local fs=require("filesystem")
local keyboard=require("keyboard")
local shell=require("shell")
local term=require("term")
local text=require("text")
local unicode=require("unicode")

if not term.isAvailable()then
return
end
local gpu=term.gpu()
local args,options=shell.parse(...)
if#args==0 then
io.write("Usage: edit <filename>")
return
end

local filename=shell.resolve(args[1])
local file_parentpath=fs.path(filename)

if fs.exists(file_parentpath)and not fs.isDirectory(file_parentpath)then
io.stderr:write(string.format("Not a directory: %s\n",file_parentpath))
return 1
end

local readonly=options.r or fs.get(filename)==nil or fs.get(filename).isReadOnly()

if fs.isDirectory(filename)then
io.stderr:write("file is a directory\n")
return 1
elseif not fs.exists(filename)and readonly then
io.stderr:write("file system is read only\n")
return 1
end

local function loadConfig()

local env={}
local config=loadfile("/etc/edit.cfg",nil,env)
if config then
pcall(config)
end

env.keybinds=env.keybinds or{
left={{"left"}},
right={{"right"}},
up={{"up"}},
down={{"down"}},
home={{"home"}},
eol={{"end"}},
pageUp={{"pageUp"}},
pageDown={{"pageDown"}},

backspace={{"back"},{"shift","back"}},
delete={{"delete"}},
deleteLine={{"control","delete"},{"shift","delete"}},
newline={{"enter"}},

save={{"control","s"}},
close={{"control","w"}},
find={{"control","f"}},
findnext={{"control","g"},{"control","n"},{"f3"}},
cut={{"control","k"}},
uncut={{"control","u"}}
}

if not config then
local root=fs.get("/")
if root and not root.isReadOnly()then
fs.makeDirectory("/etc")
local f=io.open("/etc/edit.cfg","w")
if f then
local serialization=require("serialization")
for k,v in pairs(env)do
f:write(k.."="..tostring(serialization.serialize(v,math.huge)).."\n")
end
f:close()
end
end
end
return env
end

term.clear()
term.setCursorBlink(true)

local running=true
local buffer={}
local scrollX,scrollY=0,0
local config=loadConfig()

local cutBuffer={}


local cutting=false

local getKeyBindHandler

local function helpStatusText()
local function prettifyKeybind(label,command)
local keybind=type(config.keybinds)=="table"and config.keybinds[command]
if type(keybind)~="table"or type(keybind[1])~="table"then return""end
local alt,control,shift,key
for _,value in ipairs(keybind[1])do
if value=="alt"then alt=true
elseif value=="control"then control=true
elseif value=="shift"then shift=true
else key=value end
end
if not key then return""end
return label..": ["..
(control and"Ctrl+"or"")..
(alt and"Alt+"or"")..
(shift and"Shift+"or"")..
unicode.upper(key)..
"] "
end
return prettifyKeybind("Save","save")..
prettifyKeybind("Close","close")..
prettifyKeybind("Find","find")..
prettifyKeybind("Cut","cut")..
prettifyKeybind("Uncut","uncut")
end



local function setStatus(value)
local x,y,w,h=term.getGlobalArea()
value=unicode.wlen(value)>w-10 and unicode.wtrunc(value,w-9)or value
value=text.padRight(value,w-10)
gpu.set(x,y+h-1,value)
end

local function getArea()
local x,y,w,h=term.getGlobalArea()
return x,y,w,h-1
end

local function removePrefix(line,length)
if length>=unicode.wlen(line)then
return""
else
local prefix=unicode.wtrunc(line,length+1)
local suffix=unicode.sub(line,unicode.len(prefix)+1)
length=length-unicode.wlen(prefix)
if length>0 then
suffix=(" "):rep(unicode.charWidth(suffix)-length)..unicode.sub(suffix,2)
end
return suffix
end
end

local function lengthToChars(line,length)
if length>unicode.wlen(line)then
return unicode.len(line)+1
else
local prefix=unicode.wtrunc(line,length)
return unicode.len(prefix)+1
end
end


local function isWideAtPosition(line,x)
local index=lengthToChars(line,x)
if index>unicode.len(line)then
return false,false
end
local prefix=unicode.sub(line,1,index)
local char=unicode.sub(line,index,index)

return unicode.isWide(char),unicode.wlen(prefix)==x
end

local function drawLine(x,y,w,h,lineNr)
local yLocal=lineNr-scrollY
if yLocal>0 and yLocal<=h then
local str=removePrefix(buffer[lineNr]or"",scrollX)
str=unicode.wlen(str)>w and unicode.wtrunc(str,w+1)or str
str=text.padRight(str,w)
gpu.set(x,y-1+lineNr-scrollY,str)
end
end

local function getCursor()
local cx,cy=term.getCursor()
return cx+scrollX,cy+scrollY
end

local function line()
local _,cby=getCursor()
return buffer[cby]or""
end

local function getNormalizedCursor()
local cbx,cby=getCursor()
local wide,right=isWideAtPosition(buffer[cby],cbx)
if wide and right then
cbx=cbx-1
end
return cbx,cby
end

local function setCursor(nbx,nby)
local x,y,w,h=getArea()
nbx,nby=math.floor(nbx),math.floor(nby)
nby=math.max(1,math.min(#buffer,nby))

local ncy=nby-scrollY
if ncy>h then
term.setCursorBlink(false)
local sy=nby-h
local dy=math.abs(scrollY-sy)
scrollY=sy
if h>dy then
gpu.copy(x,y+dy,w,h-dy,0,-dy)
end
for lineNr=nby-(math.min(dy,h)-1),nby do
drawLine(x,y,w,h,lineNr)
end
elseif ncy<1 then
term.setCursorBlink(false)
local sy=nby-1
local dy=math.abs(scrollY-sy)
scrollY=sy
if h>dy then
gpu.copy(x,y,w,h-dy,0,dy)
end
for lineNr=nby,nby+(math.min(dy,h)-1)do
drawLine(x,y,w,h,lineNr)
end
end
term.setCursor(term.getCursor(),nby-scrollY)

nbx=math.max(1,math.min(unicode.wlen(line())+1,nbx))
local wide,right=isWideAtPosition(line(),nbx)
local ncx=nbx-scrollX
if ncx>w or(ncx+1>w and wide and not right)then
term.setCursorBlink(false)
scrollX=nbx-w+((wide and not right)and 1 or 0)
for lineNr=1+scrollY,math.min(h+scrollY,#buffer)do
drawLine(x,y,w,h,lineNr)
end
elseif ncx<1 or(ncx-1<1 and wide and right)then
term.setCursorBlink(false)
scrollX=nbx-1-((wide and right)and 1 or 0)
for lineNr=1+scrollY,math.min(h+scrollY,#buffer)do
drawLine(x,y,w,h,lineNr)
end
end
term.setCursor(nbx-scrollX,nby-scrollY)

nbx,nby=getCursor()
local locstring=string.format("%d,%d",nby,nbx)
if#cutBuffer>0 then
locstring=string.format("(#%d) %s",#cutBuffer,locstring)
end
locstring=text.padLeft(locstring,10)
gpu.set(x+w-#locstring,y+h,locstring)
end

local function highlight(bx,by,length,enabled)
local x,y,w,h=getArea()
local cx,cy=bx-scrollX,by-scrollY
cx=math.max(1,math.min(w,cx))
cy=math.max(1,math.min(h,cy))
length=math.max(1,math.min(w-cx,length))

local fg,fgp=gpu.getForeground()
local bg,bgp=gpu.getBackground()
if enabled then
gpu.setForeground(bg,bgp)
gpu.setBackground(fg,fgp)
end
local indexFrom=lengthToChars(buffer[by],bx)
local value=unicode.sub(buffer[by],indexFrom)
if unicode.wlen(value)>length then
value=unicode.wtrunc(value,length+1)
end
gpu.set(x-1+cx,y-1+cy,value)
if enabled then
gpu.setForeground(fg,fgp)
gpu.setBackground(bg,bgp)
end
end

local function home()
local _,cby=getCursor()
setCursor(1,cby)
end

local function ende()
local _,cby=getCursor()
setCursor(unicode.wlen(line())+1,cby)
end

local function left()
local cbx,cby=getNormalizedCursor()
if cbx>1 then
local wideTarget,rightTarget=isWideAtPosition(line(),cbx-1)
if wideTarget and rightTarget then
setCursor(cbx-2,cby)
else
setCursor(cbx-1,cby)
end
return true
elseif cby>1 then
setCursor(cbx,cby-1)
ende()
return true
end
end

local function right(n)
n=n or 1
local cbx,cby=getNormalizedCursor()
local be=unicode.wlen(line())+1
local wide,isRight=isWideAtPosition(line(),cbx+n)
if wide and isRight then
n=n+1
end
if cbx+n<=be then
setCursor(cbx+n,cby)
elseif cby<#buffer then
setCursor(1,cby+1)
end
end

local function up(n)
n=n or 1
local cbx,cby=getCursor()
if cby>1 then
setCursor(cbx,cby-n)
end
cutting=false
end

local function down(n)
n=n or 1
local cbx,cby=getCursor()
if cby<#buffer then
setCursor(cbx,cby+n)
end
cutting=false
end

local function delete(fullRow)
local _,cy=term.getCursor()
local cbx,cby=getCursor()
local x,y,w,h=getArea()
local function deleteRow(row)
local content=table.remove(buffer,row)
local rcy=cy+(row-cby)
if rcy<=h then
gpu.copy(x,y+rcy,w,h-rcy,0,-1)
drawLine(x,y,w,h,row+(h-rcy))
end
return content
end
if fullRow then
term.setCursorBlink(false)
if#buffer>1 then
deleteRow(cby)
else
buffer[cby]=""
gpu.fill(x,y-1+cy,w,1," ")
end
setCursor(1,cby)
elseif cbx<=unicode.wlen(line())then
term.setCursorBlink(false)
local index=lengthToChars(line(),cbx)
buffer[cby]=unicode.sub(line(),1,index-1)..
unicode.sub(line(),index+1)
drawLine(x,y,w,h,cby)
elseif cby<#buffer then
term.setCursorBlink(false)
local append=deleteRow(cby+1)
buffer[cby]=buffer[cby]..append
drawLine(x,y,w,h,cby)
else
return
end
setStatus(helpStatusText())
end

local function insert(value)
if not value or unicode.len(value)<1 then
return
end
term.setCursorBlink(false)
local cbx,cby=getCursor()
local x,y,w,h=getArea()
local index=lengthToChars(line(),cbx)
buffer[cby]=unicode.sub(line(),1,index-1)..
value..
unicode.sub(line(),index)
drawLine(x,y,w,h,cby)
right(unicode.wlen(value))
setStatus(helpStatusText())
end

local function enter()
term.setCursorBlink(false)
local _,cy=term.getCursor()
local cbx,cby=getCursor()
local x,y,w,h=getArea()
local index=lengthToChars(line(),cbx)
table.insert(buffer,cby+1,unicode.sub(buffer[cby],index))
buffer[cby]=unicode.sub(buffer[cby],1,index-1)
drawLine(x,y,w,h,cby)
if cy<h then
if cy<h-1 then
gpu.copy(x,y+cy,w,h-(cy+1),0,1)
end
drawLine(x,y,w,h,cby+1)
end
setCursor(1,cby+1)
setStatus(helpStatusText())
cutting=false
end

local findText=""

local function find()
local _,_,_,h=getArea()
local cbx,cby=getCursor()
local ibx,iby=cbx,cby
while running do
if unicode.len(findText)>0 then
local sx,sy
for syo=1,#buffer do
sy=(iby+syo-1+#buffer-1)%#buffer+1
sx=string.find(buffer[sy],findText,syo==1 and ibx or 1,true)
if sx and(sx>=ibx or syo>1)then
break
end
end
if not sx then
sy=iby
sx=string.find(buffer[sy],findText,nil,true)
end
if sx then
sx=unicode.wlen(string.sub(buffer[sy],1,sx-1))+1
cbx,cby=sx,sy
setCursor(cbx,cby)
highlight(cbx,cby,unicode.wlen(findText),true)
end
end
term.setCursor(7+unicode.wlen(findText),h+1)
setStatus("Find: "..findText)

local _,address,char,code=term.pull("key_down")
if address==term.keyboard()then
local handler,name=getKeyBindHandler(code)
highlight(cbx,cby,unicode.wlen(findText),false)
if name=="newline"then
break
elseif name=="close"then
handler()
elseif name=="backspace"then
findText=unicode.sub(findText,1,-2)
elseif name=="find"or name=="findnext"then
ibx=cbx+1
iby=cby
elseif not keyboard.isControl(char)then
findText=findText..unicode.char(char)
end
end
end
setCursor(cbx,cby)
setStatus(helpStatusText())
end

local function cut()
if not cutting then
cutBuffer={}
end
local cbx,cby=getCursor()
table.insert(cutBuffer,buffer[cby])
delete(true)
cutting=true
home()
end

local function uncut()
home()
for _,line in ipairs(cutBuffer)do
insert(line)
enter()
end
end



local keyBindHandlers={
left=left,
right=right,
up=up,
down=down,
home=home,
eol=ende,
pageUp=function()
local _,_,_,h=getArea()
up(h-1)
end,
pageDown=function()
local _,_,_,h=getArea()
down(h-1)
end,

backspace=function()
if not readonly and left()then
delete()
end
end,
delete=function()
if not readonly then
delete()
end
end,
deleteLine=function()
if not readonly then
delete(true)
end
end,
newline=function()
if not readonly then
enter()
end
end,

save=function()
if readonly then return end
local new=not fs.exists(filename)
local backup
if not new then
backup=filename.."~"
for i=1,math.huge do
if not fs.exists(backup)then
break
end
backup=filename.."~"..i
end
fs.copy(filename,backup)
end
if not fs.exists(file_parentpath)then
fs.makeDirectory(file_parentpath)
end
local f,reason=io.open(filename,"w")
if f then
local chars,firstLine=0,true
for _,bline in ipairs(buffer)do
if not firstLine then
bline="\n"..bline
end
firstLine=false
f:write(bline)
chars=chars+unicode.len(bline)
end
f:close()
local format
if new then
format=[["%s" [New] %dL,%dC written]]
else
format=[["%s" %dL,%dC written]]
end
setStatus(string.format(format,fs.name(filename),#buffer,chars))
else
setStatus(reason)
end
if not new then
fs.remove(backup)
end
end,
close=function()

running=false
end,
find=function()
findText=""
find()
end,
findnext=find,
cut=cut,
uncut=uncut
}

getKeyBindHandler=function(code)
if type(config.keybinds)~="table"then return end


local result,resultName,resultWeight=nil,nil,0
for command,keybinds in pairs(config.keybinds)do
if type(keybinds)=="table"and keyBindHandlers[command]then
for _,keybind in ipairs(keybinds)do
if type(keybind)=="table"then
local alt,control,shift,key=false,false,false
for _,value in ipairs(keybind)do
if value=="alt"then alt=true
elseif value=="control"then control=true
elseif value=="shift"then shift=true
else key=value end
end
local keyboardAddress=term.keyboard()
if(alt==not not keyboard.isAltDown(keyboardAddress))and
(control==not not keyboard.isControlDown(keyboardAddress))and
(shift==not not keyboard.isShiftDown(keyboardAddress))and
code==keyboard.keys[key]and
#keybind>resultWeight
then
resultWeight=#keybind
resultName=command
result=keyBindHandlers[command]
end
end
end
end
end
return result,resultName
end



local function onKeyDown(char,code)
local handler=getKeyBindHandler(code)
if handler then
handler()
elseif readonly and code==keyboard.keys.q then
running=false
elseif not readonly then
if not keyboard.isControl(char)then
insert(unicode.char(char))
elseif unicode.char(char)=="\t"then
insert("  ")
end
end
end

local function onClipboard(value)
value=value:gsub("\r\n","\n")
local start=1
local l=value:find("\n",1,true)
if l then
repeat
local next_line=string.sub(value,start,l-1)
next_line=text.detab(next_line,2)
insert(next_line)
enter()
start=l+1
l=value:find("\n",start,true)
until not l
end
insert(string.sub(value,start))
end

local function onClick(x,y)
setCursor(x+scrollX,y+scrollY)
end

local function onScroll(direction)
local cbx,cby=getCursor()
setCursor(cbx,cby-direction*12)
end



do
local f=io.open(filename)
if f then
local x,y,w,h=getArea()
local chars=0
for fline in f:lines()do
table.insert(buffer,fline)
chars=chars+unicode.len(fline)
if#buffer<=h then
drawLine(x,y,w,h,#buffer)
end
end
f:close()
if#buffer==0 then
table.insert(buffer,"")
end
local format
if readonly then
format=[["%s" [readonly] %dL,%dC]]
else
format=[["%s" %dL,%dC]]
end
setStatus(string.format(format,fs.name(filename),#buffer,chars))
else
table.insert(buffer,"")
setStatus(string.format([["%s" [New File] ]],fs.name(filename)))
end
setCursor(1,1)
end

while running do
local event,address,arg1,arg2,arg3=term.pull()
if address==term.keyboard()or address==term.screen()then
local blink=true
if event=="key_down"then
onKeyDown(arg1,arg2)
elseif event=="clipboard"and not readonly then
onClipboard(arg1)
elseif event=="touch"or event=="drag"then
local x,y,w,h=getArea()
arg1=arg1-x+1
arg2=arg2-y+1
if arg1>=1 and arg2>=1 and arg1<=w and arg2<=h then
onClick(arg1,arg2)
end
elseif event=="scroll"then
onScroll(arg3)
else
blink=false
end
if blink then
term.setCursorBlink(true)
end
end
end

term.clear()
term.setCursorBlink(true)