#!/bin/bash

# omarchy:summary=Returns true when a fingerprint reader is present
# omarchy:hidden=true

# Detect straight from sysfs so this works before fprintd/usbutils are
# installed (the fingerprint setup pulls those in). USB vendor IDs listed here
# ship fingerprint readers; multi-purpose vendors (e.g. Elan/STMicro, which
# also make USB touchscreens) are left out to avoid nagging laptops with no
# reader — those still match on the product string below when present.
fingerprint_vendors=" 27c6 138a 06cb 08ff 1c7a 147e "
usb_devices_path="${OMARCHY_USB_DEVICES_PATH:-/sys/bus/usb/devices}"

# libfprint drives every reader it supports from userspace over libusb, so a
# real reader sits there with no kernel driver bound to any of its interfaces.
# The other things these vendors build — Synaptics webcam bridges (usbio-bridge
# on the Dell XPS 14), touchpads and touchscreens (usbhid), cameras (uvcvideo)
# — all bind one. Only the vendor-ID guess needs this; a device that names
# itself a fingerprint reader is trusted outright.
has_kernel_driver() {
  local intf driver
  for intf in "$1"/*:*; do
    [[ -e $intf/driver ]] || continue
    # usbfs is the exception: libusb claims an interface through it, so a reader
    # fprintd is enrolling or verifying against binds a driver for as long as it
    # holds the claim. That is userspace driving the device — what a reader is
    # supposed to look like — so it must not read as a kernel driver here.
    driver=$(readlink -f "$intf/driver")
    [[ ${driver##*/} == "usbfs" ]] || return 0
  done
  return 1
}

for dev in "$usb_devices_path"/*; do
  # The device's own product descriptor usually names it, e.g. "Goodix
  # Fingerprint USB Device" — driver-independent and vendor-agnostic.
  if [[ -r $dev/product ]]; then
    product=$(<"$dev/product")
    product=${product,,}
    # Elan's match-on-chip readers report "ELAN:ARM-M4" and Fingerprint Cards'
    # report "FPC Sensor Controller" or "FPC L:0000 FW:1425046" — the family or
    # the manufacturer rather than the function. Both vendors are left out of
    # the list above on purpose (Elan also makes touchscreens), so without these
    # they match nothing. FPC leads the string on every reader on record, and
    # three letters are little to match on, so require the prefix.
    [[ $product == *fingerprint* || $product == *biometric* || $product == *elan:arm-m4* || $product == "fpc "* ]] && exit 0
  fi

  if [[ -r $dev/idVendor ]]; then
    vendor=$(<"$dev/idVendor")
    [[ $fingerprint_vendors == *" $vendor "* ]] &&
      ! has_kernel_driver "$dev" && exit 0
  fi
done

exit 1