# route.bible URL helpers (pure Bend)
import Base

def default_base() -> String:
  "https://route.bible"

type TsPh is Data:
  TsBody{}
  TsStep{is_slash: Bool, h: Char}

def trim_slashes_go(fuel: Nat, ph: TsPh, rest: String) -> String:
  match fuel:
    case 0n:
      String.reverse(rest)
    case 1n+p:
      match ph:
        case TsBody{}:
          match rest:
            case SNil{}:
              ""
            case SCon{+h, +t}:
              trim_slashes_go(p, TsStep{Char.is_eq(h, '/'), h}, t)
        case TsStep{is_slash, +h}:
          match is_slash:
            case True{}:
              trim_slashes_go(p, TsBody{}, rest)
            case False{}:
              String.reverse(SCon{h, rest})

def trim_trailing_slashes(+s: String) -> String:
  trim_slashes_go(
    Nat.add(String.length(s), 2n),
    TsBody{},
    String.reverse(s)
  )

def normalize_base_go(+base: String, empty: Bool) -> String:
  match empty:
    case True{}:
      default_base()
    case False{}:
      trim_trailing_slashes(base)

def normalize_base(+base: String) -> String:
  normalize_base_go(String.trim(base), String.is_empty(String.trim(base)))

def route_path(+canonical: String) -> String:
  String.append("/", String.to_lower(canonical))

def build_route_url_base(+base: String, +canonical: String) -> String:
  String.append(normalize_base(base), route_path(canonical))

def build_route_url(+canonical: String) -> String:
  build_route_url_base(default_base(), canonical)

def md_link(+visible: String, +url: String) -> String:
  String.append(
    String.append(String.append("[", visible), "]("),
    String.append(url, ")")
  )

def markdown_route_link(+visible: String, +canonical: String) -> String:
  md_link(visible, build_route_url(canonical))