define pacman::hook (
  Enum['present', 'absent'] $ensure = 'present',
  Integer $priority = 50,
  Optional[String] $description = undef,
  Enum['PreTransation', 'PostTransaction'] $when,
  String $exec,
  Optional[Variant[String, Array[String, 1]]] $depends = undef,
  Boolean $abortOnFail = false, # only for PreTransation
  Boolean $needsTargets = false,
  Variant[Pacman::Trigger, Array[Pacman::Trigger, 1]] $trigger,
) {

  require ::pacman

  if ($abortOnFail and $when != 'PreTransation') {
    fail('abortOnFail only valid when "when" => "PreTransation"')
  }

  # Normalize triggers to list
  $triggers = ($trigger ? {
    Array => $trigger,
    default  => [$trigger],
  }).map |$trigger| {
    # Normalize contents of each trigger, making
    {
      type      => $trigger['type'],
      operation => $trigger['operation'] ? {
        Array   => $trigger['operation'],
        default => [$trigger['operation']],
      },
      target => $trigger['target'] ? {
        Array   => $trigger['target'],
        default => [$trigger['target']],
      }
    }
  }

  $triggers.each |$trigger| {
    if $trigger['type'] == 'Path' {
      $trigger['target'].each |$target| {
        if $target[0] == '/' {
          fail("Target paths shouldn't start with '/' ${target} in trigger ${name}")
        }
      }
    }
  }

  $str = epp('pacman/hook.epp', {
    description => $description,
    depends => $depends ? {
      Optional => [],
      Array    => $depends,
      default  => [$depends],
    },
    triggers => $triggers,
    exec         => $exec,
    when         => $when,
    abortOnFail  => $abortOnFail,
    needsTargets => $needsTargets,
  })

  $chksum = $str.md5()

  file { $chksum:
    ensure         => $ensure,
    content        => $str,
    path           => "${pacman::hooks_path}/${priority}-${name}.hook",
    checksum       => 'md5',
    checksum_value => $chksum,
  }
}