local args = { ... }
local ccpi = require("ccpi")

local bit = {
  band = function(a, b) return a & b end,
  bor = function(a, b) return a | b end,
  blshift = function(a, b) return a << b end,
  brshift = function(a, b) return a >> b end,
}

local function write_varint(fp, value)
  value = bit.band(value, 0xFFFFFFFF)
  mask = 0xFFFFFF80
  while true do
    if bit.band(value, mask) == 0 then
      fp:write(string.char(bit.band(value, 0xff)))
      return
    end

    fp:write(string.char(bit.bor(0x80, bit.band(value, 0x7f))))
    value = bit.brshift(value, 7)
  end
end

local function write_palette(fp, pal)
  for i = 1, 16 do
    fp:write(string.char(
      bit.brshift(pal[i], 16),
      bit.band(bit.brshift(pal[i], 8), 0xff),
      bit.band(pal[i], 0xff)
    ))
  end
end

local function write_pixeldata_v0(img, fp)
  for y = 1, img.h do
    for x = 1, img.w do
      fp:write(img.lines[y].s:sub(x, x))
      local bg = tonumber(img.lines[y].bg:sub(x, x), 16)
      local fg = tonumber(img.lines[y].fg:sub(x, x), 16)
      fp:write(string.char(bit.bor(bg, bit.blshift(fg, 4))))
    end
  end
end

local fp_out = io.open(table.remove(args, 1), "wb")
fp_out:write("CPI" .. string.char(0x80))

local fp = io.open(table.remove(args, 1), "rb")
print(fp, fp.close)
local img, err = ccpi.parse({
  read = function(sz) return fp:read(sz) end,
})
fp:close()
if err ~= nil then
  printError(err)
  return
end

write_varint(fp_out, img.w)
write_varint(fp_out, img.h)
write_varint(fp_out, #args)

write_palette(fp_out, img.palette)
write_pixeldata_v0(img, fp_out)

for i, arg in ipairs(args) do
  print(arg)
  local fp = io.open(arg, "rb")
  img, err = ccpi.parse({
    read = function(sz) return fp:read(sz) end,
  })
  fp:close()
  if err ~= nil then
    printError(err)
    return
  end
  write_palette(fp_out, img.palette)
  write_pixeldata_v0(img, fp_out)
end

fp_out:close()