locals {
  oncall_nodata = "${var.message_nodata == "" ? var.message_alert : var.message_nodata}"
}

data "template_file" "alerting-message" {
  template = <<EOF
$${prepend_text}
{{#is_alert}}$${message_alert}{{/is_alert}}
{{#is_recovery}}$${message_alert}{{/is_recovery}}
{{#is_warning}}$${message_warning}{{/is_warning}}
{{#is_warning_recovery}}$${message_warning}{{/is_warning_recovery}}
{{#is_no_data}}$${message_nodata}{{/is_no_data}}
{{#is_no_data_recovery}}$${message_nodata}{{/is_no_data_recovery}}
$${append_text}
EOF

  vars {
    message_alert   = "${var.message_alert}"
    message_warning = "${var.message_warning}"
    message_nodata  = "${local.oncall_nodata}"
    prepend_text    = "${var.prepend_text}"
    append_text     = "${var.append_text}"
  }
}