#!/usr/bin/env bash
# Sync every configured calendar from its .ics feed, once, and wait for it.
#
# Runs a batch Emacs rather than talking to the daemon, for the same reason
# agenda-render-cache does: the org files this writes feed the agenda, waybar
# and the projected wallpaper, and none of those should go stale because the
# editor happens to be down. Nothing here touches a running Emacs, so it is
# safe to fire from a timer alongside an active session.
#
# Why a script at all: calendar-sync used to start its hourly timer from
# `org-agenda-mode-hook', so a session where the agenda was never opened never
# synced at all. That is not a rare corner -- it is every reboot until the
# first agenda call. The timer owns the schedule now, and the editor's own
# auto-start is off.
#
# The exit code is the point. `calendar-sync-batch-run-and-report' waits for
# every calendar to leave the syncing state and returns non-zero if any did
# not land, so a failed fetch shows up in `systemctl --user status' instead of
# being swallowed.
#
# Usage: calendar-sync-run
# Env:   EMACS_D                -- config directory (default ~/.emacs.d)
#        EMACS                  -- emacs binary (default emacs)
#        CALENDAR_SYNC_CONFIG   -- private config file holding the calendar
#                                  list, instead of the configured default.
#        CALENDAR_SYNC_STATE    -- sync-state file, instead of the configured
#                                  default. Lets a test run without writing
#                                  the real session's persisted state.
#        CALENDAR_SYNC_TIMEOUT  -- seconds to wait for all calendars to settle.

set -euo pipefail

EMACS_D="${EMACS_D:-$HOME/.emacs.d}"
EMACS="${EMACS:-emacs}"

if [ ! -d "$EMACS_D/modules" ]; then
	echo "calendar-sync-run: no modules directory at $EMACS_D/modules" >&2
	exit 1
fi

# The overrides are set before the module loads on purpose: the private config
# is read at load time, and `defvar'/`defcustom' both leave an already-bound
# value alone. This is the same seam the in-editor conversion worker uses.
pre=""
if [ -n "${CALENDAR_SYNC_CONFIG:-}" ]; then
	pre="$pre (setq calendar-sync-private-config-file \"$CALENDAR_SYNC_CONFIG\")"
fi
if [ -n "${CALENDAR_SYNC_STATE:-}" ]; then
	pre="$pre (setq calendar-sync--state-file \"$CALENDAR_SYNC_STATE\")"
fi
if [ -n "${CALENDAR_SYNC_TIMEOUT:-}" ]; then
	pre="$pre (setq calendar-sync-batch-timeout $CALENDAR_SYNC_TIMEOUT)"
fi

# -Q keeps the daemon's init out of it: this needs the calendar-sync modules,
# not a full editor. load-prefer-newer stops a stale .elc from answering for
# changed source, which would silently sync with yesterday's logic.
exec "$EMACS" --batch -Q \
	--eval "(progn (setq load-prefer-newer t)$pre)" \
	-L "$EMACS_D/modules" \
	--eval '(progn
                  (require (quote calendar-sync))
                  (kill-emacs (calendar-sync-batch-run-and-report)))'