local gfx=require("yaru.gfx")
local sqrt,floor,max,min,char,concat=math.sqrt,math.floor,math.max,math.min,string.char,table.concat

local M={}


local BAYER={{0,8,2,10},{12,4,14,6},{3,11,1,9},{15,7,13,5}}
for r=1,4 do for c=1,4 do BAYER[r][c]=(BAYER[r][c]+0.5)/16 end end
local BIT={[0]={[0]=1,2,4,64},{[0]=8,16,32,128}}



M.designs={
noble={name="Noble",ramp={0x2C001E,0x330040,0x660040,0x990040,0xCC2440,0xFF4940,0xFF6D40,0xFF9240},
field=function(u,v,a)

local dx,dy=u-a*0.78,v-1.05
local g=1-sqrt(dx*dx*0.55+dy*dy)/1.05
local band=0.35-math.abs(v-(0.95-u/a*0.55))*1.4
return max(g,band,0)
end},
jammy={name="Jammy",ramp={0x2C001E,0x330040,0x660080,0x992480,0xCC4980,0xFF6D80},
field=function(u,v,a)return max(0,min(1,(u/a*0.7+v*0.6)-0.25))end},
mantic={name="Mantic",ramp={0x000040,0x002480,0x3324BF,0x6649BF,0x996DFF,0xCC92FF},
field=function(u,v,a)local dx,dy=u-a*0.3,v-0.2 return max(0,1-sqrt(dx*dx+dy*dy)/1.1)end},
ocean={name="Ocean",ramp={0x002440,0x004980,0x006DBF,0x0092BF,0x33B6BF,0x66DBFF},
field=function(u,v,a)return max(0,min(1,1.1-v*0.9-math.abs(u/a-0.5)*0.4))end},
forest={name="Forest",ramp={0x002400,0x004940,0x336D40,0x669240,0x99B640},
field=function(u,v,a)local dx,dy=u-a*0.5,v+0.3 return max(0,1-sqrt(dx*dx+dy*dy)/1.6)end},
graphite={name="Graphite",ramp={0x0F0F0F,0x1E1E1E,0x2D2D2D,0x3C3C3C,0x4B4B4B},
field=function(u,v,a)local dx,dy=u-a*0.5,v-0.35 return max(0,1-sqrt(dx*dx+dy*dy)/1.2)end},

solid={name="Solid",ramp={0x2C001E,0x2C001E},field=function()return 0 end},
}
M.order={"noble","jammy","mantic","ocean","forest","graphite","solid"}


function M.generate(name,W,H)
local d=M.designs[name]or M.designs.noble
local ramp={}
for i,c in ipairs(d.ramp)do ramp[i-1]=gfx.color(c)end
local n=#d.ramp-1
local field=d.field
local scale=1/(4*H)
local aspect=(2*W)/(4*H)
local out,row={},{}
for cy=0,H-1 do
local k=0
for cx=0,W-1 do
local s=field((cx*2+1)*scale,(cy*4+2)*scale,aspect)*n
local i=floor(s)
if i>=n then i=n-1 end
if i<0 then i=0 end
local pat=0
for dy=0,3 do
local py=cy*4+dy
local brow=BAYER[py%4+1]
for dx=0,1 do
local px=cx*2+dx
local t=field((px+0.5)*scale,(py+0.5)*scale,aspect)*n-i
if t>brow[px%4+1]then pat=pat|BIT[dx][dy]end
end
end
local f,b=ramp[i+1],ramp[i]
if pat==255 then pat,b=0,f elseif pat==0 or f==b then pat=0 end
k=k+1
row[k]=char(pat,f,b)
end
out[cy+1]=concat(row,"",1,k)
end
return concat(out)
end


function M.swatch(name)
local d=M.designs[name]or M.designs.noble
return d.ramp
end

return M