local gfx=require("yaru.gfx")
local unicode=require("unicode")

local vgpu={}
local color=gfx.color


local remapFg={[0x000000]=0x171421,[0xFF0000]=0xF66151,[0x00FF00]=0x33DA7A,[0xFFFF00]=0xE9AD0C,
[0x0000FF]=0x2A7BDE,[0xFF00FF]=0xC061CB,[0x00B6FF]=0x33C7DE,[0xFFFFFF]=0xFFFFFF}

function vgpu.new(w,h,opts)
opts=opts or{}
local termBg=opts.bg or 0x2C001E
local g={w=w,h=h,grid={},changed=true,scroll=0}
local fg,bg=0xFFFFFF,0x000000
local fgK,bgK
local palette={}
for i=0,15 do palette[i]=(i*17)<<16|(i*17)<<8|(i*17)end
local function mapFg(c)return remapFg[c]or c end
local function mapBg(c)if c==0 then return termBg end return c end
local function upd()fgK=color(mapFg(fg))<<21;bgK=color(mapBg(bg))<<29 end
upd()
local grid=g.grid
local blank=function()return 32|fgK|bgK end
for i=1,w*h do grid[i]=32|fgK|bgK end

local function touch()if not g.changed then g.changed=true;if g.onChange then g.onChange()end end end

local p={type="gpu",address=opts.address or"vgpu"}
g.proxy=p
function p.getScreen()return opts.screen end
function p.bind()return true end
function p.getResolution()return g.w,g.h end
function p.maxResolution()return g.w,g.h end
function p.getViewport()return g.w,g.h end
function p.setResolution(nw,nh)
if nw==g.w and nh==g.h then return false end
if g.onResize then return g.onResize(nw,nh)end
return false
end
p.setViewport=p.setResolution
function p.getDepth()return 8 end
function p.maxDepth()return 8 end
function p.setDepth()return 8 end
function p.getForeground()return fg,false end
function p.getBackground()return bg,false end
function p.setForeground(c,isPal)
local old=fg
if isPal then c=palette[c]or 0xFFFFFF end
fg=c;upd();return old
end
function p.setBackground(c,isPal)
local old=bg
if isPal then c=palette[c]or 0 end
bg=c;upd();return old
end
function p.getPaletteColor(i)return palette[i]end
function p.setPaletteColor(i,c)local o=palette[i];palette[i]=c;return o end
function p.set(x,y,s,vertical)
x,y=math.floor(x),math.floor(y)
local W,H=g.w,g.h
if not vertical and(y<1 or y>H)then return true end
local i=0
local k=fgK|bgK
for _,cp in utf8.codes(s)do
local xx,yy=x+i,y
if vertical then xx,yy=x,y+i end
if xx>=1 and xx<=W and yy>=1 and yy<=H then grid[(yy-1)*W+xx]=cp|k end
i=i+1
end
touch()
return true
end
function p.get(x,y)
x,y=math.floor(x),math.floor(y)
if x<1 or y<1 or x>g.w or y>g.h then error("index out of bounds")end
local v=grid[(y-1)*g.w+x]
return unicode.char(v&0x1FFFFF),gfx.rgb((v>>21)&255),gfx.rgb((v>>29)&255)
end
function p.fill(x,y,fw,fh,ch)
x,y,fw,fh=math.floor(x),math.floor(y),math.floor(fw),math.floor(fh)
local W=g.w
local v=utf8.codepoint(ch)|fgK|bgK
local x2,y2=math.min(W,x+fw-1),math.min(g.h,y+fh-1)
x,y=math.max(1,x),math.max(1,y)
for yy=y,y2 do
local base=(yy-1)*W
for xx=x,x2 do grid[base+xx]=v end
end
touch()
return true
end
function p.copy(x,y,cw,ch,tx,ty)
x,y,cw,ch,tx,ty=math.floor(x),math.floor(y),math.floor(cw),math.floor(ch),math.floor(tx),math.floor(ty)
local W,H=g.w,g.h

local x1,y1=math.max(1,x),math.max(1,y)
local x2,y2=math.min(W,x+cw-1),math.min(H,y+ch-1)
if x1>x2 or y1>y2 then return true end
local rows={}
local ystart,ystop,ystep=y1,y2,1
if ty>0 then ystart,ystop,ystep=y2,y1,-1 end
local xstart,xstop,xstep=x1,x2,1
if tx>0 then xstart,xstop,xstep=x2,x1,-1 end
for yy=ystart,ystop,ystep do
local dy=yy+ty
if dy>=1 and dy<=H then
local sb,db=(yy-1)*W,(dy-1)*W
for xx=xstart,xstop,xstep do
local dx=xx+tx
if dx>=1 and dx<=W then grid[db+dx]=grid[sb+xx]end
end
end
end

if tx==0 and ty<0 and x1==1 and x2==W and y1+ty==1 and y2==H then
g.scroll=g.scroll-ty
else
g.noscroll=true
end
touch()
return true
end

function p.getActiveBuffer()return 0 end
function p.setActiveBuffer()return 0 end
function p.buffers()return{}end
function p.allocateBuffer()return nil,"not enough video memory"end
function p.freeBuffer()return false end
function p.freeAllBuffers()end
function p.totalMemory()return 0 end
function p.freeMemory()return 0 end
function p.bitblt()return false end

function g.resize(nw,nh)
local ng={}
local b=blank()
for yy=1,nh do
for xx=1,nw do
ng[(yy-1)*nw+xx]=(xx<=g.w and yy<=g.h)and grid[(yy-1)*g.w+xx]or b
end
end
for i=1,#grid do grid[i]=nil end
for i=1,nw*nh do grid[i]=ng[i]end
g.w,g.h=nw,nh
g.noscroll=true
touch()
end
function g.setTermBg(c)termBg=c;upd()end
return g
end

return vgpu