to-signal-from-traccar/notify_signal_about_traccar_events.sh

#!/bin/bash
# shellcheck disable=SC2059

declare message_geofence_enter message_geofence_exit message_device_online message_device_unknown message_device_offline message_event_other signal_sender_phone_number signal_recipients_array signal_api_endpoint_full_path allow_unique_device_ids_posix_ere device_name event_type battery_level message

payload="${1}"

function load_config() {
    local this_script_call_cmd this_script_resolved_abs_path conf_file_resolved_abs_path conf_file_resolved_file_name
    this_script_call_cmd="${BASH_SOURCE[0]}"
    this_script_resolved_abs_path="$(readlink -f "${this_script_call_cmd}")"
    conf_file_resolved_abs_path="${this_script_resolved_abs_path}"'.conf'
    conf_file_resolved_file_name="$(basename "${conf_file_resolved_abs_path}")"
    if [[ -r "${conf_file_resolved_abs_path}" ]]; then
        # shellcheck source="${conf_file_resolved_abs_path}"
        source "${conf_file_resolved_abs_path}"
    fi
    # Optional, will use default values if not given by user
    : "${allow_list_events:='^(deviceOnline|deviceUnknown|geofenceEnter|geofenceExit)$'}"
    : "${message_event_type_not_allowed:='Event "%s" not allowed. Nothing to do.\n'}"
    : "${message_geofence_enter:='%s entered geofence %s.'}"
    : "${message_geofence_exit:='%s left geofence %s.'}"
    : "${message_device_online:='On %s Traccar Client app is now active.'}"
    : "${message_device_unknown:='On %s Traccar Client app has not checked in for 10 minutes, the app is likely off now.'}"
    : "${message_device_unhandled:='For %s we do not want to send a message to Signal. Nothing to do.\n'}"
    : "${message_event_other:='%s triggered event "%s" in Traccar server.'}"
    : "${allow_unique_device_ids_posix_ere:=''}"

    # Mandatory, user must specify
    : "${signal_sender_phone_number:?'Please specify the signal-cli-rest-api phone number of your sender Signal account. Place a file named '"'${conf_file_resolved_file_name}'"' next to this script (same dir) and define a variable signal_sender_phone_number='"'"'value'"'"' in it.'}"
    : "${signal_recipients_array:?'Please specify recipients like so: ["group.ImxvbmdpdH=","recipient.21","+18005550111","i-am-a-uuid"]. Place a file named '"'${conf_file_resolved_file_name}'"' next to this script (same dir) and define a variable signal_recipients_array='"'"'value'"'"' in it.'}"
    : "${signal_api_endpoint_full_path:?'Please specify the signal-cli-rest-api full URL for sending a message like so: https://fully.qualified.domain.name/v2/send. Place a file named '"'${conf_file_resolved_file_name}'"' next to this script (same dir) and define a variable signal_api_endpoint_full_path='"'"'value'"'"' in it.'}"
}

function get_event_data() {
    local device_unique_id
    device_unique_id="$(<<<"${payload}" jq --raw-output '.device.uniqueId')"

    device_name="$(<<<"${payload}" jq --raw-output '.device.name')"
    event_type="$(<<<"${payload}" jq --raw-output '.event.type')"

    # Discard event and stop any further action unless event is allow-listed
    if ! [[ "${event_type}" =~ ${allow_list_events} ]]; then
        printf -- "${message_event_type_not_allowed}" "${device_name}"
        exit 0
    fi

    if [[ "${event_type}" = 'geofenceEnter' || "${event_type}" = 'geofenceExit' ]]; then
        battery_level="$(<<<"${payload}" jq --raw-output '.position.attributes.batteryLevel')"
        battery_level="$(echo "${battery_level}"' / 1' | bc)"
    fi

    if ! [[ "${device_unique_id}" =~ ${allow_unique_device_ids_posix_ere} ]]; then
        printf -- "${message_device_unhandled}" "${device_name}"
        exit 0
    fi
}

function craft_message() {
    local geofence_name
    case "${event_type}" in
        'geofenceEnter')
            geofence_name="$(<<<"${payload}" jq --raw-output '.geofence.name')"
            message="${message_geofence_enter}"
            message="$(printf -- "${message}" "${device_name}" "${geofence_name}" "${battery_level}")"
            ;;
        'geofenceExit')
            geofence_name="$(<<<"${payload}" jq --raw-output '.geofence.name')"
            message="${message_geofence_exit}"
            message="$(printf -- "${message}" "${device_name}" "${geofence_name}" "${battery_level}")"
            ;;
        'deviceOnline')
            message="${message_device_online}"
            message="$(printf -- "${message}" "${device_name}")"
            ;;
        'deviceUnknown')
            message="${message_device_unknown}"
            message="$(printf -- "${message}" "${device_name}")"
            ;;
        *)
            message="${message_event_other}"
            message="$(printf -- "${message}" "${device_name}" "${event_type}")"
            ;;
    esac
}

function send_to_signal() {
    local signal_message
    signal_message="${1}"
    curl \
        --silent \
        --request 'POST' \
        --header 'Content-Type: application/json' \
        --data '{"message":"'"${signal_message}"'","number":"'"${signal_sender_phone_number}"'","recipients":'"${signal_recipients_array}"'}' \
        "${signal_api_endpoint_full_path}"
}

load_config
get_event_data
craft_message
send_to_signal "${message}"