(** URL paths, in both directions.

    One {!t} value describes a page, and the same value both generates a link
    ({!path_of}) and is recovered from an incoming request ({!dispatch}). For
    every route [r], [dispatch] inverts [path_of]:
    [dispatch (path_of r without its leading slash) = Some r]. Keeping the two
    directions in one module is what stops generated links and served routes
    from drifting apart.

    Only path-shaped routes live here. Query parameters — the commit list's
    filters and page number — are not modelled, because they refine a page
    rather than identify one.

    The segments [summary], [commits], [commit], [files], [file], and [raw] are
    reserved: they mark where a repository path ends, so a repository or
    directory carrying one of these names is not reachable. *)

(** {1 Routes} *)

type t =
  | Root
  | Project_dir of string
  | Repo of string
  | Commits of string
  | Commits_branch of string * string
  | Commit of string * string
  | Files of string
  | File of string * string
  | File_at of string * string
  | Raw_file of string * string
  | Raw_at of string * string
      (** A page in the application. The string arguments carry the repository
          name and either an object identifier ({!File}, {!Raw_file}) or a
          slash-separated file path from the repository root ({!File_at},
          {!Raw_at}).

          Path arguments are percent-encoded by {!path_of} and decoded by
          {!dispatch}, so file names survive the round trip unaltered. A
          single-segment path that is itself 40 hexadecimal characters is
          indistinguishable from an object id and dispatches as one. *)

val path_of : t -> string
(** Generate the URL path for a route. *)

(** {1 Dispatch} *)

val dispatch : string -> t option
(** Parse a request path (without leading slash) back into a route. Returns
    [None] when the path matches no known route, including a recognised route
    followed by extra segments.

    A path without a reserved segment comes back as {!Project_dir} even when it
    names a repository: only the filesystem can tell the two apart, so the
    handler resolves which page to serve. *)