#!/usr/bin/env bash
# SPDX-License-Identifier: Apache-2.0
#
# Renders the systemd unit templates deploy/systemd/*.service.in (ADR 0024).
#
# Usage: scripts/render-units.sh <bindir> <outdir>
#   writes <outdir>/<BIN_SERVER>.service, <BIN_AGENT_DNS>.service and
#   <BIN_AGENT_DHCP>.service with @BINDIR@ = <bindir>.
#
# Names come from the environment (set by the Makefile, ADR 0018): PRODUCT,
# DISPLAY_NAME, BIN_SERVER, BIN_AGENT_DNS, BIN_AGENT_DHCP, ENV_PREFIX.

set -euo pipefail

if [[ $# -ne 2 ]]; then
  sed -n '4,11p' "$0" | sed 's/^# \{0,1\}//' >&2
  exit 2
fi
bindir="$1"
outdir="$2"

PRODUCT="${PRODUCT:-ddi-suite}"
DISPLAY_NAME="${DISPLAY_NAME:-DDI-Suite}"
BIN_SERVER="${BIN_SERVER:-ddi-server}"
BIN_AGENT_DNS="${BIN_AGENT_DNS:-ddi-agent-dns}"
BIN_AGENT_DHCP="${BIN_AGENT_DHCP:-ddi-agent-dhcp}"
ENV_PREFIX="${ENV_PREFIX:-DDI_}"

# Values end up in sed replacements: allow only safe characters.
for v in "$bindir" "$PRODUCT" "$BIN_SERVER" "$BIN_AGENT_DNS" "$BIN_AGENT_DHCP" "$ENV_PREFIX"; do
  [[ "$v" =~ ^[A-Za-z0-9._/+-]+$ ]] || { echo "unsafe value: $v" >&2; exit 2; }
done
[[ "$DISPLAY_NAME" =~ ^[A-Za-z0-9\ ._+-]+$ ]] || { echo "unsafe display name: $DISPLAY_NAME" >&2; exit 2; }

src="$(cd "$(dirname "$0")/../deploy/systemd" && pwd)"
mkdir -p "$outdir"
render() {
  sed -e "s|@PRODUCT@|$PRODUCT|g" -e "s|@DISPLAY_NAME@|$DISPLAY_NAME|g" \
    -e "s|@BIN_SERVER@|$BIN_SERVER|g" -e "s|@BIN_AGENT_DNS@|$BIN_AGENT_DNS|g" \
    -e "s|@BIN_AGENT_DHCP@|$BIN_AGENT_DHCP|g" -e "s|@BINDIR@|$bindir|g" \
    -e "s|@CONFIG_DIR@|/etc/$PRODUCT|g" -e "s|@ENV_PREFIX@|$ENV_PREFIX|g" \
    "$src/$1" >"$outdir/$2"
  if grep -q '@[A-Z_]*@' "$outdir/$2"; then
    echo "unreplaced placeholder in $2" >&2
    exit 1
  fi
}
render server.service.in "$BIN_SERVER.service"
render agent-dns.service.in "$BIN_AGENT_DNS.service"
render agent-dhcp.service.in "$BIN_AGENT_DHCP.service"