-----------------------------------------------------------------------
--         FILE:  luaotfload-harf-var-t2-writer.lua
--  DESCRIPTION:  part of luaotfload / HarfBuzz / Serialize Type 2 charstrings
-----------------------------------------------------------------------
do
 assert(luaotfload_module, "This is a part of luaotfload and should not be loaded independently") { 
     name          = "luaotfload-harf-var-t2-writer",
     version       = "3.28",       --TAGVERSION
     date          = "2024-02-14", --TAGDATE
     description   = "luaotfload submodule / Type 2 charstring writer",
     license       = "GPL v2.0",
     author        = "Marcel Krüger",
     copyright     = "Luaotfload Development Team",     
 }
end

local pack = string.pack
local function numbertot2(n)
  if math.abs(n) > 2^15 then
    error[[Number too big]]
  end
  local num = math.floor(n + .5)
  if n ~= 0 and math.abs((num-n)/n) > 0.001  then
    num = math.floor(n * 2^16 + 0.5)
    return pack(">Bi4", 255, math.floor(n * 2^16 + 0.5))
  elseif num >= -107 and num <= 107 then
    return string.char(num + 139)
  elseif num >= 108 and num <= 1131 then
    return pack(">I2", num+0xF694) -- -108+(247*0x100)
  elseif num >= -1131 and num <= -108 then
    return pack(">I2", -num+0xFA94) -- -108+(251*0x100)
  else
    return pack(">Bi2", 28, num)
  end
end
local function convert_cs(cs, upem)
  local cs_parts = {}
  local function add(cmd, first, ...)
    if cmd == 19 or cmd == 20 then
      cs_parts[#cs_parts+1] = string.char(cmd)
      cs_parts[#cs_parts+1] = first
      return
    end
    if first then
      cs_parts[#cs_parts+1] = numbertot2(first*upem/1000)
      return add(cmd, ...)
    end
    if cmd then
      if cmd < 0 then
        cs_parts[#cs_parts+1] = string.char(12, -cmd-1)
      else
        cs_parts[#cs_parts+1] = string.char(cmd)
      end
    end
  end
  for _, args in ipairs(cs) do
    if args then
      local cmd = args[1]
      local height = #args - 1
      local i = 2
      while height > 48 do
        -- Special cases: hhcurveto, vvcurveto, rcurveline, rlinecurve
        -- hhvurveto/vvcurveto: In odd argument case, the first argument must be
        -- followed by a multiple of four arguments.
        if cmd == 27 and i == 2 and height % 4 == 1 then -- hhcurveto
          add(cmd, table.unpack(args, i, i + 44))
          height = height - 45
          i = i + 45
        elseif cmd == 26 and i == 2 and height % 4 == 1 then -- vvcurveto
          add(cmd, table.unpack(args, i, i + 44))
          height = height - 45
          i = i + 45
        -- rcurveline/rlinecurve: At least 8 arguments must be preserved, all previous instances
        -- need different commands
        elseif cmd == 24 then -- rcurveline
          height = height - 48
          local count
          if height >= 8 then
            count = 48
          else
            count = 48 - 8 + height
            height = 8
          end
          add(8, table.unpack(args, i, i + count - 1)) -- 8 = rrcurveto
          i = i + count
        elseif cmd == 25 then -- rlinecurve
          height = height - 48
          local count
          if height >= 8 then
            count = 48
          else
            count = 48 - 8 + height
            height = 8
          end
          add(5, table.unpack(args, i, i + count - 1)) -- 5 = rlineto
          i = i + count
        else -- Some commands have an optional last argument which can appear after multiple of 48 arguments,
             -- so it's safer to never leave a element alone in a line.
          height = height - 48
          local count
          if height > 1 then
            count = 48
          else
            -- assert(height == 1)
            count = 24--48 - 25 + height
            height = 25
          end
          add(cmd, table.unpack(args, i, i + count - 1))
          i = i + count
        end
      end
      add(cmd, table.unpack(args, i))
    end
  end
  return table.concat(cs_parts)
end

return function(cs, upem)
  return convert_cs(cs, upem or 1000)
end
