-- Copyright (C) 2018-2021 by KittenOS NEO contributors
--
-- Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
-- THIS SOFTWARE.

return {
 -- note: everything must already be unicode.safeTextFormat'd
 draw = function (sW, line, cursorX, rX)
  -- if no camera, provide a default
  rX = rX or math.max(1, (cursorX or 1) - math.floor(sW * 2 / 3))
  -- transform into area-relative
  local tl = unicode.sub(line, rX, rX + sW - 1)
  -- inject cursor
  if cursorX then
   cursorX = (cursorX - rX) + 1
   if cursorX >= 1 then
    if cursorX <= sW then
     tl = unicode.sub(tl, 1, cursorX - 1) .. "_" .. unicode.sub(tl, cursorX + 1)
    end
   end
  end
  return tl .. (" "):rep(sW - unicode.len(tl))
 end,
 clamp = function (tl, cursorX)
  tl = unicode.len(tl)
  if tl < cursorX - 1 then
   return tl + 1
  end
  return cursorX
 end,
 -- returns line, cursorX, special
 -- return values may be nil if irrelevant
 key = function (ks, kc, line, cursorX)
  local cS = unicode.sub(line, 1, cursorX - 1)
  local cE = unicode.sub(line, cursorX)
  local ll = unicode.len(line)
  if kc == 203 then -- navi <
   if cursorX > 1 then
    return nil, cursorX - 1
   else
    -- cline underflow
    return nil, nil, "l<"
   end
  elseif kc == 205 then -- navi >
   if cursorX > ll then
    -- cline overflow
    return nil, nil, "l>"
   end
   return nil, cursorX + 1
  elseif kc == 199 then -- home
   return nil, 1
  elseif kc == 207 then -- end
   return nil, unicode.len(line) + 1
  elseif ks == "\8" then -- del
   if cursorX == 1 then
    -- weld prev
    return nil, nil, "w<"
   else
    return unicode.sub(cS, 1, unicode.len(cS) - 1) .. cE, cursorX - 1
   end
  elseif kc == 211 then -- del
   if cursorX > ll then
    return nil, nil, "w>"
   end
   return cS .. unicode.sub(cE, 2)
  elseif ks then -- standard letters
   if ks == "\r" then
    -- new line
    return nil, nil, "nl"
   end
   return cS .. ks .. cE, cursorX + unicode.len(ks)
  end
  -- :(
 end
}