local Y=require("yaru.core")
local gfx=require("yaru.gfx")
local ui=require("yaru.ui")
local unicode=require("unicode")

local M={}
local KEYS={
{"C","(",")","÷"},{"7","8","9","×"},{"4","5","6","−"},{"1","2","3","+"},{"0",".","⌫","="},
}
local ENV={sqrt=math.sqrt,pi=math.pi,abs=math.abs,floor=math.floor,sin=math.sin,cos=math.cos}

local function evaluate(expr)
local e=expr:gsub("÷","/"):gsub("×","*"):gsub("−","-"):gsub("√","sqrt"):gsub("π","pi")
if e:find("[^%d%.%+%-%*/%%%^%(%)%s%a]")then return nil,"invalid"end
for word in e:gmatch("%a+")do if not ENV[word]then return nil,"invalid"end end
local f=load("return "..e,"=calc","t",ENV)
if not f then return nil,"syntax error"end
local ok,v=pcall(f)
if not ok or type(v)~="number"then return nil,"error"end
if v~=v or v==math.huge or v==-math.huge then return nil,"undefined"end
if math.type(v)=="float"and v==math.floor(v)and math.abs(v)<1e15 then v=math.floor(v)end
local s=tostring(v)
if math.type(v)=="float"then s=string.format("%.10g",v)end
return s
end

function M.open()
local st={expr="",result=nil,history={}}
local win=Y.newWindow{app="calc",title="Calculator",w=34,h=20,fixed=true}
local function press(k)
if k=="C"then st.expr,st.result="",nil
elseif k=="⌫"then st.expr=unicode.sub(st.expr,1,-2)
elseif k=="="then
local r,err=evaluate(st.expr)
if r then
table.insert(st.history,1,st.expr.." = "..r)
st.history[4]=nil
st.expr,st.result=r,nil
else st.result=err end
else
st.expr=st.expr..k
st.result=nil
end
end
function win.draw(w,cw,ch)
local t=Y.theme
gfx.fill(1,1,cw,5,t.view)
for i=1,2 do
local hline=st.history[3-i]
if hline then gfx.text(cw-1-unicode.len(hline),i,ui.trunc(hline,cw-2),t.dim,t.view)end
end
local e=st.expr==""and"0"or st.expr
gfx.text(math.max(2,cw-1-unicode.len(e)),4,unicode.sub(e,-(cw-3)),t.fg,t.view)
if st.result then gfx.text(2,3,st.result,t.danger,t.view)end
local bw=(cw-3)//4
for r,rowKeys in ipairs(KEYS)do
for c,k in ipairs(rowKeys)do
local x,y=2+(c-1)*(bw+0),6+(r-1)*3
local kind=k=="="and"suggested"or nil
local bg=kind and t.accent or(k:match("%d")or k==".")and t.button or(t.dark and 0x303030 or 0xEBEBEB)
ui.round(x,y,bw-1,2,bg)
gfx.text(x+(bw-1-unicode.len(k))//2,y,k,kind and 0xFFFFFF or t.fg,bg)
ui.hit(w,x,y,bw-1,2,function()press(k)end)
end
end
end
function win.key(w,char,code)
local K=Y.K
if code==K.enter or char==61 then press("=")
elseif code==K.back then press("⌫")
elseif code==K.esc or code==K.del then press("C")
elseif char and char>32 then
local c=unicode.char(char)
local map={["/"]="÷",["*"]="×",["-"]="−"}
c=map[c]or c
if c:match("^[%d%.%(%)%+%^%%a-z]$")or c=="÷"or c=="×"or c=="−"then press(c)end
end
end
function win.paste(w,s)st.expr=st.expr..s:gsub("%s","")end
return win
end

return M