.{log} := @use("../../stn/src/lib.hb")

PSF1Header := packed struct {
	magic: u16,
	font_mode: u8,
	character_size: u8,
}

PSF2Header := packed struct {
	magic: u32,
	version: u32,
	header_size: u32,
	flags: u32,
	num_glyph: u32,
	bytes_per_glyph: u32,
	height: u32,
	width: u32,
}

Font := struct {
	data: ^u8,
	width: uint,
	height: uint,
	num_glyphs: uint,
	bytes_per_glyph: uint,
	has_unicode_table: bool,
	line_gap: uint,
	char_gap: uint,
}

font_from_psf1 := fn(psf: ^u8): ?Font {
	header := @as(^PSF1Header, @bitcast(psf))
	if header.magic != 0x436 {
		log.error("failed to load psf font: not a psf1 font, idiot\0")
		return null
	}

	psf += @sizeof(PSF1Header)

	return .(
		psf,
		8,
		header.character_size,
		256,
		header.character_size,
		false,
		0,
		0,
	)
}

font_from_psf2 := fn(psf: ^u8): ?Font {
	header := @as(^PSF2Header, @bitcast(psf))
	if header.magic != 0x864AB572 {
		log.error("failed to load psf font: not a psf2 font, idiot\0")
		return null
	}

	psf += header.header_size

	return .(
		psf,
		header.width,
		header.height,
		header.num_glyph,
		header.bytes_per_glyph,
		(header.flags & 1) != 0,
		0,
		0,
	)
}

get_glyph := fn(font: Font, index: uint): ^u8 {
	return font.data + index * font.bytes_per_glyph
}