#!/usr/bin/env bash
#
# setup-power.sh — keep a Mac mini awake 24/7 and make it come back on its own.
#
# What it configures (only the values that differ from what you ask for):
#   pmset -a sleep 0          never put the whole system to sleep
#   pmset -a disksleep 0      never spin down / power down disks
#   pmset -a displaysleep N   the display may still sleep (default 10 min)
#   pmset -a womp 1           "Wake for network access"
#   pmset -a autorestart 1    "Start up automatically after a power failure"
#   pmset -a tcpkeepalive 1   keep network connections alive
#   systemsetup -setrestartfreeze on     restart automatically if macOS freezes
#   pmset repeat wakeorpoweron ...       optional daily safety power-on
#
# Safe by default: without --apply it only prints what it WOULD change.
# Idempotent: running it again after --apply reports "already set" for everything.
#
# Usage: ./setup-power.sh [--apply] [options]      (see --help)

set -euo pipefail

readonly SCRIPT_NAME="${0##*/}"
readonly VERSION="1.0.0"

APPLY=0
DISPLAY_SLEEP=10
WAKE_ON_NETWORK=1
RESTART_ON_FREEZE=1
DAILY_POWERON=""

usage() {
  cat <<EOF
$SCRIPT_NAME $VERSION — apply always-on power settings to a Mac mini.

Usage:
  $SCRIPT_NAME                 Dry run: show current values and planned changes.
  $SCRIPT_NAME --apply         Apply the changes (asks for your admin password).

Options:
  --apply                 Actually change settings. Without it, nothing is modified.
  --dry-run               Explicitly request a dry run (the default).
  --display-sleep MIN     Minutes before the display sleeps (0 = never). Default: 10.
  --no-wake-on-network    Leave "Wake for network access" (womp) off.
  --no-restart-on-freeze  Skip "restart automatically if the computer freezes".
  --daily-poweron HH:MM   Also schedule a daily wake/power-on at HH:MM (24h clock),
                          a safety net if the Mac is ever left shut down.
  -h, --help              Show this help and exit.
  -V, --version           Print the version and exit.

Examples:
  $SCRIPT_NAME
  $SCRIPT_NAME --apply
  $SCRIPT_NAME --apply --display-sleep 0 --daily-poweron 04:30

Undo: System Settings > Energy (or run 'sudo pmset restoredefaults').
EOF
}

die() {
  printf 'error: %s\n' "$*" >&2
  exit 2
}

log() { printf '%s\n' "$*"; }

# Run a command with root privileges: directly when already root, otherwise via sudo.
as_root() {
  if [[ ${EUID:-$(id -u)} -eq 0 ]]; then
    "$@"
  else
    sudo "$@"
  fi
}

# Reads that need admin rights (systemsetup needs root even to read a value).
# Dry runs never call sudo: unless we're already root, only --apply may elevate.
# Prints nothing when the value can't be read without sudo.
read_as_admin() {
  if [[ ${EUID:-$(id -u)} -eq 0 ]]; then
    "$@" 2>/dev/null
  elif ((APPLY)); then
    sudo "$@" 2>/dev/null
  fi
}

parse_args() {
  while [[ $# -gt 0 ]]; do
    case "$1" in
      --apply) APPLY=1 ;;
      --dry-run) APPLY=0 ;;
      --display-sleep)
        [[ $# -ge 2 ]] || die "--display-sleep needs a number of minutes"
        [[ $2 =~ ^[0-9]+$ ]] || die "--display-sleep must be a whole number of minutes, got '$2'"
        DISPLAY_SLEEP=$2
        shift
        ;;
      --no-wake-on-network) WAKE_ON_NETWORK=0 ;;
      --no-restart-on-freeze) RESTART_ON_FREEZE=0 ;;
      --daily-poweron)
        [[ $# -ge 2 ]] || die "--daily-poweron needs a time like 04:30"
        [[ $2 =~ ^([01][0-9]|2[0-3]):[0-5][0-9]$ ]] || die "--daily-poweron must be HH:MM (24h), got '$2'"
        DAILY_POWERON=$2
        shift
        ;;
      -h | --help)
        usage
        exit 0
        ;;
      -V | --version)
        printf '%s %s\n' "$SCRIPT_NAME" "$VERSION"
        exit 0
        ;;
      *) die "unknown option '$1' (try --help)" ;;
    esac
    shift
  done
}

# Current value of a pmset key from `pmset -g`, e.g. " sleep   0 (sleep prevented by ...)".
# Prints nothing if this Mac does not report the key.
pmset_current() {
  pmset -g 2>/dev/null | awk -v key="$1" '$1 == key { print $2; exit }'
}

# "04:30" -> "4:30AM", matching how `pmset -g sched` prints repeating events.
to_ampm() {
  local hh=${1%%:*} mm=${1##*:} suffix="AM" h
  h=$((10#$hh))
  if ((h >= 12)); then suffix="PM"; fi
  if ((h == 0)); then h=12; elif ((h > 12)); then h=$((h - 12)); fi
  printf '%d:%s%s' "$h" "$mm" "$suffix"
}

main() {
  parse_args "$@"

  if [[ $(uname -s) != "Darwin" ]]; then
    die "this script only runs on macOS (uname reports '$(uname -s)')"
  fi
  command -v pmset >/dev/null 2>&1 || die "pmset not found; is this macOS?"

  if ((APPLY)); then
    log "Mode: APPLY — settings that differ will be changed."
  else
    log "Mode: DRY RUN — nothing will be changed. Re-run with --apply to make changes."
  fi
  log ""
  log "Power settings (pmset):"

  local -a desired=(
    "sleep 0"
    "disksleep 0"
    "displaysleep $DISPLAY_SLEEP"
    "autorestart 1"
    "tcpkeepalive 1"
  )
  if ((WAKE_ON_NETWORK)); then desired+=("womp 1"); fi

  local -a changes=()
  local pair key want have
  for pair in "${desired[@]}"; do
    key=${pair%% *}
    want=${pair##* }
    have=$(pmset_current "$key")
    if [[ -z $have ]]; then
      log "  [skip]   $key: not reported by this Mac (unsupported here)"
    elif [[ $have == "$want" ]]; then
      log "  [ok]     $key = $have"
    else
      log "  [change] $key: $have -> $want"
      changes+=("$key" "$want")
    fi
  done

  local pending=0
  if ((${#changes[@]})); then
    pending=1
    if ((APPLY)); then
      as_root pmset -a "${changes[@]}"
      log "  applied: pmset -a ${changes[*]}"
    else
      log "  would run: sudo pmset -a ${changes[*]}"
    fi
  fi

  if ((RESTART_ON_FREEZE)); then
    log ""
    log "Restart after freeze (systemsetup):"
    local freeze
    freeze=$(read_as_admin systemsetup -getrestartfreeze | awk -F': ' '{ print $2 }' || true)
    if [[ $freeze == "On" ]]; then
      log "  [ok]     restart after freeze = On"
    elif [[ -z $freeze ]] && ((!APPLY)); then
      pending=1
      log "  [unknown] restart after freeze: reading it needs admin rights, and dry runs never use sudo."
      log "            Check it yourself: sudo systemsetup -getrestartfreeze"
      log "  would run (if not already On): sudo systemsetup -setrestartfreeze on"
    else
      pending=1
      log "  [change] restart after freeze: ${freeze:-unknown} -> On"
      if ((APPLY)); then
        as_root systemsetup -setrestartfreeze on >/dev/null
        log "  applied: systemsetup -setrestartfreeze on"
      else
        log "  would run: sudo systemsetup -setrestartfreeze on"
      fi
    fi
  fi

  if [[ -n $DAILY_POWERON ]]; then
    log ""
    log "Daily safety power-on (pmset repeat):"
    local expected
    expected="wakepoweron at $(to_ampm "$DAILY_POWERON") every day"
    if pmset -g sched 2>/dev/null | grep -qiF "$expected"; then
      log "  [ok]     $expected"
    else
      pending=1
      log "  [change] schedule: $expected"
      log "           (replaces any existing repeating power event)"
      if ((APPLY)); then
        as_root pmset repeat wakeorpoweron MTWRFSU "${DAILY_POWERON}:00"
        log "  applied: pmset repeat wakeorpoweron MTWRFSU ${DAILY_POWERON}:00"
      else
        log "  would run: sudo pmset repeat wakeorpoweron MTWRFSU ${DAILY_POWERON}:00"
      fi
    fi
  fi

  log ""
  if ((!pending)); then
    log "Everything is already set. Nothing to do."
  elif ((APPLY)); then
    log "Done. Verify with: pmset -g   (and ./health-check.sh)"
  else
    log "Dry run complete. Re-run with --apply to make these changes."
  fi
}

main "$@"