///|
fn xml_text(value : String) -> String {
  let safe = String::from_array(
    value.to_array().filter(c => c >= ' ' || c == '\n' || c == '\t'),
  )
  safe
  .replace_all(old="&", new="&")
  .replace_all(old="<", new="<")
  .replace_all(old=">", new=">")
  .replace_all(old="\"", new=""")
  .replace_all(old="'", new="'")
}

///|
fn svg_rect(x : Int32, y : Int32, width : Int32, fill : String) -> String {
  ""
}

///|
fn svg_text(
  x : Int32,
  y : Int32,
  label : String,
  color : String,
  size : Int32,
) -> String {
  "" +
  xml_text(label) +
  ""
}

///|
fn svg_edge(x1 : Int32, y1 : Int32, x2 : Int32, y2 : Int32) -> String {
  let middle = (x1 + x2) / 2
  ""
}

///|
/// Deterministic topic/document overview. Detailed headings remain in HTML/Markdown exports.
pub fn export_svg(atlas : Atlas, title : String) -> String {
  let topics : Map[String, Array[Page]] = Map([])
  for page in atlas.pages {
    if !topics.contains(page.topic) {
      topics[page.topic] = []
    }
    topics[page.topic].push(page)
  }
  let names = topics.keys().to_array()
  names.sort()
  let height = 160 + atlas.pages.length() * 68 + names.length() * 24
  let root_y = height / 2 + 25
  let parts = [
    "")
  parts.join("\n")
}