#!/usr/bin/env bash

# Fix/diagnose Xbox One (and 360) controllers on Arch Linux over USB.
# - Detects the device, relevant kernel modules, and evdev/joystick nodes
# - Loads safe modules (xpad, joydev) if missing
# - Shows dmesg hints and permission status
# - Suggests next steps (packages to test: evtest, joystick; drivers for BT/dongle)
#
# Conventions: sudo re-exec, idempotent, log with timestamps.

set -euo pipefail

SCRIPT_NAME="$(basename "$0")"
LOG_FILE="/var/log/xbox-controller-fix.log"

timestamp() { date '+%Y-%m-%d %H:%M:%S%z'; }

log() {
  local msg="$1"
  echo "[$(timestamp)] $msg"
  if [[ -w "$(dirname "$LOG_FILE")" ]] || [[ ! -e $LOG_FILE && -w /var/log ]]; then
    echo "[$(timestamp)] $msg" >> "$LOG_FILE" || true
  fi
}

require_root() {
  if [[ ${EUID:-$(id -u)} -ne 0 ]]; then
    echo "$SCRIPT_NAME needs root to load kernel modules and read some diagnostics. Re-executing with sudo..."
    exec sudo -E bash "$0" "$@"
  fi
}

print_header() {
  echo "=== $1 ==="
}

detect_distro() {
  if command -v pacman > /dev/null 2>&1; then
    echo "arch"
  else
    echo "other"
  fi
}

list_input_nodes() {
  print_header "Input device nodes"
  if [[ -d /dev/input/by-id ]]; then
    # Robust listing with proper handling of special characters
    local count=0
    while IFS= read -r -d '' f; do
      stat -c '%A %a %U:%G %N' "$f" 2> /dev/null || true
      count=$((count + 1))
      [[ $count -ge 120 ]] && break
    done < <(find /dev/input/by-id -maxdepth 1 -mindepth 1 -print0 2> /dev/null)
  else
    echo "/dev/input/by-id not present"
  fi
  echo
  if compgen -G "/dev/input/*js*" > /dev/null; then
    ls -l /dev/input/js* || true
  else
    echo "No legacy /dev/input/js* nodes (joydev) present. That's okay for most apps using evdev."
  fi
  echo
}

show_lsusb() {
  print_header "USB devices (filtered)"
  if command -v lsusb > /dev/null 2>&1; then
    lsusb | grep -Ei 'microsoft|xbox|045e:' || {
      echo "No Microsoft/Xbox device found via lsusb."
      true
    }
  else
    echo "lsusb not found (usbutils). Install usbutils for richer diagnostics."
  fi
  echo
}

show_modules() {
  print_header "Kernel modules state"
  lsmod | grep -E '(^|\s)(xpad|joydev|hid_microsoft|hid_generic|hid_xpadneo|xone)(\s|$)' || echo "No matching modules currently loaded."
  echo
}

modprobe_safe() {
  local mod="$1"
  if ! lsmod | grep -q "^${mod}\b"; then
    if modprobe "$mod" 2> /dev/null; then
      log "Loaded module: $mod"
    else
      log "Module $mod not loaded (may be built-in or unavailable)."
    fi
  fi
}

show_dmesg_hints() {
  print_header "Recent kernel messages (xpad/xbox/hid/input)"
  dmesg --color=never | grep -Ei 'xbox|xpad|045e:|Microsoft|input:.*gamepad|event.*joystick|hid.*(xbox|microsoft)' | tail -n 200 || true
  echo
}

check_permissions() {
  print_header "Permissions on event/joystick nodes"
  local any=0
  for path in /dev/input/by-id/*-event-joystick /dev/input/js*; do
    if [[ -e $path ]]; then
      any=1
      printf '%s -> ' "$path"
      local dev
      dev=$(readlink -f "$path" 2> /dev/null || echo "$path")
      stat -c '%A %a %U:%G %n' "$dev" 2> /dev/null || true
    fi
  done
  if [[ $any -eq 0 ]]; then
    echo "No event-joystick or js nodes found to check permissions."
  fi
  echo
  if [[ $(detect_distro) == "arch" ]]; then
    echo "On Arch, prefer TAG+\"uaccess\"-based access over adding users to the 'input' group."
    echo "If access is denied in apps, install: pacman -S game-devices-udev (provides modern udev rules)."
  fi
  echo
}

suggest_tests() {
  print_header "Next steps / tests"
  echo "- Test evdev: install 'evtest' and run: evtest /dev/input/by-id/*-event-joystick"
  echo "- Test joystick API: install 'joystick' (jstest) and run: jstest /dev/input/js0 (if present)"
  echo "- For force feedback test (rumble): install 'linuxconsole' (fftest): fftest /dev/input/by-id/*-event-joystick"
  echo
  echo "Steam users: Ensure Steam Input settings match your use case. If rumble fails in SDL titles, try: SDL_JOYSTICK_HIDAPI=0"
  echo
  echo "If you are actually using Bluetooth: consider xpadneo (AUR: xpadneo-dkms)."
  echo "If you are using the official wireless USB adapter: consider xone (AUR: xone-dkms and xone-dongle-firmware)."
  echo
}

main() {
  require_root "$@"
  print_header "${SCRIPT_NAME} starting"
  log "Kernel: $(uname -r) | Distro: $(detect_distro)"

  show_lsusb
  show_modules

  # Load common modules safely (idempotent)
  modprobe_safe usbhid
  modprobe_safe xpad
  modprobe_safe joydev

  # If xpad failed to load and kernel says it's a module, but it's not present, hint about out-of-sync modules
  if ! lsmod | grep -q '^xpad\b'; then
    if command -v zcat > /dev/null 2>&1 && [[ -r /proc/config.gz ]] && zcat /proc/config.gz 2> /dev/null | grep -q '^CONFIG_JOYSTICK_XPAD=m'; then
      if ! find "/lib/modules/$(uname -r)" -type f -name 'xpad*.ko*' 2> /dev/null | grep -q .; then
        log "xpad is configured as a module but missing under /lib/modules/$(uname -r). Your kernel modules may be out-of-sync or incomplete."
        if [[ $(detect_distro) == "arch" ]]; then
          echo "Arch hint: reinstall the matching kernel package (e.g. 'sudo pacman -S linux' or your variant like linux-zen) and reboot."
        else
          echo "Hint: reinstall your running kernel's modules then reboot."
        fi
        echo
      fi
    fi
  fi

  list_input_nodes
  check_permissions
  show_dmesg_hints

  # Simple heuristic: do we see an Xbox/Microsoft event-joystick?
  if compgen -G "/dev/input/by-id/*-event-joystick" > /dev/null; then
    local found_label=0
    for f in /dev/input/by-id/*-event-joystick; do
      [[ -e $f ]] || continue
      if printf '%s' "$(basename "$f")" | grep -Eqi 'xbox|microsoft|controller|wireless'; then
        found_label=1
        break
      fi
    done
    if ((found_label == 1)); then
      log "Controller event device detected."
    else
      log "Event-joystick device(s) exist but not obviously Xbox-labelled. Still likely usable."
    fi
  else
    log "No -event-joystick device found. If the controller vibrated but no input node exists, check the cable and try another USB port/cable."
    log "Also check dmesg for descriptor errors; for Xbox 360 Play&Charge cable: note it only charges and does not carry input."
  fi

  suggest_tests

  print_header "Done"
}

main "$@"