#!/usr/bin/env nix-shell
#!nix-shell -i bash -p nix-update

usage() {
  echo "update: update rev/hash for one or more packages"
  echo "usage: update [options] [attr-path]"
  echo ""
  echo "options:"
  echo "- --dry-run"
  echo "- --verbose"
  echo ""
  echo "examples:"
  echo "- update nixpkgs: update only the nixpkgs input"
  echo "- update sane: update every package under the 'sane' attribute"
  echo "- update: update everything i know how to update"
  exit 1
}

warn() {
  echo "$@"
}
info() {
  echo "$@"
}
debug() {
  if [ -n "$verbose" ]; then
    echo "$@"
  fi
}

hasEffect() {
  if [ -n "$dryRun" ]; then
    echo "dry-run: skip $@"
  else
    eval "$@"
  fi
}

# usage: getPkgs outVar prefix
getPkgs() {
  local -n attrsArr="$1"
  local attrPrefix="$2"
  if [ -z "$attrPrefix" ]; then
    attrPrefix=sane
  fi

  local attrs="$(nix-env -f . --query --available --attr-path --no-name -A $attrPrefix)"
  attrsArr+=($attrs)
}

updateOnePkg() {
  local attrPath="$1"

  if [[ "$attrPath" =~ ^"$ignore" ]]; then
    warn "ignoring $attrPath"
    return
  fi

  local updateScript="$(nix eval --raw -f . $attrPath.passthru.updateScript --apply 'builtins.concatStringsSep "'" "'"')"
  if [ -z "$updateScript" ]; then
    warn "don't know how to update '$attrPath'"
    return
  fi

  # make sure everything needed to invoke the script actually exists on disk
  nix-build -A "$attrPath.passthru.updateScript" || true

  local UPDATE_NIX_NAME="$(nix eval --raw -f . $attrPath.name)"
  local UPDATE_NIX_PNAME="$(nix eval --raw -f . $attrPath.pname)"
  local UPDATE_NIX_OLD_VERSION="$(nix eval --raw -f . $attrPath.version)"
  info "updating: '$attrPath'"
  debug "$updateScript"
  # we lose spaces inside the exec args... could `nix eval` without `--raw` to fix that.
  UPDATE_NIX_NAME="$UPDATE_NIX_NAME" UPDATE_NIX_PNAME="$UPDATE_NIX_PNAME" UPDATE_NIX_OLD_VERSION="$UPDATE_NIX_OLD_VERSION" UPDATE_NIX_ATTR_PATH="$attrPath" eval $updateScript
}

dryRun=
ignore=
toplevelsToUpdate=()
verbose=
parseArgs() {
  while [ "$#" -ne 0 ]; do
    local arg=$1
    shift
    case "$arg" in
      (--help)
        usage
        ;;
      (--dry-run)
        dryRun=1
        ;;
      (--verbose)
        verbose=1
        ;;
      (*)
        toplevelsToUpdate+=("$arg")
        ;;
    esac
  done
  if [ "${#toplevelsToUpdate[@]}" -eq 0 ]; then
    ignore=sane.feeds
    toplevelsToUpdate=(sane)
  fi
}

parseArgs "$@"
pkgsToUpdate=()
for t in "${toplevelsToUpdate[@]}"; do
  getPkgs pkgsToUpdate "$t"
done

for p in "${pkgsToUpdate[@]}"; do
  hasEffect updateOnePkg "$p"
done