#!/bin/sh
#
# Cron wrapper for push-metrics.js: load the secrets, check the install, hand
# over to node. Every five minutes, forever, unattended.
#
# NEVER add `set -x`. This script is meant to be piped into `logger`, and the
# shell would echo the `. "$ENV_FILE"` expansion — the ingest token — straight
# into /var/log/syslog and journald, where it would stay. Same reason nothing
# below ever echoes a variable that holds a secret: the checks print the NAME of
# what is missing, never its value.
#
# Suggested crontab line (see README.md):
#   */5 * * * * $HOME/.local/share/maximus-host-agent/agent/run-push.sh 2>&1 | logger -t host-agent

set -eu

SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
AGENT="$SCRIPT_DIR/push-metrics.js"

# Overridable for testing only; cron uses the default.
ENV_FILE="${HOST_AGENT_ENV_FILE:-$HOME/.config/maximus-host-agent.env}"

if [ ! -f "$ENV_FILE" ]; then
  echo "host-agent: env file not found: $ENV_FILE" >&2
  exit 1
fi

# A warning, not a refusal: a wrong mode bit is worth shouting about, but it is
# not worth silencing the heartbeat of the whole workstation over.
FILE_MODE=$(stat -c "%a" "$ENV_FILE" 2>/dev/null || echo "")
if [ -n "$FILE_MODE" ] && [ "$FILE_MODE" != "600" ]; then
  echo "host-agent: warning: $ENV_FILE is mode $FILE_MODE, expected 600" >&2
fi

# shellcheck source=/dev/null
. "$ENV_FILE"

if [ -z "${HOSTS_API_URL:-}" ]; then
  echo "host-agent: HOSTS_API_URL is not set in $ENV_FILE" >&2
  exit 1
fi
if [ -z "${HOSTS_INGEST_TOKEN:-}" ]; then
  echo "host-agent: HOSTS_INGEST_TOKEN is not set in $ENV_FILE" >&2
  exit 1
fi
if [ -z "${HOST_ID:-}" ]; then
  echo "host-agent: HOST_ID is not set in $ENV_FILE" >&2
  exit 1
fi

if [ ! -f "$AGENT" ]; then
  echo "host-agent: agent not found: $AGENT" >&2
  exit 1
fi

# cron's PATH is famously short (/usr/bin:/bin), and a node installed through
# nvm or /usr/local lives outside it. Set NODE_BIN in the env file when
# `command -v node` comes up empty under cron but works in a login shell.
NODE_BIN="${NODE_BIN:-node}"
if ! command -v "$NODE_BIN" >/dev/null 2>&1; then
  echo "host-agent: node not found (NODE_BIN=$NODE_BIN); set NODE_BIN in $ENV_FILE" >&2
  exit 1
fi

export HOSTS_API_URL HOSTS_INGEST_TOKEN HOST_ID

exec "$NODE_BIN" "$AGENT" "$@"