#!/bin/sh
set -eu

PERSIST_ROOT="${PERSIST_ROOT:-/data}"
APP_DATA_DIR="${PERSIST_ROOT}/app-data"
PERSIST_CONFIG="${PERSIST_ROOT}/config.json"
DEFAULT_CONFIG="/app/config.default.json"

mkdir -p "$APP_DATA_DIR"

if [ ! -f "$PERSIST_CONFIG" ]; then
  if [ -f "$DEFAULT_CONFIG" ]; then
    cp "$DEFAULT_CONFIG" "$PERSIST_CONFIG"
  else
    printf '{}\n' > "$PERSIST_CONFIG"
  fi
fi

link_path() {
  target="$1"
  link="$2"

  if [ -L "$link" ]; then
    current="$(readlink "$link" || true)"
    if [ "$current" = "$target" ]; then
      return
    fi
    rm "$link"
  elif [ -e "$link" ]; then
    backup="${link}.image-default"
    if [ ! -e "$backup" ]; then
      mv "$link" "$backup"
    else
      rm -rf "$link"
    fi
  fi

  ln -s "$target" "$link"
}

link_path "$APP_DATA_DIR" /app/data
link_path "$PERSIST_CONFIG" /app/config.json

exec "$@"