
			s=s[i]
			gc.rectangle("fill",x,y,s,s)
		end
		gc.translate(10,10)
	end,
	discard=function()
		stars=nil
	end,
}

--Make BG vars invisible
for _,bg in next,back do
	if bg.init		then setfenv(bg.init	,BGvars)end
	if bg.resize	then setfenv(bg.resize	,BGvars)end
	if bg.update	then setfenv(bg.update	,BGvars)end
	if bg.draw		then setfenv(bg.draw	,BGvars)end
	if bg.event		then setfenv(bg.event	,BGvars)end
	if bg.discard	then setfenv(bg.discard	,BGvars)end
end

BG={
	cur="none",
	init=NULL,
	resize=NULL,
	update=NULL,
	draw=back.none.draw,
	event=NULL,
	discard=NULL,
}
function BG.send(data)
	if BG.event then
		BG.event(data)
	end
end
function BG.set(bg)
	if bg==BG.cur or not SETTING.bg then return end
	BG.discard()
	if not back[bg]then
		LOG.print("No BG called"..bg,"warn")
		return
	end
	BG.cur=bg
	bg=back[bg]

	BG.init=bg.init or NULL
	BG.resize=bg.resize or NULL
	BG.update=bg.update or NULL
	BG.draw=bg.draw or NULL
	BG.event=bg.event or NULL
	BG.discard=bg.discard or NULL
	BG.init()
end
return BG