#!/bin/sh
# ~/.local/bin/gnome-kiosk-script — the mirror kiosk application.
#
# Installed by docs/kiosk-silverblue/install-kiosk.sh; see that runbook.
#
# `gnome-kiosk-script-session` runs this file as the kiosk user inside the
# kiosk session, and this script re-execs itself forever (the upstream example
# does the same). That has two consequences worth designing around:
#
#   1. Never launch unconditionally. The loop comes back every few seconds, so
#      an unguarded launch opens a new window every few seconds.
#   2. Never exit. `org.gnome.Kiosk.Script.service` has
#      `OnSuccess=gnome-session-shutdown.target`, so leaving this script logs
#      the kiosk out and the screen goes back to the GDM greeter.
#
# So: poll, (re)launch only when firefox is gone, and keep the loop alive.

# Source the per-client config FIRST, then derive everything from it, so the
# payload file can stay byte-identical on every client and the kiosk.conf under
# ~/.config/mirror is the only thing that differs. Deriving before the source
# is a real trap: the script silently runs on the built-in default URL forever.
CONF="${MIRROR_KIOSK_CONF:-$HOME/.config/mirror/kiosk.conf}"
if [ -r "$CONF" ]; then
    # shellcheck source=/dev/null
    . "$CONF"
fi

URL="${MIRROR_KIOSK_URL:-https://mirror.reeseapps.com/kiosk}"
PROFILE="${MIRROR_KIOSK_PROFILE:-$HOME/.mirror-kiosk}"
LOG="${MIRROR_KIOSK_LOG:-${XDG_STATE_HOME:-$HOME/.local/state}/mirror-kiosk.log}"
POLL="${MIRROR_KIOSK_POLL:-5}"

log() {
    [ -n "$LOG" ] || return 0
    # Cap the log: this script runs forever on a machine nobody logs into.
    if [ -f "$LOG" ] && [ "$(stat -c %s "$LOG" 2>/dev/null || echo 0)" -gt 1048576 ]; then
        tail -c 65536 "$LOG" >"$LOG.tmp" 2>/dev/null && mv -f "$LOG.tmp" "$LOG" 2>/dev/null
    fi
    printf '%s %s\n' "$(date '+%Y-%m-%dT%H:%M:%S%z' 2>/dev/null || echo -)" "$*" >>"$LOG" 2>/dev/null || :
}

# Keep the screen on. This has to happen here, inside the session, and not at
# install time: gsettings only commits when it can reach a D-Bus session bus,
# so `sudo -u kiosk gsettings set ...` over SSH warns "Cannot autolaunch D-Bus
# without X11" and silently leaves the default. It also cannot go in
# /etc/dconf/db/local.d, because /usr/bin/gnome-kiosk sets
# DCONF_PROFILE=gnomekiosk and that profile is `user-db:user` plus the shipped
# compiled defaults — it never reads a system db.
#
# $XDG_RUNTIME_DIR is per-login, so this runs once per kiosk start and still
# re-applies if someone changes the setting by hand.
GSETTINGS_STAMP="${XDG_RUNTIME_DIR:-/tmp}/mirror-kiosk-gsettings.done"
if [ ! -f "$GSETTINGS_STAMP" ]; then
    gsettings set org.gnome.desktop.session idle-delay 0 >/dev/null 2>&1
    gsettings set org.gnome.desktop.screensaver lock-enabled false >/dev/null 2>&1
    gsettings set org.gnome.desktop.interface enable-animations false >/dev/null 2>&1
    log "applied idle/lock gsettings"
    : >"$GSETTINGS_STAMP" 2>/dev/null || :
fi

if pgrep -u "$(id -u)" -x firefox >/dev/null 2>&1; then
    # Up already. Nothing to do but check again in a moment.
    :
elif command -v curl >/dev/null 2>&1 && ! curl -fsSL -m 10 -o /dev/null "$URL" 2>/dev/null; then
    # Don't park a "server not found" page on a wall display: keep polling and
    # load the page the moment the mirror server answers again. This is what
    # covers a reboot where the network has not come up yet.
    log "target not reachable yet: $URL"
else
    mkdir -p "$PROFILE" 2>/dev/null
    log "launching: firefox --kiosk $URL"
    # --kiosk  : fullscreen, no chrome, no exit affordances
    # --profile: our own dir, so the kiosk never collides with another profile
    #            lock and never inherits anyone's history
    # `pgrep -x firefox` above can only be false here if a launch failed
    # outright, so a foreground run cannot wedge the loop.
    /usr/bin/firefox --kiosk --no-remote --profile "$PROFILE" "$URL" >>"$LOG" 2>&1
    rc=$?
    log "firefox exited rc=$rc"
fi

sleep "$POLL"
exec "$0" "$@"