eww better battery

modules/home/wayland/apps/eww/bar/scripts/sys/battery

@@ -1,17 +1,24 @@
 #!/usr/bin/env bash
 # Battery state from sysfs; refreshes on power_supply udev events and every
-# 30 s.  Emits a `state` (charging / discharging / low / full / idle) that the
-# CSS maps to a colour, instead of hard-coding one here.
+# 30 s.  Emits a `state` (charging / discharging / low / critical / full /
+# idle) that the CSS maps to a colour, instead of hard-coding one here.
+#
+# Every refresh also appends a sample to $XDG_STATE_HOME/eww/battery.log,
+# which feeds the drain rate (%/h) and the history plot.
 
 bat=""
 for d in /sys/class/power_supply/*; do
   [[ -r $d/type && $(<"$d/type") == Battery ]] && { bat=$d; break; }
 done
 if [[ -z $bat ]]; then
-  echo '{"visible":false,"percentage":0,"wattage":"","status":"","state":"none"}'
+  echo '{"visible":false,"percentage":0,"wattage":"","status":"","time":"","state":"none","rate":"","history":[]}'
   exit 0
 fi
 
+log=${XDG_STATE_HOME:-$HOME/.local/state}/eww/battery.log
+hist_hours=6 buckets=24
+mkdir -p "${log%/*}" && touch "$log"
+
 attr() { # first readable, non-empty attribute of the list, else 0
   local a v
   for a in "$@"; do
@@ -22,39 +29,83 @@ attr() { # first readable, non-empty attribute of the list, else 0
 
 hours_to_clock() { awk -v h="$1" 'BEGIN { printf "%d:%02d", int(h), int((h - int(h)) * 60 + 0.5) }'; }
 
+# Append "epoch pct state" and, once the head is an hour past the plot window,
+# drop everything older than the window.
+log_sample() {
+  local now=$1 first
+  printf '%s %s %s\n' "$now" "$2" "$3" >> "$log"
+  read -r first _ < "$log"
+  ((first < now - (hist_hours + 1) * 3600)) || return 0
+  awk -v min=$((now - hist_hours * 3600)) '$1 >= min' "$log" > "$log.tmp" && mv "$log.tmp" "$log"
+}
+
+# %/h over the last 30 min of samples in the current state, signed; empty
+# until there are 5 min of them.
+drain_rate() {
+  awk -v now="$1" -v st="$2" '
+    $1 >= now - 1800 && $3 == st { if (!n++) { t0 = $1; p0 = $2 } t1 = $1; p1 = $2 }
+    END { if (n > 1 && t1 - t0 >= 300) printf "%.1f", (p1 - p0) * 3600 / (t1 - t0) }' "$log"
+}
+
+# The plot window split into buckets: mean % of the bucket's samples (-1 when
+# it has none), the state of its last sample, and its start time as label.
+plot() {
+  awk -v now="$1" -v hours="$hist_hours" -v n="$buckets" '
+    BEGIN { w = hours * 3600 / n; t0 = now - hours * 3600 }
+    $1 >= t0 { b = int(($1 - t0) / w); if (b >= n) b = n - 1; sum[b] += $2; cnt[b]++; st[b] = $3 }
+    END {
+      printf "["
+      for (b = 0; b < n; b++) {
+        p = -1; s = "none"
+        if (cnt[b]) {
+          p = sprintf("%.1f", sum[b] / cnt[b])
+          s = st[b] == "c" ? "charging" : st[b] == "d" ? "discharging" : "idle"
+          if (st[b] == "d" && p < 25) s = "low"
+          if (st[b] == "d" && p <= 15) s = "critical"
+        }
+        printf "%s{\"t\":\"%s\",\"p\":%s,\"s\":\"%s\"}", (b ? "," : ""), strftime("%H:%M", t0 + b * w), p, s
+      }
+      printf "]"
+    }' "$log"
+}
+
 state() {
-  local cap status rate now full power time="" wattage state
+  local now cap status rate now_e full power pct st time="" wattage state
+  now=$(printf '%(%s)T' -1)
   cap=$(attr capacity)
   status=$(attr status)
   rate=$(attr power_now current_now) # µW or µA
-  now=$(attr energy_now charge_now)  # µWh or µAh — same unit as rate, so now/rate = hours
+  now_e=$(attr energy_now charge_now) # µWh or µAh — same unit as rate, so now_e/rate = hours
   full=$(attr energy_full charge_full)
   if [[ -r $bat/power_now ]]; then power=$rate; else power=$((rate * $(attr voltage_now) / 1000000)); fi
   wattage=$(awk -v p="$power" 'BEGIN { printf "%.1f W", p / 1000000 }')
+  pct=$(awk -v n="$now_e" -v f="$full" -v c="$cap" 'BEGIN { printf "%.1f", (f > 0 ? 100 * n / f : c) }')
   if ((rate > 0)); then
     case $status in
-      Discharging) time=$(hours_to_clock "$(awk -v n="$now" -v r="$rate" 'BEGIN { print n / r }')") ;;
-      Charging) time=$(hours_to_clock "$(awk -v n="$now" -v f="$full" -v r="$rate" 'BEGIN { print (f - n) / r }')") ;;
+      Discharging) time=$(hours_to_clock "$(awk -v n="$now_e" -v r="$rate" 'BEGIN { print n / r }')") ;;
+      Charging) time=$(hours_to_clock "$(awk -v n="$now_e" -v f="$full" -v r="$rate" 'BEGIN { print (f - n) / r }')") ;;
     esac
   fi
   case $status in
     Charging)
-      state=charging
+      state=charging st=c
       status="Charging${time:+, $time left}"
       ;;
     Discharging)
-      state=discharging
-      ((cap <= 20)) && state=low
+      state=discharging st=d
+      ((cap < 25)) && state=low
+      ((cap <= 15)) && state=critical
       status=${time:+$time left}
       ;;
     Full)
-      state=full
+      state=full st=i
       status="Fully charged"
       ;;
-    *) state=idle ;;
+    *) state=idle st=i ;;
   esac
-  printf '{"visible":true,"percentage":%s,"wattage":"%s","status":"%s","state":"%s"}' \
-    "$cap" "$wattage" "$(jstr "$status")" "$state"
+  log_sample "$now" "$pct" "$st"
+  printf '{"visible":true,"percentage":%s,"wattage":"%s","status":"%s","time":"%s","state":"%s","rate":"%s","history":%s}' \
+    "$cap" "$wattage" "$(jstr "$status")" "$time" "$state" "$(drain_rate "$now" "$st")" "$(plot "$now")"
 }
 
 refresh() { emit "$(state)"; }