# router-migrate-settings RELEASE FILE: bring a settings.json up to the
# schema of a release by running its migrations/N.jq in order.
{
  writeShellApplication,
  coreutils,
  jq,
}:
writeShellApplication {
  name = "router-migrate-settings";
  runtimeInputs = [
    coreutils
    jq
  ];
  text = ''
    [ $# -eq 2 ] || { echo "usage: router-migrate-settings RELEASE SETTINGS.json" >&2; exit 2; }
    release=$1 file=$2
    schema=$(cat "$release/schema")
    version=$(jq -r '.version // 0' "$file")
    if [ "$version" -gt "$schema" ]; then
      echo "the settings are at version $version, newer than this release ($schema)" >&2
      exit 1
    fi
    while [ "$version" -lt "$schema" ]; do
      next=$((version + 1))
      echo "migrating the settings to version $next"
      jq -f "$release/migrations/$next.jq" "$file" | jq --argjson v "$next" '.version = $v' > "$file.new"
      chmod 0600 "$file.new"
      mv "$file.new" "$file"
      version=$next
    done
  '';
}