conky/battery_estimate: add debugging

hosts/common/programs/conky/battery_estimate

@@ -1,37 +1,63 @@
 #!/usr/bin/env nix-shell
 #!nix-shell -i bash
 
+usage() {
+  echo "usage: battery_estimate [options...]"
+  echo
+  echo "pretty-prints a battery estimate (icon to indicate state, and a duration estimate)"
+  echo
+  echo "options:"
+  echo "  --debug: output additional information, to stderr"
+}
+
 # these icons come from sxmo; they only render in nerdfonts
 bat_dis="󱊢"
 bat_chg="󱊥"
 
+log() {
+  if [ "$BATTERY_ESTIMATE_DEBUG" = "1" ]; then
+    printf "$@" >&2
+    echo >&2
+  fi
+}
+
 try_path() {
   # returns:
   # - perc, perc_left  (0-100)
   # - full, rate (pos means charging)
   if [ -f "$1/capacity" ]; then
+    log "perc, perc_left from %s" "$1/capacity"
     perc=$(cat "$1/capacity")
     perc_left=$((100 - $perc))
   fi
 
   if [ -f "$1/charge_full_design" ] && [ -f "$1/current_now" ]; then
+    log "full, rate from %s and %s" "$1/charge_full_design" "$1/current_now"
     # current is positive when charging
     full=$(cat "$1/charge_full_design")
     rate=$(cat "$1/current_now")
   fi
   if [ -f "$1/energy_full" ] && [ -f "$1/energy_now" ]; then
+    log "full, rate from %s and %s" "$1/energy_full" "$1/energy_now"
     # energy is positive when discharging
     full=$(cat "$1/energy_full")
     rate=-$(cat "$1/energy_now")
   fi
 }
 
-try_path "/sys/class/power_supply/axp20x-battery"  # Pinephone
-try_path "/sys/class/power_supply/BAT0"  # Thinkpad
+try_all_paths() {
+  try_path "/sys/class/power_supply/axp20x-battery"  # Pinephone
+  try_path "/sys/class/power_supply/BAT0"  # Thinkpad
+  log "perc: %d, left: %d" "$perc" "$perc_left"
+  log "full: %f, rate: %f" "$full" "$rate"
+  log "  rate > 0 means charging, else discharging"
+}
 
 fmt_minutes() {
+  log "charge/discharge time: %f min" "$3"
   # args: <battery symbol> <text if ludicrous estimate> <estimated minutes to full/empty>
   if [[ $3 -gt 1440 ]]; then
+    log "charge/discharge duration > 1d"
     printf "%s %s" "$1" "$2"  # more than 1d
   else
     hr=$(($3 / 60))
@@ -41,12 +67,31 @@ fmt_minutes() {
   fi
 }
 
-if [[ $rate -lt 0 ]]; then
-  # discharging
-  fmt_minutes "$bat_dis" '∞' "$(($full * 60 * $perc / (-100 * $rate)))"
-elif [[ $rate -gt 0 ]]; then
-  # charging
-  fmt_minutes "$bat_chg" '100%' "$(($full * 60 * $perc_left / (100 * $rate)))"
-elif [[ "$perc" != "" ]]; then
-  echo "$bat_dis $perc%"
-fi
+pretty_output() {
+  if [[ $rate -lt 0 ]]; then
+    log "discharging"
+    fmt_minutes "$bat_dis" '∞' "$(($full * 60 * $perc / (-100 * $rate)))"
+  elif [[ $rate -gt 0 ]]; then
+    log "charging"
+    fmt_minutes "$bat_chg" '100%' "$(($full * 60 * $perc_left / (100 * $rate)))"
+  elif [[ "$perc" != "" ]]; then
+    log "neither charging nor discharging"
+    echo "$bat_dis $perc%"
+  fi
+}
+
+while [ "$#" -gt 0 ]; do
+  case "$1" in
+    "--debug")
+      shift
+      BATTERY_ESTIMATE_DEBUG=1
+      ;;
+    *)
+      usage
+      exit 1
+      ;;
+  esac
+done
+
+try_all_paths
+pretty_output