#!/bin/sh
set -eu

: "${SUPERVISORD_BIN:=/usr/bin/supervisord}"
: "${SUPERVISOR_CONF_TEMPLATE:=/etc/supervisord.conf.template}"
: "${APP_BINARY_PATH:=/app/app}"
: "${RUNTIME_DIR:=/tmp/runtime}"
: "${SUPERVISOR_CONF:=/etc/supervisord.conf}"
: "${SUPERVISOR_PROGRAM_NAME:=app}"
: "${OPEN_FILE_LIMIT:=65535}"

export RUNTIME_DIR

shell_quote() {
  printf "'%s'" "$(printf '%s' "$1" | sed "s/'/'\"'\"'/g")"
}

escape_sed_replacement() {
  printf '%s' "$1" | sed 's/[\/&]/\\&/g'
}

write_supervisord_conf() {
  mkdir -p "$(dirname "$SUPERVISOR_CONF")"
  app_program_name=$(escape_sed_replacement "$SUPERVISOR_PROGRAM_NAME")

  sed \
    -e "s/__APP_PROGRAM__/$app_program_name/g" \
    "$SUPERVISOR_CONF_TEMPLATE" > "$SUPERVISOR_CONF"
}

write_run_app_script() {
  run_app_script="$RUNTIME_DIR/run-app.sh"

  {
    printf '#!/bin/sh\n'
    printf 'set -eu\n'
    printf 'exec "%s"' "$APP_BINARY_PATH"
    for arg in "$@"; do
      printf ' %s' "$(shell_quote "$arg")"
    done
    printf '\n'
  } > "$run_app_script"

  chmod +x "$run_app_script"
}

prepare_runtime_environment() {
  ulimit -n "$OPEN_FILE_LIMIT"
  mkdir -p "$RUNTIME_DIR"
  rm -f "$RUNTIME_DIR/supervisor.sock" "$RUNTIME_DIR/supervisord.pid"
}

validate_app_binary_or_exit() {
  if [ ! -x "$APP_BINARY_PATH" ]; then
    echo "错误: APP_BINARY_PATH 指向的文件不存在或不可执行: $APP_BINARY_PATH" >&2
    exit 1
  fi
}

start_supervisord() {
  exec "$SUPERVISORD_BIN" -c "$SUPERVISOR_CONF"
}

main() {
  prepare_runtime_environment
  validate_app_binary_or_exit
  write_supervisord_conf
  write_run_app_script "$@"
  start_supervisord
}

main "$@"