# I yoinked a lot of fonts from the linux source code but they are written as C arrays
# which is cool dont get me wrong, C supremacy and all that bullshit, but I need them as
# psf1 fonts, so this converts them and shit
#
# usage: revo genfonts.rv <font_8x16.c> <out.psf> [height]

fn hexval(character) -> num do
  const code = character:ascii()
  if (code >= 48 and code <= 57)
    return code - 48
  if (code >= 97 and code <= 102)
    return code - 87
  if (code >= 65 and code <= 70)
    return code - 55
  return 0
end

fn read_int(text, start) -> num do
  let position = start
  let value = 0
  let seen = :false
  while (position < text:len() and text[position]:ascii() >= 48 and text[position]:ascii() <= 57) do
    value = value * 10 + (text[position]:ascii() - 48)
    seen = :true
    position += 1
  end
  return if (seen) value else 0
end

fn parse_c(text) -> table do
  const marker = text:index_of("}, {")
  let position = if (marker == :nil) 0 else marker + 4
  const length = text:len()
  let bytes = {}

  while (position < length) do
    if (position + 1 < length and text[position] == "/" and text[position + 1] == "*") do
      position += 2
      while (position + 1 < length and (text[position] != "*" or text[position + 1] != "/")) do position += 1 end
      position += 2
    end else if (position + 3 < length and text[position] == "0" and text[position + 1] == "x") do
      bytes:push(hexval(text[position + 2]) * 16 + hexval(text[position + 3]))
      position += 4
    end else do
      position += 1
    end
  end

  return bytes
end

fn main() do
  if argv:len() < 3 do
    panic("usage: genfonts.rv <font.c> <out.psf> [height]")
  end

  const source = argv[1]
  const output = argv[2]

  let height = 0
  if (argv:len() > 3)
    height = read_int(argv[3], 0)
  else do
    const marker = source:index_of("8x")
    height = if (marker == :nil) 16 else read_int(source, marker + 2)
  end

  const handle = fs.open(source, "r"):unwrap()
  const text = file.read(handle):unwrap()
  file.close(handle)

  let rows = parse_c(text)
  let count = math.floor(rows:len() / height)

  if count < 256 do
    const padding = height * (256 - count)
    for index in 0..padding do rows:push(0) end
    count = 256
  end

  if (count != 256 and count != 512)
    count = 256

  const mode = if (count == 256) 0 else 1
  let bytes = { 0x36, 0x04, mode, height }
  const total = height * count
  for i in 0..total do bytes:push(rows[i]) end

  const data = iter.collect_string(bytes)
  const sink = fs.open(output, "w"):unwrap()
  file.write(sink, data):unwrap()
  file.close(sink)

  print("#{output}: psf1 8x#{height}, #{count} glyphs in")
end

main()