[Unit]
Description=Infoscreen Simclient (MQTT communication)
Documentation=https://github.com/RobbStarkAustria/infoscreen_client_2025
# Simclient needs network before starting — MQTT will fail otherwise.
After=network-online.target
Wants=network-online.target
# Publish an MQTT alert if systemd gives up restarting (StartLimitBurst exceeded).
OnFailure=infoscreen-notify-failure@%n.service
# StartLimit* must live in [Unit] for compatibility with older systemd (< 230).
StartLimitIntervalSec=60
StartLimitBurst=5

[Service]
# notify: simclient sends READY=1 via sd_notify once fully initialised.
# WatchdogSec: if WATCHDOG=1 is not sent within this window, systemd kills
# and restarts the process — detects hung/deadlocked main loops.
Type=notify
WatchdogSec=60
User=olafn
Group=olafn
WorkingDirectory=/home/olafn/infoscreen-dev

# Load all client configuration from the local .env file.
# Keep .env mode 600; systemd reads it as root before dropping privileges.
EnvironmentFile=/home/olafn/infoscreen-dev/.env

# Start simclient
ExecStart=/home/olafn/infoscreen-dev/scripts/start-simclient.sh

# Restart on failure (non-zero exit or signal).
# This covers crash recovery AND the reboot-command lifecycle:
#   1. Server sends reboot_host command
#   2. Simclient publishes accepted + execution_started, then exits
#   3. Systemd restarts simclient within RestartSec seconds
#   4. On reconnect, heartbeat loop detects pending_recovery_command and
#      publishes completed — closing the lifecycle cleanly.
Restart=on-failure
RestartSec=10
StandardOutput=journal
StandardError=journal
SyslogIdentifier=infoscreen-simclient

# Security settings
NoNewPrivileges=true
PrivateTmp=true

# Resource limits
LimitNOFILE=65536

[Install]
# Simclient runs in multi-user mode — no graphical session required.
WantedBy=multi-user.target