#!/usr/bin/env bash

#
# Copyright (C) 2022, Maxim Lihachev, <envrm@yandex.ru>
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# this program. If not, see <https://www.gnu.org/licenses/>.
#
# terraform-mermaid can be used to convert `terraform graph` command output
# from Graphviz to Mermaid format.

# TODO: -s simple

set -e
set -o errtrace

\unalias -a

IFS=$' \t\n'

show_help() {
	echo -e "$(basename "$0") can be used to convert \`terraform graph' command output from Graphviz to Mermaid format.\n"
	echo -e "USAGE: $(basename "$0") ?-m? ?-d DIRECTION??\n"

	echo -e "Command line arguments:"
	echo -e "    -h --help       Show this help"
	echo -e "    -m --markdown   Put the output in triple back quotes (\`\`\`)"
	echo -e "    -d --direction  Specify the direction of the graph (TB | BT | LR | RL; TB by default)"

	echo
	exit "${1:-0}"
}

UNKNOWN_ARGS=()

while [[ $# -gt 0 ]]; do
	key="$1"

	case $key in
		-h|--help)      show_help;;
		-d|--direction) DIRECTION="$2"; shift; shift;;
		-m|--markdown)  MARKDOWN="true"; shift;;
		*)            UNKNOWN_ARGS+=("$1");  shift;;
	esac
done

[ ${#UNKNOWN_ARGS} -gt 0 ] && echo "Unknown parameters: ${UNKNOWN_ARGS[*]}" >&2 && show_help 1

declare -a MERMAID

[ -n "$MARKDOWN" ] && MERMAID+=('```mermaid')

MERMAID+=("graph ${DIRECTION:-TB}")

GRAPH=$(terraform graph)

mapfile -t MERMAID_GRAPH < <(
	echo "$GRAPH" \
		| grep -v 'meta\.count' \
		| grep -- '->' \
		| sed -E 's/"//g;
			s/^[[:space:]]*|\\]|\[root\] | \((expand|close)\)//g;
			s!provider.*/!provider:!g;
			s/helm_release/helm/g;
			s/null_resource\.//g;
			s/kubernetes/k8s/g;
			s/ -> / --> /g;
			s/^(.*) --> (.*)$/\2 --> \1/;
			s/(provider:[[:alnum:]_]*)/\1((\1))/;
			s/((var|local).[[:alnum:]_]*)/\1{{\1}}/;
			s/(helm\.[[:alnum:]_]*)/\1{{\1}}/;
			s/(local_file\.[[:alnum:]_]*)/\1>\1]/;
			s/default/defaulṭ/;
			s/class/clasṣ/g;
			/^provider:[[:alnum:]_]*/d;' \
		| sed 's/^/    /'
)

MERMAID=("${MERMAID[@]}" "${MERMAID_GRAPH[@]}")

[ -n "$MARKDOWN" ] && MERMAID+=('```')

printf "%s\n" "${MERMAID[@]}"