calcurse: sync with Google Calendar via calcurse-caldav

Hourly timer started from xmonad, plus UI hooks that sync before load and after exit. calcurse-sync notifies once when the OAuth login expires and restarts the daemon after imports, since it never re-reads its files.

.local/bin/calcurse-sync

@@ -0,0 +1,52 @@
+#!/bin/bash
+# Sync calcurse with Google Calendar via calcurse-caldav; notify once when the weekly OAuth login expires.
+# --now: called from the UI's pre-load hook (skip the UI check, shorter timeout, no daemon restart).
+set -uo pipefail
+
+data=${XDG_DATA_HOME:-$HOME/.local/share}/calcurse
+state=${XDG_STATE_HOME:-$HOME/.local/state}/calcurse-sync
+expired_flag=$state/login-expired
+now=false
+[[ ${1:-} == --now ]] && now=true
+
+# The UI keeps the data in memory, so syncing under it would lose changes; its post-save hook syncs after it exits.
+ui_running() {
+    # shellcheck disable=SC2009 # pgrep can't match "has any terminal"
+    ps -C calcurse -o tty= | grep -qv '?'
+}
+
+if ! $now && ui_running; then
+    echo "calcurse UI is running, skipping"
+    exit 0
+fi
+
+mkdir -p "$state"
+# BROWSER=true: an expired login must not open browser tabs on its own.
+out=$(BROWSER=true timeout "$($now && echo 15 || echo 60)" calcurse-caldav 2>&1)
+rc=$?
+printf '%s\n' "$out"
+
+if ((rc != 0)); then
+    if grep -q 'Access token is missing or refresh token is expired' <<<"$out"; then
+        if [[ ! -e $expired_flag ]]; then
+            notify-send -a calcurse -u critical -i x-office-calendar "Google Calendar login expired" \
+                "Run calcurse-caldav in a terminal, allow access in the browser, then calcurse-caldav --authcode '<code>'."
+            touch "$expired_flag"
+        fi
+    elif grep -q 'Another synchronization instance' <<<"$out"; then
+        exit 0
+    fi
+    exit "$rc"
+fi
+rm -f "$expired_flag"
+
+# A running daemon never re-reads the data files: restart it so imported appointments get alerts.
+if ! $now && ! grep -q '^0 items imported, 0 items removed locally' <<<"$out"; then
+    pidfile=$data/.daemon.pid
+    if [[ -s $pidfile ]] && pid=$(<"$pidfile") && kill "$pid" 2>/dev/null; then
+        timeout 5 tail --pid="$pid" -f /dev/null
+        # Own scope, so the daemon outlives this oneshot service.
+        systemd-run --user --scope -q calcurse --daemon
+        echo "restarted calcurse daemon"
+    fi
+fi