#import "renderer.typ": render

#let _seq(
  p1,
  p2,
  comment: none,
  dashed: false,
  tip: "default",
  color: black
) = {
  return ((
    type: "seq",
    p1: p1,
    p2: p2,
    comment: comment,
    dashed: dashed,
    tip: tip,
    color: color,
  ),)
}

#let _par(name, display-name: auto, start-at: 0) = {
  return ((
    type: "par",
    name: name,
    display-name: if display-name == auto {name} else {display-name},
    start-at: start-at
  ),)
}

#let _par-exists(participants, name) = {
  for p in participants {
    if name == p.name {
      return true
    }
  }
  return false
}

#let diagram(elements) = {
  let participants = ()
  for elmt in elements {
    if elmt.type == "par" {
      participants.push(elmt)
    } else if elmt.type == "seq" {
      if not _par-exists(participants, elmt.p1) {
        participants.push(_par(elmt.p1).first())
      }
      if not _par-exists(participants, elmt.p2) {
        participants.push(_par(elmt.p2).first())
      }
    }
  }

  render(participants, elements)
}

#let from-plantuml(code) = {
  let code = code.text
}