#!/usr/bin/env bash

# The script assumes that basic authentication is configured
# (change the login credentials with `LOGIN`).
#
# DASHBOARD_DIRECTORY represents the path to the directory
# where the JSON files corresponding to the dashboards exist.
# The default location is relative to the execution of the
# script.
#
# URL specifies the URL of the Grafana instance.
#
# Source: https://github.com/cirocosta/sample-grafana/blob/master/update-dashboards.sh

set -o errexit

readonly URL=${URL:-"http://localhost:3000"}
readonly LOGIN=${LOGIN:-"admin:admin"}
readonly DASHBOARDS_DIRECTORY=${DASHBOARDS_DIRECTORY:-"./grafana/dashboards"}

main() {
	local task=$1

	echo "
URL:                  $URL
LOGIN:                $LOGIN
DASHBOARDS_DIRECTORY: $DASHBOARDS_DIRECTORY
  "

	case $task in
	backup) backup ;;
	restore) restore ;;
	*) exit 1 ;;
	esac

}

backup() {
	local dashboard_json

	for dashboard in $(list_dashboards); do
		dashboard_json=$(get_dashboard "$dashboard")

		if [[ -z $dashboard_json ]]; then
			echo "ERROR:
  Couldn't retrieve dashboard $dashboard.
      "
			exit 1
		fi

		echo "$dashboard_json" >"$DASHBOARDS_DIRECTORY/$dashboard".json

		echo "BACKED UP $(basename "$dashboard").json"
	done
}

restore() {
	find "$DASHBOARDS_DIRECTORY" -type f -name \*.json -print0 |
		while IFS= read -r -d '' dashboard_path; do
			folder_id=$(get_folder_id "$(jq -r '.uid' <"$dashboard_path")")
			curl \
				--silent --fail --show-error --output /dev/null \
				--user "$LOGIN" \
				-X POST -H "Content-Type: application/json" \
				-d "{\"dashboard\":$(cat "$dashboard_path"), \
					\"overwrite\":true, \
					\"folderId\":$folder_id}" \
				"$URL/api/dashboards/db"

			echo "RESTORED $(basename "$dashboard_path")"
		done
}

get_dashboard() {
	local dashboard=$1

	if [[ -z $dashboard ]]; then
		echo "ERROR:
  A dashboard must be specified.
  "
		exit 1
	fi

	curl \
		--silent \
		--user "$LOGIN" \
		"$URL/api/dashboards/db/$dashboard" |
		jq '.dashboard | .id = null'
}

get_folder_id() {
	local dashboard=$1

	if [[ -z $dashboard ]]; then
		echo "ERROR:
  A dashboard must be specified.
  "
		exit 1
	fi

	curl \
		--silent \
		--user "$LOGIN" \
		"$URL/api/dashboards/uid/$dashboard" |
		jq '.meta | .folderId'
}

list_dashboards() {
	curl \
		--silent \
		--user "$LOGIN" \
		"$URL/api/search" |
		jq -r '.[] | select(.type == "dash-db") | .uri' |
		cut -d '/' -f2
}

main "$@"